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Tissues
Anatomy and Physiology
Four tissue types
• Epithelium
• Connective
• Muscle
• Nervous
Epithelium
• Functions: protection, secretes, absorbs, excretes
• Location: covers body surfaces, lines internal organs, glands
• Is found anywhere the body has an outside link
Epithelium
• Is anchored to connective tissue
• Does not contain blood vessels
• How, then, would epithelium get needed materials?
Epithelium
• Reproduces rapidly• Heals quickly• Tightly packed
Epithelium
• Classified by cell shape and layers
• Three general groups:
simple—one layer of cells
stratified—layered
glands—produce and secrete substances
Epithelium
• Three shapes or forms:
1. squamous: flat cells
• May be simple or stratified (usually simple)
Simple squamous
Epithelium
• Shape 2: cuboidal• Cube shaped, but may
have rounded edges• May be simple or
stratified
Epithelium
• Shape 3: columnar• Longer, oval or
rectangular, tall cells• May be simple or
stratified
Connective Tissue
• Very diverse
• Functions include: to bind, support, store fat, blood and immune cells
• Though they appear to unrelated, they have the same structure microscopically
Structure
Cells farther apart than epithelium
Have fibers in between the cells
Background of either fluid, solid or semi-solid
Good blood supply (must support epithelium)
Structure
• Solid background: bone
• Semi-solid background: cartilage, loose connective
• Fluid background: blood
Major Cell Types
• Fibroblasts: produce 3 types of connective fibers
1. collagenous (made from collagen); a tough white fiber as in tendons
Fibroblasts produce
• 2. Elastic fibers: most abundant, appear yellow, made from elastin, are weaker, can stretch.
• Found in vocal chords and walls of blood vessels
Fibroblasts produce
• 3. Reticular: found in lymph organs, digestive and respiratory passages
Major Cell Types
• Macrophages (engulfers)
• Mast Cells: produce heparin, which prevents blood clotting and histamine, which reacts in allergies and inflammation
Examples of Connective
• Loose fibrous connective: binds epithelium to under layers
Examples of Connective
• Adipose: fat storing
• Cells get larger as fat is added
Examples of Connective
• Dense fibrous connective: closely packed fibers
• Ligaments
Examples of Connective
• Bone: most rigid
• Made in concentric circles
Examples of Connective
• Blood: consists of plasma, red blood cells, white blood cells, many dissolved substances and fibers
Examples of Connective
• Cartilage: fibers and background make it flexible;
• 3 types of cartilage
Muscle Tissue
• Three types:• 1. Skeletal• 2. Smooth• 3. Cardiac
• Can contract
Skeletal Muscle
• Voluntary• Attaches to bone• Long threadlike fibers• Striated (appears
striped)• Each cell has many
nuclei
Smooth Muscle
• Involuntary• Not striated (smooth)• Spindle shaped cells
with one large nucleus
• Found in walls of internal organs and blood vessels
Cardiac Muscle
• Only in the heart• Involuntary• Striated• Special branches to
interconnect cells• This makes the message to
contract reach all cells at about the same time
• Cell to cell communication proteins help with this also
Nervous Tissue
• Found in brain, spinal cord, and nerves
• Basic cell is the neuron
• Neurons can respond to a stimulus and send an impulse
Neuron
Nervous Tissue
• Mixed in with the neurons are support cells called Neuroglial cells
• They support, bind, and contain the blood supply
• Neuroglial cells do not receive and send impulses
The purple are axons from neurons; the pink cells are neuroglial cells