Tissue Repair Tissue Repair Wound healing Two ways

Tissue Repair

Tissue Repair • Wound healing • Two ways: 1. Regeneration: replace destroyed tissue by same kind of cells

Tissue Repair • Wound healing • Two ways: 1. Regeneration: replace destroyed tissue by same kind of cells 2. Fibrosis: form scar tissue (dense fibrous connective tissue) • Depends on: § Type of tissue damaged § Severity of injury

Steps to Tissue Repair:

1. Inflammatory Reaction • capillaries dilate bringing more WBC’s and clotting factors • clot forms and prevents loss of blood • surface dries forming a scab

2. Granulation tissue forms • • • Delicate pink tissue with new capillaries Connective tissue produces collagen fibers Epithelial cells multiply over granulation tissue

3. Surface epithelium regenerates • • Surface epithelium thickens Fibrous tissue matures – forms scar tissue

Regenerative Capacity of Different Tissues Extremely Well • Skin epidermis • Mucous membranes • Fibrous connective • Blood • Bones Moderate • Smooth muscle • Tendons, ligaments Weak • Skeletal muscle • Cartilage Virtually None (mostly scar tissue) • Cardiac muscle • Nervous tissue

Tissue Origin

3 Primary Germ Layers • Tissues originate from the 3 primary germ layers: 1. ectoderm 2. mesoderm 3. endoderm

1. Ectoderm • Nervous • Epidermis

2. Mesoderm - • Muscle • Connective tissue • Bone

3. Endoderm • mucosa (GI tract) • glands

How Tissue Changes Occurs with age

Tissue Changes 1. epithelium thins easily penetrated 2. collagen (a protein) decreases tissue repair becomes less efficient 3. bone, muscle, nerve degeneration Causes: • due in part to a decrease in circulatory efficiency • poor diet, also

The End