33: Synaptic Transmission And Excitation-Contraction Coupling Flashcards

1
Q

Two types of synapses and which is common in humans

A

Electrical, chemical (common in humans)

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2
Q

Best example of human electrical synapse

A

Cardiac myocytes

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3
Q

Chemical synapse

A

Neurotransmitter used to diffuse across synaptic cleft -> receptor

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4
Q

Specificity of general chemical synapse pre- and post-synaptic cells

A

Pre-synaptic: can signal 1 or many post-synaptic

Post-synaptic: can receive signals from 1 or many pre-synaptic

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5
Q

Specificity of NMJ pre- and post-synaptic cells

A

Pre-synaptic: innervates 1 or many muscle cells

Post-synaptic: receives signal from only one pre-synaptic axon

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6
Q

Motor end plate

A

Specialized synaptic region in NMJ

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7
Q

What happens when an AP reaches a muscle cell?

A

Activates DHP receptors -> physically alter ryanodine receptors -> Ca channels in SR open -> Ca into sarcoplasm

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8
Q

How does Ca get removed from muscle cell at the end of an AP?

A

Ca/ATPase pump sequesters Ca back into SR

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9
Q

Peripheral vs central fatigue

A

Peripheral: depletion of ATP
Central: feeling of fatigue due to increased levels of byproducts (H ions, lactic acid)

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10
Q

Three ways muscle cells can get ATP

A

Phosphocreatine, glycolysis, oxphos

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11
Q

Three types of skeletal muscle fibers

A
  1. Slow twitch oxidative
  2. Fast twitch glycolytic
  3. Fast twitch oxidative
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12
Q

Slow twitch oxidative muscle fibers

A

Red (myoglobin and mito present), small, fatigue resistant

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13
Q

Fast twitch glycolytic muscle fibers

A

White, large diameter

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14
Q

Preferred energy use for slow twitch vs fast twitch fibers

A

Slow twitch: O2

Fast twitch: phosphocreatine, glucose

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15
Q

Four things that alter the force of muscle contraction

A
  1. Starting length of sarcomere
  2. How rapidly fiber is stimulated by nerve
  3. Innervation type
  4. Muscle type
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16
Q

What happens if sarcomere is too short or too long?

A

Short: myosin cant pull actin v far before it hits Z line + cross sectional area increases so actin and myosin are farther apart
Long: many myosin heads not in line with actin anymore

17
Q

Tetanus

A

Overlap of twitches such that complete relaxation is not achieved

18
Q

Recruitment

A

Activating more motor neurons -> motor units generate greater force