BN chapter 2

central nervous system (CNS)

• brain (in skull)

• spinal cord (in spine)

• the main control center for the body, processing sensory information and coordinating responses.

peripheral nervous system (PNS)

• located outside skull and spine

• serves to bring info into the CNS and carry signals out of CNS

• regulates the internal environment of the body (organs, glands)

• made up of the somatic and autonomic nervous system

somatic nervous system

• part of the PNS

• regulates the nervous systems interaction with the environment

• afferent nerves (sensory)

• efferent nerves (motor)

afferent nerves

sensory

efferent nerves

motor

autonomic nervous system

• part of the PNS

• regulates the internal environment

• consists of sympathetic and parasympathetic divisions

• controls involuntary bodily functions

• neuron exiting the CNS synapses on a second-stage neuron before the target organ (first stage: pre ganglionic) (second stage: post ganglionic)

ganglion

cell body cluster in the PNS

sympathetic nervous system

• part of the autonomic nervous system

• thoracolumbar

• fight or flight

• second-stage neurons start far from the target organ (long)

parasympathetic nervous system

• part of the autonomic nervous system

• craniosacral

• rest and restore (digest)

• second-stage neurons start close to the target organ (short)

I

olfactory - smell

II

optic - vision

III

oculomotor - eye

IV

trochlear - eye

V

trigemial - facial sensations

VI

abducens - eye

VII

facial - taste, facial expressions, tears, and spit

VIII

auditory-vestibular - audition and balance

IX

glossopharyngeal - taste, swallowing, and saliva production

X

vagus - autonomic functions, heart rate, digestion, and sensation from the throat.

XI

spinal accessory - movement of neck and head

XII

hypoglossal - movement of the tongue

meninges

• CNS - encased in bone and covered by 3 meninges

• duramater

• arachnoid

• piamater

duramater

• meninge

• tough outer membrane

• looks like a swim cap

arachnoid membrane

• meninge

• weblike

• beneath is called subarachnoid space

piamater

• meninge

• adheres to CNS surface

• delicate inner membrane

• contains blood vessels and nerves

Ventricles

• central canal: runs the length of spinal cord

• 4 cerebral ventricles

• 2 lateral ventricles

• 3rd ventricle

• 4th ventricle

fluid-filled cavities in the brain

• produce cerebrospinal fluid (CSF) → serves as a cushion, protects and keeps brain from moving around

• choroid plexus: network of capillaries in ventricles

physical protection of the brain

• skull

• meninges

• cerebrospinal fluid (CSF)

chemical protection of the brain

• the blood-brain barrier: tightly packed cells of blood vessel walls prevent entry of many molecules

• protects against toxins and pathogens

the brains blood supply

• carotid arteries - either side of neck

• vertebral arteries - travel up through back of skull - give rise to basilar artery

• gains the carotid arteries at base of brain to form the circle of willis

Regular caps vs. BBB caps

in BBB most materials are moved from the blood by special transporters

top of head

dorsal/superior

back

dorsal

belly

ventral

toward nose

anterior/ rostral

toward butt

posterior/caudal

toward middle

medial

towards side

lateral

close

proximal

far

distal

horizontal

a slice parallel to the ground

frontal (coronal)

like slicing bread or salami

sagittal

a midsagittal section separates the left and right halves

spinal-cord

cross-section

the spinal cord

gray matter, white matter, dorsal horn, ventral horn

gray matter

primarily cell bodies (inner component)

white matter

mainly myelinated axons (outer component)

dorsal horn

afferent, sensory

• info. coming into the CNS

ventral horn

efferent, motor

• info. going out to PNS