praccy exam 3

Question 1

a mutation in the Ca2+ binding region of calmodulin will most likely result in ____

Answer 1

myosin cannot interact with actin

Question 2

Fish-hunting snails inject toxins into their victims that block acetylcholine receptors at the neuromuscular junction and cause muscle paralysis. The toxin is most likely binding to ___

Answer 2

ligand-gated Na+ channels

Question 3

Ca2+ binding to the TnC subunit permits the transition of thin filament from the ____

Answer 3

blocked to closed state

Question 4

In skeletal and cardiac muscles, Ca2+ is stored in the _____

Answer 4

sarcoplasmic reticulum

Question 5

Fine-tuning force generation by triggering action potentials before the muscle can fully relax is an example of _____

Answer 5

twitch summation

Question 6

muscles with predominately ____ fibers are more resistant to lactic acid buildup

Answer 6

slow

Question 7

Isometric contraction occurs when there is ____

Answer 7

no change in muscle length

Question 8

Cardiac output can be increased by ____

Answer 8

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

Question 9

the greatest diameter and lowest pressure in a blood vessel would be found in the ____

Answer 9

vena cava

Question 10

Frank-starling mechanism where muscle length determines force generation. Physiologically the cardiac muscle present in the _____ of the force-length relationship

Answer 10

ascending limb

Question 11

ventricular filling is complete immediately after the

Answer 11

p wave

Question 12

which of the following blood vessels carries oxygenated blood back to the heart

Answer 12

pulmonary veins

Question 13

The threshold for rapid depolarization in autorhythmic cardiac cells is reached by the activity of the ____

Answer 13

hyperpolarization cyclic nucleotide (HCN) gated Na+ channels

Question 14

the autonomic nervous system can ____ heart rate by causing ____ of the membrane potential of pacemaker cells

Answer 14

decrease, greater hyperpolarization

Question 15

in the pressure-volume loop, the end-diastolic volume is most directly indicative of _____

Answer 15

preload

Question 16

Type 2 pneumocytes produce surfactant which lowers the surface tension of the lungs. Where are type 2 pneumocytes located?

Answer 16

in the alveoli

Question 17

Which of the following conditions affecting the binding between oxygen and hemoglobin would decrease the affinity and make more oxygen available in the plasma

Answer 17

decrease pH

Question 18

during expiration ________

Answer 18

the intrapulmonary pressure is greater than atmospheric pressure

Question 19

The gas law which most directly relates to the fact that the greater partial pressure of the gas in contact with a liquid, the greater the amount of gas dissolved is called _____

Answer 19

henrys law

Question 20

if an enzyme in blood enhances the binding of oxygen to hemoglobin, how would you expect the O2 dissociation curve to change?

Answer 20

the curve shifts to the left

Question 21

the principle or law that state the unloading of oxygen facilitates the carrying of carbon dioxide on hemoglobin is called _____

Answer 21

Haldane effect

Question 22

Central chemoreceptors which respond to increased H+ are located in the _____

Answer 22

medulla

Question 23

an infection in what would indicate that the respiratory zone has been affected

Answer 23

alveolar sac

Question 24

the muscles involved in the normal quiet expiration are

Answer 24

diaphram

Question 25

most of the carbon dioxide in the blood is carried as HCO3- (bicarbonate ion):

Answer 25

dissolved in plasma

Question 26

during the oxygenation of blood, oxygen binds to a(n) _____ atom in the middle of the porphyrin ring

Answer 26

iron