7: Nervous System

Question 1

nervous system functions

Answer 1

monitor body’s internal and external environments
integrates sensory information
coordinates voluntary and involuntary responses

Question 2

CNS vs PNS

Answer 2

central nervous system = brain and spinal cord
integrates and coordinates sensory data and the transmission of motor commands
peripheral nervous system = all communication between CNS and rest of body

Question 3

types of receptors

Answer 3

chemo = respond to chemical change (heat, smell, taste)
mechano = respond to mechanical pressure or distortion (balance, hearing)
photo = respond to light (sight)
thermo = sense changes in temp

Question 4

neurons

Answer 4

cell body contains large round nucleus
dendrites receive incoming signals
axon carries outgoing signals toward one or more axon terminals
grey matter = clusters of RER and free ribosomes known as Nissl bodies
action potentials begin at thickened region of cell body known as axon hillock
each axon terminal part of synapse

Question 5

multipolar neuron

Answer 5

two or more dendrites and a single axon
most common in CNS
all motor neurons that control skeletal muscle are multipolar

Question 6

unipolar neurons

Answer 6

dendrites are continuous and cell body lies off to one side
most sensory neurons of PNS

Question 7

bipolar neurons

Answer 7

one dendrite and one axon with cell body in between
occur in special sense organs where they relay information about sight, smell, hearing

Question 8

anaxonic neurons

Answer 8

brain and special senses
very small
no anatomic features that distinguish dendrites from axon

Question 9

spinal cord

Answer 9

31 segments, each has a pair of dorsal root ganglia, containing the cell bodies of sensory neurons
bring sensory information to spinal cord
a pair of ventral roots contain axons of motor neurons
sensory (dorsal) and motor (ventral) roots bond together into single spinal nerve

Question 10

spinal cord sectional anatomy

Answer 10

gray matter - contains cell bodies of neurons and neuroglia (glial) cells
white matter - contains myelinated and unmyelinated axons
horns - projections of gray matter

Question 11

spinal nerves

Answer 11

31 pairs of spinal nerves are grouped according to the region of the vertebral column which they originate
each pair of spinal nerves monitors a specific region of the body surface known as a dermatome
damage to spinal nerve or dorsal root ganglia produces a characteristic loss of sensation in corresponding region of skin

Question 12

reflex arc

Answer 12

1. arrival of stimulus and activation receptor
2. activation of sensory neuron
3. information processing in the CNS
4. activation of motor neuron
5. response by peripheral effector

Question 13

the brain

Answer 13

6 major regions: cerebrum, diencephalon, midbrain, pons, medulla oblongata, cerebellum
brain stem = midbrain, pons, medulla oblongata

Question 14

cerebrum

Answer 14

large paird left and right cerebral hemispheres
origin of conscious thoughts, sensations, intellectual functions, memory storage and processing, complex movements

Question 15

diencephalon

Answer 15

connected to the cerebrum
largest portion is the thalamus which contains relay and processing centres for sensory information
hypothalamus is floor of diencephalon, contains centres controlling emotions, autonomic function and hormone production

Question 16

midbrain

Answer 16

nuclei process visual and auditory information and generate involuntary motor responses
also contains centres that help maintain consciousness

Question 17

pons

Answer 17

connects cerebellum to brainstem
tracts and relay centres
nuclei involved in somatic and visceral motor control

Question 18

medulla oblongata

Answer 18

attached to spinal cord
relays sensory information to the thalamus and other brainstem centres
autonomic centres that regulate heart rate, blood pressure, respiration, digestive activties

Question 19

cerebellum

Answer 19

adjusts voluntary and involuntary motor activities on the basis of sensory information and stored memories or previous moments

Question 20

meninges

Answer 20

meninges are three layers of specialised membranes surrounding brain and spinal cord
provide CNS tissue with physical stability and shock absorption
dura mater, arachnoid mater and pia mater

Question 21

cerebrospinal fluid (CSF)

Answer 21

fills ventricles and surrounds exposed surfaces of CNS
cushions the brain and spinal cord against physical trauma
supports brain to make it ‘float’
transports nutrients, chemical messengers, and waste products

Question 22

cranial nerves

Answer 22

olfactory nerves (I) = smell
optic nerves (II) = vision
oculomotor nerves (III) = eye movement
trochlear nerves (IV) = move eye down or laterally
trigeminal nerves (V) = sensory input of lips, gums, cheeks, pallet, chewing actions
abducens nerves (VI) = eye movement laterally
facial nerves (VII) = taste receptors, facial expressions, salivary and tear glands
vestibulocochlear nerves (VIII) = balance and hearing
glossopharyngeal nerves (IX) = posterior third of tongue, swallowing
vagus nerves (X) = thorax and abdomen
accessory nerves (XI) = neck and upper back skeletal muscle
hypoglossal nerves (XII) = motor movement of tongue