exam 2 Flashcards
(145 cards)
1
Q
What is the CNS?
A
made of the brain & spinal cord
2
Q
What is the PNS?
A
everything outside of the brain & spinal cord
3
Q
How long is the spinal cord?
A
about 18 inches in adults
4
Q
How big is the diameter of the spinal cord?
A
about the size of a pinky finger
5
Q
What shape is the spinal cord?
A
cylindrical but flat on its anterior & posterior surfaces
6
Q
What is the foramen magnum?
A
a hole in the skull where the spinal cord begins
7
Q
What does the spinal cord run continuous with?
A
the medulla oblongata
8
Q
What is the spinal/vertebral canal?
A
a hole within the vertebra where the spinal cord is located
9
Q
What is the spinal cord protected by?
A
bones (vertebrae), membranes called meninges, spaces & their contents, and dendiculate ligaments
10
Q
What bones protect the spinal cord?
A
vertebrae
11
Q
What are the meninges that protect the spinal cord?
A
pia mater, arachnoid mater, & dura mater
12
Q
What is pia mater?
A
delicate, thin connective tissue that is anchored onto the cord; it’s the deepest layer
13
Q
What is the arachnoid?
A
delicate web-like connective tissue
14
Q
What is the dura mater?
A
tough fibrous connective tissue; it’s the most superficial layer
15
Q
What do all the meninges surround?
A
the spinal cord & brain
16
Q
What is the epidural space?
A
between the dura mater & the bones; cushions the cord
17
Q
What does the epidural space contain?
A
adipose (fat) which is shown as a yellow color, connective tissue, fibers, lots of blood vessels
18
Q
What is the subdural space?
A
deep to the dura mater; between the dura mater and the arachnoid; cushions cord
19
Q
What does the subdural space contain?
A
serous fluid which is thin, clear, & watery with lots of ions & salts
20
Q
What is the subarachnoid space?
A
deep to arachnoid; between the arachnoid & the pia mater
21
Q
What does the subarachnoid space contain?
A
CSF (cerebrospinal fluid) which is a straw-colored fluid that contains water, ions, salts, some nutrients, & some cellular waste
22
Q
What are dendiculate ligaments?
A
thin bands of connective tissue that extend laterally, anchoring the cord in its left & right sides
23
Q
What is the cervical enlargement?
A
wide part in the spinal cord at the base of the neck; accommodates many nerves that innervates the neck, upper back, arms, & face
24
Q
What is the thoracic region?
A
narrow part of the spinal cord through the chest area
25
What is the lumbar enlargement?
wide area of the spinal cord between the 9th & 12th thoracic vertebra; accommodates the nerves that innervate the legs
26
What is the conus medullaris?
part of the spinal cord past the lumbar enlargement that becomes narrower on one end
27
What is the filum terminale?
1 strand of pia mater extending from the tip of the conus medullaris; non-nervous; anchors cord inferiorly
28
What is the cauda equina?
group of nerves extending from the conus medullaris
29
What is the spinal cord made of?
an area of gray matter surrounded by white matter
30
What is the gray matter area of the spinal cord made of?
dendrites, cell bodies, & axons of association & motor neurons that are arranged in regions called horns
31
What is the anterior median fissure?
a deep split lined with pia mater
32
What is the posterior median sulcus?
a shallow depression
33
What is the gray commissure?
a narrow strip of gray matter that connects the right & left sides of the cord
34
What is the central canal?
small opening in the center of the gray commissure that holds CSF
35
What is the white matter area of the spinal cord made of?
tracts (bundles of axons in the CNS) that carry impulses up and down the cord & it is organised into columns
36
What are ascending tracts?
afferent; they carry sensory information into the CNS
37
What is the lateral spinothalamic tract?
ascending; carries information such as crude touch, pain, & temperature through the spinal cord to the thalamus
38
What is the spinocerebellar tract?
ascending; carries sensations of body position to the brain’s cerebellum
39
What is the spinotectal tract?
ascending; carries sensations from eyes that result in blinking & watering
40
What does the ascending tracts include?
lateral spinothalamic, spinocerebellar, & spinotectal
41
What are descending tracts?
efferent; carry motor impulses out of CNS to effectors (muscles & gland tissue)
42
What is the corticospinal tract?
descending; controls voluntary movement of small muscle groups such as those that move the fingers
43
What is the reticulospinal tract?
descending; controls the muscles of posture when the body is moving
44
What is the rubrospinal tract?
descending; controls the coordinated muscle action of body movement
45
What is the tectospinal tract?
descending; controls movement of the head in response to vision
46
What are roots?
bundles of nerve axons & dendrites attached to the lateral edges of the cord; named by their location; serve as attachments to the PNS
47
What are the anterior/ventral roots?
contain the axons of motor neurons
48
What are the posterior/dorsal roots?
contain the axons of sensory neurons
49
What is the dorsal root ganglion?
a swollen region lateral to the dorsal roots; it is a clump of sensory neuron cell bodies
50
What is a monosynaptic reflex?
1 sensory & 1 motor neuron; can be ipsilateral or contralateral; occurs within only 1 synapse
51
What is a polysynaptic reflex?
AT LEAST 1 sensory, 1 motor, & 1 association neuron; can be ipsilateral or contralateral; occurs within 2 or more synapses
52
What is the withdrawal reflex?
allows us to withdraw from pain by stimulating some muscles & inhibiting opposing muscles; polysynaptic; can be ipsilateral or contralateral
53
What is the crossed extensor reflex?
crosses cord from one side to the other; contralateral
54
What is the intersegmental reflex?
uses white matter tracts to send an impulse up & down cord; may involve the brain; can be ipsilateral or contralateral
55
What does ipsilateral mean?
stays only on 1 side of the cord
56
What does contralateral mean?
crosses from 1 side of the cord to the other
57
What would occur if the mixed spinal nerve area was severed?
sensory neurons could not come in & motor neurons could not go out
58
What would occur if the dorsal root ganglion area was severed?
sensory neurons could not come in
59
What would occur if the ventral root was severed?
motor neurons could not go out
60
What is a reflex?
a programmed predictable response to a stimulus; most of the time it only involves the spinal cord
61
How can reflexes be grouped?
the type of response & their processing site
62
What are the types of response in reflexes?
somatic & autonomic
63
What are the processing sites in reflexes?
spinal & cranial
64
What is a somatic reflex?
involuntary control of skeletal muscles (coughing, sneezing, blinking, etc.)
65
What is an autonomic reflex?
controls/adjusts ANS effectors which are smooth muscle, cardiac muscle, & gland tissue (sweat, chill bumps, digestion, etc.)
66
What are spinal reflexes?
occur in the spinal cord only
67
What are cranial reflexes?
involves the brain
68
What parts does each mixed spinal nerve branch into?
dorsal ramus, rami communicantes, & ventral ramus
69
What is the dorsal ramus?
innervates the skin & muscles of the back
70
What is the rami communicantes?
2 small branches that connect to the ANS
71
What is the ventral ramus?
large; innervates the rest of the body that the dorsal ramus & rami communicantes do not
72
What is a plexus?
a “tangle” formed from adjacent ventral rami
73
What are the different plexus groups?
cervical, brachial, lumbar, sacral, & coccygeal
74
What is the cervical plexus?
inferior to the base of the skull; innervates the neck, diaphragm muscle, & parts of the face and shoulders
75
What is the brachial plexus?
near cervical enlargement; innervates the arms, fingers, & shoudlers
76
What is the lumbar plexus?
near lumbar enlargement; innervates the hips & legs
77
What is the sacral plexus?
arises from the superior part of the conus medullaris; innervates the hips & legs
78
What is the coccygeal plexus?
arises from the inferior part of the conus medullaris; innervates the skin around the coccyx (tailbone)
79
How many pairs of mixed spinal nerves are there?
31; they each pass between vertebra & can be organized in a very specific manner
80
Mixed spinal nerves are organized into layers; what is the first layer?
each axon is wrapped in connective tissue called endoneurium
81
Mixed spinal nerves are organized into layers; what is the second layer?
groups/bundles of axons called fascicles are held together by connective tissue called perineurium
82
Mixed spinal nerves are organized into layers; what is the third layer?
many fascicles are held together in one large group by connective tissue called epineurium
83
How much does the brain weigh?
about 3.5 pounds
84
Why is the brain folded?
to allow ample surface area for neurons/neuroglia while still fitting in our skull
85
Does the brain require continuous oxygen?
yes; it gets 20% of the blood flow from each heartbeat
86
What is the brain protected by?
skull bones, meninges, CSF, astrocytes, acidic (low) pH, & other neuroglia such ependymal cells & microglia
87
How do the skull bones protect the brain?
they form a “brain case” called the cranium that has foramina that allow blood vessels & nerves to pass in/out
88
How is the dura mater in the brain different from the dura mater in the spinal cord?
it is divided into 2 layers
89
What is the meningeal layer?
soft, deeper part of the brain’s dura mater; contours around the brain’s folds (gyri & sulci)
90
What is the dural sinus?
space between the 2 layers of the brain’s dura mater; contains serous fluid and dural sinus blood vessels
91
What is the periosteal layer?
superficial part of brain’s dura mater; tough fibrous connective tissue that adheres to the inner surface of the skull
92
What is cerebrospinal fluid?
a straw-colored, sticky fluid made of water, ions, salts, white blood cells, proteins, amino acids, etc. in a specific composition with a specific pH
93
What structure continually secretes CSF?
the choroid plexus
94
What is the choroid plexus?
a combination of blood vessels & ependymal cells; produces more CSF than our body even needs
95
Where does CSF flow from after being produced by the choroid plexus?
the 2 C-shaped lateral ventricles in each half of the brain
96
What does CSF flow through after the lateral ventricles?
the interventricular foramen of Monro (2 small holes; 1 in each lateral ventricle)
97
What structure does CSF fill after the interventricular foramen of Monro?
the 3rd ventricle (in space of diencephalon)
98
What structure does CSF travel down after the 3rd ventricle?
the cerebral aqueduct of Sylvius (long passageway near brain stem)
99
Where does the CSF flow after the cerebral aqueduct of Sylvius?
the 4th ventricle which is a triangular cavity near the cerebellum
100
What structure does the CSF exit through after flowing through the 4th ventricle?
3 holes called aperatures: median aperature, & 2 lateral aperatures
101
What is the median aperature?
hole that connects to the central canal of the spinal cord for the flow of CSF
102
What are the 2 lateral aperatures?
holes that send CSF into posterior part of the subarachnoid space
103
After exiting through the aperatures, where does CSF travel?
down the posterior side of the cord & up the anterior side; flows around the brain in the subarachnoid space
104
What are arachnoid villi?
finger-like extensions that reabsorb CSF while in the subarachnoid space; they allow CSF to be picked up by dural sinus blood vessels
105
What are the functions of CSF?
distributes nutrients & absorbs cell waste from CNS, cushions brain & spinal cord, & keeps the brain suspended in the skull because CSF has the same density as the brain
106
How do astrocytes protect the brain?
they help form the blood-brain barrier which only allows small molecules to pass from brain blood vessels into brain tissue
107
Why is it important for the blood-brain barrier to allow small molecules in?
small molecules include oxygen, carbon dioxide, sodium ions, potassium ions, & glucose which are vital in our body
108
Why is it important for the blood-brain barrier to keep big molecules out?
it keeps big molecules such as proteins out which limits bacteria from entering the brain and spreading infection
109
What is the downside to the blood-brain barrier keeping big molecules out?
it also prohibits most beneficial drugs from entering the brain
110
What happens when oxygen levels are low?
carbon dioxide levels are high & CO2 combines with H2O which produces carbonic acid
111
Carbonic acid lowers pH; why does this help protect our brain?
it dilates specific blood vessels especially in the brain & it stimulates breathing centers in the brain so we breathe deeper & faster
112
How do ependymal cells help protect the brain?
they secrete & circulate cerebrospinal fluid (CSF)
113
How do microglia help protect the brain?
they engulf & destroy harmful materials in the CNS
114
What are the 3 main brain regions?
telencephalon, diencephalon, & brainstem
115
What are characteristics of the telencephalon (cerebrum)?
highly folded due to rapid growth; divided into 2 “layers”
116
What is the cortex?
outer region of the cerebrum made of neuron cell bodies, dendrites, & axons; gray matter
117
What are the brain’s white matter tracts?
found in the cerebrum; bundles of mostly myelinated axons that connect brain areas; include association, projection, & commissural tracts
118
What are association tracts?
connect within 1 hemisphere of the brain
119
What are projection tracts?
connect vertically, ultimately connecting the cerebrum & the spinal cord
120
What are commissural tracts?
connect left & right hemispheres (ex. = corpus callosum)
121
What can be found scattered in all 3 white matter tracts of the cerebrum?
clumps of neuron cell bodies called nuclei
122
What is the basal nucleus?
controls subconscious skeletal movement
123
What are sulci & gyri?
sulci = grooves, gyri = ridges
124
What does the frontal lobe control?
skeletal muscle movement, personality, & judgement
125
What is Broca’s area?
housed in the left frontal lobe; translates thought into speech
126
What does the parietal lobe do?
receives sensations from the body & allows us to identify an object by its shape & texture
127
What is the temporal lobe?
receives & processes auditory sensations; houses auditory memory & correlation
128
What is Wernicke’s area?
housed in the left temporal lobe; translates speech to thought
129
What is prosody?
housed in the right temporal lobe; adds emotional context to spoken words
130
What is the occipital lobe?
receives & processes visual sensations; houses visual memory & correlation
131
What is the insula?
it is hidden; deep to the temporal lobe; believed to be involved in short-term & emotional memory
132
What does the diencephalon include?
thalamus, hypothalamus, & pineal body/gland
133
What is the thalamus?
oval masses of gray matter (1 per hemisphere); routes impulses from brain stem to telencephalon
134
What is the hypothalamus?
makes & transports hormones; regulates hunger, thirst, rage, aggression, & body temperature
135
What is the pineal body/gland?
small cluster of neurons that release hormones which control cyclical behavior (sleep patterns)
136
What are the 3 regions of the brainstem?
mesencephalon, metencephalon, & myelencephalon
137
What is the mesencephalon?
midbrain; contains corpora quadrigemina; has nuclei that maintain muscle tone & consciousness
138
What are corpora quadrigemina?
4 round bumps through which auditory & visual reflexes are contained in the mesencephalon
139
What are the 2 parts of the metencephalon?
the pons & the cerebellum
140
What is the pons?
oval-shaped; connects brain areas & houses respiratory centers that control breathing (stimulated by acidic blood pH)
141
What is the cerebellum?
highly folded with many gyri & sulci; adjusts the muscles relative to body position & allows appropriate force from muscle contraction
142
What are Purkinje cells?
housed in cerebellum; highly branched neurons
143
What is the myelencephalon?
medulla oblongata; continuation of spinal cord’s ascending & descending tracts
144
What is decussation of tracts?
tracts that cross from one side to the other; there are many found in the myelencephalon
145
What brainstem region contains nuclei that control blood pressure, heart rate, contraction force, blood vessel diameter, breathing, & alertness?
myelencephalon
