Overview of the Nervous System and Brain Functions

Central Nervous System (CNS)

The brain and spinal cord.

Function of the CNS

Carries messages to and from the brain.

Peripheral Nervous System (PNS)

Nerves in the body not encased in bone.

Function of the PNS

Carries messages to and from the CNS.

Somatic Nervous System

Controls voluntary muscle movement.

Source of messages for the somatic nervous system

The motor cortex.

Autonomic Nervous System

Controls automatic body functions and response to stress.

Role of the Sympathetic Nervous System

Initiates fight or flight, speeds up bodily functions.

Role of the Parasympathetic Nervous System

Slows down bodily functions after stress; acts like a brake.

Reflexes

Controlled by the spine, bypass the brain.

Neurons

Carry messages via electrical impulses.

Glial Cells

Provide physical and chemical support for neurons.

Afferent (Sensory) Neurons

Take information from the senses to the brain (PNS).

Interneurons

Process information in the CNS.

Efferent (Motor) Neurons

Carry information from CNS to muscles (PNS).

Mnemonic for Sensory and Motor Neurons

SA/ME - Sensory = Afferent, Motor = Efferent.

Neural Firing Process

Electrochemical.

Resting Potential

The neuron's inactive state.

Threshold

The level needed to trigger action potential.

Action Potential

The 'all or nothing' firing of a neuron.

Refractory Period

Time after firing when a neuron cannot fire again.

Neurotransmitters

Chemical messengers between neurons.

Types of Neurotransmitters

Excitatory and Inhibitory.

Hormones

Chemical messengers that can act like neurotransmitters.

Agonist

A substance that excites by blocking reuptake (e.g., SSRIs).

Antagonist

A substance that inhibits by blocking release.

Substances affecting Neural Firing

Stimulants, depressants, hallucinogens, pain relievers.

Main Brain Divisions (Top to Bottom)

Forebrain, Midbrain, Hindbrain.

Rule for Brain Function by Position

Higher up = Higher function.

Corpus Callosum

Connects the left and right hemispheres of the brain.

Lateralization

Specialization of function in each hemisphere.

Lobes of the Cerebral Cortex

Frontal, Temporal, Parietal, Occipital.