Connective Tissue, Specialized Tissue and Repair

Biology 2121Chapter 4

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

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

General Characteristics - Structure 1. Less Cells- More

Matrix• Refers to the “non-

cellular” part of connective tissue

2. Fibers, water, organic molecules, acid

3. Other cell types– May or may not be

present – Mast cells; macrophages;

adipose cells; plasma cells

The Matrix • Composed of ‘ground

substance’ and ‘fibers’

1.Ground Substance – 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

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

Classification of Connective Tissue

Dense CT

• Dense CT – 1. Regular Dense CT– 2. Irregular Dense CT

Classification of Connective Tissue

Classification of Connective Tissue

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

Specialized Tissue - Membranes

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

Tissue Repair • Begins with Inflammation

– 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