IV. CENTRAL NERVOUS SYSTEM (CNS):

1. Flat bones of the skull & vertebrae

A. Protective Structures of the CNS:

located along the midline of the body;

brain & spinal cord

receives sensory information and creates

a response

2. Meninges – three membranes surrounding CNS

1. dura mater – thick, tough, outer layer

2. arachnoid mater – middle layer with a web-like region

that allows fluid to circulate freely

3. pia mater – thinnest, innermost layer attached directly to

the brain & spinal cord

Pia Mater

Arachnoid

Mater

Dura

Mater

Cranial Bone

3. Cerebrospinal Fluid (CSF)

clear, lubricating fluid that bathes the CNS

acts as a cushion & provides nourishment to nervous tissue

is produced within cavities of the brain called ventricles

B. Brain – processing center composed of billions of neurons

1. Cerebrum:

largest portion of the brain

the outer portion of gray matter is

called the cerebral cortex

the wrinkles of the cerebral cortex

are called convolutions (gyri =

ridges & sulci = grooves)

divided into four regions:

frontal lobe parietal lobe

temporal lobe occipital lobe

controls memory, learning/thinking, movement, & the senses

2. Cerebellum:

inferior, posterior portion of the brain

regulates balance, posture, & muscle coordination

Cerebellum

Cerebrum

3. Brain Stem:

a. Diencephalon

i. thalamus - acts as a relay station for sensory impulses

to the brain

ii. hypothalamus - controls the autonomic (involuntary)

system to control hunger, body, temp.,

emotions, & sex drive

Thalamus

Hypothalamus

b. Midbrain

acts as a pathway for impulses between brain & spinal cord

c. Pons

connects the cerebellum to the cerebrum

d. Medulla Oblongata

connects the brain to the spinal cord and regulates heart rate,

blood pressure, respiratory rate

MEDULLA

OBLONGATA

DIENCEPHALON

PONS

MIDBRAIN

Cerebrum

Cerebellum

Brain Stem

Medulla

Oblongata

Midbrain

Pons

Diencephalon

C. Spinal Cord

extends from the brain through the vertebrae to connect the

brain with the nerves of the body

surrounded by vertebrae, the meninges, & is bathed in

cerebrospinal fluid (CSF)

V. PERIPHERAL NERVOUS SYSTEM (PNS)

1. Nerves - carry nerve impulses between CNS and skin,

muscles, glands, organs

A. Organs of the PNS:

extends from the midline to the outer portions of the body

carry information to/from the CNS

a. Types of Nerves:

i. cranial nerves – extend from the

brain to head/neck

ii. spinal nerves – extend from the

spinal cord to the

body

2. Ganglion – cluster of neuron cell bodies located outside of the CNS

3. Sensory receptors – neurons specialized to respond to stimuli such

as pressure, pain, light, chemicals, and

temperature (found in eyes, ears, nose, skin,

& tongue)