What is hereditary spherocytosis? Pattern of inheritance
Sphere shaped RBCs, more prone to rupture --> anaemia.
What is hereditary elliptocytosis? Pattern of inheritance?
elliptical RBCs, prone to rupture -- > anaemia. Caused by defect in cytoskeleton meaning the RBCs do not return to their usual shape after leaving microvasculature
What cells myelinate peripheral axons and CNS axons?
Peripheral - Schwann
CNS - oligodendrocytes
What 3 factors affect conduction velocity?
- Membrane capacitance - ability to hold charge
- Membrane resistance - high resistance = high conduction velocity
- Axon diameter
How does an AP at the presynapse result in AP at the post synapse?
- Calcium comes in
- Binds to synaptotagmin
- Results in vesicle brought to membrane and snare complex forming
- Neurotransmitter release
- Binds to receptors on post synapse
What are the 2 types of blockers of nicotinic receptors?
Depolarising and competitive.
Depolarising blockes - depolarise the membrane over a long period of time and inactivate any nAChRs, preventing new APs.
Where is calcium stored in the cell? How can it be released from its stores?
Stored in ER
- GPCR activated --> IP3 --> IP3 receptors on ER --> Calcium release
- Calcium induced calcium release - T tubule depolarised --> activated of VOCC --> calcium in subplasmalemmal area --> activates ryanodine receptors in SR membrane.
Give the 4 ways a lipid molecule can move in a lipid bilayer
- Flip flop
How does cholesterol increase membrane fluidity
Reduced phospholipid packing
Stabilises membrane by H bonding
What is the RBC cytoskeleton made up of?
Actin and spectrin bound to membrane by ankyrin and glycophorin
How does diarrhoea occur?
Phosphorylation of CFTR results in excess loss of Cl- and therefore water
Explain phagocytosis, pinocytosis, and receptor mediated endocytosis
phagocytosis - ligand binds to receptor on phagocyte, results in zipper mechanism
Pinocytosis - PM invaginates and internalises molecule
RME - Ligand binds to receptor and recruits clathrin coated pits to internalise it.
Explain RME using cholesterol as an example. How does it differ for transferrin containing iron ions and insulin?
- LDL binds to LDL receptor on surface
- Clathrin coated pit recruiting and phagosome forms
- Fuses with endosome, low pH causes dissociated of LDL and receptor.
- Receptors recycled and endosome fuses with lysosome for digestion
Same for transferrin. With insulin both receptor and insulin degraded.
What are the adrenergic and cholinergic receptors linked to: alpha, inhibitory or stimulatory g proteins? What does each g protein do?
Adrenergic Q - alpha 1 - Galpha
I - alpha 2 - Ginhib
S - beta 1 - Gstim
S - beta 2 - Gstim
Cholinergic Q - M1 - Galpha
I - M2 - Ginhib
Q - M3 - Galpha
Galpha - +PLC
Ginhib - (-AC)
Gstim - (+AC)
What is the kd of a drug?
concentration at which 50% of the receptors are occupied
What is the Emax and EC50 of a drug?
Emax - Conc of drug needed to get 100% response
EC50 - conc of drug needed to get 50% response.
What is affinity and efficacy of a ligand?
Affinity - how easily it binds
Efficacy - How good it is at effective a response from the receptor.
What is a partial agonist?
a ligand that cannot amount a 100% response
What are class 1 and class 2 drugs?
Class 2 drugs - bind to albumin to allow class 1 drugs freedom to act
Class 1 drugs - Object drug
What is first order and zero order kinetics? When does each take place?
First order - Fraction of drug eliminated per unit time. Occurs when conc of drug is less than Km
Zero order - Rate of elimination is constant per uni time. Occurs when conc of drug is greater than Km
How does pH affect how much drug is excreted?
if drug is acidic and urine acidic reabsorbs more drug and vice versa
What enzymes breaks down ACh and NA in cleft?
ACh - acetyl cholinesterase
NA - monoamine oxidase
What is tachyphylaxis?
Reduced sensitivity to a drug due to repeated exposure.
where are phospholipid made
what are integral rbc proteins
give example peripheral RBC proteins
spectrin and actin
what is function of ribophoryn
anchors ribosome to RER
how can phospholipid move
flex, rotate, lateral diffusion, flip flop
actions of cholesterol
increase fluidity by decrease phospholipid packing. decrease fluidity by decrease phospholipid motion. prevents cell state changing
how can membrane protein move
rotate, conformational change, lateral diffusion