BIOSCI 107 CONNECTIVE TISSUE

general features of connective tissue

-matrix that binds, supports, and strengthens other body tissues

-transport system (e.g. blood)

-storage place for energy (fat or adipose tissue)

-not found on body surfaces (bones, cartilage, blood)

-can be highly vascular (except cartilage and tendons)

connective tissue composed of

extracellular matrix and cells

extracellular matrix composed of

ground substance and 3 different types of protein fibres

structure of ECM dictates

CT qualities e.g. cartilage-firm and rubbery, bone- hard and inflexible

ground substance is

mixture of water, proteins, polysaccharides

polysaccaride is glycosaminoglycans (GAGS)
GAGS join with core proteins to form proteoglycans

proteoglycans comprised of

protein and GAGS

GAGS (glycosaminoglycans)

long unbranched polysaccharides composed of repeating disaccharide unit made up of amino sugar, uronic sugar (highly polar and attracts H2O)

e.g.s of sulphated GAGS

dermatan sulphate - skin, tendons, blood vessels

heparin sulphate - bind to proteins to form proteoglycans

keratan sulphate - bone, cartilage, cornea

chondroitin sulphate - cartilage, skin, blood vessels

e.g.s of non-sulphated GAGS

hyaluronic acid- does not directly bind to proteins but is joined to various proteoglycans

purpose of GAGS

trap water to make ground substance more jelly-like

hyaluronic acid

viscous, slippery substance that binds cells together

function of hyaluronic acid

lubricates joints and maintains shape of eyeball

three different types of protein fibres

1. collagen (thick)

2. reticular (thin)

3. elastic- can be distorted and returned to normal shape (good for skin etc.)

elastic protein fibre consists of

elastin surrounded by glycoprotein fibrillin

marfan syndrome

hereditary defect in elastic fibres resulting from a dominant mutation in gene on chromosome 15, which codes for fibrillin (large glycoprotein which contributes to structural scaffold for elastin)

cases are usually tall, long-limbed, with chest deformity. weakened heart valves and arterial valves (life-threatening)

fibroblast

widely distributed in connective tissues.

migratory.

secrete components of matrix (fibres and ground substance)

adipocytes

under skin, around organs (store fat)

macrophages

phagocytic.

fixed: spleen, alveolar tissue

wandering: sites of infection/inflammation/injury

plasma cells

from lymphocytes- produce antibodies.

In many CT but especially gut, lung, salivary glands, lymphrodes, spleen, red bone marrow

mast cells

produce histamine (dilates vessels).

alongside blood vessels

leucocytes

white blood cells e.g. neutrophils.

migrate out from blood

embryonic CT called

mesenchyme

mesenchyme

gives rise to all other CT.

mesenchymal cells in semi-fluid ground substance containing reticular fibres

mature CT called

connective tissue proper

loose CT proper

fibres create loose, open framework.

areolar, adipose, reticular.

FOR STRENGTH, ELASTICITY, SUPPORT

adipose CT proper situated

buttocks, flanks, abdomen.

FOR INSULATION, ENERGY

dense CT proper

fibres densely packed.

dense regular, dense irregular, elastic

e.g. tendons, ligaments.

FOR ATTACHMENT

fluid connective tissues

blood and lymph

blood flows within

cardiovascular system

lymph flows within

lymphatic system

supporting CT

cartilage, bone, hyaline

cartilage

solid, rubbery matrix. elastic or fibrous

bone

solid, crystalline matrix

hyaline

relatively weak, resilient gel- fibres present but not obvious.

abundant e.g. anterior ends of ribs, trachea

FOR FLEXIBILITY AND MOVEMENT

compact bone

contains osteons.

stores Ca and P.

FOR PROTECTION, SUPPORT.

spongy bones

no osteons

stores triglycerides (yellow marrow) and produces blood cells (red marrow)

types of bone cells

1. osteogenic cells

2. osteoblast

3. osteocytes

4. osteoclasts

osteogenic cells

mesenchymal stem cells that develop, become trapped -> osteoblasts

osteoblast

bone forming cell

osteocytes

mature bone cells derived from osteoblasts trapped within ECM.

MAINTAIN BONE TISSUE, INVOLVED IN EXCHANGE OF NUTRIENTS AND WASTES.

Have gap junctions

osteoclasts

large, multinucleated cells formed from fusion of blood monocytes.

BREAK DOWN BONE

four types of osteons

1. lamellae

2. lacunae

3. canaliculi

4. central canal

lamellae

concentric rings of mineral salts = hardness

lacunae

spaces between lamellae- contain mature bone cells

canaliculi

communication channels for cells

central canal

where blood vessels come down

blood consists of

blood plasma (liquid ECM) and form elements (red cells, white cells, platelets)

RBC: erythrocytes

transport oxygen and carbon dioxide

leukocytes

combat disease

four different types of leukocytes

1. neutrophils and monocytes

2. basophils

3. eosinophils

4. lymphocytes

neutrophils and monocytes

phagocytic (engulf bacteria)

basophils

release substances e.g. histamine that intensify inflammatory reaction

eosinophils

effective against certain parasitic norms and in acute allergic response

lymphocytes

involved in immune response

platelets involved in

clotting