Neurology Flashcards
(136 cards)
1
Q
What are 5 main functions of the NS?
A
1) Sensation
2) Motor capability
3) Cognition
4) Homeostasis
5) Emotions
2
Q
What are the 5 main parts of a neuron?
A
1) Dendrites
2) Soma / cell body
3) Axon hillock
4) Axon
5) Presynaptic terminal
3
Q
What are the 4 lobes of the brain and what are their functions?
A
1) Frontal – personality, motor planning, motor cortex
2) Parietal – integration of multiple sensory systems, somatosensory cortex
3) Occipital – visual cortex
4) Temporal – auditory processing
4
Q
What are the 3 regions of gray matter?
A
1) Dorsal horn
2) Lateral horn
3) Ventral horn
5
Q
What is found in the dorsal horn?
A
Cell bodies of interneurons upon which afferent neurons terminate
6
Q
What is found in the lateral horn?
A
Cell bodies of autonomic efferent nerve fibres
7
Q
What is found in the ventral horn?
A
Cell bodies of somatic efferent neurons
8
Q
Is Na+ more concentrated in the ICF or ECF?
A
ECF
9
Q
Is K+ more concentrated in the ICF or ECF?
A
ICF
10
Q
Is Cl- more concentrated in the ICF or ECF?
A
ECF
11
Q
Is Ca2+ more concentrated in the ICF or ECF?
A
ECF
12
Q
Is Mg2+ more concentrated in the ICF or ECF?
A
ECF
13
Q
What direction is the passive flow of Na+ and K+?
A
Na+ flows in and K+ flows out
14
Q
What direction is the active transport of Na+ and K+?
A
K+ transported in and Na+ transported out
15
Q
What is the net movement at equilibrium potential?
A
Zero
16
Q
What is equilibrium potential?
A
The membrane which would produce an electrical force that would be equal to and in the opposite direction to the chemical force produced by the ion concentration gradient
17
Q
What should be assumed when considering equilibrium potentials?
A
100% permeability
18
Q
Why is resting membrane potential not equal to Ek?
A
At rest, the cell is not completely permeable to K+ ions and there is a small permeability to Na+ ions
19
Q
What forces act on Na+ ions at the point of threshold?
A
Chemical and electrical
20
Q
What happens before reaching ENa+?
A
The voltage-dependent Na+ channels inactivate
21
Q
What other channel beside K+ channels contribute to afterhyperpolarization?
A
Ca2+ activated K+ channels
22
Q
What is the effect of a drug that opens Na+ channels?
A
Depolarization
23
Q
What is the effect of a drug that opens K+ channels?
A
Hyperpolarization
24
Q
What is the effect of a drug that opens Na+ and K+ channels?
A
Depolarization (Na+ wins)
25
What is the most important intracellular cation?
Potassium
26
What is the function of potassium?
Maintain cellular osmolarity and membrane potential inside the cell
27
What is the concentration of K+ in normal plasma?
3.5 - 5 meq
28
What is hyperkalimia?
When the concentration of K+ in plasma is greater than 5 meq
29
Why will injecting a high concentration of potassium into the ECF cause death?
Ek will depolarize, which causes neurons and muscle cells to depolarize, meaning that muscle contraction and the heart stay in contraction
30
Where does synaptic transmission occur?
Over the dendrites, soma, and axon hillock
31
What are the 7 events of chemical synaptic transmission?
1) Action potential propagation
2) Depolarization of presynaptic terminal
3) Opening of vdep Ca2+ channels
4) Ca2+-induced fusion of vesicles with presynaptic membrane
5) Binding of transmitter to postsynaptic receptor
6) Postsynaptic action
7) Termination of transmitter action
32
What 2 events happen when calcium enters the presynaptic terminal?
- Triggers the fusion of vesicles with presynaptic membrane
| - Releases transmitters into synaptic cleft
33
How much calcium is needed for synaptic function?
Very little
34
What is an analogy that can describe the relationship between transmitters and receptors, and what describe the transmitters in this analogy?
- Lock in key
| - Transmitters are the key
35
What are 2 classifications of transmitters?
1) Small fast-acting
| 2) Large slow-acting
36
What are 3 examples of small fast-acting transmitters?
1) Acetylcholine
2) Dopamine
3) GABA
37
What is one example of a large slow-acting transmitter?
Endorphins
38
What is the main excitatory neurotransmitter?
Glutamate
39
What are the 2 main inhibitory neurotransmitters?
1) Glycine
| 2) GABA (gamma-ammobutyric acid)
40
What are 2 ways that the postsynaptic terminal can be excited?
1) Na+ entry into the cell by opening Na channels (depolarization)
2) Close K+ channels, causing less positive ions to leave (depolarization)
41
What is central inhibition?
Inhibitory neurotransmitters bind to a receptor that causes ion channels to open and produce a postsynaptic hyperpolarization
42
What 2 things cause central inhibition?
1) K+ leaving postsynaptic cell
| 2) Cl- entering
43
What is an excitatory response?
Neutron depolarizes and if it reaches threshold an AP is initiated
44
What is an inhibitory response?
Neutron hyperpolarizes and APs are harder to elicit
45
Define ionotropic
Receptor is linked to an ion channel and opens/closes the channel
46
Define metabotropic
Receptor is linked to a G protein, which can activate second messengers
47
What can metabotropic synapse-activated second messenger channels do?
- Open/close channels
| - Activate enzymatic pathways
48
Define motoneuron
A motor neuron that innervates muscles
49
What is the transmitter released by motoneurons?
Acetylcholine
50
What are 4 attributes of a stimulus?
1) Modality
2) Intensity
3) Location
4) Duration
51
What are the 4 types of mechanoreceptors that convey touch?
1) Meissner's corpuscle
2) Merkel cells
3) Pacinian corpuscle
4) Ruffini endings
52
What is special about Meissner's corpuscle and Merkel cells?
- Closer to surface
- Finer discrimination
- Smaller receptive field
53
What is special about Pacinian corpuscle and Ruffini endings?
- Courser discrimination
- Larger receptive field
- Further away from surface
54
Which touch mechanoreceptors are rapidly adapting and which are slowly adapting?
Rapidly adapting -- Merkel cells and Ruffini endings
| Slowly adapting -- Meissner's corpuscle and Pacinian corpuscle
55
Define proprioception
Knowing where your body is in space
56
What kind of fibres control proprioception?
Large diameter myelinated sensory fibres
57
What are muscle spindles?
Specialized sensory organs
58
What 3 structures make up muscle spindles?
1) Intrafusal muscle fibres
2) Ia sensory fibres
3) Group 2 sensory fibres
59
What is the function of Ia sensory fibres in muscle spindles?
Sensitive to muscle stretch (change in length)
60
What is the function of group 2 sensory fibres?
Convey static length of muscle
61
What innervates intrafusal muscle fibres?
Gamma-motoneurons
62
What is the function of gamma motoneurons?
Regulate spindle length so spindles stay responsive for a range of muscle lengths
63
What would happen if a muscle body was shortened by alpha motoneurons activation?
Spindle would go slack and Ia fibres would be unresponsive
64
What is the benefit to activating alpha and gamma motoneurons together?
Keeps spindles responsive
65
What does the dorsal column system mediate?
Fine touch and proprioception
66
What does the dorsal column system convey and from where?
Afferent info from large diameter afferent myelinated sensory fibres
67
What 2 sections are found in the parietal lobe?
1) Postcentral gyrus
| 2) Parietal association cortex
68
Where is the postcentral gyrus found?
Immediately behind central sulcus
69
What is the postcentral gyrus?
Primary sensory cortex
70
Where is the sensory homunculus found?
Across the postcentral gyrus
71
What is the parietal association cortex responsible for?
Awareness of body and environment
72
What is pain?
A perception, not a sensation
73
When is pain felt?
In the absence of activation of nociceptors
74
Define nociceptor
Sensory receptor that when activated, pain would normally be perceived
75
What are 2 examples of what can produce pain?
1) Tissue injury
| 2) Disturbed central sensory transmission
76
Define paraesthesia
Abnormal sensation (ex: burning, pricking, tingling) sometimes due to "central" pain syndrome following a stroke
77
Define phantom limb
Sensation that an amputated limb is still present, often with painful paraesthesia
78
Define causalgia
Burning pain following nerve damage that persists long after tissue has healed
79
Define allodynia/hyperalgesia
A non-painful stimulus becomes painful
80
What are 3 immediate effects of pain?
1) Local burn
2) APs in sensory fibres
3) Reddening, swelling
81
What are 2 medium effects of pain (soon after immediate effects)?
1) Active compounds released from sensory nerves cause release of histamine and other substances
2) Flare -- further reddening and hyperalgesia
82
What are 2 long-term effects of pain?
1) Secondary hyperalgesia due to receptor sensitization and changes in CNS transmission
2) Pain sensation lingers beyond tissue damage
83
What is nociception mediated by?
Unmyelinated or small diameter myelinated sensory fibres
84
Describe the gate theory of pain transmission
Activity in non-nociceptive afferents activates inhibitory interneurons that inhibit ascending spinothalmic tract neurons and decrease transmission through the nociceptive pathway
85
What can cause allodynia?
Loss or disruption of large diameter fibres
86
What happens when the inhibitory interneuron is not activated in the gate theory of pain transmission?
The 2nd order (ascending) spinothalmic tract neuron becomes more active
87
Describe the endogenous opioid system
Stimulation around the cerebral aqueduct produces long lasting pain reduction
88
What causes referred pain (perception of pain in a location other than the site of origin)?
Nociceptive afferents from viscera enter spinal cord at the same spinal segment as nociceptive afferents from skin/muscle/joints
89
What are 7 strategies for managing pain?
1) Deliver anesthetic to avoid unwanted sites of action
2) Tailor the treatment to the pain
3) Target peripheral sensitization
4) Use Gate theory
5) Activate endogenous opioid system
6) Recognize potential "central pain"
7) Try to prevent pain rather than treat it
90
What are the 5 special senses?
1) Olfaction (smell)
2) Vision
3) Taste
4) Hearing/audition
5) Vestibular function
91
What sensory receptor does olfaction use?
CN 1, olfactory nerve
92
What sensory receptor does vision use?
CN 2, optic nerve
93
What sensory receptor does taste use?
- CN 7, facial nerve -- lateral border and anterior 2/3 of tongue
- CN 9, glossopharyngeal nerve (posterior 1/3 of tongue)
94
What sensory receptor does hearing use?
CN 8, vestibulocochlear
95
What sensory receptor does vestibular function use?
CN 8, vestibulocochlear
96
Define myopia
Nearsightedness
97
What causes myopia?
Eyeball too long or lens too strong
98
What corrects myopia?
Concave )( lenses
99
Define hyperopia
Farsightedness
100
What causes hyperopia?
Eyeball too short or lens too weak
101
What corrects hyperopia?
Convex () lenses
102
Define presbyopia
Loss of lens accommodation after age 40 (longer focal distance)
103
What corrects presbyopia?
Reading glasses or bi/trifocals for those with myopia corrective lenses
104
What is the function of the external ear?
Funneling/focusing of sound waves
105
What is the function of the middle ear?
Mechanical conversion of sound waves to pressure waves
106
What is the function of the inner ear?
Pressure waves converted to neural signal
107
What is the function of the cochlea?
Changes pressure waves to vibrations of the basilar membrane
108
What are the mechanoreceptors of the ear?
Organ of Corti hair cells
109
How are organ of Cortia hair cells activated?
By the movement of the basilar membrane
110
What can lead to irreversible hearing loss?
Overstimulation of hair cells
- Too high sound levels
- Some drugs that are toxic to receptor cells
111
Define conductive deafness
When there is a failure in the transmission of the sound wave in the middle or inner ear
112
What are 2 examples of causes of conductive deafness?
1) Bone calcification
| 2) Basilar membrane damage
113
Define central deafness
When there is damage to the neural pathways such as the cochlear nerve, brainstem, or cortex via lesion or disease
114
What causes acoustic neuroma and what does it result in?
- Caused by tumor growing around CN 8
| - Results in hearing loss and vestibular dysfunction symptoms
115
What are the semicircular canals?
3 canals at right angles to each other
116
What do the semicircular canals detect?
Rotational and angular acceleration or deceleration of the head
117
How do the semicircular canals detect rotation?
Through movement of fluid in canal
- Movement is detected by hair cells
- Fluid stays stationary while head rotates
118
What are the 2 otolith organs?
Utricle and saccule
119
What do the otolith organs detect?
The position of head relative to gravity
120
What are 3 functions of the vestibular system?
1) Keeps us upright
2) Tells us where we are relative to gravity
3) Senses acceleration and spinning
121
What structures of the body does the vestibular system effect?
- Muscles of body and neck
| - Eye movements
122
Define vertigo
Dizziness; sensation of spinning
123
What are 2 examples of causes of vertigo?
1) Inappropriate activation of semicircular canal hair cells
| 2) Imbalance between the 2 sides
124
Define nystagmus
Rhythmic vertical or horizontal eye movements triggered by vestibular stimulus
125
What are 2 examples of causes of nystagmus?
1) Normal response (after spinning)
| 2) Spontaneously as a sign of underlying neuropathology (episodes of vertigo)
126
What are rods specialized for?
Capturing light
127
What are rods the primary photoreceptors for?
Conveying vision in dim/dark conditions
128
What are the 3 types of cones?
1) Red
2) Blue
3) Green
129
What is needed for an image to be sharp?
It must be focused on the retina
130
When do images appear blurred?
When they come into focus ahead of or behind the retina
131
Define glaucoma
Increased internal pressure in the eye
132
Define cataracts
Clouding of normally clear lens, resulting in blurred or distorted vision
133
Define dry eye
Not enough tears, or tears of the wrong composition
134
Define colour blindness
Usually poor red and green discrimination
135
What is the cause of cataracts?
Cause is unknown
136
What is the auditory pathway?
- Cochlea
- CN 8
- Brainstem nuclei of contralateral side
- Auditory cortex (temporal lobe)
