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Pharmacology and Nutrition > Drug receptors > Flashcards

Drug receptors Flashcards

1
Q

What is a Drug Receptor?

A

Protein or protein complex on a cell membrane or within a cell = binding site of a cell to endogenous and exogenous compounds

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2
Q

Most drugs exert their effect by binding to and activating a receptor

A

Drug binds to receptor = change cellular function

Receptor on its outer surface, the cell is able to differentiate and respond to specific substances that approach the cell = the receptor ‘decides’ if the substance can enter the cell

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3
Q

Drug receptor and fit

A

poor receptor fit = no pharmacologic effect

some drug receptor fit = slight therapeutic response possible

agonist = excellent receptor fit = therapeutic response

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4
Q

RECEPTOR LOCATION

A

Outer surface of the cell membrane = recognizes endogenous (hormones) and exogenous compounds (drugs)

Receptor transmits a message through the cell membrane to create a change in activity of the cell

Transmembrane proteins – span the width of the cell membrane

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5
Q

Receptors affect cell function with the following mechanisms:

A

1) Acting as an ion channel = directly alter membrane permeability: Ligand Gated Ion Channel

2) Linked to regulatory proteins = coupled receptor: G Protein Coupled Receptor

3) Acting enzymatically = directly influence cellular function: Enzyme Linked Receptor

4) Within the cell = Intracellular Receptor

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6
Q

Receptors-Classification

A

Ligand gated Ion channel

G Protein Coupled Receptor

Enzyme linked receptors

Intracellular receptors

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7
Q

Ligand gated Ion channel:

A

Nicotinic Ach receptor & GABA receptor = binding site for GABA & Valium-Diazepam

Movement of ions = change in membrane potential

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8
Q

G Protein Coupled Receptor:

A

Muscarinic Ach receptor = vision, smell, taste, and pain = mediate responses

Membrane permeability influenced = linking of an
Intermediate regulatory protein located on the inner
Surface of the cell membrane

intermediate regulatory protein – this protein must bind with the effector substance and receptor in order to influence membrane permeability or enzyme activity

Surface receptor activated = attaches to a G Protein = G Protein activated = altered enzyme activity or ion channel = change In cell function

Example: morphine = opioid receptor = agonist = pain killer

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9
Q

Enzyme linked receptors:

A

insulin = extracellular activation translates to intracellular enzymatic activity

Transmembrane receptor = extracellular receptor site and intracellular enzymatic component

Drugs that bind to the extracellular receptor site can change the action of the intracellular catalytic component = Change to physiologic function

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10
Q

Intracellular receptors:

A

steroid = highly lipid soluble drugs

Receptors located inside the cell membrane = cell’s Cytoplasm and nucleus

Endogenous example: Hormones

Exogenous example: Steroids

Steroid/hormone forms a complex with the intracellular
Receptor = moves from cytoplasm to nucleus =
Change of function

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11
Q

Acetylcholine Receptor

A

ligand gated ion channel receptor

Located on the postsynaptic membrane of the neuromuscular junction

Acetylcholine molecule = activation of channel = increase in sodium permeability into muscle = cellular depolarization = muscle contraction

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12
Q

Gamma-Aminobutyric Acid (GABA) Benzodiazepine-Chloride Ion Channel

A

ligand gated ion channel receptor

Chloride permeability increases = binding of GABA and benzodiazepine (Valium)

GABA = endogenous
Benzodiazapines (Valium) = exogenous

In the presence of benzodiazepines = GABA effects are enhanced

Response: sedative, hypnotic, anti-anxiety, anticonvulsant, muscle relaxant

Valium is an agonist drug to GABA

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13
Q

G Protein Receptor Modulation

A

Drugs that links to a G Protein and activates the effector system = open an ion channel or activates a specific enzyme

Drugs that links to a G Protein and inhibits the effector system = close an ion channel or inhibits intracellular enzymatic activity

Therefore, the same drug can bind with two different surface receptors and G Proteins = two very different results

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14
Q

Insulin

A

Insulin acts through an enzyme linked receptor

Insulin binds to receptor = initiates enzymatic activity on the inner = Surface of the cell membrane = changes in cell function

Results in increased uptake of plasma glucose

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15
Q

DRUG-RECEPTOR INTERACTIONS

A

Ability to bind: size and shape dependent

Affinity: amount of attraction between drug & receptor = high-affinity drugs bind with low concentration, low affinity drugs need higher concentration

Receptors exist in various affinity states:
super-high, high, moderate, low

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16
Q

minimum effective concentration =

A

certain level of drug must be present in the body to produce an effect at all

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17
Q

strength of response to a drug =

A

increases proportionately as more drug is given

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18
Q

potency =

A

amount of a drug that must be given in order to produce a particular response

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19
Q

efficacy =

A

how well a drug produces its desired effect

related to its intrinsic activity

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20
Q

Drug Selectivity:

A

degree to which a drug acts on a specific site relative to other sites

Drug is selective if it affects only 1 type of cell or tissue

Function of its ability to Interact with specific receptors on the target tissue

Drug selectivity is a relative term = no drug produces only one effect

21
Q

PHARMACODYNAMICS:

A

study of a drugs effect on a body

Bring down activity when a receptor is overstimulated

22
Q

agonist =

A

drug that occupy receptors and activate them

23
Q

antagonist =

A

drugs that occupy receptors but do not activate them

block receptor activation by agonists

24
Q

agonist alone =

agonist & antagonist =

antagonist alone =

A

agonist alone = full activation

agonist & antagonist = less activation

antagonist alone = no activation

25
Q

Agonist vs. Antagonist

A

Agonist: drug that can bind to a receptor and initiate a change in cellular function = both affinity & efficacy

Antagonist: drug can only bind but no change = only affinity

Agonist and Antagonist drugs = both can be therapeutic

25
Q

MOA

How beta blockers short-circuit stress

A

1) beta-blockers enter the bloodstream through GI tract

2) beta-blockers prevent adrenaline from attaching to the receptors on the heart’s cells

3) heart rate stays normal: fight or flight reactions do not occur

25
Q

Inverse Agonist

A

drugthat binds to the samereceptoras anagonistbut induces a pharmacological response opposite to that of the agonist

have opposite actions to those of agonists but the effects of both of these can be blocked by antagonists

26
Q

Neutral antagonist

A

has no activity in the absence of an agonist or inverse agonist but can block the activity of either

27
Q

agonist vs inverse agonist

A

an agonist increases the activity of a receptor above its basal level

an inverse agonist decreases the activity below the basal level

28
Q

Theefficacyof
full agonist =
neural antagonist =
inverse agonist =

A

full agonist =100%

neutral antagonist = 0%

inverse agonist = < 0%

29
Q

Antihistamine

A

Inverse Antagonist

compete histamines for H1 receptors

produces a therapeutic effect that is mediated by negative modulation of histamine receptors

30
Q

Competitive Antagonists

A

vie for the same receptor as the agonist

Both agonist and antagonist have equal opportunity to occupy the receptor = higher concentration has predominant effect = competitive antagonists can be displaced

31
Q

Noncompetitive Antagonists

A

form strong permanent bond with receptor and cannot be displaced by agonist once bound to the receptor

32
Q

RECEPTOR REGULATION

A

Mechanism for increased or decreased sensitivity to agonists and antagonist drugs

receptor-down regulation

receptor-up regulation

33
Q

receptor-down regulation

A

prolonged use of agonists

decrease receptor number and sensitivity of the receptors

decreased drug effect

ex) chronic use of salbutamol

34
Q

receptor-up regulation

A

prolonged use of antagonists

increase receptor number and sensitivity of the receptors

increased drug effect

ex) sudden withdrawal of B blockers

35
Q

Autonomic Nervous System

A

Sympathetic Nervous System = Thoracic and upper lumbar regions of the spinal cord

Parasympathetic Nervous System = Midbrain, brainstem, and sacral regions of the spinal cord

36
Q

pharmacological actions of cholinergics

A

eye - myosis, accomodation, reduction of intraocular pressure, increase lacrymation

heart - decrease HR, decrease force of contraction, slow conduction

blood vessels - constriction of coronary arteries

stomach and intestine - increase motility and secretion

urinary bladder - relaxation of sphincters and contraction of bladder wall

resp. system - constriction of bronchi, increased bronchial secretions

exocrine glands - stimulate sweating, salivation, lacrymation

37
Q

muscarinic receptors

A

M1 = excitatory

M2 = inhibitory

M3 = excitatory

M4&5

38
Q

M1 receptor =

A

excitatory

location: CNS, gastric parietal cells

pharmacologic action: CNS excitation, gastric acid secretion

39
Q

M2 receptor =

A

inhibitory

location: heart

pharmacologic action: cardiac inhibition (bradycardia)

40
Q

M3 receptor =

A

excitatory

location: exocrine glands, smooth muscles (GIT, urinary tract, bronchial m.), vascular endothelium

pharmacologic action: secretion of glands, smooth muscle contractions, vasodilation

41
Q

M&5 receptors =

A

location: CNS

pharmacologic action: memory, arousal, attention, analgesia

42
Q

Nicotinic acetycholine receptors

A

Nn
Ng
Nm

all are ionotropic and fast acting

43
Q

Nn receptor =

A

CNS, adrenal medulla

CNS excitation = release of adrenaline

44
Q

Ng receptor =

A

autonomic ganglia

ganlionic transmission

45
Q

Nm receptor =

A

skeletal muscle

skeletal muscle contraction

46
Q

The endocrine system uses hormones to regulate many body functions including growth and development and reproductive functions. In regards to the endocrine system, which of the following is responsible for controlling the release of androgen testosterone?

Testes
Kidneys
Ovaries
Thyroid

A

Testes

The testes are responsible for controlling the release of androgens

Ovaries – progesterone and estrogen

Kidneys – vitamin D

Thyroid – thyroxine and triodothyronine

Pharmacology and Nutrition (5 decks)

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