Cell Signalling and Signal Transduction (13-17pg)

These flashcards cover key concepts from cellular signaling and hormone functionality as described in the lecture notes.

What mechanism of cellular communication uses small channels that directly connect two cells?

Gap junctions, used in heart muscle cells to synchronize heartbeats.

What is contact signaling in cellular communication?

Contact signaling involves cells touching each other and communicating through surface proteins, as seen in immune cells attacking infection.

What is autocrine signaling?

Autocrine signaling is when a cell releases a signal that affects itself, such as cancer cells releasing growth signals.

What is paracrine signaling?

Paracrine signaling is when a cell releases a signal that affects nearby cells, like nerve cells releasing chemicals affecting neighboring cells.

What is a neurotransmitter?

A neurotransmitter is a chemical messenger released by neurons that transmits signals across a synapse, e.g., dopamine or serotonin.

How does the endocrine system differ from the nervous system in terms of speed and duration of response?

The endocrine system is slow and long-lasting (minutes to days), while the nervous system is fast and short-lasting (seconds).

What is a hormone?

A hormone is a chemical made by glands that travels in the blood to instruct other cells, such as insulin which lowers blood sugar.

What is a ligand?

A ligand is a molecule that binds to a receptor to send a message, like epinephrine which speeds up the heart.

What determines if a cell will respond to a chemical signal?

A cell responds only if it has the appropriate receptor for the signal (ligand or hormone).

Define up-regulation and down-regulation of receptors.

Up-regulation: increasing receptors due to low signal; Down-regulation: decreasing receptors due to excess signal.

What is an agonist?

An agonist is a chemical that binds to and activates a receptor, mimicking the natural ligand's effect.

What is an antagonist?

An antagonist is a chemical that binds to a receptor but blocks it, preventing the natural ligand from activating it.

How does Isoproterenol act on norepinephrine receptors?

Isoproterenol is an agonist that mimics norepinephrine, used to treat slow heart rates.

How does bromocriptine act on dopamine receptors?

Bromocriptine is an agonist that mimics dopamine, helping in cases of low dopamine like in Parkinson's disease.

How does haloperidol act on dopamine receptors?

Haloperidol is an antagonist that blocks dopamine from binding, useful in treating bromocriptine overdose.

Contrast protein-based hormones with steroid-based hormones.

Protein-based hormones are made of amino acids, stored in vesicles, and bind to cell surface receptors; steroid hormones are lipid-based, made from cholesterol, not stored, and bind inside the cell.