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Principles Of Health Sciences > Skeletal Muscle As A Target For Nervous System Control > Flashcards

Skeletal Muscle As A Target For Nervous System Control Flashcards

(58 cards)

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1
Q

Muscle fibre: Sarcolemma

A

Plasma membrane
Receive electrical stimuli
Conducts an action potential to the internal structures via T tubules

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2
Q

Muscle fibre: transverse (T) tubules

A

Sarcolemma is invaginated to form membranous tunnels
Penetrate through the fibre
Conduct electrical stimuli from the Sarcolemma

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3
Q

Muscle fibre: sarcoplasmic reticulum

A

Special type of smooth endoplasmic reticulum
Contains large, concentrated stores of calcium

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4
Q

Muscle fibre: terminal cisternae

A

Sarcoplasmic reticulum becomes enlarged and forms large bands that wrap around the muscle fibres on either side of the T tubules
Action potential stimulated them to release calcium from the sarcoplasmic reticulum

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5
Q

Neuromuscular junction

A
  1. Action potential received
  2. Fusion of synaptic vesicle
  3. Sodium influx
  4. Depolarisation of postsynaptic membrane
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6
Q

Neuromuscular junction: 1. Action potential received

A

Action potential at axon terminal causes VGCC to open
Ca2+ enters the axon terminal

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7
Q

Neuromuscular junction: 2. Fusion of synaptic vesicle

A

High Ca2+ causes vesicles containing acetylcholine to fuse with the membrane
Release acetylcholine into the synaptic cleft

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8
Q

Neuromuscular junction: 3. Sodium influx

A

Acetylcholine activates acetylcholine receptors
Conformational shape change
Opens sodium channels and Na+ enters the muscle cell

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9
Q

Neuromuscular junction: 4. Depolarisation of postsynaptic membrane

A

Action potential propagated along Sarcolemma and into the T tubules
Receptors on sarcoplasmic reticulum mediate the release of stored Ca2+ to begin muscle contraction

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10
Q

Excitation-concentration coupling

A

Action potential travels across Sarcolemma
Action potential down T tubules
Sarcoplasmic reticulum releases calcium via ryanodine sensitive channels
Calcium ions bind to troponin
Troponin change shape
Tropomyosin moves with troponin exposing the myosin binding site on actin

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11
Q

Cross-bridge cycle

A
  1. ATP hydrolysis
  2. Cross bridge formation
  3. Power stroke
  4. Detachment
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12
Q

Cross-bridge cycle: 1. ATP hydrolysis

A

Bonding of ATP causes a conformational change in the myosin head orientation
Brings it closer to the actin filament
A phosphate group is lost
ADP and phosphate groups remains

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13
Q

Cross-bridge cycle: 2. Cross bridge formation

A

Myosin head attaches to the actin
The remaining phosphate groups are released

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14
Q

Cross-bridge cycle: 3. Power stroke

A

Myosin head pivots and rotates
Releasing the ADP
Generates force and pulls the actin filament to the centre of the sarcomere
Prepares myosin head to receive another ATP

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15
Q

Cross-bridge cycle: 4. Detachment

A

New ATP binds to the myosin head
Causing it to detach from the actin
Ready for ATP hydrolysis

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16
Q

Sarcomere

A

Functional unit of a myofibril
Myofilament - consisting of a complex arrangement of contractile proteins
I-band
Z-line
M-line
H-zone
A-band

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17
Q

Sarcomere: contractile proteins

A

Myosin
Actin

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18
Q

Contractile proteins: myosin

A

Thick filament
In A-band and H-zone
Interact with actin to create movement
Head, tail and neck
Acts with actin to shorten the cell

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19
Q

Contractile proteins: actin

A

Thin filament
Stays anchored
Bound to by the myosin molecule
Act with myosin to shorten the cell

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20
Q

Sarcomere: regulatory proteins

A

Tropomyosin
Troponin

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21
Q

Regulatory proteins: Tropomyosin

A

Long molecule
Twist around each filament of actin
Involved in uncovering of myosin head binding sites on the actin filament

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22
Q

Regulatory proteins: troponin

A

Involved in moving Tropomyosin away from the myosin binding sites on actin
Binding of Ca2+ causes a conformational shape change that moves Tropomyosin away from the myosin binding sites

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23
Q

Sarcomere: structure protein

A

Titin

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24
Q

Structural protein: Titin

Study These Flashcards
A

Large, singular protein coiled at one end
Sits between the M-line and Z-line
Acts as a spring for actin
Attaching them to the Z-line

25
Sliding filament theory
Muscle contraction - myosin binds onto actin forming chemical bonds (cross bridges) Myosin ‘walk’ along the actin and pull them towards the centre of the sarcomere Causes sarcomere shortening H-zone - smaller I-band - smaller A-band - same
26
Motor units
Consists of motor neurone and all the muscle fibres it innervates Overall muscle movement - recruitment of different size units, different strength of units and quantity of the units
27
Frequency of stimulation: summation
Wave summation - an increase in the number of stimuli (in quick succession) to a muscle fibres Causes an increase in the force of contraction
28
Frequency of stimulation: incomplete tetanus
Muscle is stimulated after the absolute refractory period but before the muscle can relax Tension of the muscle increases to its maximum
29
How to improve the smoothness of motor actions
Frequency coding Recruit motor units with larger and larger cells Recruit more and more motor units
30
Rigorous mortis
ATP synthesis stops Sarcoplasmic reticulum pump stops So actin/troponin complex activated No ATP available for cross bridge detachment Muscle stiffness - 3-12 hours to develop Enzymatic breakdown of proteins can reverse this
31
Muscle ageing
Sarcopenia - muscle loss Myosin production Mitochondrial malfunction Motor axon atrophy - nerve cell die back Atrophy of muscle fibres
32
Spinal reflex
Sensory receptor Sensory neurone Synapsis and interneurones Motor neurone Effector
33
Ipsilateral reflex
Motor impulse leave spinal cord via the motor neurone on the same side as the sensory impulses that enter via the sensory neurone
34
Contralateral reflex
Motor impulse leaves spinal cord via the motor neurone on the opposite side as the sensory impulses that enters via the sensory neurone
35
Stretch/ myotactic reflex
1. Muscle spindles 2. Sensory neurone 3. Excitatory synapse 4. Motor neurone 5. Skeletal muscle
36
Stretch/ myotactic reflex: 1. Muscle spindles
Sensory receptor (muscle spindle) is activated Slightly stretching of the muscle
37
Stretch/ myotactic reflex: 2. Sensory neurone
Fires action potential along neurone into spinal cord
38
Stretch/ myotactic reflex: 3. Excitatory synapse
Sensory neurone synapses ipsilaterally with motor neurone in anterior grey horn of spinal cord
39
Stretch/ myotactic reflex: 4. Motor neurone
Action potential along neurone to neuromuscular junction in the stretched skeletal muscle fibre
40
Stretch/ myotactic reflex: 5. skeletal muscle
Muscular contraction Relieving the stretching of the muscle
41
Tendon reflex
1. Golgi tendon organ 2. Sensory neurone 3. Inhibitory interneurone 4. Motor neurone 5. Skeletal muscle
42
Tendon reflex: 1. Golgi tendon organ
Sensory receptors (Golgi tendon organ) activated Located within a tendon at its junction within a muscle Activated in response to increased tension
43
Tendon reflex: 2. Sensory neurone
Action potential along neurone into spinal cord
44
Tendon reflex: 3. Inhibitory interneurone
Sensory neurone synapses with inhibitory interneurone which synapses ipsilaterally with a motor neurone in anterior grey horn of spinal cord
45
Tendon reflex: 4. Motor neurones
Interneurones release inhibitory neurotransmitters that inhibit the motor neurone Reducing chance of action potential
46
Tendon reflex: 5. Skeletal muscle
Relaxation of the muscle attached to the stretched muscle tendon Reducing tension in tendon and protecting it from damage
47
Flexor reflex
1. Pain receptor 2. Sensory neurone 3. Interneurone 4. Motor neurone 5. Flexor muscles
48
Flexor reflex: 1. Pain receptor
Free nerve endings of pain-sensitive neurones activated Response to painful stimulus
49
Flexor reflex: 2. Sensory neurone
Action potential along neurone to spinal cord
50
Flexor reflex: 3. Interneurones
Sensory neurone synapses with ascending and descending interneurones
51
Flexor reflex: 4. Motor neurones
Interneurones synapses ipsilaterally with motor neurone in anterior grey horn of spinal cord Triggering action potential to neuromuscular junction in flexor muscle fibres
52
Flexor reflex: 5. Flexor muscles
Contraction Triggers withdrawal of the limb away from the painful stimuli
53
Extensor reflex
1. Pain receptor 2. Sensory neurone 3. Interneurone 4. Motor neurone 5. Extensor muscles
54
Extensor reflex: 1. Pain receptor
Free nerve endings of a pen-sensitive neurone activated Response to painful stimulus
55
Extensor reflex: 2. Sensory neurone
Action potential along neurone into spinal cord
56
Extensor reflex: 3. Interneurone
Sensory neurone synapses with interneurones which synapses with motor neurones contralaterally in anterior grey horn of spinal cord
57
Extensor reflex: 4. Motor neurones
Action potential along neurone to the neuromuscular junction in extensor muscle fibres of the unharmed limb
58
Extensor reflex: 5. Extensor muscles
Contraction Limb to stabilise the body during the withdrawal action

Principles Of Health Sciences (11 decks)

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