Flashcards in ICPP Deck (119)
Name an amine hormone
NA, adrenaline, dopamine, 5-HT
Out of amine, peptide and steroid hormones, order how long their half lives are
Amine seconds, peptide minutes, steroids hours
Name an amino acid neuroT
Glutamate, glycine, GABA
What are metabotropic receptors?
How do ionotropic Rs carry out their effects?
Name the alpha protein and effector molecules involved in GPCRs
a1 Gaq activ PLC --> IP3 and DAG
a2 Gai inhib AC --> cAMP --> PKA
B Gas activ AC --> cAMP --> PKA
M1/3 Gaq activ PLC --> IP3 and DAG
M2/4 Gai inhib AC --> cAMP --> PKA
Describe the structure of a GPCR
7TM, single polypeptide, N terminus is extracellular and C terminus intracellular
What happens following PLC activation
Has two effectors, IP3 and DAG. IP3 joins to IP3 receptor on SR/ER which causes calcium release. DAG activates PKC which phosphorylates proteins
What happens following AC activation
AC hydrolyses ATP to create cyclic AMP which then activates PKA which phosphorylates proteins
At what stage is there signal amplification in GPCR signalling
AC activates many molecules of cAMP
PKA phosphorylates many proteins
PLC activates two effectors (IP3 and DAG)
DAG phosphorylates many proteins
Name all the calcium transporters/channels in a cell
Plasma membrane: NCX, PMCA Ca out, NOCC Ca in, LGIC Ca in
SR/ER: IP3 Ca out, SERCA Ca in, CICR (ryanodine Rs) Ca out
Which molecules can pass through the lipid bilayer?
Small uncharged polar or any hydrophobic molecules
What determines rate of passive transport?
Permeability coefficient and concentration gradients on each side J=P(C1-C2)
If ∆G is positive, what does this mean about the transport process?
Its active transport! ∆G negative is passive transport
What determines if it will be active or passive transport?
Dependent on concentration ratio and membrane potential
What are the glucose and fructose transporters for both sides?
Glucose SGLT, fructose GLUT5 and then both GLUT2 on basolateral side
Give an example of an ATPase Calcium transporter
PMCA (transports Ca out of cell)
What type of transporter is SGLT?
Cotransporter/symtransporter. Transports Na and glucose into cell
What is mainly responsible for RMP of -70mV?
Passive K+ diffusion out of cell through K+ channels
NOT Na/KATPase, this is only responsible for 5-10mV
Name two antiports
NCX (NaCa), NHE (Na H)
How does NaKATPase drive secondary active transport?
Drives Na out so provides energy for transporters that bring Na in e.g. Na/H or Na/Ca antiports or Na/glucose Na/aa symport
Name primary active, secondary active and facilitated transporters in Calcium
Primary active: PMCA (Na/CaATPase), SERCA
Secondary active: NCX
Facilitated: mitochondrial Ca uniports at high Ca to buffer harmful effects
What is NCX?
3 Na in, one Ca out (can reverse mode of operation if low Ca or high Na
Why do you get reversal of NCX activity in ischemia?
So normally NCX moves 3Na in and 1Ca out, but if ischaemic then NaCaATPase (PMCA) doesn't work so then Na accumulates in cell so NCX reverses direction
What transporters control cell pH
NHE (Na in H out antiport), AE (HCO3- out, Cl- in)
What do you need to have a membrane potential?
Ion gradients and selective ion channels
What is the nernst equation?
Gives the equilibrium potential for an ion (=where chemical and electrical charges are balance) i.e. the membrane potential where the ion will be in equilibrium
If you increase membrane permeability, you move it closer/further away from its equilibrium potential?
Closer to its equilibrium potential
What is fast synaptic transmission?
Where the R is also an ion channel e.g. Nictonic ACh R that lets sodium in