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Washburn University- BI 255 Lab Final Exam; Questions with Detailed Solutions $14.49   Add to cart

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Washburn University- BI 255 Lab Final Exam; Questions with Detailed Solutions

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Washburn University- BI 255 Lab Final Exam; Questions with Detailed Solutions

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  • September 11, 2024
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GOLDTUTORS
Washburn University- BI 255 Lab Final Exam; Questions
with Detailed Solutions
Frog Heart experiments CORRECT ANS-Mechanical, affects of temperature and various

drugs




What are the autonomic neurotransmitters CORRECT ANS-Acetylcholine, norepinephrine

(epinephrine used in lab)




What does acetylcholine do to the heart CORRECT ANS-Parasympathetic, decreases

pacemaker rate by increasing K+ and decreasing Ca2+ and Na+ movement. As the pacemaker

slows, so does the heart.




What does norepinephrine do? CORRECT ANS-Sympathetic. Increases heart rate and

magnitude of contraction, increased blood pressure, triggers release of glucose from energy

stores. It alters the permeability of the membrane and increases depolarization. (Allows more

Ca2+ to enter from an extracellular fluid)




How does temperature effect heart rate CORRECT ANS-Increased temperature increases

heart rate and decreased temperature decreases heart rate. Temp changes the rate in which

ions move in and out of heart cells and thereby affect the rate of depolarization and

repolarization. Thus, a change in heart rate and force of contraction.

, Washburn University- BI 255 Lab Final Exam; Questions
with Detailed Solutions

Absolute refractory period CORRECT ANS-Following each depolarization and subsequent

contraction of the heart muscle, there is a time period the muscle cannot be re-stimulated.

This allows time to move the blood through the heart efficiently and prevent the heart from

ever reaching a state of fatigue.




Difference between cardiac and skeletal muscle refractory periods CORRECT ANS-The

refractory period in cardiac muscle is much longer than in skeletal muscle and the heart fully

relaxes between action potentials.




How was the refractory period tested in lab? CORRECT ANS-Use of the iWorx stimulator

box, the stimulation frequency was set to consistently stimulate the heart and create action

potentials. Even with frequent stimulation, action potentials only occurred after the refractory

period ended.




Define extra systole CORRECT ANS-The absolute refractory period is followed by a relative

refractory period during which a strong electrical stimulus can elicit an early extra systole. A

heartbeat outside the normal rhythm.

, Washburn University- BI 255 Lab Final Exam; Questions
with Detailed Solutions
Compensatory pause CORRECT ANS-After an extra systole, the next naturally occurring

depolarization will fall into the absolute refractory period generated by a new contraction, the

long pause that follows is the compensatory pause.




How was extra systole created in lab CORRECT ANS-The heart was stimulated every

second, eventually the stimulation occurred during a relative refractory period causing an

extra systole




Compare cardiac action potential to skeletal muscle action potential CORRECT ANS-Cardiac

has NA+ going in , Ca2+ going in, and K+ going out. Where as Skeletal just has Na+ in and K+

out. The cardiac muscle has a much longer absolute refractory period (200 - 400ms compared

to 1-3ms in skeletal muscle). Calcium increases the action potential resulting in the plateau

phase.




What do you mean when you use the term heart block? CORRECT ANS-A condition in

which impulses fail to pass normally through the conducting system of the heart to the

ventricular muscle. If some, but not all impulses from the pacemaker reach the ventricles, the

block is partial. Usually have a consistent ratio (2:1, 3:1)

, Washburn University- BI 255 Lab Final Exam; Questions
with Detailed Solutions
Complete block CORRECT ANS-No impulses from the pacemaker reach the ventricular

muscle, the atria and ventricles beat independently of one another (mammals) and no

consistent ratio between their rates of beating is seen. (Frogs - usually results in no ventricular

activity)




What happened when we squeezed the heart with forceps? CORRECT ANS-The tissue

between the atria and ventricle were damaged. This resulted in AV node damage altering

signaling between the atria and ventricles.




How does KCl act as a euthanizing agent? CORRECT ANS-The addition of KCl to the outside

of the heart cells prevents diffusion of K+ out of the cell, thus the cell doesn't repolarize and

the heart can't fire again. Keeps the heart cells from repolarizing, if it can't repolarize, it can't

fire again.




Skeletal muscle uses motor unit recruitment and summation to increase the strength of a

contraction. How does the heart increase the strength of its contractions? CORRECT ANS-It

increases the amount of extracellular and intracellular calcium. (If I remember correctly, the

more calcium the more myosin - actin crossbridges)

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