Untitled Flashcard Set

What is the primary purpose of the nervous system?

To serve as the body's fast communication system using electrical signals and neurotransmitters.

How quickly does the nervous system produce responses compared to the endocrine system?

In milliseconds, as opposed to the minutes to hours of the endocrine system.

List the main functions of the nervous system.

Detect stimuli, process information, coordinate muscles, regulate organs, maintain homeostasis, and produce reflexes.

What are the two major cell types in the nervous system?

Neurons and glial cells.

What role do neurons play in the nervous system?

They are the functional cells that receive, process, and transmit information.

What is the most tested structure of a neuron?

The axon hillock.

What initiates an action potential in a neuron?

The axon hillock summing excitatory and inhibitory signals and reaching the threshold.

What are dendrites responsible for?

Receiving incoming information.

What is the function of the axon?

To conduct action potentials away from the cell body.

What is the synapse?

The tiny space between neurons where signal transmission occurs.

What are glial cells?

Supportive cells in the nervous system that do not conduct action potentials.

What is the function of astrocytes?

They support neurons, regulate ions, maintain the blood-brain barrier, and provide nutrients.

What do oligodendrocytes do?

They produce myelin in the central nervous system.

What is the role of Schwann cells in the peripheral nervous system?

They produce myelin and wrap around segments of axons.

What do microglia function as?

Immune cells of the CNS responsible for phagocytosis and removing debris.

What is cerebrospinal fluid (CSF) produced by?

Ependymal cells.

What is the resting membrane potential of a neuron?

Approximately -70 mV.

Why is the inside of a neuron negatively charged at resting potential?

Due to the sodium-potassium pump, potassium leak channels, and negative proteins.

What does the sodium-potassium pump do?

Moves 3 Na⁺ out and 2 K⁺ in, using ATP to maintain the resting membrane potential.

What are gated ion channels?

Membrane proteins that open only in response to specific stimuli.

What is an action potential?

A rapid reversal of membrane potential that is an all-or-none event.

What occurs during depolarization in an action potential?

Voltage-gated sodium channels open, causing Na⁺ to rush into the cell.

What happens during repolarization?

Na⁺ channels close and voltage-gated potassium channels open, allowing K⁺ to leave the cell.

What does hyperpolarization refer to?

When the membrane potential becomes more negative than the resting potential.

What are the two types of refractory periods?

Absolute refractory period and relative refractory period.

What happens in saltatory conduction?

Action potentials jump from one Node of Ranvier to the next in myelinated neurons.

What triggers synaptic transmission?

The opening of voltage-gated Ca²⁺ channels leading to neurotransmitter release.

What is acetylcholine (ACh) responsible for?

Skeletal muscle contraction and functions in the autonomic nervous system.

What are the functions of dopamine?

Control of movement, reward, and motivation.

What is the role of serotonin?

Regulating mood, appetite, and sleep.

What is GABA's role in the nervous system?

It is the main inhibitory neurotransmitter that makes neurons less likely to fire.

What does glutamate do?

It is the main excitatory neurotransmitter in the CNS.

Define EPSP.

Excitatory postsynaptic potential that depolarizes the membrane and makes it more likely to fire.

Define IPSP.

Inhibitory postsynaptic potential that hyperpolarizes the membrane and makes it less likely to fire.

What is temporal summation?

When one neuron fires rapidly causing multiple EPSPs that add together over time.

What is spatial summation?

When multiple neurons fire simultaneously and their signals combine to influence the postsynaptic neuron.

What methods are used to clear neurotransmitters from the synapse?

Enzymatic breakdown, reuptake, and diffusion.

What does tetrodotoxin (TTX) do?

It blocks voltage-gated sodium channels, preventing action potentials.

How do local anesthetics work?

By blocking sodium channels to prevent pain signal propagation.

What effect does botulinum toxin (Botox) have?

It blocks ACh release, causing muscle paralysis.

What do organophosphate nerve agents do?

They inhibit acetylcholinesterase, causing ACh accumulation and continuous muscle stimulation.

What do SSRIs do?

They block serotonin reuptake, increasing serotonin concentration in the synaptic cleft.

What is a spinal reflex?

A rapid, automatic response processed by the spinal cord without brain involvement.

What is the reflex arc?

The pathway from stimulus to response: Stimulus → Receptor → Sensory Neuron → Interneuron → Motor Neuron → Effector Muscle → Response.

What characterizes the knee-jerk reflex?

It is a monosynaptic reflex involving one synapse between sensory and motor neurons.

What is the resting membrane potential?

−70 mV.

What is the threshold potential for action potential initiation?

Approximately -55 mV.

Which ion enters the cell during depolarization?

Na⁺ (sodium ions).

Which ion leaves the cell during repolarization?

K⁺ (potassium ions).

What is the role of the Na⁺/K⁺ pump?

To move 3 Na⁺ out and 2 K⁺ in, contributing to the electrochemical gradient.

What does myelin do to the conduction of action potentials?

It speeds up conduction by enabling saltatory conduction.

What triggers neurotransmitter release?

Influx of Ca²⁺ ions into the axon terminal.

What is the function of EPSPs?

To depolarize the postsynaptic membrane and increase the likelihood of firing.

What is the function of IPSPs?

To hyperpolarize the postsynaptic membrane and decrease the likelihood of firing.

How does the body recognize antigens?

Using millions of different lymphocytes, each with a unique receptor.

What happens to memory cells after an infection?

They remain and enable a faster and stronger response upon reinfection.

What is the main function of B cells in the lymphatic system?

To produce antibodies.

Which cells in the immune system mature in the thymus?

T cells.

What are neutrophils and macrophages primarily involved in?

Phagocytosis of pathogens.

What is the main protein that antibodies are made from?

Immunoglobulin.

What is the significance of MHC proteins in the immune response?

They present antigens to T cells, enabling immune recognition.

What differentiates the humoral immune response from cell-mediated immunity?

Humoral immunity uses B cells and targets extracellular pathogens, while cell-mediated immunity uses T cells and targets infected or cancerous cells.

What type of immunity is generated by vaccines?

Active immunity.