Connective tissue

Connective tissue general features

• It binds, supports and strengthens other body tissues.

• A major transport system of the body (blood is a connective tissue).

• A major site of stored energy reserves (fat or adipose tissue is a connective tissue).

Hyaluronic acid

Viscous slippery substance binds cells together, lubricates joints and maintains shape of eyeball

Hyaluronidase

• Produces by white blood cells,c ells, some bacteria

• Makes GS more liquid so can move around more easily or makes access to the egg easier for sperm

Chondroitin sulphate

support and provide adhesive features of cartilage, bone, skin and blood vessels

Keratan sulphate

found in bone, cartilage, cornea of eye

Dermatan sulphate

found in skin, tendons, blood vessels, heart valves

Abnormal Periorbital ECM and thyroid disease (Exophthalmos)

• Most common in younger women

• Goitre (swollenness thyroid gland)

• Autoimmune over-activation of thyroid (goitre)

• Autoimmune action on fibroblasts in ECM of eye (exophthalmos)

Deposition of glycosaminoglycans and influx of water increase orbital contents

Collagen fibres

• Thick

• Very strong but flexible to resist pulling forces

• Features differ in different tissue—more water found in collagen in cartilage than in bone

• Collagen makes 25% of body, most abundant protein

Collagen fibres common in:

• Bone

• cartilage

• Tendons

• Ligaments

Parallel bundles

Reticular fibres

• Composed of collagen with coating of glycoprotein

• Collagen in reticular fibre in fine bundles, more protein than sugar

• Made by fibroblasts

• Provides strength and support

• Forms part of the basement membrane

• Thinner and branches out spreading through tissue

• Forms networks through vessels and especially through tissue

Reticular fibres common in:

• Adipose tissue, nerve fibres, smooth muscle tissue

Elastic fibres

• Thinner than collagen fibres

• Fibrous network

• Consists of protein elastin surrounded by glycoprotein fibrillin to give more strength and stability

• Can be stretched 150% without breaking

Elastic fibres common in:

• Skin

• blood vessels

• lungs

What fibre involved in Marfan syndrome?

Elastic fibre

• hereditary defect from dominant mutation in gene on chromosome 15 coding for fibrillin

Fibrillin

Large glycoprotein contributing to structural scaffold for elastin

Cause of Marfan syndrome

Body produces growth factor called Transforming Growth Factor beta which increases growth as it does not bind to fibrillin to keep it inactive (theory)

Marfan syndrome characteristics

• Tall, long limber

• chest deformity—protruding/collapsed sternum

• Normal life stain but need medical check ins controlling blood pressure

• may have weakened heart valves

• 1/20000 live births

Two common connective tissue cell types

• Fibroblasts

• Adipocytes

Also includes:

• Macrophages

• Plasma cells

• Mast cells

• Leucocytes

Fibroblasts

Location: Widely distributed in connective tissue; migratory

Function: secret components of extracellular matrix, fibres + ground substance

Adipocytes

• Fat cells

• Location: under skin and around organs

• Function: store fat, triglycerides

Embryonic connective tissue

• Mesenchyme (embryonic)

• Mucous

Mature connective tissue

• Connective tissue proper

  • Loose

  • Dense

• Fluid connective tissue

  • Blood

  • Lymph

• Supporting connective tissue

  • Cartilage

  • Bone

Connective tissue proper (loose)

Loose: fibres create loose, open frame work

• Areolar tissue

• adipose tissue

• reticular tissue

Fluid CT

• Blood: flows within CV system

• Lymph: flows within lymph system

Mesenchyme

• Gives rise to all other connective tissue

• Consists of connective tissue cells (mesenchymal cells) in a semi fluid ground substance containing reticular fibres

Mucous

Has widely scattered fibroblasts embedded in jelly like ground substance, supports umbilical cord of foetus

Areolar CT

Three types of fibre present

Widely distributed around almost every structure, like packing material

Strength, elasticity, support

Adipose

Adipocytes dominant

Central triglyceride droplet

Found with areolar CT including fibroblasts

White for storage, brown for insulation

Insulation, energy source, temp control

Reticular

Reticular fibres dominant, thin and delicate

Spleen, kidney, lymph nodes

Structure for immune cells to move around