Cells and Tissues: Connective Tissue Flashcards
Connective tissue definition
tissue made of cells in an extracellular matrix of fibres and ground substances (including blood and bone) that connect, support and protect body organs while distributing blood vessel to other tissues
Is connective tissue vascular?
Yes, unlike epithelia, connective tissue contains blood vessels
What type of connective tissue does not contain blood vessels (is avascular) or nerves?
Cartilage
What does epithelia and connective tissue both contain?
Nerves
Do tendons have blood vessels?
They have a very limited blood supply
What makes up connective tissue?
Extracellular matrix and cells
CT = ECM + Cells
What is the extracellular matrix made up of?
Ground Substances and Protein fibres
ECM = GS + Fibres
What secretes protein fibres?
The connective tissue cells in the extracellular matrix
Is connective tissue found on body surfaces like epithelia?
No, the connective tissue is found in bones, cartilage and blood
What is ground substance?
The material between cells and fibres
What is ground substance made of?
It is composed of water, proteins and polysaccharides (sugars)
GS = Water + Proteins + Polysaccharides
What are Glycosaminoglycans (GAGS or mucopolysaccharides)?
Large polysaccharides that join with core proteins to form proteoglycans
What are proteoglycans comprised of?
A core protein and glycosaminoglycans (GAGS) - GAGS stick out of protein like bristles on a brush
The main property of glycosaminoglycan
It is highly charged so it can trap water, making the ground substance in the ECM more jelly-like
How are sulphated and non-sulphated glycosaminoglycans structured differently?
Sulphated GAGS bind to proteins to form proteoglycans but non-sulphated GAGS do NOT join to proteins but instead to proteoglycans
Where is Dermatan sulphate found?
This GAG is found in the skin, tendons, blood vessels and heart valves
Where is Keratan sulphate found?
This GAG is found in the bone, cartilage, cornea of the eye
Where is Chondroitin sulphate found?
This GAG supports and provides adhesive features of cartilage, bone, skin and blood vessels
What is Hyaluronic acid and what is its function?
A non-sulphated GAG. It is slippery, viscous and binds cells together, lubricates joints and maintains the shape of the eyeball
What produces hyalurondaise?
White blood cells, sperm and some bacteria
What is hyalurondaise?
An enzyme that breaks apart hyaluronic acid causing the ground substance of connective tissue to become more liquid. White blood cells, sperm and bacteria do this to move easily /make access to egg easier/spread faster
What is Exophthalmos and what causes it?
is a bulging of the eye anteriorly out of the orbit due to a swollen thyroid gland. It is caused by an autoimmune over-activation of the thyroid and autoimmune action on the fibroblasts in the ECM of the eye causing more ECM to be produced.
The deposition of glycosaminoglycans and the influx of water increase the orbital contents
Types of connective tissue fibres in the extracellular matrix?
Collagen, reticular and elastic fibres
Collagen fibre features and what it is composed of
Composed of the protein collagen
Very strong and flexible (to resist pulling forces)
Some features (like water content) can change depending on where it is located within the body
Occurs in parallel bundles
Where are collagen fibres found?
In bone, cartilages, tendons and ligaments
Reticular fibre features and what it is composed of
Is made of collagen arranged in bundles and coated with glycoprotein (has more protein than sugar)
Is made by fibroblasts
It provides strength and support
Form part of basement membrane
Thinner than collagen and branching - forming a network through tissue and in vessels
Where are reticular fibres found?
In adipose tissue, nerve fibres, smooth muscle areas, basement membrane
Elastic fibres features and what is it composed of
consists of molecules of the protein elastin, which are surrounded by the glycoprotein fibrillin (adds strength and stability)
Thinner than collagen making a fibrous network
Can be stretched without breaking and restore its original shape
Where are elastic fibres found?
Skin, blood vessels and the lung
Marfan Syndrome
A hereditary defect in elastic cells. Normally growth factors bind to fibrillin proteins which keep them inactive. However, in Marfan syndrome, they do not bind to fibrillin glycoproteins causing increased growth in the body which can lead to weakened heart valves and arterial walls
What are fibroblasts and their function?
Large flat cells that move through connective tissue and secrete components of the extracellular matrix (protein fibres and ground substance)
Where are fibroblasts found?
Widely distributed in connective tissues and are migratory
What are adipocytes and their function?
cells that store fat (triglycerides)
Where are adipocytes found?
Under the skin and around organs
What are macrophages and their function?
Phagocytic cells that have both fixed and wandering forms in connective tissue
They destroy bacteria and cell debris
What are dust cells and where are they found?
Fixed Macrophages in the lung
What are kupffer cells and where are they found?
Fixed Macrophages in the liver
What are Langerhan cells and where are they found
Fixed Macrophages in the skin
Where are wandering macrophages found?
Sites of infection, injury and inflammation
What makes plasma cells and their function?
They develop from B lymphocytes and secrete antibodies that attack and neutralise foreign substances