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ICPP BROAD NOTES Flashcards

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1
Q

Define a ‘receptor’

A

A molecule that recognises a ligand and in response to ligand binding regulates a cellular process

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2
Q

Define a ‘ligand’

A

Any molecules that binds specifically to the receptor site

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3
Q

Distinguish between a reeptor and an acceptor

A

Receptors are silent at rest and activated by agonist binding, acceptors operate in the absence of a ligand and activity may be modulated by ligand binding

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4
Q

Explain what happens in a ligand gated ion channel using the AchR as an example

A

AchR is bound by ACh, this opens a pore in the membrane allowing cations to flow through

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5
Q

Explain the activation of a receptor tyrosine kinase

A

These operate as dimers. Agonist binds one part, receptor is activated and dimerises, catalytic domains come together and phosphorylate their partner is a process called ‘autophosphorylation’ -> this then activates a signalling cascade

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6
Q

Explain the activation of GPCR’s using adrenaline as an example

A

Adrenaline binds the EC domain -> agonist binding causes the internally bound G protein to swap A GDP for a GTP -> this causes the apha subunit to dissociate and activate the enzyme adenyl cyclase which when converts ATP to cAMP - a second messenger

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7
Q

Describe the structure of a GPCR

A

7 TMD’s, an internally bound G protein, EC N terminus, IC C terminus

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8
Q

Describe the actiation of intracellular receptors

A

Receptor contains a DNA binding domain which is held in it’s silent form, upon ligand binding disinhibition occurs and the domain binds to regulate gene transcription

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9
Q

Give three functions of a biological membrane

A

Provide a barrier/maintian control of closed environment/allow communication/recognition of signalling molecules

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10
Q

What is the most abundant component of the DRY weight of a cell membrane?

A

proteins

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11
Q

What are the four motions of phospholipids in a bilayer?

A

Flexion/rotation/flip-flop/lateral diffusion

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12
Q

Why are cis unstaturated double bonds inessential fatty acids so important in our diet?

A

They make a kink in the phospholipids in membrane bilayers and thus reduce packing thus increasing the fluidity of the membrane

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13
Q

What is the function of cholesterol in biological membranes?

A

Maintain fluidity by
- Formation of H bonds
1) Reduces phospholipid chain motion thus reducing fluidity at high temps
2) at low temps reduces packing thus increasing fluidity
we have to have some cholesterol in our diet, not enough is made internally to be sufficient

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14
Q

What are the three movemetns of proteins within the bilayer?

A

Rotation/lateral/conformational change

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15
Q

Give two ways in which protein movement is restricted

A

Proteins are segregated into fluid ‘cholesterol poor’ regions/Association with other membrane proteins/Associating with extra-membrane proteins like the cytoskeleton

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16
Q

Distinguish between peripheral and integral membrane proteins

A

Peripheral proteins are bound to the surface and bound via electrostatic interactions and H bonding, they are removed by manipulation of pH or ionic strength

Integral proteins interact with the central hydrophobic domains of the bilayer. They cannot be removed by manipulation of pH or ionic strength but are removed by detergents

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17
Q

Give some cytoskeletal proteins

A

Spectrin/ankyrin/band 3/protein 4.1

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18
Q

What GPCR’s do analgesics binds to?

A

Mu opioid receptors

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19
Q

Hw are G protein pathways turned off?

A

The alpha subunit has GTPase activity which subsequently hydrolyses the bound GTP for GDP again affter a few seconds.

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20
Q

The effect protein in Gas and Gai phatways is adenyl cyclase, what is it in Gaq pathway?

A

phospholipase C

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21
Q

How do pertussis toxin and cholera toxin work?

A

Pertussis toxin - corrupts Gai subunits so that they can’t release GDP -> pathway can’t be turned on
Cholera toxin prevents GTPase activity on Gas pathway -> pathway can’t be turned off -> diarrhoea via over working CFTR channel

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22
Q

Give three functions of calcium signalling

A

muscle contraction/neurotransmission/metabolism regulation

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23
Q

Name two transporters that keep IC calcium low

A

PMCA (ATP out the cell)
SERCA (ATP in to sarcoplasmic stores)
NCX (Sodium calcium exchanger 1:1)
Mitochondrial Calcium uniporters

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24
Q

Mu opioid receptors are G_ linked

A

i

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25
In inotropy of the heart A Gs pathway causes activation of cAMP which activates ____ which then phosphorykates VOCC's causing CICR
PKA
26
TBW is ___% of the total body weight
60%
27
What does flux describe?
Rate of flow
28
Describe a hypertonic and a hypotonic solution
Hypertonic solution - there is a greater concentration of solute in the cell than solution Hypotonic solution - there is a greater concentratino of solute outside the cell in solution that in the cell
29
List some functions of the Na/K ATPase
Main - Creates gradients that drive secondary transport (such as those controlling IC pH, cell volume, IC calcium, nutrient uptake) Minor - minor contribution to the resting membrane potential
30
Why does IC calcium need to be kept low
High levels are toxic and will calcify the cell because of the high levels of intracellular phosphate
31
PMCA and SERCA both work by swapping A H ion for a Ca ion, NCX regulates it too what other thing regulates IC calcium (transporter)?
Mitochondrial calcium uniporters
32
NCX has a role in expelling IC calcium during cell recovery. Give another role
Bringing in calcium during cardiac action potential when it is reversed - once AP passes it flips pack to original orientation and extrudes calcium/possible role in cell toxicity
33
What two exchangers regulate cell pH?
Na/H exchanger (extrudes H for Na) - acts to alkanalise the cell - inhibited by amiloride Cl/HCO3 (anion exchanger) - acts to acidify the cell
34
Describe bicarbonare reabsorption in the proximal tubule of the kidney - this is required as bicarbonate is an important pH buffer
In the lumen of the kidney tubule see image L9 Basically sodium bicarbonate is broekn down to bicarbonate and Na in the lumen of the kidney tubule. The Na is taken up by NHE and swapped for H, The H comines with bicarbobnate to form H2CO3 -> via carbonic anhydrase to water and CO2 -> diffuses into epithelial cell -> recombines to H2Co3 via carbonic anhydrase -> bicarbonate is reabsorbd via the Anion exchanger NOTE - initial gradient for sodium take up is set by the Na/K ATPase
35
Loop direct inhibit _____ Thiazide diuretics work in the DCT and block NCCT, amiloride is often used in combinate which blocks ____ channels What does spironolactone block?
``` NKCC2 ENaC channels (reabsorb sodium) blocks mineralocorticoid receptors (aldosterone) - aldosterone normally mediates na reabsorption (via upregulation of Na/K ATPase, ENaC and K channels) ```
36
The membrane potential of a cell is the electric potential (voltage) ___ the cell relative to the ____
inside/outside
37
``` Give the resting membrane potentials of the following cardiac myocytes neurones skeletal myocytes smooth muscle myocytes ```
Cardiac myocytes -80mV neurones -70mV Skeetal myocytes -90mV Smooth muscle myocytes -50mV
38
What is the equilibirum potential, use potassium as an example
The membrane potential at which there is no net movement of an ion because the electrical and concentration gradients are equal to one another In K this is around -95mV, channels opening try to push the membrane potential toward their equilibrium potential
39
Distinguish between fast and slow synpatic transmission
In fast - the receptor is also the ion channel - in these we get EPSP's and IPSP's (Ach/glutamate causing opening of Na or Ca channels) In slow - the receptor and channel are separate, the receptor is a GPCR
40
Distinguish between the absolute and relative refractory periods
Absolute - nearly all Na channels are inactivated - during this period you can't get another AP Relative - excitatry returns to normal, channels are closed rather than inactivated
41
Opening of what channels at the synpatic terminal leads to NT release?
Ca
42
nAchR's are ligand gated whereas mAchR's are GPCR's thus which show fast synaptic transmission?
nicotinic
43
What is essential in our diet for synthesis of Ach?
choline (reacts with acetyl CoA)
44
what degrades acetylcholine in in the synapse?
acetylcholinesterase
45
What are the drugs that target nAchR's at autonomic gangli called?
ganglion-blocking drugs
46
Gives some side effects of muscarinic receptor agonists
Decrease HR and CO/increase bronchoconstriction/increased sweating and salivation/increased GI peristalsis
47
SLUDGE syndrome is called by organophosphorous agents (indicative of a PARA surge), what is the treatment?
atropine (anti-cholinergic) - muscarinic antagonists
48
What is the rpecursor of noradrenaline?
tyrosine
49
salbutamo is a b2 selective adrenoceptor agonist, what is it used for?
Reverse the bronchoconstriction caused by asthma
50
``` Define the following: antagonist affinity intrinsic efficacy efficacy Bmax Kd EC50 ```
antagonist - something that binds to a receptor to prevent the binding of an endogenous ligand Affinity - The tendency of a ligand to bind to its receptor intrinsic efficacy - the ability of the agonist to change the receptor to its active form Efficacy - the ability of a drug to generate a response Bmax = the maximum binfing capacity of a receptor Kd - the concentration of a drug which binds 50% of available receptors EC50 - The concentration of a drug which gives 50% of the maximal response - a measure of potency
51
``` define full agonist partial agonist IC50 Potency ```
Full agonist - Agonists the give the maximal response Partial agonistss - agonists that cause a respone less than the maximum response IC50 - The concentration of an antagonist giving 50% inhibition Potency - a measure of the amount of drug rewuired to producre a desired effect
52
if a to the power of c = b then log(a)b = ?
c
53
What is functional antagonism?
Creation of effects that are opposite to those of the original agonist
54
Salmetreol can't be given IV because it's insoluble this is why we give salbutamol despite its lower affinity for B2 (non selective) and thus its cardiac side effects, cos salmetreol is B2 selective (higher affinity)
T
55
100% receptor occupancy isn't always required for the maximal response (Emax), thus the remaining receptors are 'spare receptors', what is their function?
Allows maximum response at a low concentration of agonist because there is higher concentration there is more chance of interactions - allows for amplification of a signal transductino pathway
56
Increased sensitivity means an upregulation of a number of receptors, this happens in times of ____ _____
low activity
57
Buprenorphine is a partial opioid agoist used to treat heroine addiction. Explain
Buprenorphine has a higher affinity but lower efficacy than morphine and doesn't have the respiratory depressive side effects. Patients will become ill because of withdrawal, they have had a downregulation of receptors due to overuse
58
Reversible competitive antagonism works on the principle of the antagonist outcompeting the agonist for receptors, give an example of one. Complexes are surmountable
Naloxone in opioid overdose
59
In irreversible competitive antagonism the complexes that form are non-surmountable. The agoinst is now needed at a higher concentratino to elicit the same response and at a point there becomes insufficient receptors to carry out the maximal response regardless of the agoinst concentration . T/F
T
60
Explain non-competitive antagonism
Antagonist binds at an allosteric (orthosteric) site to reduce the affinity and/or efficacy of the agonist
61
Distinguish between pharmacokinetics and pharmacodynamics
Pharmacokinetics - is the drug getting to the site of action? Pharmacodynamics - Is the drug producing the desired effect?
62
Give some advantages of focal administration of drugs
Concentrates the drug at the site of action/reduces off target side effects
63
Explain the advantages of an oal route drug
Good absorption in small intestine/good drug distrinbution because of constant movement of tract/good length of transit time for it to act (3-5 hours)
64
The pKa of a drug is the pH at which half of it is pronated, pronated drugs are more easily taken up across the intestinal lining via passive diffusion, thus a more acidic environment means more will be taken up
T, because if pH
65
Name three factors affecting drug absorption ni
SLT (solute carrier transporters) expression ensity/ Drug lipophilicity (high pKa = lipohphilic) GI SA and length/ blood flow around the GI tract/ GI motility/ Food and pH/charge
66
Describe what is meant by first pass metabolism
The idea that the concentration of a drug is greatly reduced before reaching the systemic circulation because of: - GI enzymes that metabolise the drugs - GI epithelium enzymes - Metabolism in the liver as the drugs are carried through via the hepatic portal system
67
Define drug bioavailability
The fraction of the original dose of drug that reaches the circulation unchanged
68
Drug distribution refers to the part of metabolism that distributes the drugs to their location once their in the bloodstream. Name some things that afect drug distribution
Lipophilicity/charge/capillary permeability/degree of drug binding to plasma proteins (only free dtugs can bind target proteins)
69
Distinguish betwen the minimum effective dose and the maximum tolerated dose
Minimum effective dose - the minimum concentration of drug required to have the desired effect Maximum tolerated dose - the maximum concentratino of drug that can be given without having adverse side effects Area between is the therapeutic window
70
What is the volume of distribution?
The theoretic volume into which the drug is distributed if it occured instantaneously
71
A low pasma concentratino of the drug after being injected suggests a ____ _____ drug
Highly penetrative - good penetration into differtent body compartments
72
Give some clinical times when Vd changes
Pregnancy - higher blood volume to distribute to | Low albumin - less drug sequestration by proteins
73
Where does drug elimination and excretion primarily occur?
Kidney
74
Phase 1 of metabolism is first pass metabolism, redox reactions occur normally causing deactivation of the drug. In phase 2 a functional group is added to the drug to make it hydrophilic and thus able to be filtered by the kidney. Give enzymes of phase 1 and 2
phase 1 - Cytochrome P450 enzymes, exist on Er | Phase 2 enzymes are mainly cytotoxic and add hydrophilic groups to the drug
75
Distinguish between first order and zero order kinetics
1st order - Rate of elimination is proportional to the drug level - half life can be dfined 0 order - Rate of elimination is constant and concentration of drug has no bearing on elimination
76
Capacitance is the ability to store charge, what strucutre contributes to this?
Lipid bilayer

ICPP broad notes (1 decks)

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