Connective and Adipose Tissue Flashcards
What are the 3 main structural components of connective tissue?
Cells- mainly mature fibroblasts/fibrocytes, fixed adipocytes
Fibres- eg collagen, elastin, reticular fibres
Ground substance- proteoglycans (sugars with a protein associated)
What makes up the extracellular matrix?
Ground substance and Fibres
Give 6 functions of connective tissue
1) Binding and supporting (holds organs together)
2) Protecting (Bones protect vital organs and fat acts as a shock absorber)
3) Insulating (fat underlying skin and bone marrow holding warm blood)
4) Storing reserve fuel cells (bone marrow and fat tissue)
5) Transporting substances within the body (blood and interstitium)
6) Separation of tissues (fascia and tendons/cartilage)
Define connective tissue
A tissue that connects, supports, binds or separates other tissues or organs, typically have collagen or other fibres eg elastin.
Describe the structure of loose connective tissue (cell types, fibres, ground substance)
Loose connective tissue has multiple cells type- mast cells, macrophages, fibroblasts, adipocytes
2 main types of fibre are elastin and collagen
It’s ground substance is ‘gel’ like and make up of proteoglycans
What is the function of loose connective tissue (areolar tissue)?
Give 4 examples
1) Holds vessels that supply fluids
2) Permits cell migration
3) INvolved in inflammation pathways
4) act as as packaging around organs
5) Generally holds everything in place
6) Cushions and stabilises organs
List the common cell types found in connective tissue
FIbroblasts, Macrophages, Mast cells, Adipocytes
What is the function of fibroblasts? Why is this important?
They synthesise and secrete the fibres that lie within the ground substance.
Fibroblasts are important in wound healing because these cells are primarily responsible for scar formation
What organelle will fibroblasts have lots of?
RER because they make lots of proteins eg collagen
What are myofibroblasts and what’s there function?
They are modified fibroblasts with actin and myosin. They are responsible for wound contraction when tissue loss has occurred.
What are Mast cells? Where are they found?
Mast cells have a key role in inflammatory response.
They are found in areolar connective tissue near blood vessels.
They are not found in the CNS as they open up blood vessels which would cause oedema on the brain
What do Mast cells look like under the microscope?
They have lots of vesicles surrounding a nucleus
What 3 granules do Mast Cells contain and what is their function?
Histamine (increases blood vessel wall permeability by creating fenestrations which allow cells into the tissue)
Heparin (an anticoagulant) This is important to allow blood flow so macrophages can get to the bacteria
Cytokines (kill pathogens)
What is the function off unilocular adipocytes? What type of adipose tissue does it make up?
It makes up white adipose tissue. Function is padding and shock absorber, insulation and energy reserve
What do white adipocytes look like under the microscope? Why are they hard to see in H&E staining?
The nucleus spreads to the outside of each droplet so look like white circles with pink outlines. They are difficult to see because in H&E the fat is stripped out so the fat doesn’t stain
What is the function of multilocular adipocytes? What type of tissue do they for on?
They form brown adipose tissue. Their function is insulation and energy reserve
Give 3 differences between white and brown adipose tissue
White is single lipid droplet whereas brown is multiple lipid droplets.
White has a normal number of mitochondria whereas brown has lots of mitochondria
In adults, white adipose tissue breakdown is slow and heat only generated after shiver reflex. Whereas only children have brown adipose tissue and the lipid breakdown is accelerated, oxidative phosphorylation is uncoupled to provide heat.
What is the definition of extracellular matrix?
A term used to describe the complex extracellular structural network that consists of ground substance and fibres
What is Type 1 collagen?
Most widely distributed type found in tendons, capsules of organs and skin dermis
What is type 2 collagen?
Fibrils don’t from fibres eg in elastic cartilage
What is type 3 collagen?
Fibrils form fibres around muscle and nerve cells and within lymphatic tissue. It is called reticulin.
What is type 4 collagen?
Unique form present basement membrane
What is the main function of collagen?
Flexible with high tensile strength
What is the main function of Reticulin?
Provides supporting framework/ sponge
What is the main function of elastin?
Allows tissues to recoil after stretch or distension
Where is loose connective tissue located? Why?
Beneath epithelia. Located around small blood vessels. Associated with epithelium of glands.
All of the above places are sites where pathogens can be destroyed
What are glycosaminoglycans (GAGs)?
Long-chained polysaccharides that attract water to form a hydrated gel this permits rapid diffusion and prevents compression.
What is the unique GAG?
Hyaluronic acid tat is bound to proteoglycans by a link protein to form a giant hydrophilic macromolecule.
Compare and contrast irregular and regular dense connective tissue
Both contain fibroblasts
In irregular collagen 1 fibres in all directions whereas in regular collagen 1 fibres in parallel
Irregular resists stresses in all directions whereas regular resists.stress in only 1 directions
What are myotendinous junctions?
The junction between muscles and tendons. The fibroblasts from collagen which coats the muscle fibres. Cross-links between fibres results in mechanical strength
What are tendons made out of?
They are very strong! As strong as bone. Made from - 68% water 30% collagen (collagen1 and 2) 2% elastin
What are the three types of fascia connective tissue?
Superficial, Deep and Visceral or parietal
Based on anatomical position
What is fascia?
A type of connective tissue that is made up of fibrous connective tissue containing lots of collagen. It is flexible and it can resist great unidirectional force
What is vitamin c required for? What can a deficiency in Vitamin C lead to?
The intracellular production of procollagen (which is converted to collagen molecules outside the celll). Therefore without vitamin C collagen formation is disrupted. It leads to scurvy.
What happens in scurvy? What are the symptoms/ signs?
Due to the deficiency in colllagen due to a lack of Vitamin C there is poor wound healing and impaired bone formation.
Symptoms/signs—
Gum disease, Bruising, Bleeding, Poor wound healing
What is Marfan’s syndrome? What are the signs?
An autosomal dominant disorder where there is a mutation in the fibrillin 1 gene. This means that elastic tissue is abnormal.
Sufferers are abnormally tall, exhibit arachnodactyly, have frequent joint dislocation and can be at risk of aortic rupture (biggest killer)
Aortic aneurism is a common life threatening risk for patients with Marfan’s syndrome. Explain why
Vessel wall weakens as the middle layer of the aortic wall is made up of elastin for recoil in Marfans less elastin is produced so can expand but cant recoil so keeps expanding, weakening it until it bursts.
Give 3 examples of places in the body where elastic fibres play an important role
Dermis
Artery Walls
Lungs
Sites with elastic cartilage eg ear
What would the presence of desmosine and isodesmosine in bodily fluids indicate about the patient?
The presence of these amino acids in bodily fluids eg urinalysis indicates that something is wrong with the fibrillin gene as they are being released from the breakdown of elastin.
What are the three tissue layers in small elastic arteries?
Tunica intima (indistinct endothelial cells line the lumen) Tunica Media (elastin lamellar to allow expansion) Tunica adventitia (collagen which keeps it all together)
How is elastin most commonly damaged? Why is this very bad?
UV and smoking most commonly damage elastin. This is bad because elastin cannot be regenerated and fibroblasts lay down scar tissue.
Within the aorta what produces elastin, collagen and the matrix?
In the aorta it is the smooth muscle that produces elastin, collagen and the matrix NOT the fibroblasts (which make scar tissue)
What is ‘Brittle Bones ‘ disease? What is the proper name? What are the signs/symptoms?
Brittle Bones disease is Osteogenesis Imperfecta. It has many genetic causes most are autosomal dominant. The mutation results in collagen fibres that don’t ‘knit together’ or not enough collagen is produced or both. Therefore any tissues containing collagen do not form properly. This results in-
Weakened Bones
Short stature
Presence of blue sclera (blue white of the eye)
Hearing loss (hearing involves bones)
Hyper mobility (loose joints)& arched feet
Poor teeth development
