COM1 Physiology Week 5 Flashcards
(84 cards)
1
Q
Explain how sensory signals enter the spinal cord
A
-Enter via posterior/dorsal roots
-Then it branches one to the local grey matter and one ascendin got higher nervous system centers
2
Q
Name the 2 types of neurons in the Gray matter
A
-Anterior Motor neuorns
( alpha motor neurons + gamma motor neurons)
-Interneurons
3
Q
What are anterior motor neurons made up of
A
- Alpha motor neurons
-Gamma motor neurons
4
Q
What type of signlas does Alpha motor neurons send out + what do they innervate
A
- Send out Alpha motor fibers
-Innervate skeletal muscle fibers
5
Q
What type of signlas does Gamma motor neurons send out + what do they innervate
A
-Send out A gamma motor fibers
-Innervate intrafusal fibers of muscle spindle
6
Q
Which one is larger between Alpha and gamma motor neurons
A
Alpha
7
Q
Where are interneurons found
A
All areas of grey matter
8
Q
Name a characterisitic of interneurons
A
- Highly excitable, fast firing
9
Q
What do interneurons form + ROLE of what they form
A
- Complex interconnections
- Which plays a major role in integrative soinal cord functionsN
10
Q
Name the type of circuits tnat Interneurons contain
A
- Diverging
-Converging
-Repetitive discharge
11
Q
What does proper muscle function require feedback about?
A
- Muscle lenght
-Muscle Tension
-Rate of chnage in length or tension
12
Q
Explain where feedback is sent for control of muscle function and why
A
- Sent to the spinal cord, cerebellum, cerebral cortex for subconscious control of muscle activity
13
Q
Name the 2 main muscle sensory receptors
A
-Muscle spindle
-Golgi Tendon Organs
14
Q
Where are muscles spindles located
A
- In the muscle belly
15
Q
What does muscle spindles detect
A
- Muscle length and rate of change of length
16
Q
Where are Golgi tendons located
A
- In the muscle tendons
17
Q
What does golgi tendons detect
A
- Tendon tension and rate of chage of tension
18
Q
What does Golgi tendons help to prevent
A
- Excessive force during muscle contraction
19
Q
Why does Muscle spindle provide feedback
A
- To help control muscle stretch
20
Q
What is muscle spindle composed of
A
- 3-12 intrafusal fibers
21
Q
In muscle spindle what are the intrafusual fibers surrounded by
A
- Extrafusual muscle fibers
22
Q
What does the central region of intrafusal fibers have + function
A
- Has few or no contractile elements
-Acts as the sensory receptor
23
Q
Name the 2 ways in which muscle spindle can be excited
A
-Stretching the whole muscle .
-Contraction of the intrafusal fiber ends
24
Q
Name the 2 types of sensory endings
A
- Primary (afferent) ending
-Secondary (afferent) ending
25
What is the alternative name for the sensory ending named PRIMARY ending
- Annulospiral ending
26
What is the alternative name for the sensory ending named SECONDARY edning
- Flower-spray ending
27
What type of fiber is the Primary ending
- Type 1a fibers
28
What type of fiber is the secondary ending
- Type 2 fibers
29
Desribe the differnce between 1a and 2 type fibers in primary vs Secondary endings
1a in primary endings is larger and faster
30
What does the primary ending respond to
-Respinds to both static and dynamic changes
31
What does the primary ending wrap around
Center of all intrafusal fibers
32
What does secondary ending respond mainly to
Static changes
33
Name the types of Intrafusal fibers
- Nuclear bag fibers
-Nuclear chain fibers
34
What does Nuclear bag fibers(type of intrafusal fiber) respond to
Dynamic changes
35
What does Nuclear chain fibers(type of intrafusal fiber) respond to
- Static changes
36
Explain the structure difference between the 2 intrafusal fibers: Nuclear bag and Nuclear chain fibers
Nuclear bag fibers:
- Large, central are contains clustered nuclei
Nuclear chain fibers;
- Smaller,nuclei is arranged in chains
37
What is static response caused by
Slow stretching
38
What is a dynamic response caused by
- Rapid stretch
39
How is Static response sustained
As long as stretch is maintained
40
What type of impulses does dynamic response produce
- Strong breif bursts of impulses
41
What responds to static response
Both primary and secondary endings
42
What responds to Dynamic response
Only primary endings
43
WHhat is the influence of gamma - dynamic on the intrafusal fibers
Stimulates nuclear bag fibers, and enhances dynamic response
44
What is the influence of Gamma static on the intrafusal fiber
Stimulates nuclear chain fibers , enhancing static response
45
WHATdoes increased muscle stetch result in
Increased firing rates
46
What does muscle shortening lead to
Decreased firing rate
47
Explain the neuronal circuit of muscle stretch
1. Type Ia afferent fibers from muscle spindles enter the dorsal root of the spinal cord.
2.Then they make monosynaptic connections with anterior horn motor neurons.
3. Enables a fast reflex response to the stretched muscle.
4. Type II fibers connect via interneurons, creating delayed responses or more complex effects.
48
Name 2 types of Stretch reflexes
- Dynamic Stretch reflexes
-Static stretch reflexes
49
What are dynamic stretch reflexes triggered by
- Rapid stretch/unstretch
50
What does dynamic stretch reflexes cause
Instantaneous, strong contractions
51
What do dynamic stretch reflexes :
-Activate
-Opposes
Activates :
-Primary la endings
Opposes:
- Sudden changes in muscle length
52
What are static stretch reflexes triggered by
- Sustained stretch
53
What do static stretch reflexes
-activat
-What does it maintain
Activted 1a and 2 endings
It maintains prolonged, weaker contraction
54
What does Damping ( Smoothing ) prevent + what’s does it smooth out
Prevents jerky or oscillating movements
-Smooths out fluctuating signals
55
What is coactivation
When the gamma and alpha motor neurons fire together
56
What does Coactivation prevent
- Prevents changes in the muscle spindle receptor length during muscle contraction
57
What does coactivation maintain
Maintains the damping function of the spindle , ensuring sensitivity
58
What is the function of intrafusal fiber contraction
Keeps the muscle spindle from going slack or overstretched
Helps the spindle detect changes in muscle length
59
What are in the brain is the gamma system controlled by
- It is primarily controlled by the bulboreticular facilitatory region of the brain stem
60
What is the gamma system influenced by
Signals from the cerebellum, basal ganglia and cerebral cortex
61
What do muscle spindle help to stailize
Joints during tension
62
What is stabilised joints useful for
Fine motor control
63
In the golgi tendon organs where are the sensory receptors located
In muscle tendons
64
How many muscles fibers is the Golgi tendon connected to
10-15
65
Explain the Dynamic response types in Golgi tendon organ reflex
-how does it react and what to
- Reacts quickly to sudden increase in tension
66
Explain the static response in Golgi tendon organ reflexes
-What do they maintain
Maintain steady firing proportional to muscle tension
67
In the Golgi tendon reflexes what are the signals carried by
Large fast-conducting type 1b fibers
68
Explain the pathway of signal transmission. In Golgi tendon reflex
- Enter the spinal cord , synapse in the dorsal horn and inhibit anterior motor neurons via inhibitory interneurons
-The signals ascend via spinocerebellar tracts to the cerebellum , and cerebral cortex
69
What are the functions of Golgi tendon reflex
Prevent excessive tension
-Prevebnt tearing
70
What is the flexor reflex ( pain reflex or nociceptive reflex)
An auomatic withdrawl of a limb in response to a painful stimuli
71
Give examples of pain stimuli the flexor reflex is triggered by
-Heat
-Injury
72
What do withdrawl reflexes involve
- Involve other parts of the body not just the limbs
73
Explain the neuroal mechanism of the reflex arc starting from sensory input
From sensory input to the spinal cord interneurons and to the Motor Neurons
74
Name the circuits the reflex arc involves
- Diverging circuits
-Reciprocal inhibition circuits
-Afterdischarge circuits
75
What is the function of the :
-Diverging circuits
-Reciprocal inhibiton circuits
-Afertdischarge circuits
In the reflex arc
Diverging circuits – spread response to multiple muscles.
Reciprocal inhibition circuits – inhibit antagonistic muscles.
Afterdischarge circuits – prolong the response after the stimulus ends.
76
After the stimulus stops why does mucle contraction continue breifly
- Due to afterdischarge
77
What is immediate afterdischarge caused by
- Repetitive firing of interneurons
78
What is prolonged afterdischarge caused by
Reverberating circuits in the spinal cord
79
What is the withdrawl pattern based on
Which sensory nerve is activated
80
When does Crossed Extensor reflex occur
occurs 0.2 seconds after a flexor reflex is triggered in one limb
81
What does crossed extensor reflex xause
It causes extension do the oppsote limb to :
-Support body weight
-Push the body away from the painful stimulus
82
Explain what is Reciprocal inhibition + what is reciprocal innervation
It is when one muscle group acitivated, the opposing group is inhibited.
-The network enabling this is reciprocal innervation
83
What is positive supportive reaction triggered by
It is triggered by pressure on the footpad
84
What does positive supportive reaction cause
- Causes limb extension to support body weight
