Download Ch 3 Tissue Repair Growth AP

Chapter 3
Tissue Development, Repair,
& Unusual Growth
Germ Layers & Specialization
Mesoderm
Ectoderm
Endoderm
Specialization
Developmental Aspects of Tissue
 Epithelial tissue
-germ layers: endoderm, mesoderm, ectoderm
 Muscle and Connective tissue
-mesoderm
 Nervous tissue
-ectoderm
 Old age = decrease in mass & viabililty
Tissue Repair
1. Regeneration
 Replacement by the same
kind of cells
2. Fibrosis
 Repair by dense fibrous
connective tissue (scar
tissue)
3. Determination of method
 Type of tissue damaged
 Severity of the injury
Events in Tissue Repair
1.Capillaries become very permeable
 Clotting proteins leak through
 Clot walls off injured area
2. Formation of granulation tissue
 Many capillaries and WBCs
3. Regeneration of surface epithelium
 Develops beneath scab
 Over the scar
Regeneration of Tissues
 Tissues that regenerate easily
- Epithelial tissue
- Fibrous connective tissue and bone
 Tissues that regenerate poorly
- Skeletal muscle
 Tissues that are replaced largely with scar
tissue (amitotic at maturity)
- Cardiac muscle
- Nervous tissue within the brain and spinal cord
Changes in Growth Patterns
1.Neoplasm – mitosis gone crazy; tumor
• Benign – doesn’t spread; stays local
• Malignant – cancerous; invades; spreads via
blood – called metastisis
• Carcinogens – agents that cause cancer;
build up of mutations
2. Hyperplasia – temporary enlargement of localized
tissues; i.e. breasts during pregnancy; can be
normal or abnormal
3. Atrophy – decrease in size due to lack of use