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Physiology > Muscle > Flashcards

Muscle Flashcards

1
Q

Types of muscle tissue

A

Skeletal
Cardiac
Smooth

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2
Q

Functions of skeletal muscle (6)

A

Pulls tendons to move skeletal system
Tension in muscles maintain body posture
Support visceral organs and protect tissues from injury
Voluntary control of swallowing, defecation, urination
Generates heat
Contractile proteins can be broken down to synthesise glucose and energy

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3
Q

Connective tissue of muscle

Fascicles - receives branches of b. vessels and nerves.
Fascicles are bundles of muscle cells (muscle fibres)

A

Epimysium - collagen fibres, separates muscle from surrounding organs and tissues. Connected to deep fascia
Perimysium - collagen & elastin. Contains b. vessels & nerves.
Endomysium - surrounds fascicles.

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4
Q 
Endomysium contains (3)
- all structures in endomysium are in direct contact with muscle fibres.
A

Capillaries to supply blood to muscle fibres.
Myosatellite cells ; embryonic stem cells repaid muscle tissue.
Nerves fibres to control muscles.

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5
Q

tendons/ aponeurosis - what are they?

A

a coming together of the collagen fibres of the endomysium, perimysium, epimysium. They extent into bony matrix of attachment.

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6
Q

Characteristics of muscle cells/ fibres

A

Enormous (up to 30cm long)
Multinucleate (nuclei just internal to plasma membrane)
Incapable of dividing. New fibres produced by satellite/ stem/ progenitor cells.

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7
Q

Anatomy of muscle cells

A

sacroplasm, sacrolemma - T tubules, sacroplasmic reticulum (related to smooth ER) and full of Calcium.
Terminal cisternae (bloated sacroplasmic reticulum at ends of T Tubules).
Triad = 2 x terminal cisternae + T Tubule.
T Tubules circle myofibrils

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8
Q

Myofibrils
1-2 um dia. Long as entire cell.
Each muscle fibre has hundreds to thousands of these.

A

Consists of bundles ofvprotein filaments called myofilaments.
Thin filaments - mainly actin
Thich filaments - mainly myosin

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9
Q

Thin filament

4 proteins

A

Troponin,
Tropomyosin,
Nebulin,
G-Actin

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10
Q

Tropomyosin (long strands)

A

Cover active sites on G-Actin and prevent actin-myosin interaction

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11
Q

Nebulin (straight strand)

A

Holds F-Actin together and controls its length

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12
Q

G-Actin (round molecules)

A

Has active sites that bind to myosin

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13
Q

Troponin

A

Bound to each tropomyosin half-way along its length.

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14
Q

What does a thick filament consist of?

A

roughly 300 myosin molecules held together by the protein titin. Titin is a coiled protein that helps prevent over stretching of the muscle.

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15
Q

Mysoin has three parts

A

tail
hinge
head (two globular protein subunits)

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16
Q

Approx how many sacromeres in a myofilament?

A

10, 000

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17
Q

what communicates between the muscle fibre and the nervous system?

A

the neuromuscular junction

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18
Q

what is a motor end plate?

A

It is the postsynaptic surface containing acetylcholine receptors. The junctional folds increase the surface area and thus the number of acetylcholine receptors.

19
Q

What enzymes is present in the junctional folds and synaptic cleft?

A

acetylcholinesterase

20
Q

when an action potential arrives at the synaptic terminal……

A

there is depolarisation of the motor end plate and the appearance of a second action potential in the sacrolemma

21
Q

what is an excitation-contraction coupling?

A

the link between the generation of an action potential in the sacrolemma and the start of a muscle contraction

22
Q

what happens when an action potential reaches a triad?

A

Ca++ is released from the terminal cisternae of the sacroplasmic reticulum.

23
Q

why is the effect of calcium release on the sacromere almost instantaneous?

A

because the terminal cisternae are situated on the zones of overlap, where the thick and thin filaments interact.

24
Q

Three different types of muscle fibre

A

Type I - referred to as “slow twitch oxidative”
Type IIA are “fast twitch oxidative”
Type IIB are “fast twitch glycolytic”

25
Q

What are type I fibres good for?

A

Type one fibers are characterized by low force/power/speed production and high endurance

26
Q

what are type II fibres good for?

A

Type IIB by high force/power/speed production and low endurance, while Type IIA fall in between.

27
Q

what’s the difference between a slow twitch motor unit ad a fast twitch motor unit?

A

The fast twitch motor unit controls more muscle fibers or cells and these cells are bigger.

28
Q

what determines the degree of motor unit involvement?

A

the nervous system

29
Q

what is the primary function of ATP?

A

the TRANSFER of energy from one location to another rather than the long-term storage or energy

30
Q

what happens to a muscle fibre at rest

A

at produces more ATP than needed and this energy is converted into creatine

31
Q

what is creatine?

A

a small molecule that muscles assemble from fragments of amino acids

32
Q

what does ATP + creatine create?

A

ADP + creatine phosphate

creatine phosphate is a high energy compound

33
Q

what enzyme facilitates the conversion of creatine into creatine phosphate?

A

CPK - creatine phosphokinase

34
Q

what happens when muscle gets damaged?

A

CPK leaks into bloodstream

35
Q

what does high levels of CPK indicate?

A

serious muscle damage (heart attack?)

36
Q

What is anaerobic endurance?

A

the length of time muscular contraction can continue to be supported to glycolysis and the reserves of ATP and CP

37
Q

what is glycolysis?

A

ATP production though the breakdown of glucose involving a sequence of glycolytic enzymes.

38
Q

where does the glucose for glycolysis come from?

A

glycogen stores in liver

carbohydrate ingestion

39
Q

what is the name of the process of converting glucose into glycogen?

A

glycogenesis

40
Q

what does glycolysis produce?

A

pyruvic acid

41
Q

what happens when glycolysis occurs without oxygen?

A

pyruvic acid is converted into lactic acid

42
Q

what happens to the muscle because of lactic acid accumulation?

A

acidity inhibits glycolytic enzymes.

acidic decreases muscle fibres’ calcium-binding capacity and thus impede muscle contraction.

43
Q

what is the rate-limiting enzyme in glycolysis?

A

PFK - phosphofructokinase

Physiology (13 decks)

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