Cellular Signal Transduction and Neurophysiology

This set of flashcards covers key concepts from the lecture on cellular signal transduction and neurophysiology, focusing on the mechanisms of signaling, the role of neurotransmitters, feedback loops, and the physiological effects of various signaling pathways.

What is the primary function of cellular signal transduction?

To convert extracellular signals into intracellular responses.

What are the two main types of signals in cellular communication?

Electrical signals and extracellular signals.

Define autocrine signaling.

A signaling process where a cell signals to itself.

What type of signal transduction involves direct cell-to-cell contact?

Contact-dependent signaling.

What are neurotransmitters?

Chemicals that transmit signals across synapses between neurons.

How does a positive feedback loop function?

It amplifies a response until a specific endpoint is achieved.

What do gap junctions facilitate in cellular communication?

Direct electrical and metabolic coupling between adjacent cells.

What two types of signaling occur in paracrine signaling?

Local mediators released by signaling cells affecting nearby target cells.

What is the role of the pancreas in glucose regulation?

It detects blood glucose levels and releases insulin or glucagon accordingly.

Describe how hormones differ from neurotransmitters.

Hormones act over longer distances via the bloodstream, while neurotransmitters act locally at synapses.

Define the concept of signal amplification.

When one ligand activates multiple downstream signaling molecules.

What is the first messenger in signal transduction?

The extracellular signal molecule that binds to a receptor.

What is signal transduction primarily mediated by?

Receptors on the cell surface or within the cell.

What is the effect of agonists on receptors?

Agonists activate the receptor, causing a biological response.

What is the result of antagonists binding to receptors?

They block receptor activity, preventing a biological response.

What role does calcium play in cellular signaling?

Calcium acts as a second messenger in various signaling pathways.

What triggers the release of neurotransmitters from a presynaptic terminal?

An action potential that causes the influx of calcium ions.

What's the function of G protein-coupled receptors?

They activate intracellular signaling pathways when bound by ligands.

What happens during receptor desensitization?

A receptor becomes less responsive to its ligand after prolonged exposure.

What is the difference between full agonists and partial agonists?

Full agonists activate receptors fully, while partial agonists activate them partially.

Define the term 'ligand-binding site.'

The specific region on a receptor where a ligand attaches.

What is the function of phosphodiesterase enzymes in cellular signaling?

They break down cyclic AMP (cAMP), thus terminating the signal.

What animal model often displays the mechanisms of neurotransmitter action?

The frog is often used in research on synaptic transmission.

What influences the action of neurotransmitters in the postsynaptic cell?

The type of postsynaptic receptor they bind to.

Describe the action of muscle fibers in response to action potentials.

They contract as a result of increased intracellular calcium following action potentials.

What type of ions typically serve as second messengers?

Calcium ions are commonly used as second messengers in signaling.

What is the role of tyrosine kinases in cellular signaling?

They phosphorylate tyrosine residues on proteins, altering their activity.

How does insulin affect glucose metabolism?

Insulin promotes the uptake and conversion of glucose to glycogen in the liver.

What triggers the electrical signal in neurons?

The rapid movement of ions across the neuron's membrane.

What is a neuromuscular junction?

The synapse between a motor neuron and a muscle fiber.

What is the primary function of the myelin sheath?

To insulate axons and speed up action potential propagation.

What is the gap junction's diameter roughly?

2-4 nanometers.

What distinguishes lipophilic and lipophobic signals?

Lipophilic signals can cross membranes; lipophobic signals cannot.

What role does nitric oxide play in the cardiovascular system?

It regulates blood vessel dilation as a signaling molecule.

What are the consequences of GTP binding to G proteins?

It activates the G protein, allowing it to interact with effector proteins.

Describe the outcome of an action potential reaching the axon terminal.

It causes neurotransmitter release into the synaptic cleft.

How does phosphorylation affect protein function?

It can activate or deactivate the target protein's activity.

What happens during the downregulation of receptors?

It decreases the number of functional receptors in response to high ligand levels.

What do receptor-ligand complexes trigger upon formation?

They initiate various intracellular signaling cascades.

What characteristic of ion channels allows them to respond to voltage changes?

Their conformation changes in response to altering membrane potential.

What is a common feature of both excitatory and inhibitory synapses?

They both use neurotransmitters to communicate between neurons.

In signaling pathways, what do calcium ions typically regulate?

They affect muscle contraction and various metabolic processes.

Name a common neurotransmitter that acts at the neuromuscular junction.

Acetylcholine is the primary neurotransmitter.

What is synaptic fatigue?

A temporary reduction in the efficiency of synaptic transmission after prolonged use.

How do phospholipase C and its products function in signal transduction?

They generate second messengers such as IP3 and DAG.

What is the primary effect of diacylglycerol (DAG) in the cell?

It activates protein kinase C (PKC) to phosphorylate target proteins.

What connects adjacent cells in a cardiac muscle tissue?

Gap junctions allow electrical signals to pass quickly between cells.

Which domain of a steroid hormone receptor binds to DNA?

The DNA-binding domain binds to specific elements in the DNA.

What is transduction in cellular signaling?

It is the process of converting a signal into a cellular response.

What initiates a muscle contraction at the neuromuscular junction?

The binding of acetylcholine to its receptor on the muscle fiber.

What is an excitatory postsynaptic potential (EPSP)?

A change in membrane potential that makes a neuron more likely to fire.

What is the primary mediator of the fight-or-flight response?

Epinephrine (adrenaline) is the primary mediator.

What is the role of the endoplasmic reticulum in calcium signaling?

It stores calcium ions, which can be released to stimulate cellular responses.

How does long-term potentiation relate to learning?

It increases synaptic strength, which is thought to underlie learning and memory.

What effect does the binding of an antagonist have on a receptor?

It blocks the receptor and prevents a response.

In signaling pathways, what do kinase enzymes do?

They transfer phosphate groups to specific substrates.

What is the main advantage of having multiple signaling pathways?

It allows for precise and diverse cellular responses.