Pharmacology of Neurotransmission

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Questions and Answers

What is a characteristic of an agonist that distinguishes it from an antagonist?

High intrinsic activity (correct)

No binding to receptor

No efficacy

Low affinity

What type of antagonism is characterized by the antagonist binding to the receptor and staying bound, making it irreversible?

Noncompetitive antagonism (correct)

Up regulation

Competitive antagonism

Desensitization

What is the effect of an agonist on the receptor, in terms of desensitization?

Desensitization of receptors (correct)

No effect on receptors

Up regulation of receptors

Increased signal transduction

What is the main difference between a full agonist and a partial agonist?

Full agonists have high efficacy, while partial agonists have low efficacy Signup and view all the answers

What is the result of increasing the agonist concentration in the presence of a competitive antagonist?

The antagonist can be overcome Signup and view all the answers

What type of signal transduction is characterized by being speedy?

Ion channel linked Signup and view all the answers

What is the primary mechanism by which many drugs interact with biological systems?

Inhibition of enzymes Signup and view all the answers

What is the term for the ability of a drug to bind with receptors?

Affinity Signup and view all the answers

What type of drug is propranolol, based on its mechanism of action?

Antagonist Signup and view all the answers

A drug with high affinity binding is most likely to:

Bind to the receptor and remain bound long enough to activate it Signup and view all the answers

What determines the degree of response to a drug, independent of its affinity?

Intrinsic activity Signup and view all the answers

Salbutamol is an example of a type of drug that:

Acts as an agonist Signup and view all the answers

What is the result of Ach binding to sites on α subunits?

A conformational change occurs that opens the central aqueous channel Signup and view all the answers

What is the characteristic of the onset and offset of responses through nicotinic Ach receptors?

Fastest as the agonists operate these channels without involvement of any coupling protein or second messenger Signup and view all the answers

What is the typical structure of enzymatic receptors?

A polypeptide with two domains: extracellular hormone binding domain and cytoplasmic enzyme domain Signup and view all the answers

What is the result of the binding of ligand to the extracellular domain of enzymatic receptors?

The receptor undergoes a conformational change that activates its enzymatic activity Signup and view all the answers

What is an example of a ligand that uses a single type of receptor to trigger multiple biochemical processes?

Insulin Signup and view all the answers

What is the result of the binding of EGF to its receptor?

The receptor undergoes a conformational change that activates its enzymatic activity Signup and view all the answers

What is the characteristic of the domain structure of the EGF receptor?

It has extracellular and cytoplasmic domains above and below the plasma membrane Signup and view all the answers

Study Notes

Synaptic Transmission

A synaptic cleft is the gap between two neurons, where chemical transmission occurs.
High affinity binding: the ligand binds well and remains bound long enough to activate the receptor.
Low affinity binding: the ligand binds less well and may not remain bound long enough to activate the receptor.

Agonists and Antagonists

Agonist: has affinity and intrinsic activity, producing a response.
Antagonist: has affinity but no intrinsic activity, blocking the response.
Partial agonist: has affinity and less intrinsic activity, producing a partial response.
Competitive antagonists: compete with agonists for receptors, and can be overcome with increasing agonist concentration.
Noncompetitive antagonists: bind to receptors and stay bound, reducing the apparent affinity of agonists.

Agonist Drugs

Full agonist: has maximal efficacy.
Partial agonist: has less than maximal efficacy.
Agonist dose-response curves: show the response to different doses of agonist drugs.

Antagonist Drugs

Competitive antagonists: reduce the apparent affinity of agonists.
Noncompetitive antagonists: bind to receptors and stay bound, reducing the response.

Desensitization

Agonists tend to desensitize receptors, reducing their number or signal transduction.
Antagonists tend to up-regulate receptors.

Signal Transduction

Enzyme-linked receptors: involve multiple actions.
Ion channel-linked receptors: involve speedy actions.
Pharmacodynamics: the effect of drugs on biological systems.

Pharmacodynamics

The effect of drugs on the body.
Mechanism of drug action.
Many drugs inhibit enzymes, controlling metabolic processes.
Some drugs bind to proteins or the genome.
Most drugs act on receptors, binding to specific sites and triggering a response.

Drug Receptor

A macromolecular component of a cell that interacts with a drug to produce a response.
Usually a protein.
Affinity: the ability of a drug to bind to a receptor.
Intrinsic activity (efficacy): the ability of a drug to activate a receptor after binding.

Receptor Types

Nicotinic Ach receptor: a ligand-gated ion channel.
Enzymatic receptors: polypeptides with extracellular hormone binding and cytoplasmic enzyme domains.
Examples: insulin, epidermal growth factor (EGF), platelet-derived growth factor (PDGF), and atrial natriuretic peptide (ANP) receptors.

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Description

This quiz covers the concepts of synaptic cleft, agonists, antagonists, and partial agonists in pharmacology, including their effects on post-synaptic cells.