Chapter 12

Central Nervous System (CNS)

Includes the brain and spinal cord.

Peripheral Nervous System (PNS)

Consists of cranial nerves and spinal nerves that connect the CNS to limbs and organs.

Somatic Nervous System (SNS)

Controls voluntary movements of skeletal muscles.

Autonomic Nervous System (ANS)

Regulates involuntary responses and consists of sympathetic and parasympathetic divisions.

Sympathetic Nervous System

Part of the ANS responsible for the 'fight or flight' response, increasing heart rate and dilating pupils.

Parasympathetic Nervous System

Part of the ANS responsible for the 'rest and digest' functions, slowing the heart rate and stimulating digestion.

Dendrites

Receive incoming signals from other neurons.

Cell body (soma)

Contains the nucleus and organelles; integrates signals from dendrites.

Axon

Transmits signals away from the cell body to other neurons or effectors.

Axon terminals (synaptic boutons)

Release neurotransmitters to communicate with the next cell.

Resting potential

The electrical charge of a neuron at rest, approximately -70 mV.

Depolarization

The process during action potential when sodium channels open and the inside of the neuron becomes positive.

Repolarization

The process that restores the negative charge inside the neuron by opening potassium channels.

Threshold potential

The voltage that triggers an action potential, approximately -55 mV.

Unipolar neurons

Neurons with one process, typically sensory neurons found in the PNS.

Bipolar neurons

Neurons with two processes, found in the retina and olfactory system.

Multipolar neurons

Neurons with many processes; the most common type, such as motor neurons.

Acetylcholine

A neurotransmitter involved in muscle contraction, learning, and memory.

Dopamine

A neurotransmitter that influences reward, mood, and motor control.

Serotonin

A neurotransmitter that regulates mood, sleep, and appetite.

GABA (gamma-aminobutyric acid)

The main inhibitory neurotransmitter in the brain.

Glutamate

The main excitatory neurotransmitter in the brain.

Neuroplasticity

The ability of the brain to strengthen neural connections through social interaction and learning.

Toxins

Substances like lead and alcohol that can cause neural damage.

Chronic stress

Prolonged stress that can alter neurotransmitter levels and affect brain structure.