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Physiology Flashcards

1
Q

What are the dark bands in muscle striation?

A

Myocin

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2
Q

What are the light bands in muscle striation?

A

Actin

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3
Q

Skeletal muscles have what innervation?

A

Somatic

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4
Q

Cardiac and smooth muscles have what innervation?

A

Autonomic

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5
Q

Skeletal muscles are organised into what

A

Motor units

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6
Q

What are motor units

A

A single alpha motor neuron

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7
Q

Muscles which are required for fine motor movements have what kind of make up?

A

They have fewer fibres per motor unit

e.g the leg muscles have hundreds to thousands of fibres

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8
Q

What units make up muscle fibres?

A

Myofibrils, made of sarcomeres (functional unit)

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9
Q

Tell me about skeletal muscles

A

Neurogenic initiation of contraction
Striated
Motor units
Neuromuscular junction
NO gap junctions
Contraction is powered by Ca entirely from sarcoplasmic reticulum
Grading of the contraction is dependant on the number of motor units

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10
Q

Tell me about cardiac muscles

A

Myogenic initiation of contraction
Striated
No neuromuscular junction
Gap junctions present
Contraction powered by Ca from ECF and sarcoplasmic reticulum
Grading of the contraction is dependant on filling of the heart

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11
Q

Where is the Ca released from in the sarcoplasmic reticulum?

A

The lateral sacs

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12
Q

Where is the Ca released?

A

When the surface action potential spreads down the transverse tubules

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13
Q

What are actin and myosin arranged into?

A

Sarcomeres

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14
Q

Where is the sarcomere found?

A

Between two Z lines

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15
Q

What are the zones of the sarcomere?

A

A band, H zone, M line and I band

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16
Q

Tell me about the A band

A

Made of thick filaments, with some thin

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17
Q

Tell me about the H zone

A

Lighter area within middle of A band where thin filaments don’t reach

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18
Q

Tell me about the M line

A

Extends vertically down the middle of A band within the centre of H zone

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19
Q

Tell me about I band

A

Consists of remaining portion of thin filaments, next to A band

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20
Q

How is muscle tension produced

A

By sliding of actin filaments on myocin filaments

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21
Q

Why is Ca required during contraction?

A

To switch on cross bridge formation

The link between excitation and contraction

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22
Q

Why is ATP needed during relaxation?

A

To release cross bridges, to pump Ca back into the sarcoplasmic reticulum
Rigor mortis, a sign of death

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23
Q

What is longer in duration? The action potential or the twitch

A

The twitch is longer

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24
Q

If the muscle fiber is stimulated so rapidly and doesn’t have the opportunity to rest what is this called?

A

Tetanus

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25
Can cardiac muscle be tetanised?
Nope
26
Tell me about isotonic contractions
Used for body movements and moving objects | Muscle tension remains constant as the muscle changes length
27
Tell me about isometric contractions
Used for supporting objects in fixed positions, for maintaining posture - tension develops at constant muscle length
28
Describe the load velocity relationship
The velocity of shortening decreases as the load increases
29
Name an abnormality in the muscle membrane ion channels
Myotonia
30
Name an inflammatory myopathy
Polymyosytis
31
What is the simplest monosynaptic spinal reflex
The stretch reflex - it resists passive change in muscle length
32
Stretching the muscle spindle during the stretch reflex increases firing in the afferent neurones
The afferent neurones synapse in the spinal cord with the alpha motor neurones that innervate the stretched muscle - rapidly stretches the quadriceps femoris
33
What is the spinal segment and peripheral nerve of the knee jerk?
L3, L4 | Femoral nerve
34
What is the spinal segment and peripheral nerve of the ankle jerk
S1, S2 | Tibial nerve
35
What is the spinal segment and peripheral nerve of the biceps jerk
C5 -C6 | Musculocutaneous nerve
36
What is the spinal segment and peripheral nerve of the brachioradialis
C5 C6 | Radial nerve
37
What is the spinal segment and peripheral nerve of the Triceps jerk
C6 C7 | Radial nerve
38
What are muscle spindles known as
Intrafusal fibres Ordinary muscle fibres are extrafusal fibres Muscle spindles are found within the belly of muscles and run parallel to ordinary muscle fibres
39
What are the sensory nerve endings of the muscle spindles?
Annulospiral | The discharge from the muscle spindles increases as the muscle is stretched
40
Does the muscle spindle have its own efferent (motor) nerve supply?
YEAH BOI - known as gamma motor neurones - they adjust the level of tension in the muscle but don't contribute to overall strength
41
What are the main differences between muscle fibres?
The pathways for ATP synthesis The resistance to fatigue The activity of myosin ATPase
42
What pathways supply ATP in muscle fibres?
ADP -> ATP Oxidative phosphorylation Glycolysis (when O2 is not present)
43
What are the three types of skeletal muscle fibres?
``` Slow Oxidative (Type I) - low work aerobic activities - slow twitch fibres Fast Oxidative (Type IIa) - intermediate twitch fibres - aerobic and anaerobic - moderate work Fast Glycolytic (Type IIx) - anaerobic - fast twitch - short term high intensity ```
44
What test is used to detect the presence of muscular activity?
EMG - electromyography Records the action potentials Helps differentiate between primary muscle disease from muscle weakness
45
What are nerve conduction studies designed to do/
Determine the functional integrity of peripheral nerves
46
Name a muscle enzyme
Creatine kinase
47
Name the 3 types of joints
Synovial, fibrous, cartilaginous
48
What are the synovial cells called?
Fibroblasts - which produce synovial fluid
49
What are the two classifications of synovial joint?
Simple - one pair of articular surfaces | Compound - more than one pair of articular surfaces (elbow)
50
What are the role of joints during motion?
Stress distribution, stability, joint lubrication (synovium, derived hyaluronic acid, mucin, a polymer of disaccharides)
51
True or false does the synovial fluid aids in the nutrition of articular cartilage?
True - supplies the chondrocytes with O2 and nutrients and removes CO2 and waste
52
Is the synovial fluid static in the knee?
Nope, its continuously replenished and absorbed by the synovial membrane
53
Why does the synovial fluid have a high viscosity?
due to the presence of hyaluronic acid (mucin) produced by the synovial cells - other constituents of the fluid are derived by dialysis of blood plasma - it normally contains a few mononuclear leucocytes
54
The viscosity and elasticity of synovial fluid change during joint movement - true or false
True Rapid movement is a decrease in viscosity and increased elasticity - these properties become defective in a disease joint
55
When does the synovial fluid turn red?
In traumatic synovial tap and in hemorrhagic arthritis
56
What is the normal white cell count in normal synovial fluid?
<200
57
What is the articular cartilage made from
Hyaline
58
What constituent accounts for 70% of the cartilage wet weight?
Water | The water content decreases with age
59
What accounts for 20% of the cartilage wet weight?
Collagen | Mainly type II collagen which decreases with age
60
What accounts for 10% of the cartilage wet weight
Proteoglycan | - Composed mainly of glycosaminoglycan e.g chondroitin decreases with age - load bearing
61
The articular cartilage is avascular
No vessels
62
What is the cartilage degraded by?
Metalloproteinase proteolytic enzymes e.g collagenase and stromelysin
63
How would joint disease occur?
If the rate of ECM degradation exceeds the rate of its synthesis
64
What are the catabolic factors of cartilage turnover?
Inhibition of proteoglycan synthesis - TNF and IL 1 Serum and synovial keratin sulphate (increased levels with age and in osteoarthritis) Type II collagen - useful in elevating cartilage erosion
65
What are the anabolic factors of cartilage turnover?
Stimulate proteoglycan synthesis and counteract effects of IL 1 - TGF and IGF (insulin like growth factor)
66
What are the physical results of wear and tear on a joint
``` Thickened capsule Cyst formation Sclerosis in subchondral bone Fibrillated cartilage Synovial hypertrophy Osteophyte formation (spikes growing out of the bone) ```
67
What shape is the uric acid crystal in gouty arthritis?
Needle shaped
68
What shape is the calcium phosphate crystal in pseudo gout?
Rhomboid shaped

MSK (11 decks)

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