1. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings PLAY InterActive Physiology ®: Nervous System I: Anatomy Review Nervous Tissue  Two Main Cell Types: 1. Neurons – specialized nerve cells that generate and conduct nerve impulse 1. Respond to stimuli 2. Transmit electrical impulses over distances 2. Supporting Cells – non-conducting cells that support, insulate, and protect neurons.

2. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings PLAY InterActive Physiology ®: Nervous System I: Anatomy Review Nervous Tissue  Description: Branched neurons with long cellular processes and support cells  Function: Transmits electrical signals from sensory receptors to effectors  Location: Found in the brain, spinal cord, and peripheral nerves

3. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Nervous Tissue Figure 4.10

4. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Muscle Tissus  Highly vascular tissue  Responsible for most body movement  Cells have myofilaments (actin and myosin filaments)  Three types of muscle tissue:  Skeletal  Cardiac  Smooth

5. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Muscle Tissue: Skeletal  Description: Long, cylindrical muscle fibers. Multinucleate cells with obvious striations (alignment of fibers)  Function: Initiates and controls voluntary movement  Location: Found in skeletal muscles that attach to bones or flesh / skin

6. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Muscle Tissue: Skeletal Figure 4.11a

7. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Muscle Tissue: Cardiac  Description: Branching cells that fit together tightly at junctions called intercalated discs. Striated, uninucleate cells  Function: Propels blood into the circulation through blood vessels. Involuntary control.  Location: Found in the walls of the heart

8. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Muscle Tissue: Cardiac Figure 4.11b

9. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Muscle Tissue: Smooth  Description: Sheets of spindle-shaped cells with one central nuclei that have no striations  Function: Propels substances along internal passageways (i.e., peristalsis). Involuntary.  Location: Found in the walls of hollow organs (except heart)

10. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Muscle Tissue: Smooth Figure 4.11c

11. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Covering and Lining Membranes  Three types of covering and lining membranes: 1. Cutaneous 2. Mucous 3. Serous  Continuous multicellular sheets composed of at least two primary tissue types: 1. Epithelium – bound to an underlying layer of CT 2. Connective Tissue - Figure 4.12a

12. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Epithelial Membranes: Cutaneous Membrane  Cutaneous  Skin = organ system consisting of  Keratinized stratified squamous epithelium (epidermis)  Thick layers of dense irregular connective tissue (dermis)  Exposed to air (dry membrane) Figure 4.12a

13. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Epithelial Membranes: Mucous Membrane  Lines body cavities open to the exterior (e.g., digestive and respiratory tracts, urogenital tracts)  Wet or moist membranes  Bathed by secretions (or urine in case of bladder)  Mucosa = location of membrane not cell composition  Mucosae contain  Stratified squamous or  Simple columnar epithelia  Under this epithelial sheet is lamina propria  Sometimes there is a third, deeper layer of smooth muscle tissue  Often adapted for absorption and secretion (digestive & respiratory) Figure 4.12b

14. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Epithelial Membranes: Serous Membranes Figure 4.12c Serous – moist membranes found in closed ventral body cavity Consist of: Simple squamous epithelium (mesothelium) Loose connective (areolar) tissue – under the simple squamous epithelium Clear serous fluid lubricates facing surfaces of parietal and visceral layers so they slide across each other easily. Named for site and specific organ (pleura – thoracic wall and lung; pericardium, peritoneum)

15. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Tissue Repair  Defenses of Body’s External Boundaries 1. Skin & Mucosae 2. Cilia of epithelial cells lining respiratory tract 3. Strong acid of stomach  Injury causes penetration of these barriers and an inflammatory response ensues  Cells must divide and migrate (initiated by growth factor released by injured cells)

16. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Tissue Trauma  Repair occurs in two ways: 1. Regeneration – replacement of destroyed tissue with the same kind of tissue 2. Fibrosis – involves proliferation of fibrous connective tissue (scar tissue)  Type of repair depends on 1. Type of tissue damaged 2. Severity of injury

17. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Inflammation 1. Trauma causes injured cells, macrophages, mast cells, and other cells to release inflammatory chemicals Inflammation characterized by:  Dilation of blood vessels (capillaries)  Increases permeability – allows WBC (neutrophils, monocytes) and plasma fluid – rich in clotting proteins, antibodies, and other substances to seep into the injured area.  Clotting proteins construct a clot – stops blood loss, holds edges of wound together. Clot becomes scab.  Redness, heat, swelling, and pain

18. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Step 1 of Tissue Repair: Organization A. Blood clot is replaced with granulation tissue  Granulation tissue – delicate pink tissue composed of several elements  Capillaries from nearby areas infiltrate area – fragile and bleed freely B. Proliferating fibroblasts in granulation tissue produce growth factors and new collagen fibers to bridge the gap  Some fibroblasts have contractile properties that pull margins of the wound together Figure 4.13a

19. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Step 1 of Tissue Repair: Organization C. Macrophages digest original blood clot. D. Collagen fiber deposit continues E. Granulation tissue (will become scar) is highly resistant to infections (bacteria-inhibiting substance) F. When enough matrix has accumulated – fibroblasts revert to resting stage or undergo apoptosis Figure 4.13a

20. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Step 2 of Tissue Repair: Regeneration & Fibrosis  Fibrous tissue matures and begins to resemble the adjacent tissue Figure 4.13b Surface epithelium begins to regenerate, growing under the scab Fibrous tissue under scab matures and contracts, regenerating epithelium thickens

21. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Steps of Tissue Repair  Results in a fully regenerated epithelium with underlying scar tissue Figure 4.13c

22. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Tissues that Regenerate Extremely Well:  Epithelial tissues  Bone  Areolar connective tissue  Dense irregular connective tissue  Blood-forming tissue Figure 4.13c

23. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Tissues that Regenerate Moderately Well:  Smooth muscle  Dense regular connective tissue Figure 4.13c Tissues that have weak regenerative capacity: Skeletal muscle Cartilage Cardiac muscle Nervous tissue Virtually no functional regenerative capacity (replaced with scar tissue)

24. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Scar Tissue  Non-regenerating tissues (and severe wounds) – fibrosis totally replaces lost tissue. Fibrous mass becomes more compact over months.  Scar tissue appears as pale shiny area – mostly collagen fibers  Scar tissue is strong but lacks flexibility and elasticity of most normal tissues.  Cannot perform normal functions of tissue it has replaced. Figure 4.13c

25. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Developmental Aspects  Primary germ layers: ectoderm, mesoderm, and endoderm  Three layers of cells formed early in embryonic development  Specialize to form the four primary tissues (from which all organs are derived)  Nerve tissue arises from ectoderm  Mesoderm - gives rise to muscle, connective tissue, endothelium, and mesothelium.  Endoderm gives rise to most mucosae  Epithelial tissues arise from all three germ layers

26. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Developmental Aspects  Most cells continue to divide through fetal period except nerve cells.  After birth, most tissues continue to divide until adult body size is achieved, then slows but maintains ability to regenerate.  In adults, only epithelia and blood forming tissues are highly mitotic  Glandular liver cells regenerate by division of mature cells  Epidermal cells of skin and lining of intestines – stem cells divide as necessary

27. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Aging and regeneration With good Nutrition, circulation, infrequent wounds or infections – tissues will function normally. Aging, thinning epithelia more easily breached Tissue repair becomes less efficient with poor circulation, worse nutrition (less money for food, worse teeth and inability to chew)

28. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Developmental Aspects Figure 4.14