Central Nervous System Flashcards
(123 cards)
1
Q
Central nervous system consists of the _________ and ________
A
brain and spinal cord
2
Q
What are the three main components of the brain?
A
Cerebrum, Cerebellum, and Brainstem
3
Q
This is the largest part of the brain and divided into 2 halves (or hemispheres): a left and right hemisphere (cerebral hemispheres)
A
Cerebrum
4
Q
Corpus callosum
A
collection of nerve axons that link the right and left hemispheres of the cerebrum, so the 2 halves may communicate
5
Q
The cerebrum is divided into two layers. What are these?
A
gray and white matter
6
Q
Cerebral cortex
A
- outer layer of gray matter of cerebrum
7
Q
What are the 4 lobes that make up the cerebral cortex? (each hemisphere each have these 4 lobes)
A
- Frontal lobe
- Parietal lobe
- Occipital lobe
- Temporal lobe
8
Q
Functions of frontal lobe
A
functions in personality, emotions, control of movement
9
Q
Functions of parietal lobe (posterior to frontal lobe)
A
mediates skin and muscle sensation
10
Q
Function of occipital lobe
A
vision
11
Q
Function of temporal lobe
A
hearing and memory functions
12
Q
Forebrain comprises of
A
comprises the cerebrum and diencephalon
13
Q
Cerebellum
A
- located at the base of cerebrum
- controlling balance and voluntary movement
14
Q
Brainstem
A
- composed of midbrain, pons, medulla oblongata
- controls respiration, locomotion, cardiovascular functions including the regulation of blood pressure & heart rate
15
Q
The spinal cord has both ____________ sensory axons and __________ sensory axons. What are the function of these?
A
Ascending sensory axons- transmits sensory information from the body to the brain
Descending axons- control movement & a variety of autonomic functions
16
Q
Cerebral cortex
A
- outer gray matter of cerebrum
- convoluted thin layer that covers the brain
- Functions: sensory perception, motor control, language, cognitive functions (thinking, memory, willed action, self-awareness)
17
Q
Why is the cerebral cortex darker?
A
Because it contains the cell bodies and this is called the gray matter
18
Q
Basal ganglia functions
A
- movement initiation
- inhibition of muscles antagonistic to the desired movement
19
Q
This is the largest part of the the brain and receives enormous amount of input form the spinal cord & from the cerebral cortex
A
Thalamus
20
Q
Thalamus functions
A
- sensory “switchboard” which selects and relays sensory signals to cortex
21
Q
Hypothalamus (located under the thalamus) functions
A
- maintains homeostasis (keeps the internal environment of the body constant: temp control, water balance, hunger)
- emotions (head ganglia of the ANS)
22
Q
Cerebellum functions
A
- motor timing
- scaling
- coordination and learning
- balance and gait
- eye movements
- mediates motor learning
23
Q
Brainstem functions
A
- cardiovascular, respiratory and digestion control
- sleep/wake cycle
- arousal
- balance and posture
- locomotor initiating center
24
Q
This mediates simple reflexes such as withdrawal reflex and muscle stretch reflex
It functions as a locomotor pattern generator
A
Spinal cord
25
Limbic system
- an interconnected group of brain structures
- involved in learning, emotion, appetite, sex function, and endocrine (hormone) integration
26
What parts of the brain are included in the limbic system?
Thalamus, hypothalamus, hippocampus, olfactory bulbs in the nose and septal nuclei
27
What is a septal nuclei?
- pleasure centers of the brain
- psychoactive drugs such as cocaine, fentanyl, and ecstasy activate the pleasure centers of the brain including the septal nuclei
28
The meninges consists of membranes that cover the brain and spinal cord.
What are the 3 layers?
- Dura mater: tough outer layer
- Arachnoid mater: spidery intermediary mesh (middle)
- Pia mater: delicate inner layer
29
Infection of the meninges
Meningitis
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Cerebrospinal fluid
- provides mechanical protection
- produced in brain ventricles
- reabsorbed into the blood in the venous system at the same rate it is produced
- maintain an appropriate electrolyte balance around neurons
- bathe and support neural tissue
31
occurs when reabsorption of cerebrospinal fluid is blocked, CSF accumulates; treated surgically with drainage tubes
Hydrocephalus ("water on the brain")
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4 types of Glial cells
- Astrocytes
- Oligodendrocytes
- Ependymal cells
- Microglia
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Astrocytes (star-like cells)
- physically support neurons by forming a scaffold that holds neurons together
- form the blood brain barrier
- forma scar tissue when CNS is damaged which inhibits regeneration of axons
- recycling of neurotransmitter
34
Oligodendrocytes
- cells with relatively few branches which form the myelin sheath around neuronal axons
35
________ electrically insulates segments of axons and increases conduction velocity
Myelin
36
Ependymal cells
produce the cerebrospinal fluid
37
Microglia
scavengers that ingest bacteria and cellular debris
38
This kind of brain tumor arise form glial cells
gliomas
39
this kind of brain tumor arise in the meninges
meningioma
40
___________ of the BBB are tightly joined (less porous than rest of body)
Capillaries
41
These protects neurons from chemical fluctuations and large molecules
Capillaries of the BBB
42
Oxygen can cross the BBB but important large molecules such as glucose cannot. Glucose is therefore transported from the capillaries to the neurons by _______________________
carrier-mediated transport systems
43
Non-porous capillaries may make block transport of beneficial drugs. ___________ that are much smaller and they can through the blood-brain barrier may need to be used
Precursor drugs
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Afferent
sensory inputs conveyed to CNS by sensory afferent nerve axons of the peripheral nervous system
45
Efferent
motor commands conveyed from CNS to muscles & glands by motor efferent axons
46
Afferent neurons involves:
- somatic sensory
- visceral sensory
- special sensory
47
Axons that terminate in peripheral receptors such as skin & muscle receptors
somatic sensory
48
Efferent
motor commands conveyed from CNS to muscles & glands by motor efferent axons
49
Efferent neurons includes:
- somatic motor
- autonomic motor
50
contains the axons which innervates skeletal muscles to cause movement
somatic motor
51
contains axons which innervates smooth muscle, cardiac muscle, & glands
autonomic motor
- sympathetic
- parasympathetic
- enteric
52
The cell body of the ___________ is located just outside the spinal cord in a posterior root ganglion, also known as a dorsal root ganglion
sensory axon
The axon enters the spinal cord and terminates with synaptic connections on interneurons and efferent neurons
53
Axons of efferent neurons innervate _______________, including muscles and glands
effector organs
54
This transmits motor information from the CNS to effector organs and tissues
Peripheral efferent nervous system
55
Boney structure that supports the trunk and the head on the legs
vertebra column
56
within the vertebrae is the ___________ where the spinal cord is found
spinal canal
57
The _________ conveys signals from sensory receptors to the brain and signals from the brain to the effector organs
spinal cord
58
How many pairs of spinal nerves that convey signals to and from the spinal cord
31 pairs
8 cervical
12 thoracic
5 lumbar
5 sacral
1 coccygeal
59
each spinal nerve innervates a specific area of the skin called a ___________ and a specific set of muscles called a ___________
dermatome, myotome
60
A disease of peripheral nerves that has destroyed all of the large sensory axons entering the spinal cord, but not the motor axons which leave the spinal cord
Peripheral neuropathy
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towards back of the body
posterior or dorsal
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towards the front of the body
anterior or ventral
63
a cluster of neurons (a ganglion) in a dorsal root of a spinal nerve
Dorsal root ganglion also called posterior root ganglion
cell bodies of sensory neurons are located in the dorsal root ganglia
64
Sensory afferent axons enter the spinal cord through the ____________
dorsal roots
65
Sensory afferent axons bifurcate (or split) into _______ and ______ axons
ascending and descending
66
Ascending sensory afferent axons
form dorsal columns which ascend to the brainstem carrying sensory information to the brain
67
Descending sensory afferent axons
travel caudally, or towards the tail, for 2 to 3 spinal segments
68
Every millimeter or so, for two or three spinal segments rostral and causal to to the bifurcation, the ascending and descending axons send branches into the _____________ of the spinal cord and these branches synapse with __________ and ___________
gray matter; interneurons; motor neurons
69
Motoneurons are located in the _______ horn
ventral
70
The efferent axons of the motoneurons leave the spinal cord through the ____________ to innervate muscles
ventral roots
71
comprised of motoneurons, interneurons, dendrites and axons
Central 'grey matter'
72
is comprised of bundles of axons (called tracts), which convey sensory signals ascending to the brain or motor commands descending from the brain; axons have myelin which gives them a white appearance
Surrounding 'white matter'
73
Refer to neural pathways by which sensory information from the peripheral nerves is transmitted to the cerebral cortex
Ascending tracts
74
Refers to neural pathways by which motor signals are sent from the brain to lower motor neurons; the lower motor neurons then directly innervate muscles to produce movement
Descending tracts
75
These spinal nerves mediate sensory input from the arms
Cervical nerves
76
These spinal nerves mediate sensory information from the abdomen (trunk)
Thoracic nerves
77
These spinal nerves mediate sensory information from the legs and feet
Lumbar, sacral, and coccygeal nerves
78
Occurs when neurons in the dorsal root ganglia, often in just one or two segments of the spinal cord, become infected with a virus related to chicken pox
Results in bands of sores and excruciating pain in the dermatomes concerned
Shingles
79
What happens when you get into a car accident & your spinal cord is completely severed at the T7 level?
- There is not information coming up to the brain from below T7 level & no signals descending from the brain & brainstem can reach the motor neurons below that level. This means that you will not have any sensation in your legs & you will be unable to move them
80
Cervical injury with a complete transection (cut across the spinal cord) of the cervical level C6 or C7 will result in
result in paralysis of hand and finger movements but not paralysis of breathing or the control of heart rate because the spinal cord is severed below the levels that control breathing and heart rate; this is called tetraplegia, or quadriplegia
Everything below C6 or C7 (blood pressure, breathing, movements of the legs, walking, knee movements, foot movements, bladder, bowel and sex function) will all be affected
81
Spinal cord injury at L1 or L2: only functions below this level will be affected; this is called
Paraplegia
Hands, fingers, wrists, and elbows will be able to move; breathing, heart rate, and blood pressure will all be normal; voluntary movements of the legs and voluntary and reflex control of the bladder, bowel and sex functions will be affected.
82
Refers to the type of sensory information that is transmitted
Modality of a sensory input
Eg. each of these is a sensory modality: vision, sense of touch, hearing, movement
83
When a stimulus is processes, the structure of the _____________ determines which modality of stimulus it will respond to
sensory receptor
84
The modality activating a given receptor is called the
adequate stimulus of that receptor
85
What are the 5 different types of sensory endings in human skin
- Meissner's corpuscles
- Merkel's corpuscles
- Free nerve endings
- Pacinian corpuscles
- Ruffini corpuscles
86
Complex bulbous receptors in which the sensory terminal of the nerve axon is spiraled inside a capsule; respond to light touch of the skin
Meissner's corpuscles
87
Respond to touch, generally requiring somewhat more pressure than Meissner's corpuscles
Merkel's corpuscles
88
Respond to pain, respond to tissue damage
Free nerve endings
89
Have a structure with slippery layers called lamellae that slide over each other as the pressure around the corpuscles rises; distributes and amplifies the mechanical deformation of the nerve endings that are right in the middle of the receptor; respond vigorously to vibration (ex: vibration of 500 Hz ilicits 500 AP/s in its afferent axon)
Pacinian corpuscles
90
Slowly adapting mechanoreceptors, responding to skin stretch; also function as thermoreceptors
Ruffini corpuscles
91
Two types of Ruffini corpuscles and definition
1. Warm receptors: increase firing rate as their temperature rises
2. Cold receptors: increase firing rate as their temperature falls
92
This type of sensory receptors include skin receptors whose axons project directly to the spinal cord
Type A
93
This type of sensory receptors comprise first order receptor cells that respond to stimuli and synaptically activate second order cells very close by, whose axons transmit the information tot he nervous system
Type B
94
These are generally small and act as an intermediary between the stimulus (stimulus energy) and the second order cells
These also release neurotransmitter to activate the second order cells
First order cells
95
A sensory axon transmits information via the
dorsal root ganglion
The cell body of the sensory axon is located in the dorsal root ganglion
96
Somatosensory receptors
cover the surface of the body and signal and a variety of sensory modalities to the CNS
97
Mechanoreceptors
sense local tissue deformation in skin & viscera
98
Thermoreceptors
sense temperature in skin & brain
99
Nociceptors
sense pain (tissue damage) in skin, viscera, muscle
100
Proprioceptors
sense movement & force in muscles & joints
101
Vestibular receptors
head acceleration and tilt
102
TRUE or FALSE
The basic mechanism of information transfer in nervous systems is the same in vertebrates as it is in invertebrates
TRUE
103
The mechanism of information transfer in nervous systems, pulse rate modulation, evolved before the divergence of ____________ an d_____________
invertebrates and vertebrates
104
Development of ______________ around nerve axons greatly increased their conduction velocity
myelin sheath
This only happened in vertebrates but not in invertebrates
105
What are the two fastest sensory axon types
- Muscle spindle primary endings (80-120 m/s)
- Golgi tendon (80-120 m/s)
106
What are the three slowest sensory axon types
- Nociceptors (0.5-2 m/s)
- Warmth receptor (0.5-2 m/s)
- Postganglionic fibers (0.5-2 m/s)
107
As the stimulus intensity increases, the membrane potential at the initial segment of the sensory receptor's afferent axon increases until _____________ are generated
action potentials
The stronger the stimulus, the greater the change in the membrane potential at the initial segment and the greater the rate of generation of action potentials
108
Recruitment
As stimulus intensity increases, the number of sensory receptors that are activated increases
109
As the intensity of a stimulus increases, the release of neurotransmitter within the CNS ___________
increases
110
What happens when a stimulus is applied?
With a mechanoreceptor, when the membrane is distorted, this causes tiny pores in the cell membrane to open up; _____ enters the cell which causes the inside of the cell to become less negative
Na+
111
The larger the stimulus intensity, the _______ the change in the voltage
larger
112
The change in voltage at the initial segment is called the ______________
receptor potential
113
The rate of generation of action potentials is proportional to the size of the receptor potential and thus to the _____________
stimulus intensity
114
3 mechanisms of intensity coding
- Frequency coding
- Population code
- Temporal pattern code
115
Frequency coding
the bigger the stimulus, the more the membrane channels in the sensory ending are distorted, the greater the number of action potentials/sec (AP/s)
116
Population code
the bigger the stimulus, the more sensory neurons are recruited into activity, so the more AP/s delivered to the spinal cord
117
Temporal pattern code
variability of firing rate (bursts vs steady firing) may mediate certain types of sensation
118
Slowly adapting receptors
- also called the tonic receptors
- generate action potentials throughout the duration of the stimulus
119
What are examples of slowly adapting receptors
- Merkel's corpuscles
- free neuron endings
- Ruffini corpuscles
120
What are examples of rapidly adapting receptors
- Pacinian corpuscles
- Meissner's corpuscles
121
Rapidly adapting receptors
- respond briefly whenever the stimulus changes quickly
122
Adaptation
There is a reduction in the number or rate of APs/s in the continuous presence of a stimulus
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