Physio

Question 0

Total tension formula

Answer 0

Passive force(preload) + active force

Question 1

Isometric twitch

Answer 1

Muscle developes force but does not shorten.

• myosin pulls on actin but there is no movement (no contraction)
• TENSION is the key word…tension is created from actin and myosin pulling
• length stays the same but force does not

Question 2

What happens to your total force as your preload force goes up ?

Answer 2

It increases

-spring will cause more force when contraction occurs

Question 3

What is active force ?

Answer 3

Represents sacromere contraction

Question 4

When does the muscle shorten ?

Answer 4

When the tension is greater than the load

Question 5

Afterload

Answer 5

The force the muscle must generate on top of the passive force(preload) for the muscle to contract

Question 6

What is constant during isometric and isotonic phases ?

Answer 6

Length is constant during the isometric phase and force is constant during the isotonic phase

Question 7

What is the force velocity relationship

Answer 7

The less force the higher the velocity…also the greater the length

Question 8

Why are isotonic contractions important

Answer 8

They are used to determine force velocity relationships

Question 9

Why is the isometric contraction important ?

Answer 9

Force-length curve

Question 10

Sliding filament theory

Answer 10

During contraction both thick and thin filaments keep the same length but the amount of overlap increases
-thin filaments slide towards center of sacromere and the distances between the Z line shortens

Question 11

What is part of the triad for skeletal muscle contraction

Answer 11

Sarcoplasmic reticulum, receptors(dihyrdopyridine voltage center and ryanodine), t tubules

Question 12

Why can you say skeletal muscle requires neuronal action potential for stimulation ?

Answer 12

Because skeletal muscle contraction can occur in the absence of extracellular calcium

Question 13

Myasthenia gravis

Answer 13

Weakness worse as the day goes on . Autoimmune that attacks nicotinic reports at NMJ.

• ptosis with repeated blinking, jaw gets tired and diplolpia
• antibody therpay can be used but is more extreme then just giving cholinesterase

Question 14

Curare

Answer 14

Bind to ACh receptors and block ACh from binding to open cation channels thus PREVENTING DEPOLARIZATION.

• die from respiratory muscles stop working even though heart is fine
• patient can survive with artificial respiratory until poison goes away
• now used as a muscle relaxant during surgery

Question 15

Succinylcholine and decamethonium

Answer 15

Causes cation channels to stay open causing persistent depolarization thus relaxant of muscle if depolarizer for too long

Question 16

What does contraction mean ?

Answer 16

Interaction of myosin with actin to generate force of tension

• can have contraction without muscle shortening
• during isometric contraction there is muscle contraction

Question 17

What prevents force as such short length of the sacromere ?

Answer 17

Actin filament overlap on each other is hiding the active sites for myosin to bind onto

Question 18

What does maximum velocity represent and what determines Vmax ?

Answer 18

The maximum velocity represents the velocity at which there is no load. This value is determined by the muscles ATPase activity

Question 19

What does increasing Afterload do to velocity until the load cannot be moved ?

Answer 19

Increasing Afterload decreases velocity

Question 20

Tetanus

Answer 20

Successive stimulation with no relaxtio between contraction.
Tetanus toxin blocks inhibitory NTs in the CNS. You get unrestrained alpha neuron stimulation and sustained skeletal contractions

EXAMPLE OF TEMPORAL SUMMATION

Question 21

Spatial summation is the same as what ?

Answer 21

It is the same as recruitment. Force increases by increasing the number of motor units activated at one time

Question 22

What is a motor unit

Answer 22

It is made up by all of the muscle fibers ONE motor neuron innervates