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 plexusSecretes 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 traumaInternal 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 functionsBPBreathingHeart 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