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MEDS1001 > movement > Flashcards

movement Flashcards

1
Q

function of muscles

A
  • movement
  • thermoregulation
  • energy metabolism + storage
  • appetite regulation
  • drug storage
  • endocrine functions
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2
Q

skeletal muscles

A

Attached to skeleton
Contract - pull on bones and cause them to move
Most common type
We control consciously

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3
Q

Cardiac muscles (Myocardium)

A
  • Forms the heart
  • Responsible for pumping blood
  • Involuntary movement
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4
Q

Smooth muscle

A
  • Located in tissues
  • Responsible for controlling the diameter of certain structures and peristalsis
  • Involuntary movement
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5
Q

muscles in general are…

A
  • Electrically excitable
  • Contracts actively - requires energy
  • Relaxes passively
  • Elastic
  • Extensible
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6
Q

Characteristics of muscles

A

75% water
20% protein - contract
5% carbohydrate and fat - energy stores, active process of muscle contraction

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7
Q

Men have more skeletal muscle than women?

A

true
Gender differences are greater in the upper body than in the lower body

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8
Q

muscle loss due to age

A

Skeletal muscle starts to decrease in the third decade but a noticeable change does not occur until the end of thefifth decade
Most loss is in the lower body

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9
Q

Contractions (general)

A

Chemical energy is transformed into mechanical energy
ATP is converted

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10
Q

muscle fibres contain…

A

myosin (thick) - has heads that project towards actin, cause it to move

actin (thin) - binding sites for myosin heads

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11
Q

filament arrangement in skeletal and cardiac muscle

A

regular, parallel pattern

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12
Q

filament arrangement in smooth muscle

A

random

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13
Q

sacromeres

A

myosin and actin are organsied into sacromeres

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14
Q

muscle contraction

A
  1. myosin heads link to actin to form cross-bridges
  2. The myosin heads cycle (rotate) towards the centre of the sarcomere (connection to actin is broken)
  3. Muscle contracts
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15
Q

muscle relaxation in skeletal muscle

A
  1. Tropomyosin blocks the binding sites on actin and prevents cross-bridge formation
  2. Electrical excitation of the muscle cell releases calcium from calcium stores in SR
  3. Calcium binds to troponin and moves the tropomyosin out of the way to allow cross-bridge formation
  4. When electrical excitation finishes, calcium pumped back into the SR and tropomyosin once again blocking the binding sites
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16
Q

T-tubules

A

brings action potentials into interior of muscle fibre

17
Q

process of contraction is the same in skeletal and cardiac muscle?

A

true

18
Q

Cross-striations in cardiac muscles

A
  • less distinct because there are many mitochondria and many lipid and glycogen droplets around the cells
  • muscles cells often branch at acute angles and are electrically connected to each other
19
Q

skeletal muscle cells

A

individual cells are electrically isolated, therefore we have more control as to which cells contract and which don’t

20
Q

ATP in cycle

A

used twice
1. when the cross bridge rotates
2. when the myosin head returns to its resting point (i.e. breaking the cross bridge)

21
Q

ATP can be produced in…

A

cytoplasm - anaerobic met (fast/inefficient)
mitochondria - aerobic met (slower/more efficient)

22
Q

smooth muscles are found in…

A

The walls of hollow organs
The walls of blood vessel
In airways
The eye
Skin

23
Q

smooth muscles can be controlled by…

A
  • Hormones
  • Neural stimulation from the ANS
  • Change in pH in muscle - change in diameter
  • Lack of oxygen - diameter or blood vessel
  • Stretching the muscles
24
Q

Ca2+ role in smooth muscles

A

Uses calcium from both inside and outside the cell
Calcium binds to calmodulin (protein) that initiates contraction

25
Q

speed of ATP use and replacement determines…

A

how quickly muscle cells contract

26
Q

Type 1/slow twitch/red

A
  • Contract slowly but fatigue slowly
  • Can’t generate that much power
  • Supplied by nerves that activate them first during muscle contraction
  • Use aerobic metabolism
  • Lots of capacity to deliver oxygen to cells
  • Contain myoglobin that transport oxygen to mitochondria
27
Q

Type 2/fast twitch/white

A
  • Much quicker but fatigue quickly
  • Generate lots of power
  • Use anaerobic metabolism
  • No myoglobin
28
Q

We increase the force of a muscle by…

A

activating more motor units simultaneously

29
Q

power of contraction

A

Change power of contraction by changing the number of motor unit used - control tension

30
Q

Small motor units

A

Few fibres innervated by a single nerve
* Generate little tension
* Enable fine control
* Are fatigue resistant

31
Q

Large motor units

A
  • Generate much more tension but figure quickly
  • Less fine control
32
Q

Twitch

A

One action potential in a motor neuron produce one contraction

33
Q

Summation

A
  1. Latent period - action potential is being propagated along the membrane and Ca2+ ions released from SR
  2. Contraction phase - period of cross bridge formation
  3. Relaxation phase - Ca is pumped back into the SR, and cross bridge cycling stops
34
Q

If a muscle cell is stimulated while a previous twitch is occurring…

A

the second twitch will be stronger

35
Q

The tension produced in skeletal muscle is a function of

A
  • The frequency of neural stimulation and
  • The number of motor neurons (i.e. number of motor units) involved
36
Q

Fast twitch fibres

A

possess smaller neuromuscular junctions (NMJs), which may facilitate efficiency and speed of neurotransmission.

37
Q

Slow twitch fibres

A

possess NMJs with larger surface area which may facilitate sustained stimulation

MEDS1001 (21 decks)

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