[PhysioEX Chapter 6 exercise 4] PEX-06-04

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Exercise 6: Cardiovascular Physiology: Activity 4: Examining the Effects of Chemical Modifiers on Heart Rate Lab Report

Pre-lab Quiz Results
You scored 100% by answering 4 out of 4 questions correctly.

1. The parasympathetic nervous system releases __________ to affect heart rate.
   You correctly answered: d. acetylcholine
2. A cholinergic drug that worked the same as acetylcholine would
   You correctly answered: c. be an agonist and decrease heart rate.
3. Norepinephrine affects the heart rate by
   You correctly answered: a. increasing the rate of depolarization and increasing the frequency of action potentials.
4. The __________ receptor binds norepinephrine and epinephrine.
   You correctly answered: b. ß-1 adrenergic

Experiment Results

Predict Question:
Predict Question 1: Pilocarpine is a cholinergic drug, an acetylcholine agonist. Predict the effect that pilocarpine will have
on heart rate.
Your answer : b. Pilocarpine will decrease heart rate.

Predict Question 2: Atropine is another cholinergic drug, an acetylcholine antagonist. Predict the effect that atropine will
have on heart rate.
Your answer : a. Atropine will increase heart rate.

Stop & Think Questions:
Which of the following is true of epinephrine?
You correctly answered: c. It increases the heart rate and mimics the sympathetic nervous system.
The final chemical modifier we will look at is digitalis (also known as digoxin and digitoxin and derived from the foxglove
plant). Individuals with weakened hearts need to allow maximum time for venous return and increased stroke volume and
would therefore most likely benefit from
You correctly answered: c. increased force of contraction and decreased heart rate

Experiment Data:
Solution Heart Rate
---- 60
Epinephrine 79
Pilocarpine 46
Atropine 70
Digitalis 42

Post-lab Quiz Results
You scored 100% by answering 4 out of 4 questions correctly.

1. Pilocarpine decreased the heart rate. Typical of cholinergic agonists, it
   You correctly answered: b. decreased the frequency of action potentials.
2. The effect of atropine was to
   You correctly answered: c. mimic the sympathetic nervous system.
3. The modifiers tested that decrease the heart rate were
   You correctly answered: c. digitalis and pilocarpine.
4. To increase the heart rate, the best choices would be
   You correctly answered: b. epinephrine and atropine.

Review Sheet Results

1. Describe the effect that pilocarpine had on the heart and why it had this effect. How well did the results compare with
   your prediction?
   Your answer:
   Pilocarpine decreased heart rate, 60 to 46 as predicted.
2. Atropine is an acetylcholine antagonist. Does atropine inhibit or enhance the effects of acetylcholine? Describe your
   results and how they correlate with how the drug works. How well did the results compare with your prediction?
   Your answer:
   Atropine increased heart rate, 60 to 70 as predicted.
3. Describe the benefits of administering digitalis.
   Your answer:
   Administering digitalis helps, inhibits or imitates the action of acetycholine. So it can be used to contol body.
4. Distinguish between cholinergic and adrenergic chemical modifiers. Include examples of each in your discussion.
   Your answer:
   cholinergic inhibits, mimics or enhances the action of acetycholine. It includes Pilocarpine and digitalis. And adrenergic
   inhibits, mimics, or enhances the action of epinephrine. It includes atropine.