Module 1: Characteristics of Living
Organism
Introduction
All living organisms share several key characteristics or functions: in
order, sensitivity or response to the environment, reproduction,
adaptation, growth and development, regulation, homeostasis,
and energy processing.
ORDER
Organisms are highly organized, coordinated structures that consist
of one or more cells. Even every simple, single-celled organisms are
remarkably complex: inside each cell, atoms make up molecules;
these in turn make up cell organelles and other cellular inclusions. In
multi-cellular organisms, similar cells form tissues.
Tissues, in turn, collaborate to create organs (body structures with a
distinct function).
Organs work together to form organ systems.
This increasing complexity of structures shows the levels of
organization in an organism.
SENSITIVITY OR RESPONSE TO STIMULI
Organisms respond to diverse stimuli. For example, plants can grow
toward a source of light, climb on fences and walls; or respond to
touch. Even tiny bacteria can move toward or away from chemicals (a
process called chemotaxis) or light (phototaxis). Movement
toward a
stimulus
is
considered
a positive
response,
while movement away from a stimulus is considered a negative
response.
REPRODUCTION
Single-celled organisms reproduce by first duplicating their DNA, and
then dividing it equally as the cell prepares to divide to form two new
cells. Multicellular organisms often produce specialized reproductive
germline cells that will form new individuals. When reproduction
occurs, genes containing DNA are passed along to an organism's
offspring. These genes ensure that the offspring will belong to the
same species and will have similar characteristics, such as size and
shape.
GROWTH AND DEVELOPMENT
Organisms grow and develop following specific instructions
coded for by their genes. These genes provide instructions that will
direct cellular growth and development, ensuring that a species'
young will grow up to exhibit many of the same characteristics as its
parents.
REGULATION
Even the smallest organisms are complex and require multiple
regulatory mechanisms to coordinate internal functions, respond to
stimuli, and cope with environment stresses. Two examples of internal
functions regulated in an organism are nutrient transport and blood
flow. Organs (groups of tissues working together) perform specific
functions, such as carrying oxygen throughout the body, removing
wastes, delivering nutrients to every cell, and cooling the body.
HOMEOSTASIS
In order to function properly, cells need to have appropriate conditions
such as proper temperature, pH, and appropriate concentration of
diverse chemicals. These conditions may, however, change from one
moment to the next. Organisms are able to maintain internal
conditions within a narrow range almost constantly, despite
environmental changes, through homeostasis (literally, "steady
state") - the ability of an organism to maintain constant internal
conditions. For example, an organism needs to regulate body
temperature through a process known as thermoregulation.
Organisms that live in cold climates, such as the polar bear, have body
structures that help them withstand low temperatures and conserve
body heat. Structures that aid in this type of insulation include fur,
feathers, blubber, and fat. Polar Bears (Ursus maritimus) and other
mammals living in ice-covered regions maintain their body
temperature by generating heat and reducing heat loss through thick
fur and a dense layer of fat under their skin.
chemical energy in food; others use chemical energy in molecules
they take in as food.
LEVELS OF ORGANIZATION OF LIVING THINGS
Living things are highly organized and structured, following a
hierarchy that can be examined on a scale from small to large.
atom
is the smallest and most fundament unit if matter. It consists of a
nucleus surrounded by electrons. Atoms form molecules.
molecule
is a chemical structure consisting of at least two atoms held together
by one or more chemical bonds. Many molecules that are biologically
important are macromolecules, large molecules that are typically
formed by polymerization (a polymer is a large molecule that is
made by combining smaller units called monomers, which are
simpler than macromolecules). An example of a macromolecule
is deoxyribonucleic acid (DNA), which contains the instructions for
the structure and functioning of all living organisms.
organelles
Cells contain aggregates of macromolecules surrounded by
membranes; Examples of organelles include mitochondria and
chloroplasts, which carry out indispensable functions: mitochondria
produce energy to power the cell, while chloroplast enable green
plants to utilize the energy in sunlight to make sugars.
cells
All living things are made of cells; the cell itself is the smallest
fundamental unit of structure and function in living organisms. (This
requirement is why viruses are not considered living: they are not
made of cells. To make new viruses, they have to invade and hijack
the reproductive mechanisms of a living cell; only then they can obtain
the materials they need to reproduce.)
Cells are classified as prokaryotic or eukaryotic.
tissues
In larger organisms, cells combine to make tissues, which are groups
of similar cells carrying out similar or related functions.
organs
are collections of tissues grouped together performing a common
function. Organs are present not only in animals but also in plants.
organ system
is a higher level of organization that consists of functionally related
organs. Mammals have many organ systems. For instance, the
circulatory system transports blood through the body and to and from
the lungs; it includes organs such as heart and blood vessels.
organisms
are individual living entities. For example, each tree in a forest is an
organism. Single-celled prokaryotes and single-celled eukaryotes are
also considered organisms and are typically referred to as
microorganisms.
population
All the individuals of a species living within a specific area may
collectively. For example, a forest may include pine trees. All of those
pine trees represent the population of pine trees in this
forest. Different populations may live in the same specific area. For
example, the forest with the pine trees includes populations of
flowering plants and also insects and microbial populations.
community
is the sum of populations inhabiting a particular area. For instance, all
of the trees, flowers, insects, and other populations in a forest form
the forest's community.
ecosystem
The forest itself is an ecosystem. Consists of all the living things in a
particular area together with the abiotic, non-living parts of that
environment such as nitrogen in the soil or rain water.
biosphere
At the highest level of organization, is the collection of all ecosystems,
and it represents the zones of life on earth. It includes land, water, and
even
the
atmosphere
to
a
certain
extent.
In hot climates, organisms have methods (such as perspiration in
humans or panting in dogs) that help them to shed excess body
heat.
ENERGY PROCESSING
All organisms use a source of energy for their metabolic activities.
Some organisms capture energy from the sun and convert it into
General Biology 2
Reviewer by Glyzce Sabado
Module 2: Plant Form and Function
Introduction
There are more than 350 thousand species of known plants and more
is to be discovered and named in the next years. Their fascinating
morphology and their ability to regulate and maintain homeostasis is
studied by botanists.
Plant Classification
A. BASED ON THEIR WATER REQUIREMENT
1. Mesophytes
•
Plants that requires moderate amount of water.
•
terrestrial plants which are neither adapted to particularly
dry nor particularly wet environments.
•
An example of a mesophytic habitat would be a rural
temperate meadow, which might contain goldenrod, clover,
oxeye daisy, and Rosa multiflora.
2. Xerophytes
•
Plants that can survive in extremely dry places like in
dessert regions.
•
species of plant that has adaptations to survive in an
environment with little liquid water, such as a desert or an
ice- or snow-covered region in the Alps or the Arctic.
•
Popular examples of xerophytes are cacti, pineapple and
some Gymnosperm plants.
3. Hydrophytes
•
Plants that can survive in moist places.
•
plants that have adapted to living in aquatic environments.
They are also referred to as hydrophytes or macrophytes to
distinguish them from algae and other microphytes.
•
grows in or near water and is either emergent, submergent,
or floating.
4. Halophytes
•
Plants that can survive in aquatic environments with high
salt content.
•
salt-tolerant plant that grows in soil or waters of high salinity,
coming into contact with saline water through its roots or by
salt spray, such as in saline semi-deserts, mangrove
swamps, marshes and sloughs and seashores.
•
The word derives from Ancient Greek ἅλας 'salt' and φυτόν
'plant'.
B. BASED ON THE ECOSYSTEMS THEY INHABIT
1. Aquatic plant
•
plants that have adapted to living in aquatic environments.
•
also referred to as hydrophytes or macrophytes to
distinguish them from algae and other microphytes.
•
A macrophyte is a plant that grows in or near water and is
either emergent, submergent, or floating.
2. Terrestrial plant
•
A terrestrial plant is a plant that grows on, in, or from land.
•
Terrestrial (land-dwelling) Invasive Plants include nonnative plants (members of the kingdom Plantae) that grow
in non-aquatic habitats, including agricultural fields,
rangelands, forests, urban landscapes, wildlands, and
along waterways.
3. Aerial plant
•
plants that do not have underground root systems; instead,
they are located in areas above the ground.
•
Plants that live above the ground and attach themselves to
other plant species.
C. BASED ON LIFESPAN
1. Annual Plant
•
Plants that complete its life cycle, from germination to the
production of seeds, within one growing season, and then
dies.
•
They live only in about a year.
2. Biennial Plant
•
Plant that lives for about 2 years.
•
flowering plant that takes two years to complete its
biological life cycle. In the first year, the plant undergoes
primary growth, in which its leaves, stems, and roots
develop.
•
•
A perennial plant or simply perennial is a plant that lives
more than two years. The term is often used to differentiate
a plant from shorter-lived annuals and biennials. The term
is also widely used to distinguish plants with little or no
woody growth from trees and shrubs, which are also
technically perennials.
•
Usually, the stem of the plant remains short and the leaves
are low to the ground, forming a rosette.
D. BASED ON GROSS MORPHOLOGY
1. Tress
•
Plants that have a single woody stem and grow about 20 ft.
•
a woody perennial plant, typically having a single stem or
trunk growing to a considerable height and bearing lateral
branches at some distance from the ground.
2. Shrubs
A shrub or bush is generally viewed as a woody plant that presents
several perennial stems and does not eclipse 13 feet in height, with
stems that are not greater than three inches in diameter.
3. Herbs
•
plants with fragrant or aromatic properties.
•
can be used to flavor food, included in fragrances, and even
a part of natural medicines.
•
Basil, parsley, rosemary, thyme, and note that for each of
these, the herb is the green or leafy part of some kind of
plant.
4. Vines
•
plant whose stems require support either climbs up a tree
or other structure, or it sprawls over the ground.
•
can climb with tendrils or with other “grasping” appendages,
or by coiling their stems.
4. Lianas
(also known as vines, climbing plants or climbers) are plants with
long, flexible, climbing stems that are rooted in the ground, and usually
have long dangling branches.
E. MORPHOLOGICAL STRUCTURE OF PLANTS
1. Roots
•
Absorbs water and dissolved inorganic nutrients
•
Store nutrients especially carbohydrates
•
Serves as the plant’s anchor and help prevent soil erosion
Types of root system
a. Taproot
consists of one main root which becomes bigger and wider in
diameter. Main root develops several secondary roots which many
rootlets arise.
b. Fibrous root
•
consists of many roots that are about the same size with
small lateral roots.
•
Originates from the base of the embryonic root.
External Parts of a Root
1. Root cap
•
Consists of a layer of parenchyma cells that covers the
external apical meristems.
•
Easily sloughs off due to direct contact to the soil particles
and is replaced by new cells formed by the apical
meristems.
2. Mesenteric or embryonic region
•
Where mitosis takes place.
•
Replaces damaged tissues.
3. Region of cell elongation or cell enlargement
Where cell increase in size particularly in length.
4. Region of maturation or cell differentiation
Where cells perform their specific roles.
2. Stem
•
Plant structure which grows above the ground that
supports the leaves and branches.
•
Serve in vegetative reproduction
•
Supports the leaves and small branches.
•
Provides support in conducting water and dissolved
minerals.
•
Grows buds and produces new tissues.
3. Perennial Plant
Plants that can live for many years.
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Reviewer by Glyzce Sabado
STEM MORPHOLOGY
1. Nodes
portion of or points on the stem where leaves and flower buds grow.
2. Internodes
intervening structures between two successive nodes.
3. Lenticels
tiny pores for gas exchange.
4. Buds
underdeveloped parts of the stem which eventually become leaves,
flowers, or shoots.
3. Leaves
Plants used their leaves to carry out photosynthesis – a process
through which plants manufacture their food. The leaves consist of an
epidermal layer cells which secrete a waxy substance. This substance
protects the leaves from insect pests and bacteria and from drying up.
The upper and lower epidermal layers are made up of pairs of guard
cells that look like bean-shaped structures. Each cells forms a pore
on an opening which is also known as stoma (plural stomata). This
opening helps facilitates gas exchange. Along a leaf surface are veins
that are filled with vessels for transportation of water and nutrients.
LEAF ANATOMY
a. Epidermis
outermost covering which protects underlying tissues against
diseases and helps prevent water loss.
b. Mesophyll
middle part of a leaf where photosynthesis takes place.
2 layers:
Palisade layer which is made up of elongated parenchymatous cells
which carry out metabolic functions and have the ability to differentiate
for tissue repair.
Spongy layer irregularly shaped parenchymatous cells that contains
fewer chloroplasts.
c. Vascular bundle
group of tissue in transporting and conducting foods and minerals.
FOUR STAGES OF EMBRYOGENESIS
1. The union of egg and sperm nuclei form a proembryo. A series of
transverse cell divisions happen before the development of apical and
basal cells. The basal cell divides and later on forms the suspensor.
In dicot plants, the suspensor usually consists of a column of multiple
cells. It pushes the proembryo into the embryo sac cavity to absorb
food nutrients and deliver them to proembryo.
2. During the globular stage, many cells of the embryo divide rapidly,
which later on form into meristem cells. When the meristem become
differentiated, formation of an embryo axis appears.
3. Organ differentiation if followed by the formation of
multiple cotyledon primordia which become thicker in the cotyledon
stage and globular stage.
4. In the globular stage, which is the heart stage of the embryo,
the endosperm develops. The embryo becomes mature. The
cotyledon of the seed embryo gives rise to the roots and stems of
plants. The root originates from hypocotyl while the stem originates
from the epicotyl of the seed embryo.
Water is an essential requirement for plants survival. Water
uptake allows plants to metabolically utilize the chemical compounds
and micronutrients obtained from the surrounding soil. The presence
of root hairs in some plants increases the surface for water absorption.
Root nodules also occur in some plants wherein nitrogen fixing
bacteria establish a symbiosis with the plant to convert nitrogen gas
to ammonia.
Plant growth, from seed germination to maturity, involves a
combination of cellular responses and molecular interaction.
Response of plant cell varies depending on the amount of water
present in its surrounding.
In days with hot temperatures, plants lose water through the
leaves. its its effort to reduce water loss, the guard cells closes the
stomatal pore.
Tonicity
Refers to the strength of a solution in relation in relation to osmosis.
When comparing two different solutions, such as that of a solution
inside the cell (cytoplasm) and that outside the cell, the terms isotonic,
hypotonic, and hypertonic solutions are used. Note that these terms
are used only in relation to a pair of solutions.
1. Isotonic Solution
•
contains equal concentration of impermeable solutes on either
side of the membrane and so the cell neither swells nor shrinks.
•
Under isotonic solution there is no net movement of water
molecules in and out of the cell, thus the shape of the cell
remains unchanged.
•
Ex. Plain Normal Saline Solution (0.9% NaCl), Lactated Ringers
Solution (Plain LRS)
2. Hypotonic Solution
When plant cells are placed in hypotonic solution, water molecules
enter the vacuoles, causing it to expand, pushing the cytoplasm
toward the cell wall. The pressure exerted by the water molecules is
referred to as turgor pressure and the phenomenon is called turgidity.
The turgor pressure in plant cells will not result in cell lysis as the cell
wall enclosing the cell does not give away. Turgidity in plant cells is
extremely important I maintaining the firm and erect position of the
plant, especially the herbaceous and non-woody plants. During hot
sunny days, evaporation rate of water in the plant cells is fast, and the
plants lose their turgidity. This causes them to wilt. Fortunately,
watering the plant reverses this condition as it brings back turgor in
the wilted plants.
3. Hypertonic Solution
In plant cells, the removal of water molecules causes the cell
membrane to be pulled away from the cell wall and the cytosol shrinks,
while cell wall remains intact. Such condition in plant cells is called
plasmolysis.
Plasmolysis
process in which cells lose water in a hypertonic solution.
Deplasmolysis or cytolysis
occurs if the cell is in a hypotonic solution resulting in a lower external
osmotic pressure and a net flow of water into the cell.
Osmosis
•
Special type of diffusion involving movement of water molecules
from a point of higher concentration to a point of lower
concentration through a semipermeable membrane.
•
Regular process that happens in all living cells.
Osmotic pressure
The force that moves water molecules through a semi permeable
membrane.
TRANSPORT SYSTEM IN PLANTS
Xylem Vessel
•
the complex tissue of plants, responsible for transporting water
and other nutrients to the plants.
•
found in all vascular plants, including the seedless club
mosses, ferns, horsetails, as well as all angiosperms (flowering
plants) and gymnosperms (plants with seeds unenclosed in an
ovary).
•
conveys water and dissolved minerals from the roots to the rest
of the plant and also provides physical support. Xylem tissue
consists of a variety of specialized, water-conducting cells
known as tracheary elements.
•
composed of dead lignified cells connected end to end. This
allows the transport of water and minerals in the upward
direction.
•
The xylem grows at a different rate, depending on the
abundance of water. With enough water, they grow to be
thicker, with scant water, they don't grow as much. This cycles
through the year, as the season go by.
Phloem
•
responsible for transporting food and other organic materials.
•
living tissue in vascular plants that transports the soluble
organic compounds made during photosynthesis and known
as photosynthates, in particular the sugar sucrose, to parts of
the plant where needed.
•
composed of sieve or filter tubes, which are closely associated
with companion cells to facilitate movement of materials
across the cell cytoplasm.
Both these conducting tubes run across the plant structure, however;
the arrangement of vascular bundle varies depending on whether it is
the stem, leaf, or root or if the plant is classified as monocot or dicot.
General Biology 2
Reviewer by Glyzce Sabado
Monocotyledons
commonly referred to as monocots, are grass and grass-like
flowering plants, the seeds of which typically contain only one
embryonic leaf, or cotyledon.
Dicotyledons
•
also known as dicots, are one of the two groups into which all
the flowering plants or angiosperms were formerly divided.
•
seed has two embryonic leaves or cotyledons.
Bundles
arrangement of vascular tissues for monocots
Rings
arrangement of vascular tissue for dicot, resulting into “annual rings”,
which can be a basis for the age of tress.
Annual Rings
result from the difference of growth rate of the plant cells between the
seasons with abundant water and scares water.
PLANT NUTRITION
1. Macronutrients
•
essential for plant growth and a good overall state of the
plant.
•
primary macronutrients are Nitrogen (N), Phosphorus (P),
and Potassium (K). Nitrogen is essential for plant
development, since it plays a fundamental role in energy
metabolism and protein synthesis.
2. Micronutrients
•
may be found in small amounts in the soil but they play a
huge role in plant growth and development.
•
most micronutrients in the soil are involved in critical
enzymatic reactions such as photosynthesis and
respiration.
•
constitutes in total less than 1% of the dry weight of most
plants.
7 essential plant nutrient elements defined as micronutrients:
•
boron (B)
•
zinc (Zn)
•
manganese (Mn)
•
iron (Fe)
•
copper (Cu)
•
molybdenum (Mo)
•
chlorine (Cl)
3. Hydrophonics
growing plants in an aqueous solution wherein nutrients, pH and
temperature are controlled.
4. Aerophonics
a plant-cultivation technique in which the roots hang suspended in the
air while nutrient solution is delivered to them in the form of a fine mist.
17 Essential Elements and their Functions in Plants
Carbon, Hydrogen, Oxygen
•
assimilation of oxidation-relation reactions.
•
Major constituent of organic plant material.
Boron
Cell wall synthesis, enzymatic reactions and metabolic pathways;
mitotic activity for root development.
Calcium
Structural component of the cell membrane, counter-ion in the
vacuole.
Chlorine
Water splitting system for photosystem II; stomatal opening
regulation.
Copper
Co-factor for metaloprotiens and enzymes; photosynthetic electron
transport; cell wall metabolism and hormone signaling; oxidative
stress response.
Iron
Regulatory component of proteins and metabolites in roots and
leaves.
Magnesium
Chlorophyll synthesis; cofactor in activation of ATPase (an enzyme
that hydrolyzes ATP).
Manganese
Photodestruction of chlorophyll and chloroplast structure, enzyme
activator; precursor of amino acid, hormones (auxins) and lignins
(important in the formation of cell walls, especially in wood and bark,
because they lend rigidity and do not rot easily).
Molybdenum
Enzyme activation (e.g. nitrate reductase, catalase, and
ribonuclease); chlorophyll synthesis.
Nickel
Endosperm development and dehydrogenase activity, urease
activation for urea breakdown, root nodule growth.
Nitrogen
General plant growth of roots, stem, leaf, flowers and fruits,
chlorophyll synthesis.
Phosphorus
Energy transferring process for photosynthesis and respiration (ADPATP synthesis); structural component of phospholipids, nucleic acids,
coenzymes, and nucleotides.
Potassium
Cell extension and stomatal regulation, enzyme activation (kinase,
starch synthase and nitrate reductase); photosynthetic activity (e.g.
CO2 fixation and pH regulation).
Sulfur
Assimilation of oxidation-reduction reactions; participates in various
enzymatic processes.
Zinc
Enzymatic function and reactivity; stem elongation, protein and starch
synthesis.
PLANT HORMONES
Plant hormones also play an important role in plant defense
against pathogenic microorganisms. Not only do these plant
hormones perform such function, but they also regulate the
development and signal networks in plants.
Plants also use other means of barrier, such as physical and
chemical, for protection against entrance of pathogenic substances.
as soon as a pathogen is recognized by the plant system, an inducible
defense cascade occurs which involves oxidative burst, expression of
defense related genes, formation of compounds with antimicrobial
properties, and programmed cell death. A zigzag model represents
the plant immune system in which the microbial-associated
molecular patterns (MAMP) by the pattern recognition of host cell
results to MAMP-triggered immunity. The activation of this response
increases the response increases the plant's survival against
diseases.
1. Auxin
•
growth hormone, promotes floral and fruit development.
•
Promotes tissue germination.
2. Gibberellins (GA)
Regulates plant height, promotes fruit set and seed germination.
3. Ethylene
Induces flowering, hastens fruit ripening, and causes fruit and leaf
abscission (the natural detachment of parts of a plant, typically dead
leaves and ripe fruit).
4. Abscisic Acid
a plant hormone which promotes leaf detachment, induces seed and
bud dormancy, and inhibits germination.
5. Cytokinin
regulates plant cell division and chloroplast maturation.
REPRODUCTION AND MODERN BIOTECHNICAL APPLICATION
1. Sexual Reproduction in Plants
•
involves the fusion of gametes (organism's reproductive
cells).
•
Chromosomes and the genes they carry, which come from
the two parent plants, play an important role in the growth
and development of a new plant.
a. Reproduction in Flowering Plants (Angiosperm)
During pollination, pollen grains are transferred from anther to the
stigma. Once pollen grain lands on the stigma, pollen grain elongates
forming a pollen tube that extends to reach the ovary. Pollen tube
discharges the sperm cell that fertilizes the egg within the ovary. When
fertilization occurs, the petals and the sepals wither, the ovary wall
becomes bigger and thicker until it develops into a fruit, the seedcontaining structure of the plant. The seed is a fertilized ovule. The
haploid cells of the seed embryo sac disappear forming an outer
covering called testa or seed coat. The endosperm cells undergo a
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Reviewer by Glyzce Sabado
series of duplication to provide food to the growing embryo. The seed
has a small scar (hilum) along the testa. The hilum consists of a small
pore that allows water to pass through during seed germination.
Pollination
•
act of transferring pollen grains from the male anther of a flower
to the female stigma.
•
Carried out by pollinators such as bees, wind, water, and man.
Flower
The reproductive organ of angiosperm or flowering plants
Pistil
•
female part of a flower
•
Produces reproductive egg cells in the ovary.
Stamen
•
Male reproductive part
•
Produces pollen grains through the anther.
Anther
The part of a stamen that produces and contains pollen and is usually
borne on a stalk.
Pollen Grain
•
carry male reproductive cells (gametes) in a plant and are
haploid microgametophytes.
•
main function is in the transferring of the male gametes to their
female counterparts (ovules – female reproductive cells) in the
embryo sac. It thereby facilitates sexual reproduction to occur in
the plant.
b. Reproduction in Non-Flowering Plants (Gymnosperm)
Reproduction in non-flowering plants or the gymnosperms can
be illustrated through the life cycle of pines, which belongs to
connifers, the largest group of gymnosperms. Reproduction starts
when a zygote or a fertilized egg forms and develops into an embryo.
The embryo and the tissues that surround it form a seed. Upon
maturity, the seed cone opens, and the seeds which have wing-like
structures, disperse from the parent plant.
c. Reproduction in Seedless Vascular Plants
Ferns have a special structure called sporangia which are located
in clusters on the underside of the sporophylls (leaves). Tiny spores
are produced in the sporangia. When the sporangia mature they break
open to release spores which eventually will be carried and dispersed
by winds. The spores will grow in a suitable environment and will
develop into a gametophyte (tiny green plant). When the gametophyte
matures it produces male and female gametes.
d. Reproduction in Nonvascular Plants
Bryophytes, the nonvascular plants, such as mosses,
liverworths, and hornworths grow from spores. These plants may
undergo sexual reproduction through fusion of gametes (sperm and
egg cells) to form zygote. The zygote develops into a mature
sporophyte generation consisting of a spore-bearing capsule
(sporangium). The sporophyte elongates and divides to become a foot
(which absorbs water and food from the parent gametophyte) that will
reach the gametophyte and hook its embryonic sporophyte to the
gametophyte. The embryonic sporophyte is covered with a calyptra to
protect the underlying tissues. The calyptra develops from the wall of
the archegonium which is responsible for gametophyte generation.
Calyptra (plural calyptrae)
an enlarged archegonial venter that protects the capsule containing
the embryonic sporophyte. The calyptra is usually lost before the
spores are released from the capsule. The shape of the calyptra can
be used for identification purposes.
Archegonium
•
serves as the site of fertilization. After the egg is fertilized, the
egg will remain in the archegonium until it develops into a
sporophyte.
•
S releases the sporophyte once it has fully developed.
Sporophyte
the spore-producing form of the plant.
2. Asexual Reproduction in Plants
•
Involves different methods of producing offspring from a parent
plant, all of which do not involve gametes or sex cells.
•
Organisms reproduce without fertilization of gametes. Does not
require two parents.
•
Parts of plants detach from the parent plants, grow, and mature
as new organisms.
a. Natural Vegetative Reproduction
methods of asexual reproduction that include strategies that plants
have developed to self-propagate. ... When these are detached from
the plant, they grow into independent plants; or, they may start
growing into independent plants if the leaf touches the soil. Some
plants can be propagated through cuttings alone.
Involves the use of non-reproductive plant parts, such as leaves and
modified stems (e.g., tuber, rhizome, stolon, and corm).
1. Leaves
Plantlets or new plants grow along the margin of the leaves for
instance kataka-taka plant (Bryophyllum specie). These new plants
detach from the parent plants and eventually mature as new
individuals.
2. Bulbs
Consist of many thin layers of modified leaves having a miniature
sprout in the center.
Ex. Onions, tulips and garlic
3. Tubers
•
Are swollen and bulky parts of an underground stem.
•
Consist of very short stems with a swollen apical structure and
bear a number of nodes or eyes.
•
With wildly varying characteristics, and flavors ranging from
earthy to sweet, roots and tubers are arguably the most
nutritious, economical, and versatile foods.
•
Ex. potatoes, yams.
4. Rhizomes
•
Root-like stems that bear adventitious roots that grow
horizontally under the ground. The lateral buds grow out to
develop new rhizome.
•
simply fleshy underground stems. They grow underground or
right at ground level with many growing points or eyes similar to
potatoes.
•
Ex. canna lilies, bearded Iris, ginger
5. Stolons or Runners
•
Horizontal stems that grow above the grow that may also
develop adventitious roots just like bulbs and rhizomes.
•
New tiny plantlets develop when the roots reach the surface of
the soil.
•
Ex. Strawberry
6. Corm
•
Fleshy underground swollen stem that is similar to a bulb in
terms of its shape and can also store food.
•
Usually they have a papery outer skin.
•
Ex. gladiolus and crocus.
b. Artificial Vegetative Reproduction
Methods
1. Stem Cutting
•
Common method of asexual reproduction in which a small piece
of a woody stem is cut off from a mother plant.
•
Ex. Gumamela, Santan, San Francisco
2. Grafting and Budding
•
Methods of combining the scion, the stem of a plant, and the
rootstock, or the roots of another plant.
•
Generally used by horticulturist to reproduce fruit trees.
3. Tissue Culture and Micropropagation
Refers to the propagation of tiny fragments of plants through plant
hormone treatment in a sterile growth medium.
General Biology 2
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Module 3 - Animal Form and Function
Introduction
The organs that make up the systems of higher vertebrates and the
simple organ-like structures used by invertebrates enable these
organisms to maintain homeostasis. It follows a feedback loop that
communicates with other organs to allow for a coordinated function.
Lesson 1. Animal Reproduction
A. Asexual
type of reproduction that does not involve the fusion of gametes or
change in the number of chromosomes. The offspring that arise by
asexual reproduction from either unicellular or multicellular organisms
inherit the full set of genes of their single parent.
1. Budding
Involves forming a new individual from an outgrowth on the parent’s
body.
form of asexual reproduction that results from the outgrowth of a
part of the body leading to a separation of the “bud” from the original
organism and the formation of two individuals, one smaller than the
other.
occurs commonly in some invertebrate animals such as hydras and
corals.
2. Fragmentation
also known as splitting, is a form of asexual reproduction in which
an organism splits into fragments. Each fragment develops into a
mature clone genetically and morphologically identical to its parent.
3. Regeneration
type of asexual reproduction in which the organism is capable of
re-growing certain body parts.
occurs via mitosis. Since the egg is haploid, it produces organisms
which are also haploid. In some cases, the organism can regain its
diploid number of chromosomes.
The growing back of the loss part of the body of an organ
It is usually used as a method of defense.
4. Parthenogenesis
Development that involves an activated unfertilized egg that
undergoes mitosis in the absence of cytokinesis (division of
cytoplasm).
form of reproduction in which an egg can develop into an embryo
without being fertilized by a sperm.
derived from the Greek words for “virgin birth,” and several insect
species including aphids, bees, and ants are known to reproduce by
parthenogenesis.
B. Sexual
type of reproduction that involves a complex life cycle in which a
gamete with a single set of chromosomes combines with another to
produce an organism composed of cells with two sets of
chromosomes.
Human Reproduction
form of sexual reproduction resulting in human fertilization. It
typically involves sexual intercourse between a man and a woman.
These are specialized reproductive cells called gametes, created in a
process called meiosis.
In the reproductive process, a male sperm and a female egg provide
the information required to produce another human being. Conception
occurs when these cells join as the egg is fertilized. Pregnancy begins
once the fertilized egg implants in the uterus.
Fertilization: A Sperm and an Egg Form a Zygote
When a sperm cell penetrates and fertilizes an egg, that genetic
information combines. The 23 chromosomes from the sperm pair with
23 chromosomes in the egg, forming a 46-chromosome cell called a
zygote. The zygote starts to divide and multiply.
Four stages of fertilization
1. sperm preparation
2. sperm-egg recognition and binding
3. sperm-egg fusion
4. fusion of sperm and egg pronuclei and activation of the zygote
Fertilization Process
involves a sperm fusing with an ovum. The sperm plasma then
fuses with the egg's plasma membrane, triggering the sperm head to
disconnect from its flagellum as the egg travels down the Fallopian
tube to reach the uterus.
Anisogamy (also called heterogamy)
form of sexual reproduction that involves the union or fusion of two
gametes, which differ in size and/or form. ... The form of anisogamy
that occurs in animals, including humans, is oogamy.
Oogamy
Occurs when large, non-motile egg (ovum) is fertilized by a small,
motile sperm (spermatozoon).
Isogamy
form of sexual reproduction that involves gametes of similar
morphology (generally similar in shape and size), found in most
unicellular organisms. Because both gametes look alike, they
generally cannot be classified as male or female.
Ex. fungi, algae, mammals
Hermaphrodites
a person or animal having both male and female sex organs or
other sexual characteristics, either abnormally or (in the case of some
organisms) as the natural condition.
Protogyny
Process that occurs in organisms that are born female and at some
point, of their life span change sex to males.
Protandry
maturing as a male and changing sex to female during the life
history.
Ex. fish families like clownfish
Lesson 2. Growth and Development
A. Types of Development
1. Indirect Development
animal's birth form is very different from the adult form. The embryo
hatches from the egg in a larval form. The larva undergoes a drastic
metamorphosis in order to achieve its adult stage. Animals that
undergo indirect development lay numerous eggs.
2. Direct Development
a young is directly born as a small version of an adult and it
develops into a mature individual without undergoing metamorphosis.
Ex. mammals
Eutherian mammals
Mammals having placenta. Placenta serves as a pathway for
nutrient exchange to supply the needs of a developing embryo. At
birth, young eutherians are essentially dependent on milk for quite
some time.
Metamorphosis
striking change of form or structure in an individual after hatching
or birth.
B. Embryonic Development
The process by which an offspring increases in size and complexity
from fertilized egg to a complex organism.
Four Stages of Development
1. Cleavage: Cell Division Begins
The early rapid series of mitotic divisions of a fertilized egg
resulting in a hollow sphere of cells known as the blastula.
Cleavage starts when the zygote undergoes rapid cell division
resulting in cells called Blastomeres. The cells of the blastomeres
decrease in size but the size of the embryo remains the same. Thus,
the embryo becomes cluster of cells in which tissues and organs will
be derived.
2. Gastrulation: Three Layers Form and Migrate
The movement of cells in the embryo that generates three cell
layers, the ectoderm, mesoderm, and endoderm, each layer in turn
giving rise to specific body organs and tissues.
Early embryo has three main body layers that give rise to all organs
and tissues of the developing, enlarging individual. The process that
converts the blastula into three-layered embryo is gastrulation, “the
formation of the stomach”. The three layers become arranged as a
tube within a tube within a tube. The stomach and digestive tube lie
inside; a tube of blood vessels, muscles, bones, kidneys, and other
organs come to surround the digestive tube: an outer tube, the skin,
covers both of the others. Cell movements in the hollow blastula give
rise to these three nested tubes.
These cell movements of gastrulation are a living sculptural
process. The result is three primary tissue layers.
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a. Endoderm
inner layer (inner skin) will produce the digestive tract and
parts of the liver and lungs.
b. Mesoderm
middle layer (“middle skin) will form the blood vessels, kidneys,
and reproductive organs, as well as the body’s muscles and most of
the bones.
c. Ectoderm
outer layer (outer skin) will become the outer parts of the skin
and the nervous system.
3. Organogenesis: Organs Unfold
The formation of organs during embryonic development.
As gastrulation ends, the three embryonic layers are composed to
generate the next phase of development, organogenesis, or the
formation of the body’s organs and tissues with proper shapes,
positions, and functions. This stage last several weeks and bring into
existence all the embryo’s systems for moving, digesting, exchanging
air, expelling wastes, protecting itself from disease, and so on.
Refinements and maturation of these organs and systems will
continue throughout development, well into youth and adolescence. A
cell-to-cell communication process (induction) helps determine
where organs like the spinal cord and brain will form. A set of cellsculpturing process (morphogenesis) brings about the proper shape
of the organs once positioned. This, for example, allows the human
brain to take on its hallmark contours. It also causes the somites,
segmentally repeating blocks of mesoderm, to become your
vertebrae. Pattern formation helps shape a whole region of the
embryo, so several parts – such as the features of the face and
regions of the brain – are in proper relationship to each other. And the
cells of the organs take on their specialized functions through the
differentiation process so that, for example, cells in the eye detect light
and cells in the stomach wall secrete acid and not vice versa.
In the human embryo, the neural tube first closes in the mid trunk and
then zips up toward the front and down toward the back. This process
will not complete until about 29 days after fertilization in a human
embryo. If the human neural tube does not completely close at the
back end (posterior) of the embryo, spinal bones (vertebrae) do not
grow to encircle the unclosed portion of the tube, and the spinal cord
can squeeze out of the gap. The result is spina bifida, or open spine,
the most common severe major birth defect among live-born infants,
affecting one in every 2,000 live births.
4. Growth: The Organism Enlarges to Adult Size
Along with the emergence of embryonic organs comes growth or
expansion in size. The cleavage that divides a fertilized egg into a ball
of cells is only the beginning of cell division in the embryo. A major
size increase is needed, and cell division – usually rapid – continues
until hatching or birth and then throughout the development of the
young organism.
C. Human Development
➢ In ovulation, the ovary releases an egg cell into the fallopian
tube.
➢ At fertilization, egg and sperm fuse.
➢ During day 1, the egg divides into two cells.
➢ By day 4, the embryo is a solid ball of cell, the morula.
➢ On day 5, the blastocyst, a hollow ball of cells, hatches from the
protein and carbohydrate coat that surrounded the egg.
➢ By day 7, the implantation is under way.
➢ On day 9, the embryo consists of two cell layers, and the chorion
has begun to form.
➢ On day 16, gastrulation is occurring, producing 3 cell layers:
ectoderm, which forms skin and nervous system, mesoderm,
which becomes muscle, blood and bone; and endoderm, which
forms the lungs and digestive tract.
➢ On day 21, neural tube is forming
➢ Day 25, the yolk sac will become incorporated into the umbilical
cord.
➢ On day 36, the embryo is vaguely fishlike, with eyes, gill-like
arches, a large heart, paddle-shaped limbs and a tail.
➢ By day 48, fingers start to form.
➢ By day 52, almost two months, the embryo begins to look like a
person.
D. Developmental Stages in a Human Embryo in Months
1. The First Three Months
▪
4th week heart begins to pump
▪
5th week brain looks like lumpy inchworm
▪
8th weeks most organs are present
▪
Primary sex organ develops
2. The Second Three Months
▪
12th week mother feels her uterus enlarged
▪
16th weeks face looks human
▪
20-24th weeks downy hair covers the body
▪
Fetal heart sound can be detected using the stethoscope
▪
Fetus respond to mother’s voice
▪
Lungs are formed but not yet functioning
▪
Grip reflex begins
3. The Third Three Months
▪
fetus’s eyelids open
▪
eyebrows and eyelashes form
▪
can detect light
▪
brain grows rapidly
▪
cerebral cortex fills 80% of the skull
Lesson 3. Nutrition
A. Essential Elements and Physiology
1. Calcium
•
Component of bone and teeth, involved in blood clotting,
muscle and nerve function.
•
mineral that is necessary for life. In addition to building bones
and keeping them healthy, calcium enables our blood to clot,
our muscles to contract, and our heart to beat.
•
About 99% of the calcium in our bodies is in our bones and
teeth.
2. Chlorine
•
Formation of hydrochloride in stomach, acid-base balance,
and nerve function.
•
It helps keep the amount of fluid inside and outside of your
cells in balance.
•
It also helps maintain proper blood volume, blood pressure,
and pH of your body fluids.
3. Copper
•
Component of enzymes involved in the synthesis of melanin,
hemoglobin, and iron metabolism.
•
works with iron to help the body form red blood cells. It also
helps keep the blood vessels, nerves, immune system, and
bones healthy.
•
also aids in iron absorption.
4. Fluorine
•
Maintenance of bone and teeth.
•
essential for the maintenance and solidification of our
bones and prevents dental decay.
•
However, if it is absorbed too frequently, it may act in
reverse way causing teeth decay, osteoporosis and harm
to kidney, bone, nerve and muscle also.
5. Iodine
•
Component of thyroid hormone that control the body's
metabolism and many other important functions. The body
also needs thyroid hormones for proper bone and brain
development during pregnancy and infancy.
6. Iron
•
Component of hemoglobin, myoglobin, cytochromes, and
electron carriers.
•
helps form and oxygenate our blood cells and hemoglobin.
•
One of the most important functions of iron is in heme
synthesis, which forms hemoglobin, a protein found in red
blood cells. Hemoglobin's primary role is to transport oxygen
from the lungs to body tissues to maintain basic life
functions.
7. Magnesium
•
Muscle and nerve function, coenzyme.
•
muscle and nerve function, blood glucose control, and blood
pressure regulation.
•
for energy production, oxidative phosphorylation, and
glycolysis.
8. Phosphorous
•
Component of bone, ATP, DNA, and RNA.
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•
build and repair bones and teeth, help nerves function, and
make muscles contract.
•
about 85% of the phosphorus contained in phosphate is
found in bones. The rest of it is stored in tissues throughout
the body.
•
The kidneys help control the amount of phosphate in the
blood.
9. Potassium
•
Acid-base balance, water balance, and neural function.
•
helps your heartbeat stay regular.
•
helps move nutrients into cells and waste products out of
cells.
•
A diet rich in potassium helps to offset some of sodium's
harmful effects on blood pressure. Your kidneys help to keep
the right amount of potassium in your body.
10. Sodium
•
Acid-base balance, water balance, and neural function.
•
helps keep the water (the amount of fluid inside and outside
the body's cells) and electrolyte balance of the body. Sodium
is also important in how nerves and muscles work. Most of
the sodium in the body (about 85%) is found in blood and
lymph fluid.
11. Sulfur
•
Component of body proteins.
•
plays an important role in crucial functions in your body, such
as making protein, regulating gene expression, building and
repairing DNA, and helping your body metabolize food.
12. Zinc
•
Components of digestive enzymes.
•
helps the immune system fight off invading bacteria and
viruses. The body also needs zinc to make proteins and
DNA, the genetic material in all cells. During pregnancy,
infancy, and childhood, the body needs zinc to grow and
develop properly.
B. Essential Vitamins and Physiology
1. Fat Soluble Vitamins (A-D-E-K)
similar to oil and do not dissolve in water.
most abundant in high-fat foods and are much better absorbed
into your bloodstream when you eat them with fat.
Vitamin A (Retinol)
also known as retinol because it produces the pigments in the
retina of the eye.
helps form and maintain healthy teeth, skeletal and soft tissue,
mucus membranes, and skin.
promotes good eyesight, especially in low light. It also has a
role in healthy pregnancy and breastfeeding.
Vitamin D (Calciferol)
maintains normal blood levels of calcium and phosphorus.
aids in the absorption of calcium, helping to form and maintain
strong bones.
Vitamin E (Tocopherol)
acts as an antioxidant, helping to protect cells from the
damage caused by free radicals. Free radicals are compounds formed
when our bodies convert the food we eat into energy.
Vitamin K (Phylloquinone)
helps to make various proteins that are needed for blood
clotting and the building of bones. Prothrombin is a vitamin Kdependent protein directly involved with blood clotting. Osteocalcin is
another protein that requires vitamin K to produce healthy bone tissue.
2. Water Soluble Vitamins
•
meaning they dissolve in water.
Vitamin B1 (Thiamine)
helps the body's cells change carbohydrates into energy. The
main role of carbohydrates is to provide energy for the body,
especially the brain and nervous system.
plays a role in muscle contraction and conduction of nerve
signals.
Vitamin B2 (Riboflavin)
heat-stable, water-soluble vitamin that the body uses to
metabolize carbohydrates, fats, and protein into glucose for energy.
In addition to boosting energy.
functions as an antioxidant for the proper functioning of the
immune system, healthy skin, and hair.
Vitamin B3 (Niacin)
a vitamin that's made and used by your body to turn food into
energy.
helps keep your nervous system, digestive system and skin
healthy. Niacin (vitamin B-3) is often part of a daily multivitamin, but
most people get enough niacin from the food they eat.
Vitamin B6 (Pyridoxine)
Make antibodies. Antibodies are needed to fight many
diseases.
Helps maintain normal nerve function.
Make hemoglobin. Hemoglobin carries oxygen in the red
blood cells to the tissues.
Break down proteins
Keep blood sugar (glucose) in normal ranges.
Vitamin B5 (Pantothenic Acid)
essential nutrient that is naturally present in some foods, added
to others, and available as a dietary supplement.
main function of this water-soluble B vitamin is in the synthesis
of coenzyme A (CoA) and acyl carrier protein.
Vitamin B9 (Folic Acid)
aids in the production of DNA and RNA, the body's genetic
material, and is especially important when cells and tissues are
growing rapidly, such as in infancy, adolescence, and pregnancy.
Folic acid also works closely with vitamin B12 to help make
red blood cells and help iron work properly in the body.
Vitamin B7 (Biotin)
Helps the body to metabolize carbohydrates, fats, and amino
acids, the building blocks of protein.
recommended for strengthening hair and nails, and it's found
in many cosmetic products for hair and skin.
Vitamin C
needed for the growth and repair of tissues in all parts of your
body.
Lesson 4. Nervous System
A. Central Nervous System
Functions:
▪
receiving sensory input
▪
integrating information
▪
controlling muscles and glands
▪
maintaining homeostasis
▪
serves as the center of mental activity
BRAIN
3 main parts of the Brain
▪
▪
1. Cerebrum
contains the major lobes of the brain and is responsible for
receiving and giving meaning to information from the sense
organs, as well as controlling the body.
composed of the right and left hemispheres, which are
joined by the corpus callosum.
Functions of the cerebrum include:
initiation of movement
- touch
coordination of movement
- hearing
temperature
- reasoning
- vision
- judgement
- emotions
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-
problem solving
- learning
2. Cerebellum
▪
Produces signals that stimulates reactions in other parts of the
nervous system.
▪
It also coordinates muscle movement.
3. Brain Stem
▪
Harmonizes breathing, heart rate, sleep and wakefulness
3 regions of Brain Stem
Midbrain
Controls the movement of the
eyes and constriction and
dilation of the pupils.
Pons
Regulates the breathing and
helps control eye movement.
Medulla Oblongata
Controls involuntary actions
such as heartbeat, breathing,
and BP, including swallowing.
Thalamus
Serves as relay station for the senses.
Responsible for processing the information from the sense
organ.
Hypothalamus
▪
Regulates the body’s temperature, use of water, blood
pressure, and release of regulatory chemicals.
Spinal Cord
▪
long, thin, tubular structure made up of nervous tissue, which
extends from the medulla oblongata in the brainstem to the
lumbar region of the vertebral column. It encloses the central
canal of the spinal cord, which contains cerebrospinal fluid.
▪
The brain and spinal cord are your body's central nervous
system. The brain is the command center for your body, and
the spinal cord is the pathway for messages sent by the brain
to the body and from the body to the brain.
B. Peripheral Nervous System
1. Somatic Nervous System
▪
Responsible for voluntary actions or those over which a person
has control such as actions carried out by the skeletal muscles
and the sensory neurons of the skin. All these are under the
person’s conscious voluntary control.
2. Autonomic Nervous System
▪
Maintains homeostasis, just like the endocrine system.
a. Sympathetic Nervous System - prepares the body for action and
stress
b. Parasympathetic Nervous System - helps the body to conserve
energy
Lesson 5. Sensory Mechanism
▪
▪
GENERAL SENSES
Provides
environment.
sensory
1. Somatic senses
information about
the
body
and
the
2. Visceral senses
Provide information about various internal organs, primarily
involving pain and pressure.
3. Special senses
▪
They are more specialized in structure and are localized to
specific parts of the body.
▪
Smell, taste, sight, hearing and balance
SENSORY RECEPTORS
▪
are sensory nerve endings or specialized cells capable
responding to stimuli by developing action potentials.
▪
A major role of sensory receptors is to help us learn about the
environment around us, or about the state of our internal
environment. Different types of stimuli from varying sources
are received and changed into the electrochemical signals of
the nervous system.
1. Mechanoreceptors
respond to mechanical stimuli, such as the bending or stretching.
2. Chemoreceptors
respond to chemicals. Ex. odor molecules bind to chemoreceptors,
allowing us to perceive smells.
3. Photoreceptors
respond to light.
4. Thermoreceptors
respond to temperature changes.
5. Nociceptors
▪
respond to stimuli that result in the sensation of pain.
▪
The neuronal pathways of olfaction carry action potentials from
the olfactory neurons to the areas of the cerebrum that allow
for perception and interpretation of the stimuli. Axons from
olfactory neurons form the olfactory nerves (cranial nerve I),
which pass through foramina of the cribriform plate and enter
the olfactory bulb. There the olfactory neurons synapse with
interneurons that relay action potentials to the brain through
the olfactory tracts. Each olfactory tract terminates in an area
of the brain called the olfactory cortex, located within the
temporal and frontal lobes. Olfaction is the only major
sensation that is relayed directly to the cerebral cortex without
first passing through the thalamus. The olfactory cortex is
involved with both the conscious perception of smell and the
visceral and emotional reactions that are often linked to odors.
Taste sensation are carried to the brain by three cranial nerves:
Facial nerve (Cranial Nerve VII)
transmits taste sensation from anterior two-thirds of the tongue.
Glossopharyngeal nerve (Cranial Nerve IX)
carries the taste sensations from the posterior one-third of the tongue.
Vagus nerve (Cranial Nerve X)
carries some taste sensations from the root of the tongue.
Axons from these three cranial nerves synapse in the gustatory (taste
portion of brainstem nuclei. Axons of neurons in these brainstem
nuclei extend to and synapse with interneurons in the thalamus.
Senses
The means by which the brain receives information about the
environment and the body.
Sensation
Process initiated by stimulating sensory receptors and perception
(the conscious awareness of those stimuli.
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Axons from neurons in the thalamus project to the taste area in the
insula of the cerebrum Neuronal Pathways for Vision
The optic nerve (Cranial Nerve II) leaves the eye and exits the orbit
through the optic foramen to enter the cranial cavity. Just inside the
cranial cavity, the two optic nerve connect to each other at the optic
chiasm. Though it may appear that all the fibers of the optic nerves
cross over and extend to the opposite side of the brain, that is not
completely accurate. Each side of the brain receives signals from
each eye. Axons from the nasal (medial) part of the retina cross the
optic chiasm and project to the opposite side of the brain. Axons from
the temporal(lateral) part of each retina pass through the optic nerves
and project to the brain on the side of the body without crossing.
Neuronal Pathways for Hearing
The senses of hearing and balance are both transmitted by the
vestibulocochlear nerve (cranial nerve VIII). This nerve functions as
two separate nerves, carrying information from two separate but
closely related structures. The cochlear nerve is the portion of the
vestibulocochlear nerve involved in hearing; the vestibular nerve is
involved in balance. The cochlear nerve sends axons to the cochlear
nucleus in the brainstem. Neurons in the cochlear nucleus project to
the other areas of the brainstem and to the inferior colliculus in the
midbrain. Neurons from the inferior colliculus also project to the
superior colliculus, where reflexes that turn the head and eyes in
response to loud sounds are initiated. From the inferior colliculus,
fibers project to the thalamus and from there to the auditory cortex of
the cerebrum.
Neuronal Pathways for Balance
Axons forming the vestibular portion of the vestibulocochlear nerve
(cranial nerve VIII) project to the vestibular nucleus in the brainstem.
Axons run from this nucleus to numerous areas of the CNS, such as
the cerebellum and cerebral cortex. Balance is a complex sensation
involving sensory input to the vestibular nucleus not only from the
inner ear but also from the limbs (proprioception) and visual system
as well. In abstinence test, people are asked to close their eyes, while
their balance is evaluated because alcohol affects proprioceptive and
vestibular components of balance to a greater extent than the visual
component of balance. Seasickness is a form of motion sickness,
which is caused by conflicting information reaching the brain from
different sensory sources, such as the eyes and the semicircular
canals of the inner ear. The brain reacts with feeling of vertigo (a
feeling of spinning) and nausea.
Lesson 6. Immune System
KINDS OF DEFENSE MECHANISM
1. Innate Immunity
▪
Nonspecific response to a broad range of microbes formed by
skin and mucous membranes together with macrophages and
other phagocytic cells that ingest and destroy pathogens that
penetrates through the external barrier.
▪
Innate immunity also comes in a protein chemical form, called
innate humoral immunity. Examples include the body's
complement system and substances called interferon and
interleukin-1 (which causes fever).
▪
If an antigen gets past these barriers, it is attacked and destroyed
by other parts of the immune system.
▪
Skin and mucous membrane
✓ First line of defense that covers the digestive, respiratory,
and genito-urinary tract, which acts as barrier on invading
pathogens.
✓ acidic (pH 3.5) which can kill potential pathogenic
microorganisms.
Examples of innate immunity include:
✓ Cough reflex
✓ Enzymes in tears and skin oils
✓ Mucus, which traps bacteria and small particles
✓ Skin
✓ Stomach acid
2. Acquired Immunity
▪
Highly specific response developed only after exposure to
pathogens and cells by the recognition of lymphocytes.
▪
Acquired immunity is immunity that develops with exposure to
various antigens. Your immune system builds a defense against
that specific antigen.
▪
The body detects the foreign object or pathogen by certain
molecules attached on the outside of invading pathogens or by
other foreign objects. This molecule or foreign substance is
called as antigen. The immune system produces antibodies,
which will attach to these antigens. The acquired immune system
utilizes 2 major cell types.
3. Passive Immunity
▪
This is due to antibodies that are produced in a body other than
your own. Infants have passive immunity because they are born
with antibodies that are transferred through the placenta from
their mother. These antibodies disappear between ages 6 and
12 months.
▪
can be due to injection of antiserum, which contains antibodies
that are formed by another person or animal. It provides
immediate protection against an antigen, but does not provide
long-lasting protection.
Example
✓ Immune serum globulin (given for hepatitis exposure)
✓ tetanus antitoxin
Blood Components
▪
The immune system includes certain types of white blood cells.
It also includes chemicals and proteins in the blood, such as
antibodies, complement proteins, and interferon. Some of these
directly attack foreign substances in the body, and others work
together to help the immune system cells.
▪
Special white blood cells called lymphocytes play a key role in
the immune system's response to foreign invaders. There are
two main groups, both of which form in bone marrow.
Lymphocytes are a type of white blood cell. There are B and T type
lymphocytes.
B lymphocytes become cells that produce antibodies. Antibodies
attach to a specific antigen and make it easier for the immune cells to
destroy the antigen.
The other group of lymphocytes are called B-lymphocytes or B cells.
They mature in the bone marrow and gain the ability to recognize
specific foreign invaders.
Mature B cells migrate through the body fluids to the lymph nodes,
spleen, and blood. In Latin, body fluids were known as humors. So Bcells provide what's known as humoral immunity. B-cells and T-cells
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both circulate freely in blood and lymph, searching for foreign
invaders.
T lymphocytes attack antigens directly and help control the immune
response. They also release chemicals, known as cytokines, which
control the entire immune response.
One group, called T-lymphocytes or T-cells, migrates to a gland called
the thymus.
Influenced by hormones, they mature there into several types of cells,
including helper, killer, and suppressor cells. These different types
work together to attack foreign invaders. They provide what's called
cell-mediated immunity, which can become deficient in persons with
HIV, the virus that causes AIDS. HIV attacks and destroys helper T
cells.
As lymphocytes develop, they normally learn to tell the difference
between your own body tissues and substances that are not normally
found in your body. Once B cells and T cells are formed, a few of those
cells will multiply and provide "memory" for your immune system. This
allows your immune system to respond faster and more efficiently the
next time you are exposed to the same antigen. In many cases, it will
prevent you from getting sick. For example, a person who has had
chickenpox or has been immunized against chickenpox is immune
from getting chickenpox again.
TYPES OF T CELLS
1. Killer T cells
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Injects chemicals into the pathogens.
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recognizes and kills a virus-infected cell because of the viral
antigen on its surface, thus aborting the infection because a virus
will not grow within a dead cell.
2. Helper T cells
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attack and assist B cells in antibody production
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are arguably the most important cells in adaptive immunity, as
they are required for almost all adaptive immune responses.
They not only help activate B cells to secrete antibodies and
macrophages to destroy ingested microbes, but they also help
activate cytotoxic T cells to kill infected target cells.
3. Suppressor T cells
▪
type of immune cell that blocks the actions of some other types
of lymphocytes, to keep the immune system from becoming
over-active.
ANTIGEN
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substances that can worsen an immune response.
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Causes disease or allergic reactions.
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Each four major blood groups A, B, O, and AB have its own
antigen. Thus, only compatible blood types are allowed to be
transfused from one person to another. If the wrong blood type
is transfused, the antibody will attach to the foreign blood
antigen, which will lead to clotting and death.
ANTIBODY
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These are secreted into the blood and mucosa, where they bind
to and inactivate foreign substances such as pathogens and
toxins (neutralization).
▪
Antibodies activate the complement system to destroy bacterial
cells by lysis (punching holes in the cell wall).
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Examples: Breast milk, tears, saliva, sweat, and mucus.
The three functions of antibodies
▪
secreted into the blood and mucosa, where they bind to and
inactivate foreign substances such as pathogens and toxins
(neutralization).
▪
activates the complement system to destroy bacterial cells by
lysis (punching holes in the cell wall).
▪
facilitates phagocytosis of foreign substances by phagocytic
cells (opsonization).
CLASSIFICATIONS OF ANTIBODIES AND THEIR FUNCTIONS
1. Immunoglobulin G (IgG)
▪
activates complement and increases phagocytosis.
▪
Can cross the placenta and provide immune protection to the
fetus and newborns.
▪
Responsible for RH reaction, such as hemolytic disease of the
newborn.
2. Immunoglobulin M (IgM)
▪
Activates complement and acts as an antigen-binding receptor
on the surface of B cells.
▪
Responsible for transfusion reactions in the ABO blood system.
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The first antibody produced in response to an antigen.
3. Immunoglobulin A (IgA)
▪
Are secreted into saliva, into tears, and onto mucous membranes
to protect body surfaces.
▪
Found in colostrum and milk to provide immune protection to the
newborn.
4. Immunoglobulin E (IgE)
It stimulates the inflammatory response.
5. Immunoglobulin D (IgD)
Functions as antigen-binding receptor on B cells.
INFLAMMATION
➢ inflammatory response (inflammation) occurs when tissues are
injured by bacteria, trauma, toxins, heat, or any other cause.
➢ damaged cells release chemicals including histamine,
bradykinin, and prostaglandins.
➢ These chemicals cause blood vessels to leak fluid into the
tissues, causing swelling.
➢ This helps isolate the foreign substance from further contact with
body tissues.
➢ The chemicals also attract white blood cells called phagocytes
that "eat" germs and dead or damaged cells.
➢ phagocytosis.
➢ Phagocytes eventually die.
➢ Pus is formed from a collection of dead tissue, dead bacteria,
and live and dead phagocytes.
IMMUNE SYSTEM DISORDERS AND ALLERGIES
Immune system disorders occur when the immune response is
directed against body tissue, is excessive, or is lacking. Allergies
involve an immune response to a substance that most people's bodies
perceive as harmless.
IMMUNIZATION
Vaccination (immunization) is a way to trigger the immune response.
Small doses of an antigen, such as dead or weakened live viruses,
are given to activate immune system "memory" (activated B cells and
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Reviewer by Glyzce Sabado
sensitized T cells). Memory allows your body to react quickly and
efficiently to future exposures.
Complications due to an altered immune response
An efficient immune response protects against many diseases and
disorders. An inefficient immune response allows diseases to
develop. Too much, too little, or the wrong immune response causes
immune system disorders. An overactive immune response can lead
to the development of autoimmune diseases, in which antibodies form
against the body's own tissues.
Complications from altered immune responses include:
▪
Allergy or hypersensitivity
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Anaphylaxis, a life-threatening allergic reaction
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Autoimmune disorders
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Graft versus host disease, a complication of a bone marrow
transplant
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Immunodeficiency disorders
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Serum sickness
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Transplant rejection
Lesson 7. Endocrine System
The Role of Endocrine System in Humans
▪
▪
▪
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Hormones secreted by the endocrine glands directly flow into the
blood stream to regulate bodily activities. Hormones are
chemical messengers in the body that help stimulate target
organs, tissues and cells. These hormones are responsible for
causing changes in the activity of your body. These changes are
responses that correspond to messages sent from your brain.
The endocrine system is like a system of checks and balances
through which the parts of the body work properly to ensure
overall wellness of the body. If this system of checks and
balances goes twisted, the body becomes affected by diseases.
The endocrine system is like a thermostat that regulates body
temperature. It turns on and off as a response to the level of
hormones secreted by the endocrine glands, which in effect is a
response to changes in temperature of the environment.
When the endocrine system is not properly doing its job, the
overall wellness of the body may be affected such as decrease
energy level, changes physical appearance, and inability to
produce offspring.
SOME DISEASES ASSOCIATED WITH THE ENDOCRINE GLAND
1. Acromegaly
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rare disorder that is caused by excess levels of growth
hormone (GH) in the body. In the majority of cases, excess
levels of GH are causes by a benign (noncancerous) tumor in
the pituitary gland (pituitary adenoma).
▪
in children, the condition is called gigantism. In adults, it is
called acromegaly.
Signs and symptoms
✓ swollen hands and feet
✓ tiredness and difficulty sleeping, and sometimes sleep
apnea.
✓ gradual changes in your facial features, such as your brow,
lower jaw and nose getting larger, or your teeth becoming
more widely.
2. Hypoglycemia
Occurs when blood sugar level decreases below normal. It is
characterized by insulin reaction.
▪
Normal range 70-140 mg/dL
Signs and symptoms
✓ Fast heartbeat
✓ Hunger, dizziness and nausea
✓ Blurred vision, headache, and fatigue
✓ Numbness in the lips and tongue
✓ Excessive sweating, chills and nervousness
3. Cushing’s Syndrome
▪
There’s a tumor in the pituitary gland.
▪
disorder that occurs when your body makes too much of the
hormone cortisol over a long period of time. Cortisol is
sometimes called the “stress hormone” because it helps your
body respond to stress. Cortisol also helps. maintain blood
pressure. regulate blood glucose, also called blood sugar.
Signs and symptoms
✓ Fatigue
✓ Weight gain
✓ Sleeping difficulty
✓ Irregular menstruation
✓ Hirsutism (Excessive hair growth)
✓ Depression
4. Metabolic Disorder
▪
Also known as insulin resistance, occurs when the liver and
pancreas do not function normally.
▪
Can be corrected by maintaining a low carbohydrate diet and
improving insulin action through intake of diabetes medications
(e.g. metformin).
Signs and symptoms
✓ High BP
✓ Weight loss
✓ Men may suffer from gout
✓ Women may suffer from hirsutism and irregular periods
5. Hypothyroidism
▪
condition in which the thyroid gland is not able to produce
enough thyroid hormone (tri-iodothyronine or T3 and tetraiodothyronine or T4. Since the main purpose of thyroid hormone
is to "run the body's metabolism," it is understandable that people
with this condition will have symptoms associated with a slow
metabolism.
▪ Can be corrected treated through hormonal replacement
therapy.
Signs and symptoms
✓ Fatigue, weight gain, sluggishness
✓ Decreased memory, dry skin, heavy menstruation (for
women)
✓ Decreased body temperature
✓ Enlarged thyroid
6. Estrogen and Testosterone deficiency
Estrogen deficiency
- Cause by the decrease in estrogen level among females
especially when they start to menopause.
Testosterone deficiency
- Caused by low level of testosterone due to pituitary, adrenal or
testicular problem. Can be treated through hormonal
replacement therapy.
▪
Lesson 8. Homeostasis and Feedback Mechanism
GLUCOSE HOMEOSTASIS
glucose
pancreas
insulin
receptors in liver, muscle,
other cells
glucose uptake from blood into cells
production of glycogen (liver muscle) or fat (adipose cells)
blood glucose
glucose
pancreas
glucagon
liver
(a) convert
glycogen
glucose (b) convert amino
acids and other molecules
glucose (glycogenesis), (c) converts
fats
glycerol + 3 fatty acids
released into blood
glucose
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Negative Feedback
Control system that slows down or stops certain process of the
body and it helps in maintaining homeostasis.
▪
Denotes deviation from a set point, the normal value or ideal
condition around which the body performs normal functions.
Example
body temp
from set point
▪
sweat is produce
cools the body
temp
Components of Negative Feedback
1. Stimulus
Produces a change that evokes a specific function to a variable
2. Receptor
Detects the changes within the body and receives chemical signals
from outside a cell of the body.
3. Input
The gathered information outside a cell that travels along the
pathway to the control center.
4. Effector
Responsible for the response to change.
Positive Feedback
A condition of the body that deviates from the set point
encourages a disturbance in the physiological process of the
body.
▪
Uses information from sensors to
the rate of processes.
Example
Brain stimulates the pituitary gland to secrete oxytocin hormone.
▪
During labor, oxytocin is released in the uterus to intensify and speed
up contractions.
The birth ends the release of oxytocin and ends the positive feedback
mechanism.
The released of oxytocin stops when the baby is born.
General Biology 2
Reviewer by Glyzce Sabado