1. Last Part of the Ch. 4 Power Point

2. Mucous Membranes Mucosa indicates location not cell composition
All called mucosae
Line body cavities open to the exterior (e.g., Digestive, respiratory, urogenital tracts)
Moist membranes bathed by secretions (or urine)
Epithelial sheet lies over layer of connective tissue called lamina propria
May secrete mucus
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3. Figure 4.11b Classes of membranes.
Mucous membranes
Mucous membranes line body
cavities that are open to the
exterior.
Mucosa of
nasal cavity
Mucosa of
mouth
Esophagus
lining
Mucosa of
lung bronchi
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4. Serous Membranes Serosae—found in closed ventral body cavity
Simple squamous epithelium (mesothelium) resting on thin areolar connective tissue
Parietal serosae line internal body cavity walls
Visceral serosae cover internal organs
Serous fluid between layers
Moist membranes
Pleurae, pericardium, peritoneum
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5. Figure 4.11c Classes of membranes.
Serous membranes
Serous membranes line body cavities that are closed to the exterior.
Parietal
pleura
Visceral
pleura
Parietal
peritoneum
Parietal
pericardium
Visceral
pericardium
Visceral
peritoneum
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6. Necessary when barriers are penetrated Cells must divide and migrate
Tissue Repair
Necessary when barriers are penetrated
Cells must divide and migrate
Occurs in two major ways
Regeneration
Same kind of tissue replaces destroyed tissue
Original function restored
Fibrosis
Connective tissue replaces destroyed tissue
Original function lost
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7. Steps in Tissue Repair: Step 1
Inflammation sets stage
Release of inflammatory chemicals
Dilation of blood vessels
Increase in vessel permeability
Clotting occurs
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8. Scab Epidermis Vein Blood clot in incised wound Inflammatory chemicals
Figure Tissue repair of a nonextensive skin wound: regeneration and fibrosis.
Slide 1
Scab
Epidermis
Vein
Blood clot in
incised wound
Inflammatory
chemicals
Migrating white
blood cell
Artery 1
Inflammation sets the stage:
• Severed blood vessels bleed.
• Inflammatory chemicals are released.
• Local blood vessels become more permeable, allowing white blood cells,
fluid, clotting proteins, and other plasma proteins to seep into the injured area.
• Clotting occurs; surface dries and forms a scab.
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9. Steps in Tissue Repair: Step 2
Organization restores blood supply
The blood clot is replaced with granulation tissue
Epithelium begins to regenerate
Fibroblasts produce collagen fibers to bridge the gap
Debris is phagocytized
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10. Organization restores the blood supply:
Figure Tissue repair of a nonextensive skin wound: regeneration and fibrosis.
Slide 2
Regenerating
epithelium
Area of
granulation
tissue
ingrowth
Macrophage
Budding capillary
Fibroblast
Organization restores the blood supply:
• The clot is replaced by granulation tissue, which restores the vascular
supply.
• Fibroblasts produce collagen fibers that
bridge the gap.
• Macrophages phagocytize dead and dying cells and other debris.
• Surface epithelial cells multiply and migrate over the granulation tissue. 2
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11. Steps in Tissue Repair: Step 3
Regeneration and fibrosis
The scab detaches
Fibrous tissue matures; epithelium thickens and begins to resemble adjacent tissue
Results in a fully regenerated epithelium with underlying scar tissue
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12. Regeneration and fibrosis effect permanent repair:
Figure Tissue repair of a nonextensive skin wound: regeneration and fibrosis.
Slide 3
Regenerated
epithelium
Fibrosed area 3
Regeneration and fibrosis effect permanent repair:
• The fibrosed area matures and contracts; the epithelium thickens.
• A fully regenerated epithelium with an underlying area of scar tissue results.
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13. Regenerative Capacity in Different Tissues
Regenerate extremely well
Epithelial tissues, bone, areolar connective tissue, dense irregular connective tissue, blood-forming tissue
Moderate regenerating capacity
Smooth muscle and dense regular connective tissue
Virtually no functional regenerative capacity
Cardiac muscle and nervous tissue of brain and spinal cord
New research shows cell division does occur
Efforts underway to coax them to regenerate better
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14. Developmental Aspects
Primary germ layers
Superficial to deep: ectoderm, mesoderm, and endoderm
Formed early in embryonic development
Specialize to form the four primary tissues
Nerve tissue arises from ectoderm
Muscle and connective tissues arise from mesoderm
Epithelial tissues arise from all three germ layers
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15. 16-day-old embryo (dorsal surface view) Muscle and connec-
Figure Embryonic germ layers and the primary tissue types they produce.
16-day-old embryo
(dorsal surface view)
Epithelium
(from all three
germ layers)
Ectoderm
Mesoderm
Endoderm
Inner lining of
digestive system
(from endoderm)
Nervous tissue
(from ectoderm)
Muscle and connec-
tive tissue (mostly
from mesoderm)
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16. Aging Tissues
Normally function well through youth and middle age if adequate diet, circulation, and infrequent wounds and infections
Epithelia thin with increasing age so more easily breached
Tissue repair less efficient
Bone, muscle and nervous tissues begin to atrophy
DNA mutations possible  increased cancer risk
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