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.