Nature Of Receptors

Question 1

The nature of receptors was an hypothesis T/F

Answer 1

True

Question 2

Functions of receptors are determined by the interaction of

Answer 2

lipophillic or hydrophillic domains of the peptide chain within the drug molecule.

Question 3

Non-polar hydrophobic portion of the amino acid(receptor)______________________while polar hydrophilic remain on cell surface.

Answer 3

remain buried in membrane

Question 4

hydrophilic drugs cannot cross the membrane and has to bind with

Answer 4

the polar hydrophilic portion of the peptide chain of receptor

Question 5

All four major families of receptors have common properties but individual receptors

Answer 5

have different amino acid sequencing.

Question 6

Binding of polar drugs in ligand binding domain induces conformational changes (

Answer 6

alter distribution of charges and transmitted to coupling domain to be transmitted to effector domain.

Question 7

Subtypes of nicotine receptors

Answer 7

Nn : neuronal
Nm: muscle

Question 8

Subtypes of muscarinic receptor

Answer 8

M1
M2
M3
M4
M5

Question 9

5 criteria for classifying receptors

Answer 9

Pharmacological criteria
Tissue distribution
Ligand binding
Transducer pathway
Molecular cloning

Question 10

Pharmacological criteria is the _______ & ___________ approach.

It’s based on?

Examples include

Answer 10

classical
oldest

The potencies of selective agonist and antagonists

Eg Muscarinic, nicotinic, alpha and beta adrenergic etc.

Question 11

I’m tissue distribution, what is the basis for the subtype

The _______________ receptor is beta 1
____________________ is beta 2

Answer 11

the relative organ or tissue distribution is the basis for designating the subtype

cardiac beta adrenergic

bronchial beta adrenal receptor/ adrenoreceptor

Question 12

Ligand binding: Measurement of specific binding of high affinity _________________ to _________________ (usually membranes) in ________ and its selective displacement by various selective ____________\_________is used to delineate receptor subtype. E.g. multiple __________ receptors were distinguished by this approach.

Answer 12

Radio labeled Ligand (radioactive substance used for research)

Cellular fragments

In vitro (Petri dish)

Agonists/ antagonists

5-HT (hydroxytryptamine / serotonin)

Question 13

In Transducer pathway, receptor subtype may be distinguished by?

e.g. M cholinergic receptor acts through?

while N cholinergic receptor?

Answer 13

the mechanism through which their activation is linked to the response,

G proteins

Gates Influx of Na+ ions

Question 14

In Molecular cloning, the receptor protein is cloned and its __________ as well as __________ is worked out. This approach has resulted in a flood of receptor subtypes and several isoforms, even in orphan receptors?

Answer 14

detailed amino acid sequence
as well as three dimensional structure

Receptors without known ligands

Question 15

What are silent receptors?

They are also known as _______ or _______

Example is _______

Answer 15

These are sites which bind specific drugs but no pharmacological response is elicited

Drug acceptors or Sites of loss

e.g. plasma proteins

Question 16

What are spare receptors

Answer 16

The remaining unoccupied receptors are just serving as receptor reserve because drug can produce the maximal response when even less than 1% of the receptors is occupied; and are called spare receptors.

Question 17

What is upregulation?

Depletion of noradrenaline/ treatment with adrenergic antagonists results in?

administration of β-blocker causes?

Answer 17

The increase in the number of receptors with subsequent increase in receptor sensitivity)

supersensitivity of tissues to noradrenaline & increased in receptor no.

an increase in adrenergic receptor

Question 18

What is down regulation

Due to continued exposure to a drug/ agonist: It results in blunted response which is?

Repeated administrations of adrenergic agonists in asthma leads to

Answer 18

reduction in the number of receptors available for activation & reduced affinity to drug reduced no. of receptors

Desensitisation/ refractoriness/ tolerance

down regulation of beta receptors

Question 19

Diseases linked to receptor malfunction are of 2 major types

Answer 19

1. Autoantibodies directed against receptor proteins

Eg: Myasthenia gravis

2. Mutations in genes encoding receptors and proteins involved in signal transduction.

Eg
Mutations of genes encoding GPCRs: hypoparathyroidism, cancers

Question 20

What happens in Myasthenia Gravis

Answer 20

autoantibodies that inactivate nicotinic acetylcholine receptors.

Myasthenia gravis (MG) is a disease of the postsynaptic neuromuscular junction (NMJ) where nicotinic acetylcholine (ACh) receptors (AChRs) are targeted by autoantibodies.

Question 21

Autoantibodies can also mimic the effects of agonists, as in many cases of

Answer 21

thyroid hypersecretion, caused by activation of thyrotropin receptors

Question 22

What happens in insulin resistance

Answer 22

Having fewer insulin receptors or less than expected receptor response upon insulin stimulation

Question 23

Testicular feminization

Answer 23

TF or Androgen insensitivity syndrome (AIS) occurs when someone is genetically male but receptor is insensitive to androgens (male sex hormones).

This means the person has male sex chromosomes (one X and one Y chromosome) but may have female genitals.

Question 24

Familial hypercholesterolemia involves

Answer 24

Familial hypercholesterolemia is caused by a reduction or defect in the LDL receptor, that result in reduced LDL-receptor activity and defective clearance of lipoproteins from the circulation.

This causes, on average, a twofold increase in plasma LDL-cholesterol concentration

People with FH have increased blood levels of low-density lipoprotein (LDL) cholesterol, sometimes called “bad cholesterol