b. Its cells usually form concentric circles around osteonic canals. Canaliculi connect them.
c. It is an active tissue that heals rapidly.
12. Blood a. Blood is composed of cells suspended in fluid.
b. Blood cells are formed by special tissue in the hollow parts of certain bones.
Muscle Tissues (page 160)
1. General characteristics a. Muscle tissue contracts, moving structures that are attached to it.
b. Three types are skeletal, smooth, and cardiac muscle tissues.
2. Skeletal muscle tissue a. Muscles containing this tissue usually attach to bones and are controlled by conscious effort.
b. Cells or muscle fibers are long and threadlike, containing several nuclei, with alternating light and dark cross-markings.
c. Muscle fibers contract when stimulated by nerve impulses, then immediately relax.
3. Smooth muscle tissue a. This tissue of spindle-shaped cells, each with one nucleus, is in walls of hollow internal organs.
b. Usually it is involuntarily controlled.
4. Cardiac muscle tissue a. This tissue is found only in the heart.
b. Cells, each with a single nucleus, are joined by intercalated disks and form branched networks.
c. Cardiac muscle tissue is involuntarily controlled.
Nervous Tissues (page 161)
2. Neurons a. Neurons sense changes and respond by transmitting nerve impulses to other neurons or to muscles or glands.
b. They coordinate, regulate, and integrate body activities.
3. Neuroglial cells a. Some of these cells bind and support nervous tissue.
b. Others carry on phagocytosis.
c. Still others connect neurons to blood vessels.
d. Some are involved in cell-to-cell communication.
1. Joints such as the elbow, shoulder, and knee contain considerable amounts of cartilage and loose connective tissue. How does this explain the fact that joint injuries are often very slow to heal?
2. Disorders of collagen are characterized by deterioration of connective tissues. Why would you expect such diseases to produce widely varying symptoms?
3. Sometimes, in response to irritants, mucous cells secrete excess mucus. What symptoms might this produce if it occurred in (a) the respiratory passageways or (b) the digestive tract?
4. Tissue engineering combines living cells with synthetic materials to create functional substitutes for human tissues. What components would you use to engineer replacement (a) skin, (b) blood, (c) bone, and (d) muscle?
5. Collagen and elastin are added to many beauty products. What type of tissue are they normally part of?
6. In the lungs of smokers, a process called metaplasia occurs where the normal lining cells of the lung are replaced by squamous metaplastic cells (many layers of squamous epithelial cells). Functionally, why is this an undesirable body reaction to tobacco smoke?
1. Define tissue.
1. Define tissue.
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