Introduction to the
Human Body
Chapter 1
What is A&P?
 Anatomy describes the structures of the body. Anatomy (“a
cutting open”) is a plan or map of the body.
 Physiology studies the function of each structure,
individually and in combination with other structures.
History
 The study of anatomy begins at least as early as 1600 BCE in Egypt
 In Greece Hippocrates shows an understanding of certain organs.
 In the 4th century BC men were given permission to do live dissections on
criminals
 Around 1300 in Europe the first major dissections of cadavars were
performed. The increase in demand for cadavers led to rumors about
“anatomical murders.”
 Only certified anatomists were allowed to perform dissections, and
sometimes then only yearly. These dissections were sponsored by the city
councilors and often charged an admission fee, rather like a circus act for
scholars.
 In Britain the Anatomy Act of 1832 finally provided for an adequate and
legitimate supply of corpses by allowing dissection of destitute due to the
increased rate of body snatching and anatomy murders.
Anatomy
Microscopic anatomy is divided into two major divisions:
 Histology, the study of
 Cytology, the study of
tissues and their
cells and their structures.
structures.
Organization
of the Body
Levels of Organization
 The levels of organization of living things, from smallest to
largest, are:
 Atoms, the smallest functional units of matter.
 Molecules, active chemicals.
 Organelles, specialized structures within a cell.
 Cells, the smallest living units.
 Tissues, a group of similar cells that work together.
 Organs, two or more tissue types working together.
 Organ systems, two or more organs working together.
 Organism, a single individual, including all of the above.
 Any change that occurs at one level -- such as a disease at the
cellular level or an injury at the organ or tissue level, affects the whole
body at all levels.
The Systems
 Integumentary:
protection, temperature
control
 Skeletal: support,
protection, red blood
cells
 Muscular: movement
 Nervous: direct control
 Endocrine: indirect
control
 Cardiovascular:
circulation
 Respiratory: oxygen
supply
 Lymphatic: immune
 Digestive: uptake of
nutrients
 Urinary: filters blood
 Reproductive: survival of
the species
Homeostasis=
balance
 As the environment around or within us changes,
physiological systems work together to maintain a stable
internal environment, the condition of homeostasis.
 Systems monitor and adjust the volume and composition
of body fluids, and keep body temperature within normal
limits.
 When the body does not function within its normal range, organ
systems malfunction, resulting in disease.
Mechanism to regulate
homeostasis
#1 Autoregulation
or intrinsic
regulation, an automatic
response by a cell, tissue,
organ or organ system to
a change in its
environment.
#2 Extrinsic
regulation,
changes regulated by the
nervous system or
endocrine system.
Parts of Regulation
 A homeostatic regulatory
mechanism consists of 3 parts:
 Receptors, sensors that
respond to a stimulus.
 The control center, receives
information from sensors and
sends out commands.
 Effectors, the cell or organ
that responds to the control
center.
Negative Feedback
 When the response of an effector opposes the original stimulus,
that is called negative feedback
 An example of negative feedback is the temperature thermostat
in your home.
 Temperature sensors turn the air conditioner off and on to
maintain air temperature within a specific, limited range.
 When body temperature is too high or too low, the control
center instructs an effector to oppose the effects of the stimulus
by increasing or decreasing blood flow and sweat.
Positive Feedback
 In the opposite response, positive feedback, the effector adds
to the initial stimulus instead of negating it, speeding up the
process.
 Positive feedback is useful in emergencies, such as speeding
up blood clotting.
 Or laughing
Equilibrium
 A state of equilibrium exists when opposing forces are in
balance.
 When homeostasis is threatened, physiological systems
attempt to restore balance.
 Failure to maintain internal conditions in a state of
equilibrium within normal limits results in disease or death.
Equilibrium
Equilibrium
 The body is constantly working, changing and responding to
stimuli, a state of dynamic equilibrium.
 Dynamic=movement
 All body systems must work together to maintain homeostasis.
 Body temperature, body fluid composition, body fluid volume,
waste product concentration and blood pressure are among the
most important internal characteristics which must be
maintained in homeostasis.
Frames of
Reference
 Anatomical descriptions
refer to standard anatomical
position: standing with the
hands at the sides, palms
facing forward, feet together.
Body Cavities
 Internal compartments called body
cavities protect internal organs, hold
them in place, and allow them to
change size and shape.
 Moist layers of connective tissue
cover both the walls of internal
cavities and the visceral organs
themselves, providing a double layer
of membrane between an organ and
its surroundings.
 Serous membrane contains a
watery lubricant that reduces
friction.
Chemical Level of
Organization
 Chemistry is the foundation of all living organisms. All basic
physiological processes of life take place at the chemical level.
 http://www.livescience.com/3505-chemistry-life-humanbody.html
Atom, Molecules, and Bonds
 The physical world (matter) is made up of atoms, which
join together to form chemicals with different
characteristics.
 These chemical characteristics determine the physiology
of living organisms at the molecular and cellular level.
Atoms
the smallest units of matter with their own chemical characteristics.
 Atoms are divided into 2 basic
 Atoms have 3 major types of
regions:
 the central nucleus,
contains heavy particles
 the electron cloud, contains
very light, moving particles
smaller or subatomic particles.
Particles are defined by electrical
charge, mass, and location within
the atom.
 protons (p+): positive
charge, in the central
nucleus
 neutrons (n): no electrical
charge (neutral), in the
central nucleus
 electrons (e-): negative
charge, very small mass,
spin rapidly in a cloud
around the central nucleus
Elements
 Atoms are also elements, the basic chemicals found in the
Periodic Table are the most common elements found in the
human body.
 Elements are defined by their atomic number, which is the
number of protons in the nucleus. The number of protons is the
positive electrical charge of the atom.
 Electrons, rapidly orbiting the nucleus in the electron cloud,
contain the negative charge. The number of electron is the
negative electrical charge of the atom.
 An element’s mass number is determined by adding together
the number of protons and neutrons in the nucleus. Although
neutrons have no electrical charge, they have significant mass.
 Chemical properties of an individual
atom or element depend upon several
factors, such as its electrical charge.
 Any atom with an equal number of
protons (positive) and electrons
(negative) has a neutral charge.
 If the atom loses or gains electrons, it
will have a net positive or negative
charge. Atoms with positive or negative
charges are called ions.
 Electrons orbit around the nucleus in
patterns called energy levels, which are
like shells or steps.
 Each energy level holds a specific number
of electrons.
 Level 1 holds 2 electrons.
 Levels 2 and 3 each hold 8 electrons.
 Electrons must fill the lowest available
energy level first. When a lower level is
full, higher levels can be occupied.
 The outermost energy level is the
“surface” of the atom. The number of
electrons in the outermost level
determines the chemical properties of the
atom.
 Atoms with unfilled outer levels are
unstable -- they react with other
elements.
 Atoms with filled outer levels do not
react with other atoms -- they are
inert.
Bonding: holds the atoms together.
Ionic Bond
 form between atoms with opposite
electrical charges (ions).
 An atom that loses electrons
(electron donor) has a net positive
charge, and is called a cation.
 An atom that gains electrons
(electron acceptor) has a net
negative charge, and is an anion.
Covalent bond
 Covalent bonds occur when
atoms share, rather than gain or
lose electrons, forming molecules.
 Each atom contributes the same
number of electrons to the bond,
called electron pairs.
???
Chemical Reactions
 The functions and structures of life all depend on
chemical reactions making and breaking chemical
bonds.
 Chemicals that go into reactions are reactants.
 Chemicals that come out are products.
 Chemical reactions are started by a catalyst.
 All reactions taking place in an organism’s cells and
tissues are its metabolism.
 Chemical reactions involve energy, which is defined as the
power or capacity to do work.
 Work is measured by any change in mass or motion.
* Chemical reactions in a cell are work.
 The 2 major types of energy are kinetic energy, the energy of
motion; and potential energy, or stored energy.
 The chemical energy in a molecular bond is a form of potential
energy.
 Energy cannot be created or destroyed. It can only be changed
from one form to another.
*Each time energy changes form, some
energy is lost in the form of heat.
This is why our bodies are warm,
and car engines get hot.
Types of reactions
 Decomposition reactions break larger
molecules into smaller parts. - Hydrolysis
(hydro = water; -lysis = breaking down) is a
decomposition reaction in which bonds of
large molecules are broken.
 Synthesis reactions are the opposite of
decomposition. Small molecules join
together to form larger molecules.Synthesis reactions require energy.
 Exchange reactions are paired
decomposition and synthesis reactions.
The reactants exchange components to
produce new products.
Types of reactions
 A chemical reaction which releases  When the activation energy of a
more energy than it uses to get
started is an exergonic reaction
(exo = outside).
reaction is greater than the
energy it produces, it is an
endergonic reaction (endo =
inside).
H+
 Hydrogen ions are very reactive and essential to most physiological
processes.
 The concentration of hydrogen ions in body fluids is called pH and
must be carefully regulated.
 More H+ ions means lower pH, less H+ ions means higher pH.
Since pure water consists of a balance between H+ ions and OHions, the pH of water is neutral, and is assigned a pH of 7.0
 A pH lower than 7.0 (high H+ concentration, low OH- concentration)
is acidic.
 A pH higher than 7.0 (low H+ concentration, high OHconcentration) is basic.
 Excess H+ ions (low pH) damage cells and tissues, alters
proteins and interferes with normal physiological functions. An
excess of OH- ions (high pH) also causes problems, but occurs
rarely.
Organic Compounds
 Organic compounds are usually very large molecules
containing carbon, hydrogen and oxygen atoms.
 The 4 major classes of organic compounds are carbohydrates,
lipids, proteins, and nucleic acids (RNA and DNA)
 As cellular parts wear out, your body
must recycle and renew all of its
chemical components at intervals
ranging from minutes to years.
 Metabolic turnover lets your body
grow, change and adapt to new
conditions and activities.
Introduction to Cells
 Cell theory (Robert Hooke, 1665)
- Cells are the building blocks of all plants and animals.
- All cells come from division of preexisting cells.
- Cells are the smallest units that perform all vital physiological
functions.
- Each cell maintains homeostasis at the cellular level.
 An organism maintains homeostasis through the coordination of
all its cells, working individually and together.
 Cytology: the study of cell structure and function.
 Two classes of cells in the human body:
 sex cells (germ cells): reproductive cells [male sperm, female
oocytes (eggs)] (half the chromosomes)
 somatic cells (soma = body): all body cells except sex cells
The Cell Membrane
 The cell membrane is an active organelle containing
lipids, carbohydrates and several types of functional
proteins.
 Cell membrane or plasma membrane has 4 basic
functions:
 Physical isolation: forms a physical barrier between the inside and
outside of the cell. Keeps things in or out.
 Regulate exchange with the environment: controls entry of ions
and nutrients, eliminates waste, releases cellular products.
 Monitor the environment: detects changes in composition,
concentration or pH of extracellular fluid. Contains receptors that
respond to chemical signals.
 Structural support: keeps cells in place and stabilizes tissues
 The cell membrane is made up of a double layer of
phospholipid molecules (phospholipid bilayer) with their
hydrophilic heads toward the watery environment on both
sides.
 The hydrophobic fatty-acid tails inside the membrane form a
barrier to ions and water soluble compounds, isolating the
inside of the cell from the outside.
Membrane Proteins
 These large protein molecules are divided into 6
specialized functions:
 anchoring proteins (stabilizers): attach cell membrane to





inside or outside structures.
recognition proteins (identifiers): label cells as normal or
abnormal to the immune system.
enzymes: catalyze reactions inside or outside the membrane.
receptor proteins: bind and respond to extracellular
molecules
carrier proteins: bind specific solutes and transport them
through the cell membrane using energy.
channels: pores that regulate the flow of water and specific
solutes through membrane.
Cytoplasm
 Cytoplasm includes all
materials inside the cell
membrane but outside the
nucleus. The 2 components
of cytoplasm are:
 cytosol (intracellular fluid): thick
liquid with dissolved nutrients,
ions, soluble and insoluble
proteins, waste products.
 organelles: structures with
specific functions inside the
cell.
Cytoplasm
 Cytosol differs from extracellular (interstitial) fluid in 3
ways:
 Potassium ions are concentrated inside, and sodium ions
outside, the cell.
 Cytosol has a high concentration of suspended proteins.
 Cytosol stores some carbohydrates, large amounts of amino
acids and lipids.
Organelles: Each organelle has a specific function related to cell
structure, growth, maintenance or metabolism.
 Nonmembranous




Cytoskeleton (shape, strength, metabolic functions)
Centrioles (spindle for cell division)
Microvilli (increase surface area for absorption)
Cilia (extensions of cell membrane-move fluid
across)
 Ribosomes (carry our orders from the nucleus for
protein synthesis)
 Proteasomes (enzymes that disassemble damaged
proteins)
Membranous Organelles
 Endoplasmic Reticulum (ER) (synthesis of organic compounds,
storage, transport, detoxification)
 Golgi apparatus (modifies/packages proteins for exocytosis,
modifies cell membrane, packages enzymes used in cytosol)
 Lysosomes (clean up internal environment, break down and
recycle materials)
 Through the Wormhole:
 Peroxisomes (contain enzymes that break down fatty
acids/organic compounds-produce free radical hydrogen
peroxide)
 Mitochondria (produce energy for cell metabolism by breaking
down carbohydrates)
Cellular Respiration
 Mitochondria provide most of the energy needed to keep your
cells alive. Aerobic respiration requires oxygen and organic
substrates, and generates carbon dioxide and ATP.
The Nucleus
 The cell’s control center, the nucleus, is the largest organelle in
the cell. It’s surrounded by a double membrane with
communication passages.
 The nucleus contains all of our DNA, all the information needed
to reproduce and run our bodies.
Other organelles within the nucleus include:
- chromatin: loosely coiled DNA (cells not dividing)
- chromosomes: tightly coiled DNA (cells dividing)
 The nucleus contains genetic instructions
for proteins that determine cell structure
and function. Information is stored in
chromosomes made of DNA and various
proteins.
 Genes are functional units of DNA
containing instructions for one or more
proteins. Protein synthesis requires
several enzymes, ribosomes, and 3 types
of RNA.
 A mutation is a change in the nucleotide
sequence of a gene, caused by chemical
or radiation exposure or by mistakes
during DNA replication, and can change
gene function.
How Things Get Into and Out of Cells
 The cell membrane is a barrier -- but nutrients must get in, and
products and wastes must get out.
 Permeability determines which materials move in and out of a
cell.
- A membrane which lets nothing in or out is impermeable.
- A membrane that lets anything pass is freely permeable.
- A membrane that restricts movement is selectively permeable.
 Transport through a cell membrane can be active (requiring
energy/ATP) or passive (no energy required).
Types of Transport
In carrier-mediated transport, integral proteins bind ions
and organic substrates and carry them across the cell
membrane.
Molecules that are too large to fit through a channel protein
can be passively transported across the cell membrane by
facilitated diffusion.
Active transport moves specific substances across the cell
membrane regardless of their concentrations. Moving
against a concentration gradient requires energy, such as
ATP.
Phagocytosis large solid objects (bacteria, debris) are
engulfed and fuse with lysosomes
Diffusion
 All atoms are constantly in motion. Random motion causes
mixing. When a solute (e.g. sugar) is added to a solvent (e.g.
water), and there are more molecules of solute in one part of
the solvent than in another, that is a concentration.
 As molecules of concentrated solute begin mixing through
random molecular motion, the concentration of the solute gets
lower and lower. This range of concentrations is a concentration
gradient.
 Concentration gradients always move in one direction, from
high concentration to low concentration.
Osmosis
 Refers to the diffusion of water across the cell membrane.
 The more solutes in an aqueous solution, the lower the
concentration of water molecules.
Sodium Potassium Exchange Pump
constantly pumps sodium ions (Na+) out of the cell and potassium
(K+) ions into the cell
The energy of 1 ATP moves 3 Na+ out and 2 K+ into the
cell (up to 40% of a cell’s ATP use).
 All cells carry a complete set of
DNA, with instructions for all
bodily functions.
 In order for tissues to form, cells must
specialize or differentiate
 This requires turning off all the genes
not needed by that cell.
 All your body cells (except sex
cells) contain the same 46
chromosomes. What makes
cells different from one another
is which genes are active, and
which genes are inactive.
 Undifferentiated (non-specialized cells)
 Have the ability to replicate or become
specialized (heart cells, fat cells, etc)
Stem Cells
Stem Cells Research
 Discovered in humans in 1998
 In 2000 the National Institute of Health issued guidelines for stem-cell
research.
 In 2001, US government implemented a policy limiting stem cell research
 2006 a Presidential veto was issued on the Stem Cell Research
Enhancement Act and it was not enacted into law.
 In November 2004, California voters approved Proposition 71, creating a US
$3 billion tax-payer funded institute for stem cell research.
 2009, the US government removed restrictions of federal funding for stem
cell research passed in 2001/2006
 This was amended in 2009 limiting the creation of new stem cells for
research
 In 2011 US district court threw out a lawsuit that challenged the use of
federal funds for embryonic stem cell research
Cell Life Cycle
2 Major periods
Interphase:
Cell Division:
Mitosis (in all cells but bacteria and sex cells)
Cytokinesis
Cancer
 A tumor is an enlarged mass of cells produced
by abnormal cell growth and division.
 A benign tumor is contained and not life
threatening.
 Cells a malignant tumor spread into surrounding
tissues and start new tumors (metastasis).
 An illness that disrupts normal cellular controls
and produces malignant cells is cancer.
 Cancer results from mutations that disrupt normal
controls over cell growth and division.
 Cancers often begin where stem cells are
dividing rapidly. More chromosome copies mean
greater chance of error.
Cancer Type
Estimated New Cases
 Bladder
 Breast (F/M)
69,250
230,480 – 2,140
Estimated Deaths
14,990
39,520 – 450
 Colon and Rectal
141,210
 Endometrial
46,470
8,120
 Kidney/Renal Cancer
56,046
12,070
 Leukemia (All Types) 44,600
21,780
 Lung (Incl. Bronchus)
221,130
 Melanoma
70,230
 Non-Hodgkin Lymph.
49,380
156,940
8,790
66,360
 Pancreatic
44,030
 Prostate
240,890
 Thyroid
48,020
19,320
37,660
33,720
1,740
Cancer Growth
 Cancer develops in series of
steps:
 abnormal cell
 primary tumor
 metastasis
 secondary tumor
Cancer Treatment Options
 Surgery can be used to prevent, treat, stage, and diagnose
cancer. Surgery is done to remove tumors or as much of the
cancerous tissue as possible. It is often performed in
conjunction with chemotherapy or radiation therapy.
 Chemotherapy is a type of cancer treatment that uses of drugs
to eliminate cancer cells, it affects the entire body, not just a
specific part.
 It works by targeting rapidly multiplying cancer cells. Unfortunately,
other types of cells in our bodies also multiply at high rates, like
hair follicle cells and the cells that line our stomachs.
 Chemotherapy is most commonly given by pill or IV, but can be
given in other ways and can be prescribed alone, in conjunction
with radiation therapy or biologic therapy.
Cancer
 A protein ‘bullet’ fired by immune
system cells, can gun down cancer
cells. It blasts open cancerous cell
membranes to allow toxic enzymes
to enter and destroy
 “Perforin is a powerful bullet in the
arsenal of our immune system –
without it, we could not deal with
the thousands of rogue cells that
turn up in our bodies through our
lives.
 ”Perforin is released by two key
weapons in the immune system
arsenal, ‘killer’ T-cells and ‘natural
killer’ (NK) cells
 studies suggests that defective
perforin leads to the development
of cancers, particularly leukemia
 Synthetic molecule makes cancer
cell “commit suicide”
Cancer Treatment Options
 Radiation therapy uses certain types of energy to shrink tumors
or eliminate cancer cells. It works by damaging a cancer cell's
DNA, making it unable to multiply. Cancer cells are highly
sensitive to radiation and typically die when treated. Nearby
healthy cells can be damaged as well, but are resilient and are
able to fully recover.
 Biologic therapy is a term for drugs that target characteristics of
cancerous tumors. Some types of targeted therapies work by
blocking the biological processes of tumors that allow tumors to
thrive and grow or they cut off the blood supply to the tumor,
causing it to basically starve and die because of a lack of blood.
 Targeted therapy is used in select types of cancer and is not
available for everyone. It is given in conjunction with other cancer
treatments.
 Tissues: Tissues are
collections of cells and cell
products that perform
specific, limited functions.
Four tissue types form all
the structures of the
human body
 Histology: the study of
tissues.
4 Basic Types of Tissues
 Epithelial: covers surfaces
exposed to environment (skin,
airways, digestive tracts, glands)
 Connective: fills internal spaces,
supports other tissues,
transports materials, stores
energy.
 Muscle: is specialized for
contraction (skeletal, heart
(cardiac), walls of hollow
organs).
 Neural: carries electrical signals
from one part of the body to
another.
Epithelial
 Epithelial tissue includes:
 epithelia: layers of cells
that cover internal or
external surfaces.
 glands: structures that
produce fluid secretions.
 Epithelia line digestive,
respiratory, urinary and
reproductive tracts.
 Also fluid or gas-filled internal
cavities and passageways such
as the chest cavity, inner surfaces
of blood vessels and chambers of
heart
Epithelial
 Epithelia have 5 important characteristics:
 Cellularity: cells are tightly bound




together by cell junctions.
Polarity: the structural & functional
differences between exposed &
attached surfaces of the tissue.
Attachment: the base of the
epithelia is bound to a basal lamina
or basement membrane.
Avascularity: epithelia are
avascular
Regeneration: a high rate of cell
replacement by stem cells
4 basic functions of
epithelial tissues:
Provide Physical Protection from abrasion,
dehydration, biological and chemical agents.
 Control Permeability to proteins, hormones, ions or
nutrients.
 Provide Sensation such as touch or pressure.
 Produce Specialized Secretions for physical
protection or chemical messengers.
 gland cells are scattered among other epithelial cells.
 glandular epithelium, most cells produce secretions.
Cell Junctions
Maintenance and Repair
 Epithelial cells are exposed to toxic chemicals, pathogens
and mechanical abrasion.
 An epithelial cell of the small intestine may survive only a
day or two before it is destroyed.
 New epithelial cells are produced by division of stem cells
located near the basal lamina.
 Three factors make the epithelium an effective barrier:
intercellular connections, attachment to basal lamina, and
maintenance and repair.
Glandular Epithelium
 Glands are cells, or collections of
cells, specialized for secretions
ranging from sweat to hormones.
 Endocrine glands (endo = in)
release hormonal secretions into
interstitial fluids.
 The blood stream carries
hormones throughout the body.

Hormones control specific
tissues, organs and organ
systems.
 Exocrine glands (exo = out)
release secretions into ducts which
carry the secretions onto an
epithelial surface such as the skin,
or an internal passageway that
communicates with the outside
environment.
 Examples of exocrine secretions are
digestive enzymes, sweat, tears and
milk.
Secretions
 Serous glands produce watery
secretions containing enzymes.
 Example: parotid salivary glands
 Mucous glands secrete mucins.
 Examples: sublingual salivary
glands, submucosal glands of
small intestine
 Mixed exocrine glands produce
both serous and mucous
secretions.
 Example: submandibular salivary
glands.
Connective Tissue
 Connective tissue connects the epithelium to the rest of
the body (basal lamina). Other connective tissues
provide structure (bone), store energy (fat), and
transport materials throughout the body (blood).
 Unlike epithelial tissues, connective tissues are never
exposed to the exterior environment.
Characteristics of Connective
Tissue
 Though there are many different kinds of connective tissues,
all have three basic characteristics:
 1. Specialized cells
 2. Extracellular protein fibers
 3. A fluid, extracellular ground substance
 The extracellular components (protein fibers and ground
substance) together form a matrix surrounding the cells.
 Connective cell matrix makes up most of the volume of
connective tissue.
 Matrix is a connective cell’s specific product, and determines its
specialized function.
3 Categories of Connective
Tissue
 Connective tissue proper can have many
types of protein fibers and a syrupy ground
substance.
 (1) loose connective tissue more ground
substance, less fibers (fat)
 (2) dense connective tissue- more fibers, less
ground substance (tendons)
 2. Fluid connective tissues have a watery
matrix of dissolved proteins, carrying specific
cell types. There are 2 types
 (1) blood
 (2) lymph
 3. Supportive connective tissues support soft
tissues and the weight of the body. The 2
types:
 (1) cartilage: a gel-type ground substance with
various fibers for shock absorption and
protection.
 (2) bone: which is calcified
Connective Tissue Proper
 Fibroblasts: The most abundant cell type, found in all connective tissues







proper.
Macrophages (macro = large, phagein = eat): Large, amoeba-like cells of
the immune system which eat pathogens and damaged cells.
Adipocytes (fat cells): Each cell stores a single, large fat droplet.
Mesenchymal cells: Stem cells that respond to injury or infection by
differentiating into fibroblasts, macrophages or other types of cells.
Melanocytes: Synthesize and store the brown pigment melanin.
Mast cells: Release the chemicals histamine and heparin to stimulate
inflammation after injury or infection.
Lymphocytes: Specialized immune cells carried by the lymphatic system.
Microphages : Phagocytic blood cells responding to chemical signals from
macrophages and mast cells.
Fibroblasts
The most abundant cell type,
found in all connective
tissues proper.
Fibroblasts secrete proteins and
the polysaccharide derivative
hyaluronan (the cement which
locks cells together).
Macrophages
(macro = large, phagein =
eat):
Large, amoeba-like cells
of the immune system
which eat pathogens and
damaged cells.
fixed macrophages stay in the
tissue.
free macrophages migrate
through tissues.
Adipocytes
FAT CELLS
Each cell stores a single, large
fat droplet.
Mesenchymal
Cells
Stem cells that respond to injury
or infection by differentiating into
fibroblasts, macrophages or other
types of cells.
Melanocytes
Synthesize and store
the brown pigment
melanin.
Mast Cells
Release the chemicals
histamine and heparin to
stimulate inflammation after
injury or infection.
Lymphocytes
Specialized immune
cells carried by the
lymphatic system,
including plasma cells
which produce
antibodies.
Microphages
Phagocytic blood cells
responding to chemical
signals from
macrophages and mast
cells.
Collagen Fibers
The most common fibers in
connective tissue proper.
- long, straight and
unbranched
- strong and flexible
- resists force in one
direction
- examples: tendons and
ligaments
Reticular Fibers
Similar to collagen fibers but
shaped differently.
- network of branching,
interwoven fibers
- strong and flexible
- resists force in many
directions
- stabilizes the positions
of functional cells and structures
Organs with a large amount of
reticular fibers/tissue; spleen, liver,
lymph nodes and bone marrow
Elastic Fibers
(Elastin)
Elastic fibers: Contain the protein
elastin.
- branched and wavy
- return to original length
after stretching
- example: elastic
ligaments of vertebrae
Fat: Adipose Tissue
Brown Fat
White
Fat
 the most
common adipose
tissue
 Adipocytes in adults do
not divide. They expand or
shrink as fats are stored
or released. If there are
not enough fat cells to
store available lipids,
mesenchymal stem cells
divide and differentiate to
produce
more
fat cells.
 a more vascularized
tissue with adipocytes
containing many
mitochondria. These cells
are metabolically active,
breaking down fat and
producing heat.
Dense Connective Tissue
 Dense regular connective tissue has tightly packed,
parallel collagen fibers
 Tendons attach muscles to bones.
 Ligaments connect one bone to another, or stabilize organs.
 Dense irregular connective tissues have interwoven
networks of strengthening fibers.
 Examples:- layered in skin
 around cartilages
 around bones
 forms capsules around some organs (e.g. liver, kidneys)
 Elastic tissue: Though both dense regular and dense irregular
connective tissues contain elastic fibers, elastic tissue is mostly elastic
fibers.
 e.g. elastic ligaments of the spinal column
Tendons: Attach Muscle to Bone
Ligaments: Attach Bone to Bone
Fluid Connective
Tissue
Red blood cells (erythrocytes)
make up about half the volume
of blood. Their main function is
to transport oxygen to the cells.
White blood cells (leukocytes)
include several types of
immune system cells
Platelets are cell fragments
containing enzymes and
proteins that aid clotting.
The fluid element of blood is
the watery matrix called
plasma. Plasma is one of the 3
forms of extracellular fluid
Lymph
Interstitial fluid then drains into
the lymphatic vessels, where it
is called lymph.
Immune system elements of
the lymphatic system screen
the fluid for infections before
returning it to the blood where,
once again, it is called plasma.
Cartilage cells in the matrix are called
chondrocytes.
Cartilage has no blood vessels because
chondrocytes produce an anti-growth
chemical.
The outer cover, consists of an outer,
fibrous layer (for strength) and an inner,
cellular layer (for growth and
maintenance)
Cartilage grows by 2 mechanisms:
(1) Interstitial growth increases cartilage
size from the inside.-
(2) Appositional growth increases the
outer size of a cartilage by adding
new layers.
*Neither interstitial growth nor
appositional growth normally occurs
in adults
There are 3 major types of cartilage:
(1)Hyaline cartilage: lines the
ends of bones and reduces
friction between bones.
(2)Elastic cartilage has tightly
packed elastic fibers,
supportive but bends
easily- is found in the
external ear and epiglottis.
(3) Fibrocartilage has very
dense collagen fibers.limits movement and
prevents bone-to-bone
contact.- pads knee joints,
intervertebral discs.
Osseous Tissue
Bone or osseous tissue is
strong and resists shattering
due to its flexible collagen
fibers.
Osteocytes are arranged
around blood vessels within
the matrix. Small channels
through the matrix allow
osteocytes to exchange
nutrients and wastes with
their blood supply.
Unlike cartilage, bone is
metabolically active, and can
repair itself or adapt to
activity.
Membranes
Mucous membranes: line
passageways that
communicate with the
outside environment
pleural membrane lines pleural
cavities and covers the lungs.
 The epithelial surfaces are moist
(lubricated) to reduce friction, or
facilitate absorption and excretion.
 Serous
membranes line
cavities that are not open to
the outside environment.
peritoneum lines the peritoneal cavity
and covers abdominal organs.
pericardium lines the pericardial cavity
and covers the heart.
Membranes (cont)
Cutaneous membrane is
the skin that covers the
surface of the body.
It is thick, waterproof and dry.
Synovial membranes line
articulating (moving) joint
cavities and produce the
synovial fluid which
lubricates the joint.
 protect the ends of bones and
allow free movement.
Fascia
Layers that surround and support
organs. There are 3 types of these
layers:
Superficial fascia or subcutaneous
layer (sub = below, cutis = skin) is the
tissue and fat that separates the skin
from underlying tissues. It allows
independent movement, pads, and
insulates deep tissues.
Deep fascia is a strong, fibrous
network of dense irregular connective
tissue which ties structural elements
together. Internal organs are
anchored to deep fascia.
Subserous fascia is tissue that
separates the deep fascia of muscles
from serous membranes, allowing
independent movement.
Smooth Muscle
Smooth muscle tissue is
found within the walls of
hollow organs that contract
(blood vessels; urinary
bladder; respiratory, digestive
and reproductive tracts).
Smooth muscle cells:
• small and tapered.
• can divide and
regenerate
•
are nonstriated,
involuntary, and have
a single nucleus.
Skeletal Muscle
Muscle tissue is specialized for
contraction. All body movement is
produced by muscle tissue.
Skeletal muscle tissue forms the
large body muscles responsible
for major body movements such
as walking.
Skeletal muscle cells:
• are long and thin, and are
usually called muscle fibers.
•do not divide, new fibers are
produced by stem cells called
satellite cells.
• are striated, voluntary, and
multinucleated.
Cardiac Muscle
Cardiac muscle tissue is
found only in the heart.
Cardiac muscle cells:
- are called
cardiocytes.
- form a branching
network connected at
intercalated disks.
- are regulated by
pacemaker cells.
- are striated,
involuntary, and have a single
nucleus.
Neural Tissue
 Neural tissue (nervous or nerve tissue) is
specialized for conducting electrical impulses
that rapidly sense the internal or external
environment, process information and control
responses.
 Most neural tissue is concentrated in the brain and spinal
cord
 There are 2 kinds of neural cells:
 neurons, the nerve cells that do the electrical
communicating, and
 neuroglia, the support cells that repair and
supply nutrients to neurons.
Tissue Injury
and Repair
The restoration of homeostasis
after a tissue has been injured
involves 2 processes:
Inflammation (itis) is the tissue’s
first response to injury.
Signs include: swelling,
redness, heat, and pain and
dysfunciton at the site of the
injury.
The presence of harmful
bacteria (pathogens) in a
tissue (an infection) also
causes an inflammatory
response.
Inflammation
The process of inflammation occurs in several
stages:
Damaged cells release prostaglandins, protein
and potassium ions into the surrounding
interstitial fluid.
As the cell breaks down, lysosomes release
enzymes that destroy the injured cell and attack
surrounding tissues. Tissue destruction is
called necrosis.
Necrotic tissues and cellular debris (pus)
accumulate in the wound. (Pus trapped in an
enclosed area is an abscess.)
The injury stimulates mast cells in the tissue to
release histamine, heparin, and prostaglandins,
which trigger changes in the surrounding blood
vessels.
-.
Inflammation
- Dilation (widening) of blood
vessels increases blood
circulation in the area, causing
warmth and redness.
- Plasma diffuses into the
area, causing swelling and
pain.
- Increased blood flow brings
more nutrients and oxygen to
the area, and removes
wastes.
- Phagocytic white blood cells
clean up the area.
Regeneration
When the injury or
infection has been cleared
up, the regeneration or
healing phase begins.
- Fibroblasts move into the
necrotic area, laying down
collagen fibers that bind the
area together (scar tissue).
- New cells migrate into the
area, or are produced by
mesenchymal stem cells.
- Not all tissues can
regenerate. Epithelia and
connective tissues regenerate
well. Cardiac cells and
neurons do not regenerate.