Cells and Tissue - Connective Tissue Flashcards
Connective tissue definition
tissue made of cells in an extracellular matrix of fibres and ground substances (including blood and bone)
C.T = ECM + FIBRES
These 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 and is highly vascular
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 (rigidity)
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 (ie more water in cartilage than bone)
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. Is a DOMINANT gene
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 the 3 I’s: 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
Where are plasma cells found?
In the gut, lung, salivary glands, lymph nodes, spleen, red bone marrow
What is mast cells function?
Produce histamines
Dilate blood vessels during inflammation
Kill bacteria
Where are mast cells found?
Alongside blood vessels where they can influence blood vessel size
What are Leucocytes and their function?
White blood cells (neutrophils and eosinophils)
Fight infections
Destroy microbes
Create allergic responses
Where are leucocytes found?
Found in tissues and migrate out of blood
The two types of connective tissue
Embryonic and mature
What is Mesenchyme and what is it made up of?
An embryonic tissue that gives rise to other connective tissue
Consists of connective tissue cells (mesenchymal cells) in a semi-fluid ground substance containing reticular fibres
What is Mucous and what is it made up of?
An embryonic connective tissue
Has widely scattered fibroblasts
Embedded in a jelly-like ground substance
What is the function of the mucous tissue?
To support the umbilical cord of the foetus
What are the three types of mature loose connective tissue?
Areolar
Adipose
Reticular connective tissue
What is in the Areolar tissue?
Collagen, reticular and elastic fibres
Composition of loose connective tissue?
Many cells, fewer fibres
Function of areolar connective tissue
Wraps and cushions organs
Provides strength, elasticity and support
What is the composition of adipose tissue?
Adipocytes with central triglyceride droplets
What is the function of adipose tissue?
Insulation Energy storage (white adipose) Temperature control (brown adipose)
Where is adipose tissue found?
Found within areolar tissue (including fibroblasts)
Under skin, around buttocks, flanks, abdomen, orbit of the eye
What is reticular tissue made up of?
Interlacing network of reticular fibres and reticular cells
Where is reticular tissue located?
Stroma of the liver spleen lymph nodes red bone marrow reticular layer of basement membrane around blood vessels and muscles
What is the function of the reticular tissue?
Forms stroma, binds smooth muscle tissue cells, filters and removes worn-out blood cells in spleen and microbes in lymph nodes
What is dense connective tissue made up of?
More fibres, fewer cells
Thicker and more densely packed
Made mainly of collagen
Fibres arranged regularly in bundles with fibroblasts
What is the function of dense regular connective tissue?
To provide a strong attachment between various structures
Tissue structure withstands pulling (tension)
Slow healing due to a lack of cells involved in healing
Where is dense regular connective tissue found?
Tendons
Ligaments
Aponeuroses
What is dense regular connective tissue made of?
Regularly arranged collagen fibres
What is dense irregular tissue made up of?
Collagen fibres with irregular fibroblasts in-between
What is the function of dense irregular connective tissue?
Provides tensile (pulling) strength from all directions
What is dense elastic tissue made of?
Elastic fibres with fibroblasts
The unstained tissue is yellowish
Where is dense elastic tissue found?
Lung tissue
Walls of arteries
Trachea
vocal chords etc
What is the function of dense elastic tissue?
Allows stretching and recoiling
Provides strength
What is the supportive connective tissue cartilage made of?
Collagen and elastin fibres in chondroitin sulphate (part of ground substance)
What is compact bone?
Is the outer layer of bone and forms the long shaft of bones
What is compact bone also known as?
The cortical bone
C of compact = C of cortical
What is compact bone comprised of?
Many rod-shaped units known as osteons or Haversian systems
What is spongy bone?
Porous inner bone tissue that lies underneath bone
Lacks osteons
What is spongy bone also known as?
Cancellous bone
What is the function of compact bone?
Stores calcium & phosphorous Protection & support
What is the function of spongy bone?
Stores triglycerides (yellow marrow) and produces blood cells( red marrow)
What are the four cells found within bone?
Osteogenic cells, osteoblasts, osteocytes and osteoclasts
What are osteogenic cells?
Mesenchymal stem cells that develop and start to lay down collagen
Become trapped and become osteoblasts.
What are osteoblasts?
Bone-forming cells
Lay down more collagen, mineralization process starts.
What are osteocytes?
Mature bone cells from osteoblasts trapped within the extracellular matrix.
Maintain bone tissue.
Involved in exchange of nutrients and wastes.
Have gap junctions.
What are osteoclasts?
Large Multi-nucleated cells Formed from the fusion of blood monocytes Break-down bone Ruffled border/edged appearance
What is the structure of an osteon?
Has four parts: Lamellae Lacunae Canaliculi Central (Haversian) canals
Where are osteons located?
Osteons are aligned along lines of stress (e.g. long axis of bone shaft).
Describe the structure of the lamellae
concentric rings of mineral salts for hardness
(e.g. calcium phosphate and calcium hydroxide, which together form hydroxyapatite)
Collagen (for tensile strength).
Describe the structure of the lacunae
‘Little lakes’
Small spaces between lamellae that contain mature bone cells (osteocytes)
Describe the structure of the canaliculi
“minute canals” (containing EC fluid and minute osteocytic processes) that radiate from lacunae and provide routes for oxygen, nutrients and waste.
CONTAIN GAP JUNCTIONS
What do osteoclasts do?
Reabsorb dead bone
What do chondroblasts do?
lay down hyaline cartilage callus
What do osteoblasts do?
Lay down new bone
What do osteoclasts do?
Remodel new bone
Blood CT =
ECM (plasma) + cells
What type of C.T is blood?
Liquid
What does the liquid C.T consist of?
Consists of blood plasma( a liquid extracellular matrix) and formed elements (red cells, white cells and platelets)
What are the types of the formed elements of blood?
Erthryocyes
Thrombocytes
Granular leucocytes
Agranular leucocytes
What are the types of the formed elements of blood?
Erythrocytes
Thrombocytes
Granular leucocytes
Agranular leucocytes
What formed elements of blood are classified as granular leucocytes?
T & B lymphocytes
What is the function of erythrocytes?
Transport oxygen and carbon dioxide
What do leucocytes do?
Combat disease
What are neutrophils and monocytes and what is their function?
Neutrophils and monocytes (macrophages)are phagocytic
Engulf bacteria.
What is the function of the basophils and mast cells?
Release substances (e.g. histamine) that intensify the inflammatory reaction.
What are eosinophils effective against?
Parasitic worms and in an acute allergic response
What are involved in the immune response?
Lymphocytes (ie white blood cells)
What is the function of the platelets and what are they formed from?
Platelets (from megakaryocytes in red marrow)
Clotting
