Nervous System Organization Chapter 3

Central Nervous System (CNS)

Brain and Spinal Cord, encased in bone.

Peripheral Nervous System (PNS)

Nerves carrying information to and from the CNS, not encased in bone.

Brain

Weighs 3 lbs, contains 50-100 billion neurons, and 1 quadrillion connections.

Neurons

Communication cells that react and respond to stimuli, learn and store information about the environment.

Glial cells

Structural support cells that perform tasks essential to healthy brain function.

Astrocytes

Fill the space between neurons and regulate how far neurotransmitters can spread.

Oligodendrocytes

Produce myelin.

Microglia

Remove debris from the nervous system.

Dendrites

Receive information from other neurons.

Soma

Contains genetic information.

Axon

Carries electrical impulse to transmit information.

Terminal Buttons

Release neurotransmitters into synaptic cleft.

Synapse

Site of transmission of electric nerve impulses between two neurons.

Neurotransmitters

Chemical messengers in the body that carry messages from one neuron to the next neuron or muscle.

Neural Communication

The process where a neuron gets a signal, action potential fires, neurotransmitters are released, and the message crosses the gap.

>100 neurotransmitters

Examples include glutamate, GABA, dopamine, serotonin, with many others yet to be discovered.

Anterior

Front

Posterior

Back

Superior (dorsal)

Above or topmost

Inferior (ventral)

Below or bottommost

Rostral

Towards the head

Caudal

Towards the tail

Medial

Middle

Lateral

Outside

Ipsilateral

Same side

Contralateral

Opposite side

Afferent

Movement toward CNS

Efferent

Movement away from CNS

Sulcus

Groove or 'valley' in brain's surface

Gyrus

Ridge or 'hill' between two sulci

Fissure

A deep, prominent sulcus

Tract

Bundle of axons - 'highway' that carries information between brain regions

Grey Matter

Outermost layer of brain, pinkish grey in tone (unmyelinated)

White Matter

Myelinated axons that connect regions of brain, passes messages between different areas of grey matter

Corpus Callosum

Large bundle of myelinated nerve fibers that connects two hemispheres, permits communication between right and left sides of the brain

Metencephalon

Division of hindbrain that includes cerebellum, coordinating movement and balance

Pons

Links brain to spinal cord; unconscious processes (e.g., sleeping, breathing)

Myelencephalon

Division of hindbrain that includes the Medulla

Medulla Oblongata

Breathing, blood pressure, heart rate, and other automatic functions

Cerebellar Agenesis

Impairment of motor function, especially an inability to coordinate voluntary movements; born without a cerebellum

Superior Colliculus

Directing gaze and object directed behaviour

Inferior Colliculus

Main auditory center for the body

Thalamus

Relays motor and sensory signals to cortex, regulates sleep, alertness, and wakefulness

Hypothalamus

Regulates body temperature, hunger, thirst, mood, sex drive, blood pressure, and sleep

Cerebral Cortex

Higher cognitive functions

Basal Ganglia

Group of structures near center of brain that fine-tunes voluntary movements and is involved in decision-making and reward

Limbic System

Responsible for regulating emotion, learning and memory, motivation, and survival behaviours (e.g., feeding, mating, fight or flight)

Cranial Nerves

12 pairs of nerves that emerge from the brain and brainstem

Circle of Willis

Forms the redundant blood supply, gives rise to anterior, posterior, and middle cerebral arteries

Spinal Cord

Primary role is to transmit sensory information to the brain and motor commands from the brain to the body