A&P C8

Central Nervous System (CNS)

Brain and spinal cord; control center of the body

Peripheral Nervous System (PNS)

Nerves outside CNS; connects body to brain and spinal cord

Nerve Structure

Bundles of neurons (axons) wrapped in connective tissue; carry electrical signals

Neuron

Basic nerve cell that transmits electrical impulses

Dendrites

Receive signals and carry them toward the cell body

Axon

Transmits signals away from the cell body

Myelin Sheath

Fatty covering around axons that speeds up nerve impulses

Brain Regions

Include cerebrum, cerebellum, brainstem, and diencephalon; each controls specific functions

Cerebrum

Thinking, memory, voluntary movement, senses

Cerebellum

Balance, coordination, posture

Brainstem

Controls vital life functions like breathing and heart rate

Diencephalon

Includes thalamus and hypothalamus; regulates hormones, temperature, and sensory relay

Excitatory Response

Increases likelihood of a neuron firing an action potential

Inhibitory Response

Decreases likelihood of a neuron firing an action potential

Reflex

A fast, automatic response that does not require conscious brain control

Reflex Arc

Pathway of a reflex: sensory neuron → spinal cord → motor neuron → response

CNS Infections

Conditions affecting brain and spinal cord such as meningitis and encephalitis

Meningitis

Infection/inflammation of membranes (meninges) surrounding brain and spinal cord

Encephalitis

Inflammation of the brain, often caused by viral infection