Cell Communication and Neurotransmitters Ch. 13 AI

This set of flashcards covers key concepts related to cell communication, neurotransmitters, and their effects on the nervous system.

What happens to a cell that receives no external signals?

It undergoes apoptosis.

What do survival signals A, B, and C provide?

Signals required for cell survival.

What do external signals D and E stimulate?

Entry into the cell division cycle.

What happens if a cell divides without receiving signals D and E?

It becomes cancerous.

What do signals F and G cause?

Cell differentiation.

What are the four requirements for cell communication?

A signal, a receptor, intracellular signaling proteins, modification of target proteins.

What are fast responses to signals characterized by?

Use of existing proteins; seconds to minutes; short-lived.

What characterizes slow responses?

Require gene expression; minutes to hours; long-lasting.

What are gap junctions?

Connexon-based channels connecting cytoplasms of adjacent animal cells.

What are plasmodesmata?

Fused membrane channels through plant cell walls.

What is juxtacrine signaling?

Direct contact signaling via membrane-bound molecules.

What is endocrine signaling?

Signals enter the bloodstream and reach distant targets.

What is autocrine signaling?

A cell responds to its own secreted signal.

What is paracrine signaling?

Secreted signals act on neighboring cells only.

Why is synaptic signaling a special paracrine form?

Short-range neurotransmitter diffusion to a specific target.

How are action potentials propagated?

Voltage-gated ion channel opening, inactivation, and closing.

What opens Ca2+ channels in the presynaptic terminal?

Depolarization by the action potential.

What does Ca2+ influx cause?

Vesicle fusion and neurotransmitter release.

What conversion happens presynaptically?

Electrical → Chemical signal.

What happens when neurotransmitters bind postsynaptically?

Ligand-gated ion channels open.

What conversion happens postsynaptically?

Chemical → Electrical signal.

What do excitatory neurotransmitters cause?

Na+ influx and depolarization (EPSP).

What do inhibitory neurotransmitters cause?

Cl– influx and hyperpolarization (IPSP).

What does acetylcholine do at neuromuscular junctions?

Opens Na+ channels → muscle depolarization and contraction.

What terminates ACh signaling?

Acetylcholinesterase.

What is the main excitatory CNS neurotransmitter?

Glutamate.

What channels do glutamate receptors open?

Na+ and Ca2+ channels.

What disease results from excessive glutamate?

Huntington’s disease.

What is the major inhibitory CNS neurotransmitter?

GABA.

What channels do GABA receptors open?

Cl– channels.

What drugs enhance GABA binding?

Valium and Xanax.

Is dopamine excitatory or inhibitory?

Excitatory (EPSP-inducing).

What functions does dopamine regulate?

Body movement and pleasure.

Degeneration of dopamine neurons leads to what?

Parkinson’s disease.

Where is dopamine active in pleasure pathways?

The amygdalae of the limbic system.

How is dopamine normally removed?

Reuptake by transporters.

How does cocaine affect dopamine?

Blocks reuptake → excess dopamine.

What does excess dopamine cause?

Down-regulation of dopamine receptors.

What causes withdrawal?

Reduced receptor numbers make normal dopamine insufficient.

What determines serotonin’s effect?

Its receptor (EPSP or IPSP).

What does serotonin regulate?

Sleep and emotional states.

What causes clinical depression (per slides)?

Insufficient serotonin activity.

How does Prozac work?

SSRI that blocks serotonin reuptake.

What does ecstasy do?

Causes massive serotonin release.

What does LSD act on?

Certain excitatory serotonin receptors.

What is Substance P?

Pain neurotransmitter causing EPSPs.

What are endorphins?

Inhibitory neuropeptides that block pain perception.

How do morphine and heroin work?

Bind to endorphin receptors.

How is nitric oxide produced?

NO synthase converts arginine.

What stimulates NO production in endothelial cells?

ACh binding.

What is unique about NO?

Diffuses rapidly; half-life of seconds.

What does NO cause?

Smooth muscle relaxation and vasodilation.

Why does nitroglycerin work?

It is oxidized into NO.

How does sildenafil work?

Enhances NO response in smooth muscles.