CENTRAL NERVOUS SYSTEM

At the center of everything… but separated by layers of membranes

It’s all about connections… Brain spinal cord via foramen

magnum Spinal cord runs through vertebral canal,

formed by vertebral foramina

Meninges mater (umm… matter) Dura mater – “durable” tough, dense;

protection from impact, friction Arachnoid mater – cushion from impact

Subarachnoid space – CSF runs here Pia mater – in the “pits”

direct contactCarries blood vessels Forms nerve sheathsHelps form CSF

More on the pia mater Associated with choroid plexus

Secretes CSFCombination of blood vessels & neuroglia

○ Remember which kind? Ependymal cells

It’s not all black and white… but it is gray! Gray matter = unmyelinated neuron cell

bodiesAccumulate lipofuscinFound primarily in cortex (surface of brain)

○ Highly folded/ridged = gyriIncrease surface area

Small pockets of gray found in interior White matter = myelinated axons, neuroglia

Found in brain’s interior In spinal cord, colors are reversed… outside

white, inside gray

Concept check! 1. Describe the three layers of the

meninges 2. What is the function of the choroid

plexus? 3. Describe the locations of gray and

white matter in the CNSWhy are they those colors?

The Brain

Three-Pound Marvel: The Brain Billions of neurons, neuroglia

Most multipolar (1 axon, many dendrites)Receive many signals, process them

Tracts of axonsInformation conduit other regions of brain,

body

Forebrain: Cerebrum and diencephalon Largest, most anterior portion

EmotionsMemoryMotor movementThought

Contain basal nuclei, cerebral cortex

Forebrain: Basal nuclei/ganglia 4 pockets of gray matter – relay motor

information to spinal cordPermit coordinated, steady body

movements

Cerebral cortex Convoluted gray matter covering brain Large surface area (18 sq ft.)

Blood-brain barrier Cerebral cortex nourished by vessels in

arachnoid layer “Barrier” exists between bloodstream

and CSF… Which neuroglia create this?Astrocytes!

Prevents harmful substances from entering brain (also medications)

Cerebral Hemispheres Halves of cerebrum divided by

longitudinal cerebral fissure Some division of labor…

But you use both halves!

Communication between hemispheres Corpus callosum connects left and

right hemispheresContributes to plasticity of brain

Four lobes of the cerebrum

Central sulcus

Lateral sulcus

Brain stem?

Areas of specialization

Deep, medial portion Hypothalamus, thalamus, ventricles

Thalamus Sensation, spatial

sense, motor signals to cortex

Surrounds 3rd ventricle

Hypothalamus Link nervous

system to endocrine system via pituitary gland

Ventricles 4 connected cavities in the forebrain that

contain CSF Associated w/ choroid plexus, continue

into spinal cord Protect brain from trauma

Internal cushion Swelling: hydrocephaly

Brainstem: Midbrain & Hindbrain

Midbrain Strip of neurons, connects cerebrum to hindbrain.

Smallest region of the brain

Relay station for audio and visual info

Eye movement Substantia nigra:

dopamine neurons

Hindbrain

Pons Attached to midbrain Organize & transmit sensory info from

the body

Medulla oblongata Reg’s involuntary body functions

BPBreathingHeart rateSwallowing

Cerebellum Posterior to pons Means “little cerebrum”

In appearance only Balance Posture Coordination of body movement

The Spinal Cord

Spinal Cord Where does it

start from? (picture)

Paper towel roll Blanket Model of spine

White matter15 pairs nerve tractsAscending tracts

○ Dorsal○ Sensory to the brain

Descending tracts○ Lateral & ventral○ Motor info to

effectorsExtrapyramidal tracts

○ Info from medulla oblongata posture & muscle tone

Gray matter Made of nerve cell

bodies reflexes Transfer info to white

matter Dorsal horn

sensory Ventral horn

MotorWhite mattermuscles

Intermediate gray matterb/t “wings”Sensory/motor for

glands/muscles

Spinal nerves 31 pairs spinal nerves Part of PNS Reflex arcs for respective body regions