1. Connective Tissue, Specialized Tissue and Repair
Biology 2121
Chapter 4

2. Characteristics of Connective Tissue
General Characteristics
Less cellular; nonliving part
Vascular (exception is cartilage)
Innervated
Functions
Protection and insulation (organs)
Binds tissues – ligaments
Transports vital substances (blood)
Stored energy source (adipose tissue)
Supports epithelial tissue
Stem Cell – Mesenchyme
All CT cells originate

3. CT Stem Cell Stem Cell – Mesenchyme
All CT cells originate from this embryonic stem cell
Each type of CT has a specific ‘main’ cell type
Secretes the matrix
Maintains the tissue

4. General Characteristics - Structure
Less Cells- More Matrix
Refers to the “non-cellular” part of connective tissue
Fibers, water, organic molecules, acid
3. Other cell types
May or may not be present
Mast cells; macrophages; adipose cells; plasma cells

5. The Matrix Composed of ‘ground substance’ and ‘fibers’
Between cells and fibers
Water
Organic molecules – ‘Glycosaminoglycans’ (GAG’s)
Protein core (proteoglycans) with GAGs attached
Chondroitin sulfate; keratan sulfate; Hyaluraonic acid
2. Function of the Ground Substance
Water storage; binds and supports cells; tissue development

6. Fibers
3. Fibers
(a). Collagen – found in bone, cartilage, tendons, ligaments
Fibrous Protein
(b). Elastic – ‘elastin’ protein; stretch and contract; found in skin, BVs, lung tissue
(c). Reticular – fine collagen bundles; thin; support spleen and lymph structures; forms part of basement membrane

7. Classification of Connective Tissue
Connective Tissue Proper
Main Cell Type: Fibroblasts
Characteristics
Examples – Loose CT
1. Areolar CT
2. Adipose
3. Reticular CT
Dense CT
1. Regular Dense CT
2. Irregular Dense CT

8. Dense CT
Dense CT
1. Regular Dense CT
2. Irregular Dense CT

9. Classification of Connective Tissue
2. Cartilage
Main Cell Type: Chondrocytes
Characteristics
Examples:
1. Hyaline
2. Elastic
3. Fibrocartilage

10. Classification of Connective Tissue
3. Osseous Tissue
Main Cell Type: Osteocytes
Characteristics
Example:
1. Compact Bone
2. Spongy Bone
4. Blood
Cells: Erythrocytes, Leukocytes; Platelets
Why is blood considered a connective tissue?
Plasma

11. Specialized Tissue - Membranes
Parts of the body are covered by ‘membranes’ which are composed of several different types of tissue
Connective Tissue bound to Epithelial Tissue
Examples:
1. Cutaneous membranes
2. Mucous membranes
3. Serous membranes

12. Specialized Tissue - Membranes
Cutaneous
Stratified squamous (keratin) + Dense Irregular CT
“Dry Membrane” ; Skin
Mucous
Stratified squamous/simple columnar + Loose CT
Moist; Lines body cavity; digestive and respiratory
Serous
Simple squamous + areolar loose CT
Referred to as ‘mesothelia’
‘closed’ ventral cavities
Serous fluid (anti-frictional)
Examples: Pleura, Pericardium, Peritoneum

13. Injury and Repair of Tissue
Ability to Repair
1. Epithelium, bone, CT proper, dense irregular, blood regenerates well
2. Smooth muscle and dense regular regenerate moderately well
3. Skeletal muscle and cartilage repair but poorly
4. Cardiac and nervous tissue (none)
Fibrous scar tissue
Depends on:
Supporting CT ability produce new cells
Functioning organ and tissue ability to produce new cells

14. Tissue Repair Begins with Inflammation Granulation Fibrosis
Capillaries dilate; tissue inflamed
Dying cells/tissue release chemicals
WBCs, macrophages, platelets enter
Granulation
New collagen develops; BVs branch to all parts of injured tissue
Connective tissue grows – ‘granulation tissue’ across the wound
SCAB and Tissue Regeneration
Fibrosis