📘 Study Guide: Human Anatomy and Physiology

Central Nervous System (CNS)

Brain and spinal cord; integrates, processes, and coordinates sensory data and motor commands.

Peripheral Nervous System (PNS)

All neural tissue outside the CNS; links the CNS to the body.

Afferent Division

Sensory input that carries signals from receptors to the CNS.

Efferent Division

Motor output that carries signals from the CNS to effectors.

Somatic Nervous System (SNS)

Controls skeletal muscles.

Autonomic Nervous System (ANS)

Controls smooth and cardiac muscles, and glands; includes sympathetic and parasympathetic divisions.

Neurons

Nerve cells that transmit electrical impulses.

Myelin Sheath

Insulates axons and is produced by Schwann cells in the PNS.

Action Potential

A sequence of electrical events that occurs when a neuron fires.

Depolarization

Process where Na⁺ enters the neuron, making the membrane potential positive.

Repolarization

Process where K⁺ leaves the neuron, returning the membrane potential to negative.

Continuous Propagation

Propagation of action potentials in unmyelinated axons, occurring slowly.

Saltatory Propagation

Propagation of action potentials in myelinated axons, jumping between Nodes of Ranvier.

Synaptic Cleft

Gap between presynaptic neuron and postsynaptic neuron.

Neurotransmitter

Chemical messengers released into the synaptic cleft that bind to receptors on the postsynaptic neuron.

Reflex Arc

Pathway of a reflex action involving a receptor, sensory neuron, interneuron, motor neuron, and effector.

Monosynaptic Reflex

A reflex involving a single synapse, as seen in the patellar reflex.

Cerebrum

Part of the brain responsible for conscious thought, memory, and sensory processing.

Cerebellum

Region of the brain responsible for balance and coordination.

Nociceptors

Sensory receptors for pain.

Thermoreceptors

Sensory receptors for temperature.

Mechanoreceptors

Sensory receptors for touch, pressure, vibration, and proprioception.

Accommodation

Process by which the lens adjusts its shape to focus light.

Hearing Process

Sequence of events from sound wave entry to brain processing.

Dynamic Equilibrium

Sense of motion detected by the semicircular ducts.

Static Equilibrium

Balance maintained when stationary, detected by the vestibule.