Unformatted text preview: 4/15/2020 PhysioEx Exercise 6 Activity 5 PhysioEx Lab Report
Exercise 6: Cardiovascular Physiology
Activity 5: Examining the Eﬀects of Various Ions on Heart Rate
Name: Courtney Paulsen
Date: 15 April 2020
Session ID: session-d474c3c2-f392-83cf-7256-4f2f1af6bf74 Pre-lab Quiz Results
You scored 75% by answering 3 out of 4 questions correctly.
1 Which organelle in the cardiac muscle cell stores calcium?
You correctly answered: sarcoplasmic reticulum.
2 Verapamil is a calcium-channel blocker. Its eﬀects could be described as
You correctly answered: negative chronotropic and negative inotropic.
3 When the cardiac muscle cell is at rest, where is most of the potassium found?
Your answer: in the sarcoplasmic reticulum.
Correct answer: in the cytosol.
4 Resting cardiac muscle cells are most permeable to
You correctly answered: potassium. Experiment Results
1 Predict Question 1: Because calcium-channel blockers are negative chronotropic and
negative inotropic, what eﬀect do you think increasing the concentration of calcium will have
on heart rate?
Your answer: positive chronotropic, positive inotropic.
2 Predict Question 2: Excess potassium outside of the cardiac cell decreases the resting
potential of the plasma membrane, thus decreasing the force of contraction. What eﬀect (if
any) do you think it will initially have on heart rate?
Your answer: increase heart rate.
Stop & Think Question
1/4 4/15/2020 PhysioEx Exercise 6 Activity 5 1 Where in the cardiac muscle cell is most of the sodium normally found?
You correctly answered: outside of the cell.
Solution Heart Rate (beats/min) ---- 59 Calcium 69 Sodium ~34 Potassium ~28 2/4 4/15/2020 PhysioEx Exercise 6 Activity 5 Post-lab Quiz Results
You scored 100% by answering 4 out of 4 questions correctly.
1 The addition of most of the ions resulted in
You correctly answered: an erratic, decreased heart rate.
2 The eﬀect of potassium on the heart is
You correctly answered: negative chronotropic, negative inotropic.
3 The ion that had the most pronounced eﬀect on heart rate was
You correctly answered: potassium.
4 Ectopic pacemakers can be caused by excessive leakage of potassium into cardiac cells,
resulting in pacemakers appearing in abnormal locations in the heart muscle. This hyperkalemia (excess potassium) decreases the resting potential of the cardiac muscle cell.
What eﬀect do you think this would have on the force of contraction?
You correctly answered: decrease, negative inotropic. Review Sheet Results
1 Describe the eﬀect that increasing the calcium ions had on the heart in this activity. How well
did the results compare with your prediction?
Increasing calcium ions caused an increased heart rate. My prediction was correct since the
modiﬁers that increase are positive inotropic and chronotropic.
2 Describe the eﬀect that increasing the potassium ions initially had on the heart in this
activity. Relate this to the resting membrane potential of the cardiac muscle cell. How well
3/4 4/15/2020 PhysioEx Exercise 6 Activity 5 did the results compare with your prediction?
The eﬀect of increasing the potassium ions caused the heart rate to decrease and with the
increase of potassium, this lowers the resting membrane potential. I predicted that it will
increase and I was wrong.
3 Describe how calcium channel blockers are used to treat patients and why?
The use of calcium channel blockers is used to block calcium movement through the
channels of cardiac action potentials. They are used to treat patients with high blood
pressure and abnormal heart rates. 4/4 ...
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