week 6 Flashcards
(185 cards)
1
Q
What is complex/ volitional movement
A
Highly evolved skilled action, which motor output is planned and refined by motor cortex, basal ganglia and cerebellum
2
Q
Where is red nucleus found
A
Midbrain
3
Q
Where is Rubrospinal cells found
A
within the red nucleus
4
Q
What does Rubrospinal cells do
A
Activate localized synergies in distal limb/ face
5
Q
What does Red nucleus cell deal with
A
More precise and complex movement of the distal limbs, as it’s very precisely connected to distal motor nuclei
6
Q
What does Rubrospinal tract project to
A
Corss the midline, and ends up in the intermediate zone on the contralateral side, not the motor neurons
7
Q
What is synergy
A
Group of muscles contracting together for a specific purpose (action/ movement)
8
Q
What is the spread of synergies organized by ruticulospinal tract
A
Very widespread, as they work together to generate support postures
9
Q
Why motor cortex replace much of the function of red nucleus
A
Red nucleus is located in midbrain
As animal evolve, more highly elaborate movement in distal limb is developed, and more spaces is needed to organize these movement
Midbrain doesn’t have enough space, so move to motor cortex
10
Q
What is the ogranization of motor cortex
A
Somatotopic mapping.
Size/area is not proportionate
11
Q
Where does most of the descending axons from motor cortex to spinal cord go
A
interneurons
12
Q
Does descending acon from motor cortex always end up in interneurons?
A
No
some has direct corticospinal synapses on motor neurons, mostly to distal limb/ speech motor nuclei
13
Q
Is area of the cortex proportional to the size of the body part
A
NO
distal limbs and lips take the greatest area
14
Q
What is the descending pathway of motor cortex to spinal cord.
A
Motor cortex send command
Axon project to the brainstem cross and end up in the contralateral spinal cord, either in interneurons or directly activate motor neurons
15
Q
What is the multiple representation of muscles
A
Same single motor nuclei in muscle is represented multiple times at many loci
16
Q
What is each muscle column ( same single motor nuclei) neighboured in? Why?
A
They are in different neighbourhood, surround by other different adjacent columns
This result in different synergy for different movement
17
Q
What does each cortical locus in muscle represent
A
A different synergy for different movement
18
Q
What muscle has the biggest representation (in term of multiple representation in motor cortex)
A
The muscle that participate in the most synergies
19
Q
What is the map of multiple representation based on
A
Personal difference, vary from one to another individual
20
Q
Why does native Chinese speaker who learned english at a later period of time have trouble pronouncing certain words
A
The motor map is developed at a very early stages
Lack of certain synergies in the motor cortex makes it hard for them to pronounce certain word
21
Q
What happen to the activity of a neuron up in the motor cortex, when a precision grip and a power grip is performed
(given the neuron directly synapse to thumb motor neuron)
A
Precision grip: very active in motor cortex
Power grip:it is not active, since the motor cortex neurons deal with more precise activity involving thumb
22
Q
What is a motor field
A
One corticospinal axons synapses with a set of / a bunch of motor nuclei
23
Q
What are the activity of many synapses in a motor field
A
Many are silent, not operating
24
Q
Why motor field exist, if many of the synapses are silent
A
Provide potential for plasticity
Helps learning new skill/ turning off prior connection and target new connection
25
What sensory input has direct access to motor cortex
Somatosensory inputs (proprioceptive)
26
What is cutaneous input related to? How is it sent to motor cortex
From mechanoreceptors, contain postural/ motion information
Processed in somatosensory cortex before sending to motor cortex
27
What proprioceptive input direct from?
From thalamus or somatic association cortex, tot he motor cortex
28
Wha is premotor areas? (location and connection wise0
Upper of motor cortex, project into motor cortex
29
What does premotor area do
Select motor cortical synergies and put them into proper sequence, determine the sequence of synergies activation in motor cortex to generate a given movement
30
What is the pattern generational role of premotor area for
Highly evolved, learned movement
31
What sensory input does premotor cortex process
All kind of input, especially visual and auditory
32
What is the Broca's area
Premotor zone for sequencing language elements for speech/ writing typing
33
How does sensorimotor cues act
These environmental cues trigger motor reaction, and these cues are recognized by the sensory association area, the signal is forwarded to premotor cortex, where appropriate response synergies is selected
34
What is visuomotor response
Coordinated sets of sctivities and cues to initiate synergies (association between object and movement)
35
What is the preparatory phase of movement
When premotor neurons is active, facilitating appropriate synergies in motor cortex
36
Is premotor neurons active during performance of movement
No
37
What is a "warning" cue
Delivered before a go cue, signalling "ready"
38
What happen if the delay of preparatory phase prolonged
Premotor neuron will maintain its activity until go cue is given
39
What is the role of supplementary motor area
Controls bilateral coordination of limb, when different motion is done on each side
Process internal volitional signals, which drive movements
40
What does cingulate motor area do
process emotional and motivational drive to movements
Mediate emotional movements
41
What is a fake smile VS genuine smile
Fake: driven by SMA using volitional signals
Genuine: driven by CMA using emotional cue
42
How does different are generate same movements?
They generate the same sequence of synergies in the motor cortex, but different cue/ source of info is used
43
What is the 2 subsystem of ANS
Sympathetic and parasympathetic
44
What does sympathetic and parasympathetic control
Para: rest and digest
Sympathetic: fight/ flight
45
What does ANS control
a series of autonomic and involuntary stuff
46
What are the 2 components of ANS
pre and postganglionic components
47
Where is preganglionic neuron cell body located
In the CNS, either brain stem/ spinal cord
48
What is autonomic ganglia, where is it located?
Where conversation/ projection between pre and postganglionic occur
It is located between CNS and target tissue
49
Where does postganglionic project to
target tissue
50
Why we need pre to postganglionic, then postganglionic to target tissue arrangement? (why not straight to target tissue)
Allow more divergence, single pre can synapses with multiple postganglionic neurons
51
What does preganglionic neuron release? (for sympathetic/ parasympathetic)
Both release Ach (acetylcholine)
52
What receptors receive neurotransmitter from preganglionic neurons
Nicotinic receptors, accept Ach
53
What does sympathetic postganglionic secrete? To what receptor?
NE (norepinephrine)
Adrenergic receptor
54
What does parasympathetic postganglionic secrete? To what receptor?
Ach (acetylcholine)
Muscarinic receptor
55
Where is sympathetic autonomic ganglia linked
Sympathetic chain, close to spinal cord
56
What is the length of preganglinoic neuron to sympathetic chain, and the length of post ganglionic to effector organ
Short preganglionic neurons to sympathetic chain
Long postganglionic neurons from sympathetic chain to effector organ
57
Where is parasympathetic autonomic ganglia close to
Effector organ
58
What is the length of preganglinoic neuron to parasympathetic autonomic ganglia, and the length of post ganglionic to effector organ
Long pre
Short post
59
Where is preganglionic efferents from
Intermedio-lateral horn of thoracic cord
60
Is NA always used for sympathetic postganglionic neurons?
No, Ach is used for skin sweat glands
61
Whhich ANS is in active, during exercise
Sympathetic
62
What happen to pupil during sympathetic activity
Dilate, allow more light in, better vision
63
What is released from adrenal medulla
Epinephrine
64
What is the pathway of adrenal medulla ,as a sympathetic ganglion
Preganglionic sympathetic neuron trigger chromaffin cells, release epinephrine into blood
65
Where is parasympathetic efferent originated from
Several cranial motor nuclei, and intermediolateral part of sacral cord
66
What does vagus nerve do
Carry majority of parasympathetic efferent
67
Is Ach always used for parasympathetic efferent?
No
NO (nitric oxide) is used, for penile erection
68
Which ANS is dominate when you are relaxed
Parasympathetic
69
What does duel innervation mean for ANS
Both sympathetic and parasympathetic are complementary, both are active
But one will dominate the other depending on the state
70
What are the target of autonomic neurons
Smooth muscle, cardiac muscle, glands, etc
71
What is neuroeffector junction
Synapse between the post ganglionic autonomic neurons and the target cells
72
What is Varicosities (varicosity)
Axon swelling, contained vesicles filled with neurotransmitter
released when AP arrival
73
What is the pathway of releasing NE in sympathetic neuroeffector junction
1: AP arrives varicosity
2: depolarization, open Ca2+ channel and Ca2+ influx
3: Exocytosis of. synaptic vesicles with NE
4: NE bind to adrenergic receptor on target, trigger target response
5: receptor activation ceases when NE diffuses away from synapse
74
How is NE removed from neuroeffector junction
It is removed from synapse, and either reuptaken back into vesicles for re-release, or metabolized by MAO
75
How does MAO inhibitor treat depression? What's the side effect
Depression= lack of NE
MAO inhibitor drug inhibit MAO recycling of NE, increasing NE available
The drug is not brain specific, so it acts on other MAO in other part of the brain
Increase NE in other body part, increase symp activity, cause constipation
76
What is the overall goal of autonomic reflex
Maintain homeostasis
77
What type of feedback is atunomic reflexes
Negative ffedback loop for homeostasis
78
what is ANS linked to, to produce functional reflexes
sensory system
79
Why can we control "urination", even when it's a autonomic spinal reflexes
Autonomic reflexes can be modulated by CNS
80
What happen during pupillary light reflex
Too bright, parasympathetic reflex constrict pupil by contracting circular iris muscle
Too dark, sympathetic reflex dilate pupil by radial muscle contraction
81
Why does brightness illusion occur (pupil constrict looking at a "brighter" image)
Not only brightness influence the eye
Cortical influences also affect pupillary light reflex
82
What is responsible for Baroreflex
Cardiovascular centre, by adjusting blood pressure depending on posture
83
What is NTS involved in
Baroreflex
It receives input from the baroreceptors
84
What do baroreceptors do
Detect pressure in blood vessels
85
What does the caudal half of VLM do
If blood pressure is too high, it inhibits rostral half and drops blood pressure
86
What does rostral half of the VLM do
Excites sympathetic pathway, raise blood pressure and heart rate when low BP
87
What is baroreflex
Adjusting the blood pressure using sympathetic output
88
What is the major influence for muscle sympathetic effect
noradrenergic vasoconstriction
89
What is muscle sympathetic effect
Part of the baroreflex
Maintain blood pressure by tightening blood vessels
90
Where is autonomic reflexes integrated in
The brain
91
Which part of the brain contain control centre for autonomic functions
Brainstem
92
What do brainstem autonomic centers do
Receive sensory input, relay output to muscle/ glands/ etc
93
What is PAG
Midbrain premotor center for autonomic behavioural program
Coordinate autonomic behaviours
94
What does reticular activating system do
Cause a global shift in CNS activity, mainly metabotropic mechanism, via diffuse modulatory system
95
Why antihistamine makes you drowsy
Histamine is responsible for sleep wake control
96
What type of muscle is under conscious control
Skeletal muscle
97
What is the control of cardiac and smooth muscle
Autonomic activity
98
What activate the skeletal muscle
Somatic nervous system
99
What is in a motor units
Motor neurons & associated muscle fibres
100
What is neuro-muscular junction (NMJ)
Chemical signalling/ synapse between motor neuron and skeletal muscle fiber
101
What contractile filament is in sarcomeres, for skeletal muscle
Actin and myosin
102
What does it mean that contractile filament is striated
Very regularly overlapping
103
Which muscle has the most well developed sarcoplasmic reticulum
Skeletal muscle
104
What is sarcoplasmic reticulum
Intracellular organelle, specialized for Ca2+ storage
105
What is fascicles
Bundles of muscle fibers
106
In skeletal muscle, how does muscle fibers extend length of muscle
From tendon to tendon
107
What is myofibril
This make up muscle fibers
108
What is sarcolemma
Plasma membrane of muscle fibers
109
What is T-tubule system, and what's it role
Invagination of sarcolemma into muscle fibers, allow the spread of AP deep into muscle, enabling muscle fibre response
110
What determine the smoothness and precision of movement
Number and timing of motor units that are activated
111
How does muscle contraction begin (which is activated first)
Small motor units are activated first, since they are easier to be activated
112
In one motor unit, how many type of muscle fibers are presented
Only one, they are all the same type of muscle fibre in each unit
113
How many categories of muscle fibres (motor units) are there
3
slow twitch, fast twitch and in between
114
What is smaller and larger motor unit for
Larger: stronger force
smaller: more precise
115
Why does it get harder to perform very precise action, wit age (get older)
With age, motor unit become larger, so less precise action can be performed
116
What is the metabolism used in slow twitch oxidative fibres
Oxidative metabolism, relying on many mitochondria
117
What is the speed of contraction of slow twitch oxidative fibres
Slow contracting, generate small maximal force
118
What is the main usen of slow twitch oxidative fibres
Postural formations
119
What is the endurance of slow twitch oxidative fibres
Fatigue-resistant, non fatiguing
120
What is the metabolism of fast twitch glycolytic fibres
Glycolytic, anaerobic, less mitochondria
121
What is the use of fast twitch glycolytic fibres
sprint/ lifting weight, etc
generate large amount of force/ tension
122
What is the endurance of fast twitch glycolytic fibres
rapid fatigue, due to build up of lactic acid
123
What fibres do small/ large diameter motor neurons innervate
Small: slow oxidative fibres
Large: fast glycolytic fibres
124
Which fibres/ size of motor neurons is excited easier
Small diameter/ slow twitch require less excitatory synaptic input, so easier to excite
125
What is release by motoneurons in NMJ
Acetylcholine
126
What type of synapses are in NMJ (inhibitory/ excitatory)
Excitatory
127
In NMJ, what is the activation of motor neurons depended on
Summation of EPSP/IPSP
128
What happen when action potential reach the terminal bouton of motor neuron
Calcium gated channel is opened, Ca2+ influx
129
What happen when Ca2+ influx in terminal bouton of motor neuron
Release Ach
130
What does Ach released by terminal bouton of motor neuron bind to
Nicotinic receptors on motor end plate
131
What happened after Ach binding on motor end plate
Open cation channel, cation influx, depolarization of skeletal muscle membrane, cause AP and muscle contraction
132
What does Curariform drugs do
Block nicotinic receptor, cannot bind to Ach and generate AP in muscle fibre, lead to muscle relax
Used for esophagus/ anal check up
133
What does Botox do
Block exocytosis, inhibit release of Ach vesicles, no depolarization/ AP
Used to smooth wrinkles
134
What happen if Ach-esterase is inhibited
Ach-esterase breakdown Ach
If Ach is not broken down, it keeps and continues the depolarization, cause paralysis
135
What is the thin filament of skeletal muscle fibre made up of
Actin
136
What is the thick filament of skeletal muscle fibre made up of
Myosin
137
How does muscle contract relate to sarcomere
Sarcomere shortening, due to actin and myosin slide past one another (overlap), cause muscle contraction
138
What are contained on myosin head (2 components)
Actin binding site, ATP binding site
139
how does actin molecules make up thin filament
2 strands of actin coil up, and has a binding site of myosin
140
What does troponin complex do, when there's no calcium
Troponin holds tropomyosin over myosin binding site on actin, so no crossbridge can occur, no muscle contraction
141
What happen to troponin complex, when there's calcium is present
Calcium binds to troponin, which move the tropomyosin, exposing the myosin binding site on actin
Crossbridge can form, muscle contract
142
What are the 2 forms of myosin heads (undegoes conformation changes, ATP dependent)
1: High energy form, high affinity for actin
2: Low energy form, low affinity for actin
143
What is powerstroke
Myosin head move propelling thin filament toward muscle centre
144
What happen to binding of myosin head and actin, when Ca2+ increases
Bind stronger, and power stroke occur
145
What happen to myosin at the end of power stroke
Low energy, low affinity, release ADP
Still bind to actin
146
What happen in rigor mortis
Stiff/ contracted muscle, since no ADP, cannot detach myosin head from actin
remain contracted, tight binding
147
When does Myosin head detach
After rigor state, ATP binds to myosin, allowing it to release actin
148
What happen after myosin detach
Myosin hydrolyze ATP, rotate back to cocked position, in high energy form, ready for power stroke
Weak binding due to lack of Ca2+
149
When does powerstroke begin
When Ca2+ bind and move tropomyosin off binding site, allowing tight binding
150
What lead to muscle AP generation
Binding of Ach to nicotinic receptor on motor end plate, leading to Na+ entry and depolarization
151
What is the effect of AP in t-tubule
Alteration of DHP, conformational change
152
What does DHP do
Opens RyR Ca2+ release channel in SR, allowing Ca2+ to enter cytoplasm
153
How to terminate muscle contraction
Calcium leave binding site, by Ca2+ ATPase in SR, sending calcium back to SR
154
What is a muscle twitch
Single contraction-relaxation cycle
155
How to generate force using muscle twitch
Many twitches working together, as a single twitch is not sufficient for force production
156
What are the 3 phases of muscle twitch
Latent period
period of contraction
period of relaxation
157
What happen in latent period
Muscle is excited by motor neurons, but no contraction force is yet developed
AP is travelling down t-tubule to SR, and Ca2+ is entering cytoplasm
158
What happen in period of contraction
High level of Ca2+ in muscle membrane, crossbridge is occuring, allowing force production
159
What happen during period of relaxation
Ca2+ ATPase pump Ca2+ back to SR, Ca2+ level fall, tension gradually fall to zero, decline of force
160
What happen to high frequency AP firing in skeletal muscle
Successive twitches fuse together, increase tension via summation
161
What is tetanus
Repeated stimulation fuse into 1 continuous contraction, generating a maximum isometric force
162
What happen after a complete tetanus
Fatigue occur, causing muscle to rapidly lose tension despite stimulus
163
Is sarcomeres arrangement found in smooth muscle
No
164
What control smooth musle
Involuntary control by ANS
165
Is actin and myosin parallel in smooth muscle
No, run in several direction
166
What is the most common type of smooth muscle (by communication with neighbouring cell)
Single unit
167
What control the activity of single unit smooth muscle
Spontaneous control, or by ANS
168
Is external stimulus always needed for single unit smooth muscle to exert tension
No, it can contract on its own, in order to maintain function of certain tissue
169
How does the fibres in multi-unit smooth muscle act
Individually
170
When is multi-unit smooth muscle contracted, generally
When nervous supply is stimulated
171
Is NMJ found in smooth muscle
No
172
Where is the source of Ca2+ for powerstroke, in smooth muscle excitation-contraction coupling
Extracellular fluid, or SR (small portion)
173
What trigger the release of Ca2+ from SR, in smooth muscle
Calcium, which influx from plasma membrane
Calcium induced calcium release
174
How does crossbridge cycling occur in smooth muscle
Ca2+ bind to calmodulin, which activate MLCK, phosphorylating myosin, allowing crossbridge cycling
175
How does relaxation of smooth muscle occur
1: phosphatase remove phosphate from myosin
2: Calcium removed from cytoplasm
176
Where is the contractile filament of cardiac muscle found
In sarcomeres
177
What is gap junction of cardiac muscle for
Synchronous beat of heart beat
178
What control cardiac muscle activity
ANS
179
How does cardiac muscle have a long lasting AP, and prolonged contraction time
2 voltage gated channel is opened when cardiac muscle is depolarized
1 Na+ channel that open quickly, and a Ca2+ channel that open more slowly, and stay open for longer
Both work together to prolong AP, and contraction time
180
How long does cardiac contractile AP last
As long as the contraction and relaxation
181
Why does AP last as long as contraction and relaxation, in heart
To prevent tetanus, no summation can occur as new AP only occur in relaxation state
This ensure heart to function like a steady pump
182
How to increase heart contraction force
Increase muscle length, by increasing volume of blood in cardiac chamber
More stretch= stronger contraction force
183
What is the major source of Ca2+ for cardiac muscle
From ECF, the rest from SR
184
How is Ca2+ removed from heart for relaxation
Ca2+ pump in SR, and Na+/Ca2+ membrane exchange
185
How does digitalis work to treat heart condition
inhibit Na+/Ca2+ exchange, increase Ca2+ level
higher Ca2+ level increase force of contraction, strengthen heart beat
