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Physiology 2015
Tissues
A. Connective Tissue is a diverse group of tissues ranging from a liquid (blood
– Flowing! Matrix/ECF = plasma) to semi solid (cartilage) to a solid (bone).
All of these tissue posses a common characteristic, a large amount of extracellular material (matrix) that separates the cells. These cells are not in close
contact!
a. Common Structural Features –
i. Extra-cellular material (matrix of CT) has 3 major components
1. protein fibers – 3 types
% of these proteins
Each of these proteins is built
a. collagen – resemble microscopic ropes, are
will give you an idea
from Amino Acids… We must
flexible but resist stretching (Cant pull it, not of the function!
consume/eat the AA’s in order
elastic, only bendable) Remember this is the
to build these in our cells.
most abundant protein in the body!
Each of these proteins
Ex: eggs, fish, meat, beans, nuts,
b. reticular – short collagen fibers that branch to add certain/specific
soy, dairy
qualities to the tissue
form a support network
c. elastic – fibers with the ability to recoil(elastic) they make up.
to original shape after having been stretched
(Ex: Bladder/smooth muscle tissue)
Ex. BONE: prefix OSTEO
OsteoBLAST- produce the matrix of
bone
OsteoCYTES- maintain bone cells
OsteoCLASTS –
breakdown/remodel bone repair
2. ground substance – Matrix itself !shapeless, colorless
background in which the protein fibers and cells sit
a. made of a protein called prosteoglycan (protein
with a polysaccharide attached – Protein with
giant sugar)
3. water
a. large amounts of water are trapped between
the polysaccharides of the prosteoglycan
molecule
b. The % of water determines if the tissue is liquid,
semisolid, or solid tissue… Blood has more
%water than bone!!
ii. connective tissue cells are named by their function (suffix)
a. -blast cells produce matrix
b. -cyte cells maintain the matrix (everyday cells)
c. -clast cells break down the matrix (reabsorb
materials for remodeling/change)
b. Functions of Connective Tissue – due to the diversity of cell structure
Ex: Pericardial Sac – heart -- [ion], within this tissue category, there is also functional diversity. Here are
the major categories of function.
decrease heat, sugar increased
Pleural Membrane – lungs –
maintain vacuum chamber
Meninges – brain/spinal cord (keep
out possible bacteria/viruses)
i. Enclosing and separating – sheets form capsules that cover
organs and layers that separate tissues and organs – i.e.
separation of muscles, blood vessels and nerves from on
another You WANT separation – each organ needs its own
mini environment (maintain homeostasis in each organ)
Cartilage – avascular, white shiny “cap”
on the ends of bone. O2/CO2 nutrients
diffuse into/out
Decrease in friction, prevents wear and
tear – don’t want bones to rub against
each other on the grooves (eburnation)
Skull = BRAIN
Vertebral Column = SPINAL CORD
Ribs = LUNGS & HEART
ii. Connecting tissues to one another – example tendons(coming
off of a muscle bundle) connect muscle to bone and act as
strong (longer, thinner) cables.
iii. Supporting and moving – bones are rigid support for the body
and cartilage, which is semi rigid, supports the nose, ear and
joint surfaces. Joints allow one part of the body to move
relative to another
iv. Storing – many of the connective tissues are reservoirs for
minerals and ions needed for metabolic reactions. Bones
store calcium and phosphate, while adipose tissue stores high
energy molecules (triglycerides).
v. Cushioning and Insulating – adipose tissue cushions and
protects many of the organs, for example the kidneys and the
heart and provides and insulation layer under the skin that
helps to conserve heat.
vi. Transporting – blood transports a number of materials
throughout the body including oxygen (CO2) and enzymes,
hormones ,nutrients, plasma proteins and cells of the immune
system.
vii. Protecting – Bones protect underlying structures, for example
the rib cage and immune system cells protect the body from
toxins and bacterial infection.
Ligaments –
connect bone to
bone –
wide/short/thick
Ca2+, PO4- (get P
from living things
you eat!! DNA!)
form crystals
which harden in
matrix (long,
looks like a
needle)
Fits into specific
places in the bone
c. Classification/Types of Connective Tissues and where they are found
Fun Fact! You are born with
all of your fat cells!! Over time
they just enlarge (weight gain)
or shrink down (weight loss)
Extra Notes:
Nervous System
Central Nervous System
Brain
Spinal Cord
Peripheral Nervous System
Sensory:
pick up info
Motor: ensures an
effect/response (a way to
maintain homeostasis)
1 Nerve Cell = 1 Neuron
Born with (almost) all of your nerve cells- they cannot REPRODUCE, however recent
studies have shown that stem cells can make more (regenerate) brain cells if needed.
B. Nervous System – Nerve tissue is responsible for controlling and
coordinating many bodily activities. Many of these functions depend on the
ability of the nervous tissue cells to communicate with one another and with
other cells by electrical signals called action potentials. Nerve impulses end
on different tissue/glands/muscles/other nerves
1. composed of neurons and support cells Generic Nerve Cell –
there are many different structures a nerve cell can take… we will
use this as our example.
Dendrites (receptors)
receive (pick up) the
information and bring it to
the Cell Body
Axon – longest of all the
fibers, comes out of the cell
body, can be several feet
long, AKA “sending” fiber.
Neuroglial Cells – support
cells, nourish and help
nerve cell functions
a. neuron or nerve cell
i. responsible for the conduction of the action potential
(bioelectrical signal)
Impulse always moves in 1 direction (D  CB  A)
ii. made of 3 parts Know the general structure!!
1. cell body (soma)
2. dendrites
3. axons
SEE IMAGES OF
AXONS IN
OTHER
DOCUMENT OF
unmyelinated vs
myelinated!!
b. support cells (majority in our body) called neuroglia (one type)
i. do not conduct electrical impulses
ii. function to nourish, protect and insulate the neurons
iii. form myelin sheath around axon of cell
1. gaps in myelin sheaths called Nodes of Ranvier
serve as sites for accelerating (RAPID!) an
impulse
1 type = Schwann cells (wrap around axon to)
form myelin sheath
Remember
Nimisha’s acronym
S - sensory
A- afferent
M – motor
E – efferent
Sensory Neuron  Interneuron  Motor Neuron  Destination
(muscle/tissue/gland
/neuron)
2. 3 categories of nerve cells
a. Sensory neurons AKA – AFFERENT NEURONS
i. Found in eyes (light/color), ears, surface of skin
(temperature/pressure/pain)
ii. Receive information about the body’s condition and the
external environment (Take info from receptors and
bring to CNS)
b. Motor neurons AKA – EFFERENT NEURONS
i. Found in brain and spinal cord
ii. Conducts impulses out of central nervous system
towards muscles(contraction) and glands (secretion of
hormones) and stimulates (cause a response) them
See other document
for image of
Synapse!!
c. Interneurons
i. Found in brain and spinal cord
ii. Integrate information – conducts information between
neurons within the central nervous system
Connect sensory info and send it to motor neurons
Impulse always
travels in one
direction
Terminal Branches
end on effectors
CNS (brain
and spinal
cord)
Lots of
receptors!!
PNS
“Generic”
PNS
Causes effects
Remember they
contain chemicals
(neurotransmitters)
that get released
which will trigger the
response
II:
Tissue Inflammation, Repair, Aging and Death
A. Tissue Inflammation – (cut, sprain, burn, tissue damage) a consequence of
injury; is a body’s response to maintain homeostasis when tissues are
damaged. Inflammation mobilizes the body’s defenses (immune system),
isolates and destroys microorganisms, foreign materials and damaged
cells so that tissue repair can proceed. Finger tips/feet = highly innervate,
even if someone cannot feel it, your body is still working to FIX IT!
a. five major responses/symptoms
a. heat
b. redness
c. pain
d. swelling (AKA – edema)
e. disturbance of function
b. responses initiated by release of chemicals called mediators of
inflammation which act on injured tissue and associated blood vessels
a. histamine – causes vessels to dilate(open wide) and become
more permeable(release of liquids)
i. produce responses of redness and heat & swelling
ii. also allow materials and blood cells to move out of the
blood vessels and into the damaged tissue with its
antibodies, oxygen and clotting (Platelets will start the
chemical clotting chain reactions) factors Diapedesis
– Essentially histamine allows the capillary cells to
separate slightly so that WBC can leave a capillary by
squeezing through the space between two squamous
cells – wbc will then hunt down the bacteria/the site of
injury
Antihistamine – STOPS the dilation/permeability – most
popular with allergies (dry out your sinuses)
b. pain (protective mechanism) is caused by either
i. nerve cell endings (or nerves themselves) are directly
damaged (Limit movement – don’t want to cause more damage at
the point of injury)
ii. as a consequence of fluid accumulation (edema
swelling adds pressure) from the vessels with increased
permeability
c. pain, limitation of movement due to the edema, and tissue
destruction all contribute to disturbance of function (cant use
injured part)
C. Tissue Repair - the substitution of viable (living) cells for dead ones; can be
achieved by regeneration or replacement and is determined by the type of
tissues and severity of the wound. (some cannot be regenerated or replaced)
a. Regeneration – like to like new cells are the same type as those that
were destroyed and normal function resumes plain cell division,
mitosis
b. Replacement – new type of tissue develops that causes scar (not the
orginal tissue type being manufactured) (accumulation of connective
tissue) production and the loss of some tissue function - usually
occurs when the wound is severe
3 Types of Cells:
1. Labile Cells: Cells that divide all throughout your life. Ex: skin, mucus membranes.
Repaired by regeneration
2. Stable Cells: cells that retain the ability to divide after injury BUT do not divide
regularly once growth has stopped. Ex: bone cells and glands. More regeneration (but
some replacement)
3. Permanent Cells: little or no ability to divide. If they are destroyed replaced by
connective tissue (scar) Ex: nerve cells, skeletal, muscle cells
D. Tissue Aging – some changes are obvious while others subtle.
a. Affect cells and the extra-cellular matrix produced by those cells
b. Cells divide more slowly as one ages
c. Collagen fibers become more irregular in structure, even though they
increase in number.
i. As a result, tissues with collaged (i.e. tendons) become less
flexible and more fragile
d. Elastic fibers fragment and bond to calcium ions and become less
elastic
e. Reduced flexibility and elasticity are causes of wrinkles as well as
increased tendency for bones to break
E. Tissue Shrinkage and Death
1. Atrophy – shrinkage of tissue through decrease in cell size or cell number.
Limb immobilized in a cast due to breakage
Normal Aging- Senile Atrophy
Lack of Use – Disuse Atrophy
2. Necrosis – Premature pathological death of tissue due to trauma/ infection
/toxin
Gangrene – necrosis due to insufficient blood supply
Gas gangrene – due to bacteria
Infarction – sudden tissue death (ie. Heart muscle) when blood supple is
cut off
3. Apoptosis – programmed cell death (Normal!!) Cells are quickly phagocytized
by WBC (no inflammation)
Webbing between fingers – in embryo
Shrinkage of Uterus after pregnancy