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Z 2021 Phase 2 Limbs and Back Others > limbs and back week 3 > Flashcards

limbs and back week 3 Flashcards

(107 cards)

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1
Q

Describe the ATP pool in skeletal muscle

A

it is small and capable of supplying only for a very few contractions if not replenisehd

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2
Q

Why are ATP supplies only moderately depleted even as the muscle fatigues?

A

It is continually replenished

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3
Q

What is the function of creatine phosphate?

A

It is used to convert ADP to ATP and thus replenish the ATP store during muscle contraction.
Represents the immediate high-energy source for replacing the ATP supply in skeletal muscle, especially during intense exercise

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4
Q

What enzyme catalyses the reaction between ADP and creatine phosphate?

A

creatine phosphokinase

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5
Q

Where is CPK found?

A

Mostly in the sarcoplasm but some at the myosin heads too

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6
Q

How big is the creatine phosphate store?

A

Only 5 times to size of the ATP store and can’t last over 1 minute

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7
Q

How is creatine phosphate replenished?

A

During recovery from fatigue by using the ATP synthesised by oxidative phosphorylation

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8
Q

Where do muscles get carbohydrates from?

A

Muscle cells contain glycogen stores which can be metabolised during muscle contraction to provide glucose for oxidative phosphorylation and glycolysis
Muscle cells can also take up glucose from the blood
ATP yields are dependent on an adequate oxygen supply

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9
Q

When are fatty acids important sources of energy for muscle?

A

During prolonged exercise

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10
Q

Where do muscles get fatty acids from?

A

Muscle cells contain fatty acids
they can uptake fatty acids from the blood
muscle cells can store triglycerides, which can be hydrolysed to produce fatty acids

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11
Q

How are fatty acids metabolised in muscle?

A

they are converted into acyl-carnitine in the cytosol then transported into the mitochondria
Then they are converted into acyl-CoA
Within the mitochondria acyl-CoA is then subjected to Beta oxidation and yields acetyl-CoA
This enters the citric acid cycle and ultimately produces ATP.

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12
Q

What is fatigue?

A

The inability to maintain power output of muscle, reversible by rest

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13
Q

What occurs as a result of fatigue?

A

reduced force, shortening and relaxation rate

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14
Q

Describe central fatigue

A

within the nervous system
loss of excitability of the motor cortex, possible reflex inputs from “metabo-receptors” in muscle
can include failure of transition in peripheral nerve and neuromuscular junctions (usually pathological)

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15
Q

Describe peripheral fatigue

A

within the muscle fibres
failure of excitation - contraction coupling, T-tubule action potential, SR activation, Ca2+ release

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16
Q

How can you determine the type of fatigue?

A

external stimulation - if direct muscle stimulation delivers smaller forces then fatigue is peripheral. If stimulation delivers “normal” forces, then fatigue is central

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17
Q

Describe excitation failure

A

most likely in short intensity exercise
High AP firing rates leads to accumulation of K+ ions in tubules
This would make the T-tubule unexcitable and impairs excitation contraction coupling
recovery from this type of fatigue would be rapid

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18
Q

When is central fatigue likely?

A

Probably likely in occupational work and recreational sport. sensation of fatigue may involve discomfort and lack of motivation.
probably not a factor in elite sport

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19
Q

When does peripheral fatigue occur?

A

fatigue is not due to decreased ATP
In fatigue concentrations of H+, Pi and ADP all increase
these changes impair calcium fluxes and impair force delivery at cross bridges

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20
Q

Why does the build up of ADP, Pi and H+ inhibit the function of ATP?

A

An increase in the right and side of the equation will shift the equilibrium to the left and hence slow the break down of ATP

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21
Q

What else do ADP, Pi and H+ all inhibit?

A

Ca2+ release and reuptake into the sarcoplasmic reticulum. This affects the force and speed of shortening and relaxation.
H+ also competes with Ca2+ for troponin binding

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22
Q

What is the main energy source for long duration exercise?

A

Carbohydrate and lipid metabolism

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23
Q

What is the main energy source for moderate duration exercise?

A

aerobic, fuel mix uses more carbohydrates

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24
Q

What is the main energy source for short duration exercise?

A

aerobic and anaerobic metabolism, carbohydrate dependent, inefficient glycolytic metabolism

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25
Describe the processes of training
requires multiple repetitions of the exercise concerned for strength - small numbers of high power contractions for endurance - large numbers of low force contractions in strength training type 2 fibres enlarge in true endurance training (e.g. marathon) no demand for increased strength, type 1 fibres may enlarge but type 2 decrease. Usually there is a loss of fat.
26
Describe the neural phase of strength training
first 4-6 weeks CNS response, increased recruitment of largest motor units and higher maximum firing rates
27
Describe the hypertrophy phase of strength training
large motor units grow significant hormonal changes - after strenuous strength training, GH, local growth hormones and testosterone are all elevated for hours connective tissues also strengthen hypertrophy is slow starts with the development of new filaments attached laterally to existing myofibrils Later there is fibril splitting - the most enlarged fibrils split longitudinally - thus become more numerous
28
How can skeletal muscle fibres be classified?
As fast twitch (2a/2b) or slow twitch (1)
29
How can the different types of muscle fibres be distinguished from one another?
the activities of oxidative and glycolytic pathways.
30
Describe fast twitch fibres
the activity of the glycolytic enzymes is high and the activity of the oxidative enzymes is low. - very few mitochondria more extensive sarcoplasmic reticulum than slow twitch fatigue quickly
31
Describe slow twitch fibres
meet metabolic demands by oxidative phosphorylation fatigue more slowly
32
What is special about 2a fibres?
They contain both high glycolytic and oxidative capacity - rare in humans
33
What is spacial summation?
Since fast-twitch muscle fibres are more difficult to excite slow twitch muscle fibre motor units are recruited first. As more force is required, fast fibres are recruited
34
What are the advantages of spacial summation?
The first muscle fibres recruited have high resistance to fatigue the small size of the slow-twitch muscle units allows fine motor control
35
What are the three bones of the elbow joint?
The humerus, ulna and radius
36
What are the two articulations of the elbow joint?
Humeri-ulnar = between the trochlea of the humerus and the trochlear notch of the ulna Humero-radial = between the capitulum and upper surface of the radial head
37
What limits movement at the elbow joint?
fossas
38
Describe movement at the elbow joint
Flexion and extension - hinge joint, very stable, not likely to dislocate
39
How can hyperextension occur?
If the olecranon fossa forms a foreman instead, the olecranon of the ulna can pass right through
40
Describe the proximal radioulnar joint
also contained within the elbow joint capsule the articulation between the head of the radius and the radial notch of the ulna annular ligament wraps around the head of the radius and maintains stability of the radius allows rotation during pronation and supination of the forearm. Primary supination muscle is the biceps
41
What are the 3 flexors of the elbow joint?
Brachialis (primary flexor) Brachioradialis (accesorry) only when forearm is mid-pronated Biceps bracchi - only if palm is upwards
42
What is the extensor muscle of the elbow joint?
triceps brachii (long head, lateral head, medial head)
43
What forms the compartments of the forearm?
The interosseous membrane
44
What is the function of the interosseous membrane?
Stabilises the radius and ulna
45
What muscles are contained within the superficial and intermediate layers the anterior compartment of the forearm?
flexor carpi ulnaris palmaris longus flexor carpi radialis pronator teres
46
What is the nerve supply to the superficial and intermediate layers of the anterior compartment of the forearm?
all musculocutaneous nerve except flexor carpi ulnaris which is supplied by the ulnar nerve
47
What muscles are contained in the deep layer of the anterior compartment of the forearm?
flexor digitorum profundus flexor policis longus pronator quadratus
48
What is the nerve supply to the deep layer of the anterior compartment of the forearm?
Musculocutaneous expect half of flexor digitorum profundus is supplied by the ulnar nerve - the part that flexes the ring and little fingers
49
Which muscles are contained within the superficial layer of the posterior compartment of the forearm?
brachioradialis extensor carpi radialis longus extensor carpi radialis brevis aconeus extensor digitorum extensor digiti minimi extensor carpi lunaris extensor retinaculum
50
What is the nerve supply of the superficial layer of the posterior compartment of the forearm?
Radial nerve
51
Which muscles are contained within the deep layer of the posterior compartment of the forearm?
Abductor policis longus extensor policis brevis extensor indicis extensor policis longus
52
What is the nerve supply to the deep layer of the posterior compartment of the forearm?
radial nerve
53
What is epicondylitis?
Tennis / golfer's elbow caused by resisting / limiting wrist movement pain radiates along affected muscles
54
What side is tennis elbow?
lateral
55
What side is golfer's elbow?
medial
56
how is epicondylitis treated?
rest or injection of corticosteroids if pain is severe
57
What is the cubital fossa?
A triangular shaped depression anterior to the elbow
58
What is the lateral boundary of the cubital fossa?
brachioradialis
59
What is the medial border of the cubital fossa?
pronator teres
60
What is the superior border of the cubital fossa?
imaginary line between the medial and lateral epicondyles
61
What is the floor of the cubital fossa?
brachialis
62
What is the roof of the cubital fossa?
deep fascia reinforced by bicipital aponeurosis
63
What is contained in the cubital fossa?
tendon of biceps brachial artery median nerve radial nerve (underneath brachioradialis)
64
Why is the cubital fossa an important site for venipuncture?
deep fascia protects the underlying brachial artery and median nerve safe place to take blood sample
65
Describe the blood supply to the forearm
the brachial artery bifurcates in the cubital fossa into the radial and ulnar arteries.
66
Where do the radial and ulnar arteries lie?
lateral to the tendons of the flexor carpi ulnas and flexor carpi radialis
67
Why is the ulnar artery more difficult to palpate?
Mostly covered by the flexor carpi ulnaris
68
what is gastrulation?
a process of cell division and migration resulting in the formation of 3 germ layers
69
What are the three germ layers called?
ectoderm, mesoderm, endoderm
70
What does ectoderm form?
epidermis of skin and its derivatives epithelial lining of mouth and anus cornea and lens of eyes nervous system sensory receptors in the epidermis adrenal medulla tooth enamel epithelium of pineal and pituitary glands
71
What does mesoderm form?
notochord skeletal system muscular system muscular layer of stomach lining excretory system circulatory and lymphatic systems reproductive systems lining of body cavity adrenal cortex
72
What does endoderm form?
epithelial lining of digestive tract epithelial lining of respiratory system lining of urethra, urinary bladder and reproductive system liver pancreas thymus thyroid and parathyroid glands
73
When does mesoderm differentiate?
days 17-21
74
what does mesoderm differentiate into?
paraxial intermediate lateral plate
75
what does paraxial mesoderm form?
cells moving bilaterally and cranially forms somites
76
what does intermediate mesoderm form?
genitourinary systems
77
what does lateral plate mesoderm form
somatic and splanchnic layers
78
where does skeletal muscle originate from?
paraxial mesoderm
79
where does smooth muscle originate from?
visceral layer of the lateral plate mesoderm
80
where does cardiac muscle originate from?
visceral later of the lateral plate mesoderm
81
what type of mesoderm gives rise to somites?
paraxial
82
what stimulates the start of somitogenisis?
NOTCH accumulation on the pre-somatic mesoderm signal for somite formatoin once somite is formed NOTCH decreases
83
What is a somite?
a block of mesoderm which gives rise to skeletal muscle
84
what do somites split into?
sclerotome and dermatomyotome
85
What does sclerotome form?
the vertebrae and ribs
86
what does dermatomyotome split into?
dermatome and myotome
87
what does dermatome form?
dermis of the back
88
what does myotome form?
muscles
89
What are myoblasts?
myotome cells - committed muscle cell precursors
90
What are the transcription factors involve in skeletal muscle formation?
MYOD and MYF5
91
Which molecules regulate somite differentiation?
WNT proteins (activating) BMP (inhibitory) sonic hedgehog noggin
92
describe smooth muscle
orientates from splanchnic mesoderm serum response factor (SFR) is responsible for smooth muscle cell differentiation SFR unregulated by kinase phosphorylation pathways Myocardin / myocardin-related transcription factors enhance SFR activity
93
Describe skeletal muscle
myoblasts fuse to form long multinucleate fibres striated , contain many mitochondria under control of genes sets including MYOD, Mfy5 and myogenic tendons are derived from the sclerotome under the control of the transcription factor sceraxis
94
Describe cardiac muscle
splanchnic mesoderm surrounding developing heart tube striated - different from skeletal myoblasts adhere to each other via intercalated disks MYOD not involved in early cardiac muscle development TInnman - homeobox gene responsible for specification of cardiac muscle
95
what do sensory neurons do?
relay information centrally to the spinal cord
96
What do motor neurons do?
responsible for causing muscle contraction - ventral horn of the spinal cord
97
What are peripheral nerves?
The axons of motor and sensory neurons
98
Describe the spinal cord in terms of innervation
caudal part of the CNS continuous with the brain stem organised segmentally - 8 cervial, 12 thoracic, 5 lumbar and 1 coxygeal each segment gives rise to a pair of spinal nerves
99
What nerves form the cervical plexus?
C1-C5
100
What nerves from the brachial plexus?
C5-T1
101
What nerves from the lumbosacral plexus?
T12-S5
102
Describe the difference between myelinated and unmyelinated nerves/
myelinated - large diameter, fast conduction, touch, vibration, motor output non-myelinated - small diameter, slow conduction, pain, hot, cold
103
What is a myotome?
each muscle is supplied by a particular level / segment of the spinal cord and its corresponding spinal nerve
104
What is a dermatome?
An area of skin innervated by a particular level / segment of the spinal cord
105
What is the ASIA scale used for?
to determine the level and extent of spinal cord injury
106
What is proprioception?
sensations arising from the deep field as a result of the actions of the organism
107
What factors contribute to proprioceptive sensations?
passive displacement of the joints (and skin) movement sense (awareness of joint movement) Position sense (awareness of static joint position)

Z 2021 Phase 2 Limbs and Back Others (6 decks)

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