Mix Flashcards
(54 cards)
Name two important substances produced from intermediates of glycolysis and their roles
Glycerol phosphate made from 3C dihydroxyacetone in adipose tissue= needed for the synthesis of triglycerides
2,3 bisphosphoglycerate made from 1,3 bisphosphoglycerate in RBCs= regulator of oxygen affinity of haemoglobin
Main functions of connective tissue
Connection: join together other tissues
Support the body and its structures
Protection for underlying organs
Where does areolar connective tissue occur widely?
Superficial fascia aka subcutaneous tissue: general coating of body beneath the skin
- face or dorsum of the hand
What is deep (investing) fascia?
Dense CT mostly associated with muscles, bones, nerves and blood vessels
What is adipose tissue composed of and what is its function?
Fat cells
acts as energy reserve
thermal insulator
mechanical shock absorber
What are the three types of dense regular connective tissue and what do they consist of?
Tendon: a cylindrical mass of connective tissue
Ligament: parallel arranges of collagen fibres
Aponeurosis: tendon flattened into a thin board sheath
What causes Marfan’s syndrome?
Mutations in the fibrillin gene whose protein
product binds to and supports the function of elastin.
Loss of fibrillin protein,
results in disorders of elastin function leading to tissue irregularities such as long bones, lax joints and fragile vascular walls
What causes Scurvy?
Vitamin C deficiency
results in the synthesis of abnormal collagen
that lacks its usual strength; it is also associated with an inability to heal
wounds and bone fractures.
What are the defence cells in connective tissue?
Macrophages
Mast Cells
Plasma cells
Blood cells (blood is considered to be a specialised connective tissue that ‘communicates’ throughout the body and so communicates the
actions of one tissue on another, e.g. the hormonal control exerted by the hypothalamus and pituitary on a number of end endocrine
glands.)
Examples of Loose connective tissue
subcutaneous tissue, the septa and trabeculae that make up the framework inside some organ adipose tissue Blood
What does the dermis consist of?
Lies below the epidermis
Consists of a thick layer of connective tissue containing blood vessels, lymphatics, skin
appendages (e.g. hair follicles, sebaceous glands and sweat glands), sensory
nerves and nerve endings.
consists of bundles of collagenous fibres running in various directions. There are also variable amounts of elastic fibre which form a network between the collagenous bundles.
Fascicles are formed from
Groups of collagenous
fibres and fibroblasts
What separates fascicles from each other?
loose connective tissue, called endotendineum
Where is loose connective tissue first seen?
in the developing embryo as mesenchyme, consisting of mesenchymal cells surrounded by a relatively fluid intercellular substance. With time in utero, IC substance becomes more mucoid
What is mucous connective tissue called in the umbilical cord?
Wharton’s jelly: oose, amorphous connective
tissue with a jelly-like matrix composed mainly of hyaluronic acid, sparsely populated with
type I and III collagen fibres and fibroblasts.
Describe the properties of amphipathic molecules and explain the progress of formation of lipid bilayers
Amphipathic molecules- hydrophillic and hydrophobic moieties
= form micelles (circle) and bilayers in water
Bilayer formation is spontaneous in water driven by VDW attractive forces between hydrophobic tails
Stabilised by non-covalent forces; electrostatic and hydrogen bonding between hydrophillic moieties and interactions between hydrophillic groups and water
Low permeability to ions and most polar molecules
Describe the features of integral proteins which explains their topology in the membrane
Most integral proteins contain residues with hydrophobic side chains that interact with fatty acyl groups of the membrane phospholipids, thus anchoring the protein to the membrane
What is membrane asymmetry?
when the inner and outer leaflet have different molecular architecture
Discuss the influence of unsaturated fatty acids and cholesterol on membrane fluidity
When compressed: unsaturated fatty acids= the “kinks” in their tails
-elbow adjacent phospholipid molecules away= maintaining some space between the phospholipid molecules.
Helps to maintain fluidity in the membrane at temperatures at which membranes with saturated fatty acid tails in their phospholipids would “freeze” or solidify.
cholesterol functions as a buffer, preventing lower temperatures from inhibiting fluidity and preventing higher temperatures from increasing fluidity too much
Describe the main features of fluid mosaic model of membrane structure
Plasma membrane as a fluid combination of phospholipids, cholesterol, and proteins. Carbohydrates attached to lipids (glycolipids) and to proteins (glycoproteins) extend from the outward-facing surface of the membrane.
Explain the restrictions on protein movement in the membrane, including potential interactions with cytoskeleton elements
Lipid mediated effects: proteins tend to separate out into the fluid phase or cholesterol poor regions
Membrane protein associations
Association with extra-membranous proteins via cytoskeletons
What are the two types of sphingolipid?
Sphinogomyelin
Conformation resembles other phospholipids in membrane
Can be a glycolipid if phosphocholine is replaced with sugar
Glycolipd
Cerebrosides- head group sugar monomers
Gangliosides head group oligosacchide
How does cholesterol contribute to membrane stability?
Cholesterol is 45% of total membrane lipid
Polar head group
Rigid planar steroid ring structure
Non-polar hydrocarbon tail
= reduces phospholipid packing = increased fluidity
What are the dynamics in lipid bilayers
Fluid structures.
Lipid molecules posses four permitted modes of mobility:
1. Intra-chain motion- kink formation in fatty acrylic chains
2. Fast axial rotation
3. Fast lateral diffusion within the plane of the bilayer
4. Flip-flop- movement of lipid molecules from one half of the bilayer to the other
