Tissue Types and Functions
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Mammals have four basic types of tissue
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Epithelial
Connective
Muscle
Nerve
Tissue is a collection of cells, organized
for a particular function.
Epithelial Tissue
•
Epithelial tissues are packed together in
sheets.
– Line the body’s surface and openings.
•
Perform many functions
– Offers the body a defense
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Trauma
Sun
Extreme temperatures
Drying
Bacterial invasion
Epithelial Tissue

Epithelial cells that line the respiratory
tract, intestinal tract, urinary and
reproductive tracts also provide
protection.
◦ Respiratory – cilla

Epithelial cells provide secretions
◦ Tears, saliva, mucus, urine, sweat, and milk
Epithelial Tissue

Epithealial cells can also absorb materials.
◦ Intestines, lungs, kidneys all absorb materials
from the surroinding fluids.
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Epithelium has no direct blood supply.
◦ Connective tissue provides support, nutrition,
and removes waste via the ECF
Epithelial Tissues

Epithelial tissues are classified based on their
shape.
◦ Simple with one cell layer
◦ Stratified with multiple layers
◦ Transitional with multiple layers
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There are also descriptive terms for the shape
◦ Squamous (very flat)
 Found where there is a need for exchange
 Blood vessels
 Respiratory system lining
Epithelial Tissues
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Cuboidal (cube shaped)
◦ Associated with secretion or absorption
 Glands and tubules in the kidneys
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Columnar (more tall than wide)
◦ Associated with secretion or absorption
 Glands, stomach and intestines
Integument

Skin performs a variety of functions
◦ Keeps damaging agents out of the body
◦ Keeps fluids and nutrients in the body
◦ Specialization of the skin (hair, fur) helps to
maintain body temperature.
◦ Detects pain, pressure, and temperature
 Sensory organ
Muscle Types
Three muscle types
skeletal, smooth, and cardiac
Skeletal Muscle
muscle that is attached to the skeletal structure
voluntary control through nerve signals from the nervous
system. (Think sphincter)
Smooth Muscle
located in many of the hollow organs of the body, including the
GI tract, urinary bladder, blood vessels.
Involuntary muscle
Cardiac Muscle
-found in the heart
-Involuntary muscle
Involuntary muscles- function at all times even when the animal is
asleep.
Voluntary muscles- function when an animal wants to move.
Skeletal Muscle
Formation
-striated voluntary muscle
-muscle consists of thousands of muscle fibers
(muscle cells)
-entire muscle cell is called a myofiber
Myofiber
-myofibers have several nuclei and large mitochondria.
-organized in parallel rows
-separated by connective tissue that includes blood vessels
and nerves.
Myofilaments
-made up of two proteins, actin and myosin
-organized at entire length of muscle cell
-contraction happens when the actin and myosin filaments
slide along each other
-contraction of muscle fibers begin with stimulation from a
nerve cell.
-Impulses stimulate the release of calcium (stored in
endoplasmic reticulum)
-Energy is needed for this process
-once relaxed, the cell transports calcium back into the ER
Muscle
Cardiac Muscle
Formation
-striated, but is involuntary in action.
-appearance of cardiac myofilaments is very similar to
skeletal muscle
Function
-mechanism is also very similar to the skeletal system, but
contain more mitochondria.
-muscle contracts on own, but nerve cells help establish rate
of contraction.
-glucose and oxygen need to be present in order for the
heart to beat
-Cells are very organized in the action of the heart beating.
Electrical signals are sent between cells which allows the
heart to function as one unit.
Smooth Muscle
Formation
-lacks striated appearance
-still contains actin and myosin filaments, but are not
arranged the same as the skeletal muscle.
-individual myfibers is a spindle-shaped cell, tapered at
each end, with one nucleus.
-arranged in sheets around hollow openings like the GI
tract.
Function
-contractions may make openings smaller
-in blood vessels it is called constriction
-in an organ (esophagus) the contraction helps in
propelling food toward the stomach. (peristalsis)
-automatic nervous system controls the action of
smooth muscle.

Porcine Stress Syndrome
◦ Disease in pigs where calcium is not
transported back to the ER. Muscles are left
stiff.
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Rigor Mortis
◦ Occurs after death because there is no energy
to transport calcium back to the ER.
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Hypocalcemia (Milk Fever)
◦ Due to a lack of calcium before calving, causes
weakness…cow can’t stand. Cured by
administration of calcium solution to the
bloodstream.
CRASH COURSE
TISSUES
Nerve Tissues

Communication super highway.
◦ Central Nervous System
 Brain and spinal cord
◦ Peripheral Nervous System
 All nerves outside of the CNS
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Nerve tissue is comprised of bundles of
nerve cells
◦ Neurons
Neurons
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Sensory – stimulate nerve response to
change environment
◦ Light, heat, pressure, hearing, balance, taste,
smell, internal
Interneurons – Connections or pathways
between neurons
 Motor – Begin in the CNS and extend to
a muscle or gland. When stimulated, an
action occurs.
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◦ A sensory or interneuron stimulates motor