module 1: 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?
water
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
Where are plasma cells found?
In the gut, lung, salivary glands, lymph nodes, spleen, red bone marrow
What is mast cells function?
Mast cells produce histamine that dilates blood vessels during inflammation and kills 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)
that fight infection, destroy microbes and create allergic responses
Where are leucocytes found?
They are found in tissues and migrate out of the blood
The two types of connective tissue
Embryonic and mature
What is Mesenchyme and what is it made up of?
An embryonic connective 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 that has widely scattered fibroblasts embedded in 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 and Reticular connective tissue
What is in the Areolar tissue?
Collagen, Reticular and elastic fibres
Composition of loose connective tissue
Many cells and fewer fibres than in other CT types
The 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)(especially in infants)
Where is adipose tissue found?
Found with areolar tissue (including fibroblasts)
Under skin, around buttocks, flanks, abdomen, orbit of eye
What is reticular tissue made up of?
Interlacing network of reticular fibres and reticular cells
Where is reticular tissue located?
Stroma of 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?
Has more fibres and fewer cells than loose connective tissue. It is thicker and more densely packed. Made of mainly collagen fibres regularly arranged in bundles with fibroblasts. This forms a shiny white extracellular matrix
What is the function of dense regular connective tissue?
To provide a strong attachment between various structures. Tissue structure withstands pulling (tension)
Is slow healing due to a lack of cells that are involved with healing
Where is dense regular connective tissue found?
Tendons (muscle to bone), ligaments (bone to bone) and aponeuroses (muscle to muscle)
What is dense regular connective tissue made of?
Regularly arranged collagen fibres
What is dense irregular tissue made up of?
Made up of collagen fibres with irregular fibroblasts between
What is the function of dense irregular connective tissue?
Provides tensile (pulling) strength from all directions
Where is dense irregular tissue found?
Fasciae, the reticular region of dermis, fibrous pericardium, periosteum, perichondrium, joint and membrane capsules, heart valves
What is dense elastic tissue made of?
Elastic fibres with fibroblasts between them and the unstained tissue is yellowish
Where is dense elastic tissue found?
Lung tissue, walls of arteries, trachea, bronchial tubes, vocal chords, suspensory ligaments of penis, some ligaments between vertebrae
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 hyaline cartilage made of?
Made of a resilient gel (as a ground substance) and fibres are not obviously present. Is relatively weak so can be easily fractured
What is the function of hyaline cartilage?
Hyaline cartilage gives flexibility and support for the movement at joints
Where is hyaline cartilage found?
Anterior ends of ribs, respiratory cartilage (e.g. larynx, trachea, bronchi), nasal septum, ends of long bones, embryonic skeleton
What is fibrocartilage made of?
Chondrocytes (a cell which has secreted the matrix of cartilage and becomes embedded in it) scattered among thick bundles of collagen fibres within the extracellular matrix. Its strength and rigidity making it the strongest cartilage
Where is fibrocartilage located?
Pubic symphysis, intervertebral discs, cartilage pads of knee, portions of tendons
What is the function of fibrocartilage?
Supports and joins structures
What is elastic cartilage made of?
Chondrocytes in threadlike networks of elastic fibres within the extracellular matrix. Perichondrium present.
Where is elastic cartilage found?
Epiglottis (top part of larynx) and external ear, auditory tubes
What is the function of elastic cartilage?
Provides strength and elasticity; maintains shape of certain structure
What is compact bone and what is it made up of?
Many rod-shaped units called Osteons. It is the outer layer of bone and forms the shaft of long bones. Very strong
What is spongy bone and what is it made up of?
It is the porous inner bone tissue that lies underneath compact bone and lacks osteons. Where bone marrow is located
The function of compact bone?
Stores calcium, phosphorous, provides protection and support.
The function of spongy bone?
Stores triglycerides in Yellow Bone Marrow, forms erythrocytes in Red Bone Marrow
What are Osteogenic cells?
Mesenchymal stem cells that develop, lay down collagen, become trapped and become osteoblasts
What are Osteoblasts?
Bone forming cells. Lay down more collagen, starts the mineralization process.
What are Osteocytes?
Mature bone cells derived from osteoblasts trapped in ECM. Maintains the bone tissue. Involved in exchange of nutrients and waste. Have gap junctions
What are Osteoclasts?
Large, multinucleated cells formed from the fusion of blood monocytes. Break down and reshape bone
What are the main parts of Osteons?
Lamellae, lacunae, canaliculi and central canal
What are Lamellae?
Concetric rings of mineral salts (hydroxyapatite) for hardness, collagen for tensile strength
What are Lacunae?
Small spaces between lamellae that contain osteocytes
What are Canaliculi?
Tiny channels that radiate from lacunae and provide routes for oxygen, nutrients and waste
What is in the Central (Haversian) canal?
Blood vessels and nerves
What is the bone healing process?
Osteoclasts reabsorb dead bone -> Chondroblasts lay down hyaline cartilage callus -> Osteoblasts lay down new bone -> Osteoclasts remodel new bone
What is liquid connective tissue comprised of?
Consists of blood plasma (a liquid ECM) and formed elements (red and white blood cells and platelets)
What are Erythrocytes and their function?
Red blood cells and transport oxygen and carbon dioxide
What are thrombocytes and their function?
Platelets (in red bone marrow) and they are involved in blood clotting
What is the function of neutrophils and monocytes (which turns into macrophages)?
To be phagocytic, engulfing bacteria
What is the function of basophils and mast cells?
To release substances (histamines) that increase immune response
What is the function of Eosinophils?
To kill parasitic worms and effective in acute immune responses
What is the function of lymphocytes?
They are involved in the immune response
What are macrophages and their function?
They develop from monocytes and destroy bacteria and cell debris by phagocytosis
