RPA 5 muscular system

Question 1

What does the end diastolic volume indicate in a pressure volume loop?

Answer 1

preload
-describes the final length of heart muscles before contraction. the length of these muscle fibers increase during diastole due to the blood filling the ventricles.

Question 2

At what point in a electrocardiogram (ECG) recording is ventricular filling complete?

Answer 2

p-wave
-represents the depolarization of the atria, leading to atrial contraction

Question 3

In what situation would mechanoreceptors, in a primary sensory afferent, open to allow sodium into the input region?

Question 4

The activity of what channel causes autorhythmic cardiac cells to reach the threshold for triggering depolarization?

Answer 4

hyperpolarization-activated cyclic nucleotide-gated (HCN) gated Na+ channels
-specialized in allowing a slow influx of Na+ ions into hyperpolarized cell, leading to initiation of an action potential

Question 5

Mutation of the Ca2+ binding region of calmodulin has which effect?

Question 6

Which type of fibers are most resistant to lactic acid buildup?

Answer 6

slow
-generate ATP by aerobic metabolism

Question 7

What transition does the thin filament undergo after Ca2+ binds to the TnC sub unit

Answer 7

blocked to closed state
-due to conformational change in the troponin-tropomyosin complex

Question 8

Where do upper motor neurons cross mid-line?

Answer 8

brainstem
decussation of pyramids

Question 9

what fine tunes force generation by triggering action potentials before the muscle fully relaxes?

Answer 9

twitch summation
-fine-tuning force by triggering action potentials before the muscle fully relaxes allows for successive twitches to sum up and generate stronger contractions

Question 10

what is an isometric contraction?

Answer 10

no change in muscle length
-generates force without changing length

Question 11

each muscle fiber is innervated by multiple lower motor neurons true or false?

Answer 11

false

Question 12

where is Ca2+ stored in skeletal and cardiac muscle?

Answer 12

sarcoplasmic reticulum

Question 13

what blood vesel has the greatest diameter and the lowest blood pressure?

Answer 13

vena cava

Question 14

what can occur rapidly and without warning?

Answer 14

cardiac arrest
-caused by abnormal electrical activity of the heart occurring rapidly and without warning

Question 15

the withdrawal reflex involves interneurons that stimulate multiple motor units to contract simultaneously, moving the limb away from the pain stimulus. what is this an example of?

Answer 15

polysynaptic reflex
-interneurons that connect sensory neurons to motor neurons resulting in a more complex pathway
-generally more involved and slower compared to monosynaptic due to additional processing steps

Question 16

where are the cell bodies of upper motor neurons of the lateral corticospinal tract located?

Answer 16

precentral gyrus
primary motor cortex

Question 17

what increases cardiac output?

Answer 17

increased heart rate
increased venous return
increased end-systolic volume
increased stroke volume

Question 18

when does the cardiac muscle physiologically function in the force-length relationship

Question 19

what is the equation for cardiac output?

Answer 19

cardiac output = stroke volume x heart rate