Cells
Cells are the basic building block of
life.
- Composed of
- Carbon –oxygen-hydrogennitrogen
- Surrounded by interstitial fluids
- Concentration important- must
be isotonic
- If hypertonic –greater
concentration of molecules
outside the cell
- If
–
hypotonic
concentration
of
lower
molecules
outside the cell
- If isotonic – concentration equal
inside and outside the cell
- To
maintain
homeostasis
interstitial fluid needs to be
isotonic.
- Hypertonic- molecules move into
cell
and
water
moves
out
(expands)
- Hypotonic – molecules move out
of the cell and water moves in (
contracts)
- Isotonic – there is equilibrium
inside and s\outside the cell
- The movement of any molecules
from an area of high to low
concentration is passive transport
( down concentration gradient)
- Diffusion is passive transport of
molecules easy to move
MITOSIS
- Cell Division- cell’s life cycle: 2
main phases
o Interphase – most of life :
grow, carry on regular activity
o Cell Division – period when
cell reproduces itself prepares
by duplicating DNA exactly
- Transcription-
Replication
of
DNA (know as template)
- Mitosis- Events of cell division
when an exact copy of the cell is
made
- Prophase- First stage: chromatin
coils and shortens to become
chromosomes, spindle fibers and
centrioles appear.
- Chromatids- Two sections of the
chromosome and they separate
into each daughter cell
- Centromeres-
Holds
the
chromatids together and help
divide
- Metaphase- when chromosomes
line up in the middle of the cell
- Anaphase- 2 chromatids begin to
pull apart
- Telophase-
Chromatids
uncoil
and become chromatin and a true
nucleus
chromatin
forms
around
the
-cytokinesis- cytoplasm is divided
in 2 new cells (called cleavage after
the cells split)
Protein Synthesis
- gene:
segment
of
DNA
that
carries info to build one protein
chain
- enzymes:
regulate
chemical
reactions in cells
- DNA
is
“encoded”
with
its
information inside the sequences
of steps
- Each triplet codon (set of 3
steps/bases) requires a specific
amino acid
- Amino acid: building blocks of
proteins: joined during protein
synthesis
- A,C,T,G put in different orders
make different genes using 3 of
them
- Ribosome: manufacturing sites of
proteins
- Ribonucleic acid :RNA decoder
and messenger for nucleus
- tRNA: transfer RNA: transfer
messages
- rRNA: helps from ribosome’s (
r=ribosomal)
- mRNA : carries messages to
ribosome’s (m=messenger)
- Two major Phases:
- Transcription :MRNA is made at
the DNA gene (only MRNA and
DNA)
- Translation: info in MRNA is
“decoded” and used to form
proteins (all RNA invloved)
- Codons:
corresponding
triplet
sequences on mRNA
- Anticodon:
special
3
step
sequence on head of RNA
- Each tRNA at the beginning of
the mRNA which are lined up
and joined by enzymes and amino
acids are by the mRNA and
joined by enzymes tRNA is then
released and moves to another
amino acid. When last condon is
read protein is released.
Body Tissues
Human Body , a single cell divides
endlessly to become specialized for
particular function.
- Groups of cells that are similar in
structure and function are called
Tissues
Four Primary Tissue Types
- epithelium (covering)
- connective tissue (support)
- nervous tissue (control)
- muscle (movement)
They all form “Fabric” of Body
Tissues Organized into organs and
arrangement of tissues determine
organ’s structure and what it can do.
Epithelial tissues, or Epithelium
Lining, covering, and glandular tissues
of the body.
Epithelial functions include
Protection, absorption, filtration, and
secretion.
-Epithelia cells fit closely to form
continuous sheets. Bound together by
cell junctions.
- Membranes always have one free
surface or edge. Apical Surface is
exposed to the body’s cavity of
internal organ. (slick & smooth).
- Lower surface rest on a Basement
membrane, structure less material
secreted by the cell.
-No blood supply, depend on diffusion.
-Regenerates by itself if nourished
right.
Classification of Epithelium
Simple epithelium: 1 layer of cells,
classification by cell arrangement.
Columnar: cells that are shaped like
columns.
Cuboidal: Cells that cube- shaped, like
dice.
Squamous: cells that are flattened like,
fish scales.
Stratifiedepithelium: More than 1
layer, named for the cells at the free
surface of the epithelial membrane.
Simple epithelia: Most concerned with
absorption, secretion, and filtration,
very thin protection is not 1 of their
specialties.
Simple Squamous Epithelium: A
single layer of thin squamous cells
resting on a basement membrane
closely together, like floor tiles.
Simple Squamous Epithelium forms:
Serous membranes serosae.
Types of Connective Tissue
Most rigid to softest bone, cartilage,
dense connective and loose connective.
Bone- Osseous Tissue
Bone cells sitting in cavities called
lacunae and surrounded by layers of a
very hard matrix that contains
calcium salts and large amounts of
collagen fibers
-rock like hardness
-protects and supports
Cartilage- less hard and flexible
- hyaline cartilage many collagen
fibers hidden by a rubbery matrix
with a glassy blue-white
appearance.
- Forms larynx (voice box)
structures
- attaches ribs to breastbone
- Elastic cartilage only where
elasticity is desired (ear)
- Fibro cartilage- highly compressed
forms cushion like disks between
vertebrae.
- Tendons- attach skeletal muscles to
bone.
- Ligaments- connects bones to bones
at joints.
- (D.C.T.) Dense Connective tissueDense fibrous collagen fibers are
the main matrix. Between fibers
are rows of fibroblasts that
manufacture the fibers. D.C.T.
forms Strong, ropelike structures,
such as tendons and ligaments.
D.C.T. makes up the lower layers
of the skin
Loose Connective tissue
Loose Connective tissue fibers are
softer than any other connective tissue.
Arelar Tissue- most widely distributed
tissue it cushions the organs, provides
a reservoir of water and salts. When
the tissue is inflamed and soaks up
water like a sponge and becomes puffy
is called edema.
Adipose tissue- Commonly called fat,
stored oil occupies most of a fat cells
volume Fat cells volume and
compresses the nucleus, displacing it
to one side. This tissue forms beneath
the skin insulates the body and
protects it form heat and cold, protects
the kidneys and cushions the eye
sockets.
Reticular Connective tissue- Network
of interwoven fibers, it is limited to
certain sites it form the stoma or
internal supporting frame work
supports many blood cells in lymphoid
organs such as the spleen and bone
marrow.
Blood- vascular tissue is a connective
tissue because it consists of blood cells.
The fibers of blood are soluble protein
molecules that become visible clotting.
Blood carries nutrients, wastes and
gases.
Tissue Repair
- skin, mucous, cilia, and strong aids
- some of bodies defenses
- when injury happens
inflammatory, immune, and
healing begins
- Inflammation prevents further
injury
- Immune Fights bacteria, viruses,
toxins
- Two major ways to repair
- Regeneration replacement of
destroyed tissue fibrosis repair
connective tissue scar tissue
- Depends on type of tissue damage
or severity
- When injury occurs
- Capillaries allow fluid to help
clotting
- Clotting proteins construct clot
- Stop blood loss
- Granulation tissue forms
- Grows in damaged area
- Bleed a lot
- Contain phagocytes
- Disposes of clot
- Epithelium regenerates under scab
- Covers scar
- Different tissues regenerate in
different ways scar tissues very
strong, lacks flexibility
- Can’t do what original tissues did.
DEVELOPMENTAL ASPECTS OF
CELLS & TISSUES
Most cells except neurons under go
mitosis. Cells exposed to abrasion
wear away, like skin and intestinal
cells. Amitotic tissues are hurt by
injury because the cells can’t be
replaced.
The aging process begins once
maturity has been reached. It is
believed that” chemical insults” are
responsible for it, but no one knows
for sure. Another factor could be that
could cause aging is radiation. X rays
or ultraviolet waves and still another
reason could be that our genes are
genetically programmed to start the
aging process.
The effects of getting older starts to
become obvious when we get wrinkles
and our skin start to sag. That is
because our epithelial membranes
become thinner. Skin loses it’s
elasticity. Hormones also decrease.
The bones weaken, tissues ability to
repair itself decreases, and muscles
and nervous tissues begin to atrophy.