Chapter 5

Central Nervous System

what makes up the central nervous system

brain and spinal cord

what makes up the peripheral nervous system

nerve fibers that carry info between CNS and rest of body

cranial nerves and spinal nerves

what division of the peripheral nervous system carriers information to the CNS from the body

afferent division

what division of the peripheral nervous system carriers information from CNS to the effector organs in the body

efferent division

what are the division of the peripheral nervous system

afferent and efferent nerves

what are the efferent nerve subdivisions

somatic and autonomic systems

what is the somatic system

axons of motor neurons that innervate skeletal muscle

what kind of movement does the somatic system control? (voluntary or involuntary)

voluntary

what is the autonomic system

axons that innervate smooth muscle, cardiac muscle, and glands

what kind of movement does the autonomic system control (voluntary and involuntary)

involuntary

what are the autonomic system subdivisions

sympathetic, parasympathetic, enteric

sympathetic nervous system

variety of effects engaged during stressful situations

parasympathetic nervous system

variety of effects engaged during restful situations

enteric system

network of nerves in the digestive tract partially controlling digestive activities

which peripheral nervous system subdivision causes an effect

efferent nerve

what are the 3 functional classes of neurons

afferent, efferent, interneurons

afferent neurons

bring sensory information from the periphery to the CNS

efferent neurons

bring commands from the CNS out to muscles and glands in the periphery

interneurons

integrate information from afferent neurons to send the correct commands to efferent neurons

what do interneurons form

the complex circuits underlying all sensory, motor, and cognitive abilities

glia

the other major cell type in nervous system
many more than neurons and take up half the volume of brain

what are the 4 major types of glia

astrocytes
oligodendrocytes
microglia
ependymal cells

what type of glia are most abundant

astrocytes

what do oligodendrocytes do

wrap patches of axon with myelin

myelin

fatty insulation that speeds action potential conduction

What do mircoglia do?

immune defense cells of the CNS

migrate to damaged area and engulf invaders and debris thru phagocytosis

What do ependymal cells do?

help form cerebrospinal fluid

what are ependymal cells

are stem cells that produce new glia throughout life but not new neurons

what are the 4 levels of protection of the CNS

bony enclosures
meninges
cerebrospinal fluid (CSF)
blood-brain barrier

what are the bony enclosures that protect the CNS

skull and vertebral column

what are the meninges that protect the CNS

membranous coverings between nervous tissue and surrounding bone

what is the cerebrospinal fluid (CSF) that protect the CNS

shock-absorbing fluid that surrounds brain and spinal cord

what is the blood-brain barrier that protect the CNS

selective barrier that limits access of blood-borne materials into CNS interstitial fluid

what do the brain and spinal cord float in

cerebrospinal fluid

the CSF is high in \________ and low in \__________

Na+
K+

how does the CSF keep concentrations of Na+ and K+ in check

exchanges fairly freely with brain interstitial fluid

where is the CSF formed

choroid plexus

what is the choroid plexus

small pits of capillaries lined by ependymal cells

what does the choroid plexus line

ventricles

what are ventricles

hollow spaces within the brain

CSF flows thru \________ into \__________

ventricles
meninges

what wraps the brain and spinal cord

meninges

what are the 3 layers of the meninges

dura mater
arachnoid mater
pia mater

which layer of the meninges is the outermost layer

dura mater

which layer of the meninges is the toughest layer

dura mater

which layer of the meninges is the middle layer

arachnoid mater

which layer of the meninges is richly vascularized

arachnoid mater

which layer of the meninges is the innermost layer

pia mater

which layer of the meninges is the lining surface of the brain and spinal cord

pia mater

where does the CSF drain to

drains out of ventricles into subarachnoid space of meninges

what is the subarachnoid space

space between arachnoid and pia mater

CSF absorbed by \______________ and dumped into blood-filled \______________ in pockets in \_______________

arachnoid tissue
dural sinuses
dura mater

what is the pathway of CSF

choroid plexus --\> ventricles --\> subarachnoid space --\> blood

what do blood capillaries consist of

single layer of endothelial cells

what usually flows out between the endothelial cells in most body capillaries

ions and nutrients

what is the blood-brain barrier formed by

tight junctions between neighboring capillary endothelial cells

what can freely diffuse across the blood-brain barrier

O2, CO2, water

what must be transported through the blood brain barrier

glucose, ions, amino acids

how are glucose, ions, and amino acids transported through the blood brain barrier

membrane-bound carrier proteins in endothelial cells to reach neurons

what does the blood brain barrier prevent

- harmful blood-borne substance from reaching neural tissue
- various hormones form disturbing neural function
- ion concentrations from being disrupted by concentration changes in blood

what are the parts of the brain

brain stem
cerebellum
forebrain

what are the parts of the brain stem

midbrain, pons, medulla

what are the parts of the forebrain

diencephalon and cerebrum

what does the diencephalon contain

thalamus and hypothalamus

what does the cerebrum contain

basal nucleu, cerebral cortex, and other

what is the spinal cord encased in

bony vertebrae and covered by meninges

how many pairs of spinal nerves exit between vertebrae

31 pairs

what does the spinal cord contain

gray matter
white matter

what is in gray matter of the spinal cord

cell bodies and dendrites

what is in the white matter of the spinal cord

myelinated axons

spinal nerves are bundles of what

afferent and efferent axons

afferent axons enter through what

dorsal root

where do afferent axons have their cell bodies

in the dorsal root ganglion

where do efferent axons exit through

ventral root

where do efferent axons have cell bodies

in the ventral horn of gray matter

what is the gray matter divided into

dorsal, ventral, and lateral horns

what does white matter contain

multiple tracts that target different brain ares

what is a bundle of axons in the CNS

tract

what is a bundle of axons in the PNS

nerves

dermatome

patch of skin innervated by afferent fibers of one spinal nerve

what can dermatomes be used to determine

the location of spinal cord injury

what are responses that occur automatically without conscious effort, mediated by the spinal cord alone

spinal reflexes

what do spinal reflexes require (5 parts)

1. sensory receptor
2. afferent pathway
3. integrating center
4. efferent pathway
5. effector organs

monosynpatic reflex

sometimes afferent neurons synapse directly on efferent neuron

what is the major crossroads between brain and periphery

brain stem

what do all sensory and motor information pass through

brain stem

what is a cluster of cell bodies in the CNS

nucleus

what is a cluster of cell bodies in the PNS

ganglion

what are 3 important functions of the brain stem

1. contain nuclei that control essential functions: heart rate, respiration, digestion
2. Site of entry or exit of 12 pairs of cranial nerves
3. Contains the reticular formation

what does the brain stem also control besides HR, respiration, and digestion?

equilibrium and postural muscles, sleep, auditory processing

of the 12 pairs of cranial nerves that enter or exit the brain stem where do they mostly innervate

head and neck

what is a network of interconnected neurons that aids in directing attention and maintaining alertness

reticular formation

which portion of the brain has the functions to coordinate ongoing movements and learn skilled sequences of movements

cerebellum

what does the cerebellum reduce for ongoing movements

reduces moment-to-moment errors

what are some skilled sequence movements the cerebellum coordinates

learning to dance, pitch a baseball

what are the 3 main divisions of the cerebellum

vestibulocerebellum
spinocerebellum
Cerebrocerebellum

which division of the cerebellum is Involved with reflexive eye movements with respect to head movements; maintaining balance

vestibulocerebellum

which division of the cerebellum is Involved with coordinating muscle contractions during movement to reduce error

spinocerebellum

which division of the cerebellum is Involved with coordinating muscle contractions during highly skilled movements, like speech or dancing

cerebrocerebellum

we can function without a cerebellum but what happens?

tend to make errors in ongoing movement
cannot learn new skilled movements