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Physio > Lecture 11 > Flashcards

Lecture 11 Flashcards

1
Q

What are the 4 skeletal muscle characteristics?

A

Excitable - responds to stimuli for action potentials

Contractile - shorten or thicken

Extensible - stretch when pulled

Elastic - returns to original shape after stretch/contraction

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2
Q

What are the skeletal muscle functions?

A

Movement

Posture/ expressions

Heat production

Protection of viscera (abdominal cavity)

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3
Q

How many neurons innervate each muscle fiber?

A

Only one

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4
Q

How many muscle fibers can be innervate by one neuron?

A

Can innervate up to 150 fibers

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5
Q

What constitutes a motor unit?

A

A single motor neuron and all the muscle fibers it innervates

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6
Q

What type of gate releases Ca+ into the synaptic end bulb?

A

A voltage Ca+ gate to releases the Ach neurotransmitters and exocytosis out

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7
Q

What is the role of ACH in the neuromuscular junction?

A

Ach is released by Ca+ to pass through the synaptic cleft and attach to chemical gated channels of the motor end plate and allow Na+ to enter the muscle fiber and reach end plate potential

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8
Q

What is the role of Na+ in the motor end plate?

A

Muscle fiber reaches endplate potential to open more Na+ channels along the sarcolemma -> depolarization causes Ca+ to be released from Sarcoplasmic reticulum

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9
Q

What is the role of Ca+ at the motor end plate?

A

Is released from sarcoplasmic reticulum to bind with troponin to move tropomyosin and expose actin sites

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10
Q

How does muscle contraction occur?

A

The ADP + Pi is bound to resting myosin head -> attaches to actin -> power stroke (movement) by releasing Pi -> after power stroke ADP is released -> ATP attaches to release head form actin -> left with ADP + Pi

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11
Q

What line of the sarcomere do the actin filaments move towards?

A

M line

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12
Q

What area of the sarcomere is in the A band?

A

The myosin heads (thick filament)

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13
Q

Which band changes shape with the sarcomere movement?

A

H and I band

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14
Q

What zone does the H band represent in the sarcomere?

A

The distance between the actin sites (thin filament)
Shortens when contraction occurs
Expands when stretch occurs

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15
Q

What zone does the I band represent on the sarcomere?

A

The distance between the myosin heads (thick filaments) when they move towards each other during muscle contraction

Becomes smaller in muscle contraction

Becomes larger in muscle stretch

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16
Q

What does the Z disc represent?

A

The boundary of the sarcomere

Attaches to actin (thin filament)

17
Q

What condition must be met for muscle contraction to occur?

A

A high influx of Ca+ for actin to remain exposed

18
Q

How does muscle fiber relaxation initiated?

A

Ach is broke down by ACHe to make acetic acid and choline -> Ca+ is reabsorbed by SR -> myosin heads are unable to bind to actin as tropomyosin moves over sites

19
Q

What is the role of ATP in muscle contraction?

A

The cross bridge release of myosin head and actin site

The catabolic reaction (ATP ->ADP + Pi) allows for myosin activation

Na+/K+ pump for ATPase activity

20
Q

What is botulism?

A

Toxins found in contaminated canned foods that prevent exocytosis of ACH resulting in paralysis

Used as Botox for uncontrolled muscles (blinkin/cross eyed) and prevent wrinkles and sweating

21
Q

What is Rigor mortis?

A

Stiffness of death

Leaking of Ca+ from SR causes myosin heads to attach and contract but cannot release due to lack of ATP produced

3hrs after death till 12hrs

Subsides as cells breakdown

22
Q

What is myasthenia gravis?

A

Low ACH receptors causing paralysis (motor will not respond)

ACHe inhibitors

Allows for more binding to receptors options

23
Q

What is curare poisoning?

A

Prevents Ach from binding to receptors -> paralysis

Using in surgery and tranquilizers (blow darts)

24
Q

How does nicotine affect the muscle?

A

Pretends to be Ach and binds to receptors to produce muscle spasms

25
Q

What happens to the muscle from a black widow bite?

A

Massive release of ACH causing muscles to continuously contract and stop breathing

Physio (19 decks)

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