Lec 6

Question 1

What do we need for continual, repeated power strokes?

Answer 1

• Sustained nerve impulses (w/o them we just have a twitch)
• Ca++ (secreation)
• ATP (production)

Question 2

When considering action potentials, what occurs for sensory motor integration to take place?

Answer 2

sensory stimuli (rec’d) –> central processing [CNS] (interpretation - determination) –> muscular action/response.

Question 3

What are our 5 main sensory receptors?

Answer 3

• mechanoreceptors (pressure, touch, vibration, stretch)
• photoreceptors
• chemical receptors
• thermoreceptors
• nociceptors (pain)

Question 4

fewer muscle fibers = < force; therefore, > fine (motor) control. Why?

Answer 4

Bc the amount of force produced by a single alpha motor is contignt upon how many muscle fibers that neuron intervates

e.g. eyeballs vs glut muscles

Reminder: Ca++ release helps regulate force

Question 5

What does the neuromuscular synaptic cleft seperate?

Answer 5

the neuron and muscle fiber.

Question 6

What is the motor end plate?

Answer 6

the region of the fiber sarcolemma that lies under the terminal branches; the pocket of folded sarcolemma

Question 7

What is the importance of acetylcholinesterase in muscle contraction and relaxation?

Answer 7

It helps acetylcholine detach from the ACH receptor (at the synaptic membrane/cleft)by breaking it down into acetate and choline to help terminate muscle contraction.

Once done acetate gets removed thru circulation and choline goes back to the axon (alpha motor) terminal

Question 8

T tubules extend into the muscle fiber from the _______ and _____ _____ transmit through T-tubules. Once the voltage-sensing receptior, dihydropyridine (DHP), interacts with the ______ receptor, Ca++ is released from the _____ ______

Answer 8

Sarcolemma; action potentials; ryanodine ; SR

(Ryanodine receptors are located in the SR & are responsible for Ca++ release from intracelluar stores in the SR during excitation-coupling)

Question 9

What is tropomyosin?

Answer 9

Its a regulatory protein that blocks the myosin binding site on actin when at rest.

Once troponin (specifically TnC) binds to its it exposes the binding cite for myosin & actin to interact & the myosin head to attach and cock back for contraction.

Keep in mind troponin is a 3-part complex: TnI(g-actin binding; spaced every 7), TnC (Ca++ binding for “tropomyosin shift” - myosine binding cite exposure), & TnT (tropomyosin binding)

Question 10

Hybrid fibers contain more than 1 myosin heavychain.

True or False.

Answer 10

True.

hybrid, so, it has a little of booth. MHC helps determine fiber type

Question 11

Why is ACTN3 gene important?

Answer 11

Bc it helps to keep the z line and sarcromeres in the appropriate place. (Its a structural protein)

its exclusively expressed in type II fiber composition. Its an important gene for strength, force, power type activity.