Pt2 CNS

Question 1

What’s the difference between white matter & grey matter? (Cerebrum)

Answer 1

1. White matter =
   -myelinated axons
   -connect CC w/ other brain regions
   -divided into: projection fibers, association fibers, commissural factors
2. Grey matter =
   -part of CC
   -contains nerve cell bodies & their processes
   -surface of cerebrum

Question 2

What are the 3 white fiber tracts of the cerebral hemispheres?

Answer 2

Projection, association, & commissural fibers

Question 3

Describe projection fibers. (Cerebrum)

Answer 3

-leave white matter & terminate in basal nuclei or CNS
-originate in thalamus & terminate in CC

Question 4

Describe association fibers. (Cerebrum)

Answer 4

-connect regions of CC within one hemisphere

Question 5

Describe commissural fibers.

Answer 5

-connect cortices from right to left & cerebral hemispheres (ex. Corpus callosum)

Question 6

Describe basal nuclei.

Answer 6

(ganglia in cerebrum)
-gray matter nuclei deep in white matter
-produce output via thalamus into premotor cortices = imp for planning & prep for movement -> sends output to brainstem
-accessory motor system helps execute initiation & control of movement
-cognitive control of motor activity -> use of sensory input & memory to make a motor action (ex. Bear = run)
-inhibitory output = motor system becomes active when inhibitory effect of basal nuclei is released (ex. Dopamine containing neurons of substancia nigra help regulate inhibition)
degen of this neuron = Parkinson’s disease

Question 7

Describe association areas.

Answer 7

-integration & interpret info
-complex patterns of linking sensory & motor systems via short interneurons, memory, emotion & behavior
-in cats/dogs the primary somatic sensory areas & motor cortex (projection area) = majority of CC opp for humans

Question 8

Describe motor cortex, and what are the 3 parts?

Answer 8

-gives rise to motor fibers that descend to CNS
-corticospinal or pyramidal tract = pair of descending motor tracts on ventral medulla - fibers originate in CC
what allows you to play piano - controls distal phalanges
1. Primary motor area = muscle activation
2. Premotor frontal area = plan & organize the sequence of movements
3. Supplementary motor cortex = prep orientation of body to do a motor task

Question 9

What are the 5 primary cortical sensory areas in the cerebrum?

Answer 9

1. Somatosensory = touch, pain, temp, pressure, taste
2. Visual = visual input
3. Vestibular area = input from vestibular apparatus
4. Auditory area = auditory input
5. Olfactory bulb = olfactory input

Question 10

What are the 3 functions of the cerebral cortex?

Answer 10

1. Sensory perception = receive fibers carrying sensory signals (ex. Pain, touch, smell, hearing, visions)
2. Voluntary (skilled) movements = rise to motor fibers that descend to CNS
3. Learning & intelligent behavior

Question 11

Describe the cerebrum.

Answer 11

-left & right hemispheres
-conscious experience of sensation
-initiation of voluntary movement
-cortex grows faster than white matter
-surface is folded
*Sulcus = inward fold
*Gyrus = outward fold
*Fissure = deep sulcus
“Decussation”: fibers cross & connect the 2 cerebral hemispheres (ex. Corpus callosum)
-basal nuclei = cluster of neuron cell bodies in CNS located deep in cerebral hemispheres & brain stem

Question 12

Describe cerebellum.

Answer 12

-synchronizing muscle activity & controlling equilibrium & eye movement
-contact w/ CC & CNS
-complex skeletal muscle activity
-assess disparities between intended motor action & muscular response
-receives sensory info from:
>skin, joints, muscles, vestibular system, visual system
*damage = loss of spatial accuracy & smooth execution of movements & equilibrium

Question 13

Describe thalamus.

Answer 13

-lg nucleus that extends into each cerebral hemisphere
-processes most info reaching CC
gateway to CC
-integrates & process info coming from sensory system & nonsensory areas like basal nuclei & cerebellum
-imp for consciousness, attention, alertness

Question 14

Describe the limbic system.

Answer 14

-related w/ behavior, arousal, emotions, memory, socials, instinct
-found at limbus (border) between cerebrum & thalamus
-ANS & NS (ex. Hypothalamus, thalamus, cingulate gyrus, amygdala, hippocampus, mammillary nuclei)
-emotions affect visceral functions = HR, BP, GI motility
-

Question 15

Describe hypothalamus.

Answer 15

-center of homeostasis
-4 F’s (fight, fuck, fleet, feed)
-coordinate adenohypophysis, HR, BP, body temp, water balance, food intake, circadian rhythm, gonadal function, emotions
-neurological & endocrine connection
-more than 12 nucleus & areas that regulate:
Body temp, endocrine system, appetite, sexual/defense behavior, circadian rhythm, ANS
-secretes releasing & inhibitory hormones that control anterior pituitary secretion
hypothalamic-hypophysial portal blood vessels