Lecture 3: Connective tissue Flashcards
What are the two components of connective tissue?
CT is made up of extracellular matrix and cells
What are the two types of connective tissue?
Embryonic and mature
What are the functions of connective tissue?
Binds, supports strengthens body structures
Transport system of body - blood
Site of stored energy reserves - adipose tissue
Is CT vascular or avascular?
CT is vascular unlike epithelial tissue meaning it contains blood vessels
Does CT have a supply of nerves?
Yes, all CT contain nerves except cartilage
Is CT found on body surfaces?
No
What are the components of the ECM?
Ground substance and protein fibres
What are the components of the ground substance?
1) water
2) protein
3) polysaccharide (glycosaminoglycans)
What are glycosaminoglycans?
GAGS are long unbranched polysaccharides made up of amino sugar and uronic sugar (disaccharides)
There are two types: sulphated and non-sulphated
What are proteoglycans?
Formed by the long polysaccharide chains binding to core proteins
These molecules have lots of sugar and less protein
What is hyaluronic acid?
Type of non-sulphated GAGS therefore not bound to a core protein
Highly polar therefore can attract and trap water becoming sort of slippery
Viscous slippery substance that binds cells together
What is the function of hyaluronic acid?
Lubricates joints
Maintains shape of eyeball
What is hyaluronidase?
Enzyme that breaks down hyaluronic acid
Produced by sperm, white blood cells and bacteria
It allows species to navigate connective tissue by making ground substance more liquid
What is the chondroitin sulphate?
Type of sulphated GAGS that support and provide the adhesive features of cartilage, bone, skin , blood vessels
What is keratan sulphate?
Sulphated GAGS found in bone, cartilage and cornea of eye
What is dermatan sulphate?
Sulphated GAGS found in skin, tendons, blood vessels, heart valves
What is exophthalmos?
A disorder related to abnormal ECM causing the bulging of the eyes.
Occurs when the immune system attacks tissue in the thyroid gland causing over-activation and production of hormones. The extra hormones stimulate fibroblasts in the eye causing an influx of water and pushing eyes forward
What are the three types of protein fibres?
1) Collagen
2) Reticular fibre
3) Elastic fibre
What is collagen
A protein fibre that makes up the ECM of CT.
Strong and flexible allowing to resist pulling forces
Common in bone, cartilages, tendons and ligaments
What is reticular fibre
A protein fibre that makes up the ECM of CT
Made up of fine bundles of collagen + glycoprotein coating
Made by fibroblasts (like reticular lamina of basement membrane)
Provides strength and support
Found in basement membrane, vessels, adipose tissue, nerve fibres, smooth muscle tissues
What is elastic fibre
A protein fibre that makes up the ECM of CT
Made up of elastin surrounded by fibrillin giving strength and stability
Allows tissue to be stretched
Found in skin, blood vessles, and lung
Symptoms of marfan syndrome
Abnormal growth of limbs caused by defect in fibrillin of elastic fibres
Stability of heart valves and arterial walls are decreased.
How is marfan syndrome caused?
Hereditary defect on chromosome 15 for the coding of fibrillin, a glycoprotein that usually binds to TGFbs regulating growth. Fibrillin cannot bind to TGFbs causing abnormal growth.
What is fibrillin?
A type of glycoprotein that makes up elastic fibres along with elastin. It forms a scaffold for elastin and also binds to transforming growth factor betas controlling growth.
What are the two most common types of cells that make up CT?
Fibroblasts and adipocytes
What are fibroblasts?
Cells of CT
Secretes components of matrix (eg secretes reticular fibres forming reticular lamina of basement membrane)
Migratory
What are adipocytes?
Cells of CT
store fat (energy reserves)
found under skin and around organs
What are macrophages?
Cells of CT
phagocytic
Resonant and migratory forms
Found at sites of infection, inflammation and injury
What are plasma cells?
Formed from B-lymphocytes
Produce antibodies
Found widely
What are mast cells
Produce histamine - dilates blood vessels
Found in blood vessels
What are leucocytes?
White blood cells of immune system
Move around blood
What are the two types of embryonic CT?
Mesenchyme and mucous
What is mesenchyme CT?
Type of embryonic CT
Gives rise to all CT
Consists of mesenchymal cells in a semi-fluid ground substance containing reticular fibres
What is mucous CT?
Type of embryonic CT
Supports umbilical cord of foetus
Contains fibroblasts embedded in jelly-like ground substance
What are the types of mature CT?
Loose CT
Dense CT
Supporting CT - cartilage and bone tissue
Fluid CT - blood
What is the difference between loose CT and dense CT?
Loose CT contain more cells less fibres
Dense CT contains more fibres lee cells
What are the 3 types of loose CT?
Areolar
Adipose
Reticular
What is areolar CT?
Made up all types of protein fibres
Found in all structures (most common CT)
Provides structure, elasticity and support
What is adipose CT?
Made up of adipocytes
White adipose stores energy
Brown adipose produces heat
Provides energy source, temperature control and insulation
What are the two types of adipose tissue and their functions
White adipose stores energy
Brown adipose produces heat
What is reticular CT?
Made up of reticular fibres and reticular cells
Forms stroma of organs
Binds muscle tissue
What are the three types of dense CT?
Dense regular
Dense irregular
Elastic
What is dense regular CT?
Regular arranged collagen fibres
Found in tendons, ligaments, and aponeuroses
Provide attachment between structures
What is dense irregular CT?
Irregular arranged collagen fibres
Found as sheets in skin, around muscles and organs
Provides tensile strength in many directions
What is elastic CT?
Contains elastic fibres with fibroblasts
Found in lungs, wall of blood vessels, bronchial tubes
Allows organs to stretch
What are the two types of supporting CT
Cartilage and bone tissue
What are the three types of cartilage ?
1) hyaline
2) fibrocartilage
3) elastic cartilage
What is hyaline cartilage?
Relatively weak cartilage
Found in nose, trachea and bronchi (respiratory system)
Allows flexibility and movement
What is fibrocartilage?
Made up of chondrocytes and thick bundles of collagen fibres
Found where hips join, intervertebral discs, cartilage of knee
Supports and joins structures together
Strongest type of cartilage
What is elastic cartilage?
Made up of chondrocytes and elastic fibres
Found on larynx lid, ear, and auditory tubes
Provides strength and elasticity; maintains shape of certain structures
What are the two types of bone tissue?
Compact and spongy
What is compact bone tissue
Forms outer layer of bones
Has rod-shaped units called osteons or harversian systems
Stores calcium and phosphorus
Protection and support
What is spongy bone tissue
Forms inner layer of bone
No osteons
Stores triglycerides (yellow bone marrow)
Produces red blood cells (red bone marrow)
What are the 4 types of cells found in bones?
Osteogenic cells -> Osteoblasts -> Osteocytes
Osteoclasts
What are osteogenic cells?
Mesenchymal stem cells that develop
Begin to lay down collagen
Become trapped in matrix and form osteoblasts
What are osteoblasts?
Bone-forming cells
Lay down more collagen
Mineralisation process starts
What are osteocytes?
Mature bone cells formed from osteoblasts
Maintain bone tissue
Exchange nutrients and wastes
Contains gap junctions
What are osteoclasts?
Large cells with many nuclei
Break down bone
Formed from fusion of blood monocytes
What are the 4 components that make up osteons (harvesian systems)
Lamellae - rings of mineral salts for hardness
Lacunae - small spaces between lamellae containing osyteocytes
Canaliculi - Canals containing EC fluid, route for oxygen nutrients and waste
Central (harvesian canal) - Blood, lymph and nerves
What happens in a bone fracture?
1) Osteoclasts reabsorb dead bone by breaking it down
2) Chondroblasts lay down hyaline cartilage callus
3) Osteoblasts lay down new bone
4) Osteoclasts remodel new bone
What is blood made up of?
Blood plasma which is a form of ECM and formed elements (rbc, wbc, platelets)
What are erythrocytes?
RBCs transport oxygen and CO2
What are thrombocytes?
Platelets - initialise blood clotting
What are leukocytes?
WBCs
What do neutrophils and macrophages do?
Carry out phagocytosis - engulf bacteria
What do basophils and mast cells do?
Release substances that intensify inflammatory reaction
What do eosinophils do?
Fight against parasitic worms and allergic response
What do lymphocytes do?
Carry out immune response
