Chapter 5 Tissues

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Chapter 5 - Tissues

• Histology the study of tissues

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Chapter 5 - Tissues

• There are 4 basic types of tissue
• Epithelium lines and covers body surfaces
• Connective job varies by individual tissue
• Muscle contracts and produces movement
• Nerve initiates and conducts action potentials
  (nerve impulses)

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Chapter 5 - Tissues

• Epithelium
• All epithelial cells have an attached surface and
  a free surface. The attached surface is held by
  the basement membrane and is in close proximity
  to the blood supply to the area.
• Epithelium is avascular, anervous, and highly
  regenerative.

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Chapter 5 - Tissues

• Simple epithelium performs the job of
  absorption/excretion
• S. squamous found in the lung and lines the
  walls of the blood vessels
• S. cuboidal found primarily in the tubules of
  the kidneys and in some glands.
• S. Columnar lines the G.I. tract to include the
  stomach, small and large intestines.
• Pseudo stratified Columnar appears to have more
  than one layer, but all cells are attached to the
  basement membrane. Found in the upper
  respiratory system, these ciliated cells move
  mucus superiorly in order to keep it out of the
  lungs.

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Chapter 5 - Tissues

• Stratified Epithelium performs the job of
  protection as it has many layers of cells.
• Strat. Squamous this tissue is found widely
  distributed in the skin. The cells nearest the
  basement membrane are undergoing constant
  mitosis, while the layers above them are in
  varying stages of dying. Dead cells are lost and
  replaced by new ones.
• Transitional this form of epithelium has a lot
  of elastin fibers allowing for a great degree of
  stretch and recoil.

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Chapter 5 - Tissues

• Glandular Epithelium is composed of cells
  specialized to produce and secrete substances
  into ducts or body fluids.
• Endocrine glands secrete their products into
  tissue fluid or blood
• Exocrine glands secrete their products onto open
  surfaces, such as the skin or the lining of the
  digestive tract

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Chapter 5 - Tissues

• Connective
• Major Cell types
• Fixed cells fibroblasts are the most common.
  These cells sit fast in their position
• Wandering cells Macrophages and Mast Cells are
  able to move about to areas where they are
  needed.

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Chapter 5 - Tissues

• Fiber Types
• Collagen a major structural protein, this fiber
  is found in great quantity in connective tissue.
  Heaviest abundance is in dense regular connective
  tissue in the ligaments and tendons.
• Elastic made of elastin, a stretchy protein,
  these fibers allow for recoil when stretched out
  of their normal form.
• Reticular very thin collagenous fibers that are
  highly branched.

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Chapter 5 - Tissues

• Categories
• Loose Connective Tissue aka Areolar Tissue,
  this tissue binds the skin to the underlying
  organs and fills the spaces between the muscles.
  The cells here are called fibroblasts.
• Adipose Tissue these cells contain stored
  neutral fat. This tissue acts as an insulator, a
  cushion, and a stored energy reserve.

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Chapter 5 - Tissues

• Dense Connective Tissue this tissue has a lot
  of collagen fibers and is found most
  predominately in tendons and ligaments. Blood
  supply to this tissue is usually somewhat poor.
• Elastic Connective Tissue Found in larger
  arteries, some portions of the heart and larger
  airways, this tissue allows for considerable give
  on part of the structure involved. Fibroblasts
  are the cells here.

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Chapter 5 - Tissues

• Cartilage Chondrocytes are the chief cells
  here. This tissue provides protection, support,
  attachments and forms structural models for
  future bone. All cartilage is avascular and thus
  one of the slowest healing tissues in the body.

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Chapter 5 - Tissues

• There are three types of cartilage
• Hyaline cartilage is the most common and
  strongest type of cartilage. It is the precursor
  to bone in all the long bones and in most other
  bones. It provides a smooth frictionless surface
  for bony articular surfaces.
• Elastic cartilage possess a recoil quality and is
  found in the external ears and the epiglottis.
• Fibro cartilage possesses qualities of both of
  the above tissues. It is found in the
  intervertebral discs of the spine, the pubic
  symphysis and the menisci of the knee joints.

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Chapter 5 - Tissues

• Bone the strength of this tissue is largely due
  to the matrix of calcium and phosphorus salts,
  but is augmented by collagen fibers found
  dispersed throughout the matrix.

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Chapter 5 - Tissues

• The functional unit of bone is the Osteon (aka
  the Haversian Sx.). The Central Canal (aka the
  Haversian Canal) is found at the center of the
  osteon. Osteocytes are the mature cells found
  here. They live in secluded spaces called
  lacunae. The lacunae are connected to the
  central canal by a series of minute tubes called
  caniliculi. The osteocytes grow to maturity from
  cells called osteoblasts.
• As bone is quite well vascularized it is a very
  active and heals will amazing speed.

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Chapter 5 - Tissues

• Blood This tissue has two parts, plasma and
  formed elements. Plasma is the watery portion in
  which all other cells/parts are suspended. The
  formed elements consist of erythrocytes (RBCs),
  leukocytes (WBCs), and thrombocytes (platelets).
  RBCs transport O2 and CO2, WBCs fight
  infection and play a role in immunity, while
  platelets act in the clotting process.

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Chapter 5 - Tissues

• Membranes
• Two types of membranes exist, Epithelial and
  Connective. The following membranes are
  classified as epithelial
• Serous Membranes line closed body cavities,
  surround and support certain organs, and produce
  a lubricating fluid to decrease friction for
  active organs.
• Mucous Membranes line open body cavities. They
  usually have a layer of epithelium overlying
  connective tissue. This epithelium is invested
  with Goblet cells that produce mucus.

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Chapter 5 - Tissues

• Cutaneous Membranes found in the skin, and is a
  part of the integumentary system.
• The connective tissue membrane of note is the
  synovial membrane which is found in major joints.
  

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Chapter 5 - Tissues

• Muscle
• All muscle tissue is contractile, that is it is
  able to shorten. As the tissue shortens it pulls
  on its attached ends and the overall result is
  movement. There are three types of muscle tissue

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Chapter 5 - Tissues

• Striated Muscle aka skeletal muscle or
  voluntary muscle, these cells are marked with
  dark stripes (striations) and make up the major
  muscle groups of the body. Striated muscle is
  multinucleate and have many mitochondria per
  cell. Control of this tissue is under somatic
  control.
• Smooth Muscle aka visceral muscle or
  involuntary muscle, these cells lack striations
  and are mononucleate. This tissue is found
  primarily in the walls of the hollow organs of
  the digestive, urinary, respiratory, and
  reproductive systems. Control of this tissue is
  under autonomic control.

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Chapter 5 - Tissues

• Cardiac Muscle found only in the wall of the
  heart, cardiac muscle is striated yet under
  involuntary control. This tissue is mononucleate
  and the cells has a specialized cellular junction
  called an intercalated disc that allows rapid
  cell to cell communication. Rapid communication
  enhances the hearts rythmicity and improves
  performance.

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Chapter 5 - Tissues

• Nerve Tissue
• Nerve tissue is highly specialized in that it can
  conduct action potentials (nerve impulses).
• There are two types of nerve cells
• Neurons these are the cells that undertake the
  nerve impulse. They control and regulate many
  body functions.
• Neuroglia These are support cells for the
  neurons. They perform many functions in support
  of the activities of the nervous sx.