Tissue Types and Functions

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Tissue Types and Functions
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• Mammals have four basic types of tissue
• Epithelial
• Connective
• Muscle
• Nerve
• Tissue is a collection of cells, organized for a
  particular function.

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Epithelial Tissue

• Epithelial tissues are packed together in sheets.
• Line the bodys surface and openings.
• Perform many functions
• Offers the body a defense
• Trauma
• Sun
• Extreme temperatures
• Drying
• Bacterial invasion

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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

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Epithelial Tissue

• Epithealial cells can also absorb materials.
• Intestines, lungs, kidneys all absorb materials
  from the surroinding fluids.
• Epithelium has no direct blood supply.
• Connective tissue provides support, nutrition,
  and removes waste via the ECF

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Epithelial Tissues

• Epithelial tissues are classified based on their
  shape.
• Simple with one cell layer
• Stratified with multiple layers
• Transitional with multiple layers
• There are also descriptive terms for the shape
• Squamous (very flat)
• Found where there is a need for exchange
• Blood vessels
• Respiratory system lining

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Epithelial Tissues

• Cuboidal (cube shaped)
• Associated with secretion or absorption
• Glands and tubules in the kidneys
• Columnar (more tall than wide)
• Associated with secretion or absorption
• Glands, stomach and intestines

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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

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• 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

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• 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.

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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.

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• 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

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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.

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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.

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• Porcine Stress Syndrome
• Disease in pigs where calcium is not transported
  back to the ER. Muscles are left stiff.
• Rigor Mortis
• Occurs after death because there is no energy to
  transport calcium back to the ER.
• Hypocalcemia (Milk Fever)
• Due to a lack of calcium before calving, causes
  weaknesscow cant stand. Cured by
  administration of calcium solution to the
  bloodstream.

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Crash Course Tissues
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Nerve Tissues

• Communication super highway.
• Central Nervous System
• Brain and spinal cord
• Peripheral Nervous System
• All nerves outside of the CNS
• Nerve tissue is comprised of bundles of nerve
  cells
• Neurons

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Neurons

• 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.
• A sensory or interneuron stimulates motor

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