AP Biology Nervous System Unit 4

Action Potential

The electrical signal that travels along the axon of a neuron.

Synapse

The gap between two neurons where neurotransmitters are released.

Neurotransmitter

The chemical messengers that transmit signals across a synapse.

Myelin Sheath

A fatty layer that covers axons, speeding up the transmission of nerve impulses.

Axon

The part of the neuron that transmits impulses away from the cell body.

Dendrite

The part of the neuron that receives signals from other neurons.

Sodium-Potassium Pump

The mechanism that maintains the resting membrane potential by moving sodium and potassium ions across the cell membrane.

Synaptic Vesicle

Small sacs in the presynaptic terminal that contain neurotransmitters.

Resting Membrane Potential

The electrical charge difference across the neuronal membrane when the neuron is not active.

Refractory Period

The period during which a neuron cannot fire another action potential.

Acetylcholine

A neurotransmitter involved in muscle contraction.

Depolarization

The process of making the inside of a neuron more positive, initiating an action potential.

Repolarization

The process by which a neuron returns to its resting state after an action potential.

Central Nervous System (CNS)

The main components of the nervous system, including the brain and spinal cord.

Peripheral Nervous System (PNS)

The system that includes all the nerves outside the brain and spinal cord.

Sarcomere

The basic contractile unit of a muscle fiber.

Myosin

The protein that forms thick filaments in muscle fibers and interacts with actin for muscle contraction.

Actin

The protein that forms thin filaments in muscle fibers and interacts with myosin for muscle contraction.

Troponin

A protein that binds to calcium ions and initiates the contraction process by moving tropomyosin.

Tropomyosin

A protein that blocks myosin-binding sites on actin molecules, preventing muscle contraction until moved by troponin.

Sliding Filament Theory

The theory that explains muscle contraction as the sliding of actin filaments over myosin filaments.

Calcium Ions (Ca^2+)

Ions that bind to troponin, causing a conformational change that moves tropomyosin and exposes binding sites on actin.

Cerebrum

The largest part of the brain, responsible for voluntary activities, intelligence, learning, and judgment.

Cerebellum

The part of the brain that coordinates movement and balance.

Medulla Oblongata

The part of the brainstem that controls vital life-sustaining functions such as heartbeat, breathing, blood pressure, and digestion.