BL - Connective And Adipose Tissues Flashcards
What are the four types of tissue?
Epithelial, muscle, nerve, connective
Name some types of specialised connective tissues. (6)
Adipose, lymphatic, blood, haemopoietic, cartilage, bone
List some functions of connective tissue. (6)
CONNECTS cells, tissues and organs; TRANSPORTS nutrients/wastes; PROTECTS (cushions/insulates); STORES fat; DEFENDS against infection; HEALS
What does CT proper consist of and contain?
Consists of loose CT + dense CT
Contains cells, fibres and ground substance
Name the three fibres found in connective tissue.
Collagen (flexible and strong)
Reticular (provides framework)
Elastin (allows tissues to recoil)
Which disease occurs due to lack of vitamin C affecting collagen production?
Scurvy - poor wound healing and impaired bone formation.
How is collagen produced?
FIBROBLASTS secrete PRE-COLLAGEN that is converted to collagen molecules OUTSIDE the cell. The collagen molecules are then AGGREGATED to form the final collagen fibrils.
How is type one collagen (98% of all collagen) structured?
It is formed of a triple helix of alpha chains.
How is type three collagen (reticulin) structured?
FIBRILS form FIBRES around muscle and nerve cells and within lymphatic tissues and organs.
What disease results from abnormal type one collagen?
Osteogenesis imperfecta
What is the primary component of elastic fibres (which occur in most connective tissues)?
Elastin, but it enfolds and is surrounded by fibrillin.
Where does elastin play an important role?
Dermis, artery walls, lungs, other sites bearing elastic cartilage
Which syndrome occurs when expression of the fibrillin gene is abnormal?
Marfan’s Syndrome
What is ground substance?
A viscous clear substance with a slippery feel made from proteoglycans
What are proteoglycans?
Large macromolecule consisting of a core protein to which glycosaminoglycans are covalent bonded.
What are glycosaminoglycans?
Long chain polysaccharides which attract water to form a gel, e.g. hyaluronic acid
What is the extracellular matrix?
Complex extracellular structural network that consists of ground substance and fibres
List the characteristics of loose connective tissue
Many cells, not many collagen fibres, lots of ground substance, viscous, important for diffusion
Where is loose connective tissue mostly found?
Beneath epithelia, around epithelium of glands, around blood vessels (so can swell if pathogens enter).
List the characteristics of dense connective tissue
Few cells (mostly fibroblasts), many collagen fibres, not much ground substance
Which type of dense connective tissue has collagen fibres in densely packed parallel bundles with fibroblasts in them?
Regular - can withstand stress in one direction
Which type of dense CT has collagen fibres in random bundles with fibroblasts?
Irregular - can withstand stress in multiple directions
What connects muscles to bones and has parallel collagen bundles?
Tendons
What connects bones to bones and has densely packed collagen bundles?
Ligaments
What is an aponeurosis?
A flat sheet of regular CT with criss-crossing bundles of fibres
Which sort of tissue is the dermis made out of?
Dense irregular, as bundles of collagen resist tearing of skin
What do fibroblasts synthesise and secrete?
Ground substance and the fibres within it
Which actin-containing cell causes the wound to contract?
Myofibroblasts
Which cells move into inflamed loose CT?
Macrophages
Where are mast cells found in CT?
Found in connective tissue near blood vessels BUT not by nerves as swelling would damage them. Can cause anaphylaxis.
How are histamine and heparin released from the granules?
Cells are coated with IgE which binds allergens. When an allergen cross links, contents of the granules are rapidly released from the cell.
Name the two types of fat cells
White and brown
Which type of fat cell is almost entirely filled by one fat droplet, squashing the nucleus and cytoplasm?
White fat cells
Which type of fat cell contains multiple droplets and a central nucleus?
Brown fat
Why is brown fat brown?
Rich vascular supply and mitochondria so can generate heat.
What is ghrelin?
Appetite stimulator released from stomach
What is leptin?
Appetite SUPPRESSOR released by fat cells when eating.
