Chemical Communications: Neurotransmitters & Hormones

Flashcards covering key concepts related to chemical communications, neurotransmitters, and hormones.

What types of molecules are involved in chemical communications?

Molecules involved in chemical communications include neurotransmitters and hormones.

How do neurotransmitters act as messengers?

Neurotransmitters act between nerve cells with a faster response than hormones.

What is the effect of hormones?

Hormones travel through the bloodstream and have a longer-lasting effect compared to neurotransmitters.

What are the origins of hormones and neurotransmitters?

Hormones originate from glands of the endocrine system, while neurotransmitters originate from neurons of the nervous system.

How are hormones and neurotransmitters transported?

Hormones are transported through the bloodstream, while neurotransmitters are transported through the synaptic cleft.

What are the targets of hormones and neurotransmitters?

Hormones target distal and local organs far from their origin, while neurotransmitters target local receptors on nerve cells and muscle cells.

What is the duration of effect for hormones and neurotransmitters?

Hormones have a slow action (up to a few days) and prolonged response, while neurotransmitters have a fast action (up to a few milliseconds) and short-lived effect.

What is a synapse?

The junction between pre- and post-synaptic neurons.

Where are neurotransmitters stored?

Neurotransmitters are stored in synaptic vesicles of presynaptic neurons.

How can drugs influence chemical communications?

Chemical communications can be influenced by drugs affecting messengers, receptors, secondary messengers, or enzymes.

What is an agonist?

Agonists mimic the effect of a natural compound by binding and activating the same cellular receptor.

What is an antagonist?

Antagonists counteract the effects of a natural compound by binding to the cellular receptor and blocking its action.

How are chemical messengers classified?

Chemical messengers can be classified as neurotransmitters or hormones.

According to chemical nature, how are chemical messengers classified?

Chemical messengers can be classified based on their chemical nature (e.g., cholinergic, amino acid, adrenergic, peptidergic, steroid).

what are the four action classifications of chemical messengers?

Activate enzymes, Affect the synthesis of enzymes, Affect the permeability of membranes, Act directly or through a secondary messenger

What is a ligand in chemical signaling?

A ligand is a chemical messenger (neurotransmitter or hormone) that binds to respective receptors.

Nicotinic vs. Muscarinic receptors?

Nicotinic receptors are fast and direct, while muscarinic receptors are slower and indirect involving multiple steps inside the cell (cAMP).

What are second messengers?

Second messengers relay signals from receptors on the cell surface to target molecules inside the cell and greatly amplify the strength of the signal.

How is acetylcholine removed from the receptor site?

Acetylcholine is removed from the receptor site by the hydrolyzing enzyme acetylcholinesterase (AChE).

Why is the removal of acetylcholine important?

Rapid removal of acetylcholine from the receptor site allows nerves to transmit more than 100 signals per second.

What happens if the enzyme acetylcholinesterase is inhibited?

Inhibition of acetylcholinesterase leads to incomplete removal of ACh and cessation of nerve transmission, leading to muscle paralysis.

What is the role of Amino Acid Messengers within the CNS?

They are responsible for muscle contraction and stopping unnecessary movement.

What are adrenergic messengers?

Adrenergic messengers are neurotransmitters/hormones derived from amino acids, also known as biogenic amines, and utilize a secondary messenger.

What impact does hormone binding have at the cellular level?

If one molecule of hormone binds to a receptor, it can give rise to many cAMP molecules, bringing a change to the cell.

What are G-protein linked receptors?

G-protein linked receptors contain a neurotransmitter/hormone binding site coupled to a G protein, which activates a secondary messenger pathway.

How does norepinephrine binding affect cell signaling?

Norepinephrine absorption onto a receptor site leads to the G-protein producing many signals inside the cell (amplification).

What utilizes the G-protein-adenylate cyclase cascade?

G-protein-adenylate cyclase cascade utilized by Monoamine messengers as well as other neurotransmitters & peptide hormones.

How does Histamine synthesis from Histidine?

Histamine synthesized from Histidine by decarboxylation and are two kinds of receptors for histamine, H₁ and H₂

Which molecule directly activates protein kinase?

CAMP directly activates protein kinase in the G-protein adenylate cyclase signaling cascade.

What are neuropeptides?

Neuropeptides like endorphins act as natural painkillers produced by the brain.

Through what do peptidergic messengers act?

Peptidergic messengers (hormones & neurotransmitters) act through secondary messengers, with many using the G-protein-adenylate cyclase cascade.

How do steroid messengers interact with the cell?

Steroid hormones (hydrophobic) cross plasma membranes by diffusion and interact inside cells with protein receptors, influencing protein synthesis.

How do agonists mimic natural compounds?

Agonists mimic the effects of a natural compound by binding to and activating the same cellular receptor.

How do antagonists counteract natural compounds?

Antagonists counteract the effects of a natural compound by binding to the cellular receptor and blocking its action.