Question 1

Using the appropriate equations,predict the effects in each scenario.
A.Vessels X and Y have the same diameter.X is 5 cm long and Y is 10 cm long.Which has the faster velocity of flow for the same fluid?
B.A blood vessel has a radius of 4 cm.Vasoconstriction reduces the radius to 1 cm.In order to maintain the same flow,by what factor must pressure increase?
C.The blood vessel in B above dilates from 1 cm to 4 cm.Does the flow rate increase or decrease?
D.A new subdivision is built between your house and the water storage tower.If the water company makes no adjustments,will the water pressure at your house change? If so,in which direction? Why?

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Question 2

Why is it necessary to direct the electrical signals in the heart through the AV node instead of allowing them to spread directly from the atria to the ventricles?

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Question 3

What are ryanodine receptors? What type of tissue are they present in? Are all ryanodine receptors regulated in the same way? Explain your answer.

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Question 4

Explain what is meant by the contractility of the heart.How is contractility controlled?

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Question 5

Explain what is meant by the terms respiratory pump and skeletal muscle pump.Why are these important to the cardiovascular system?

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Question 6

List the four types of autorhythmic cells that drive the heartbeat.Draw a sketch of the heart and indicate the location of each type of cell.

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Question 7

Vern,suffering from cardiac arrhythmias,is brought into the emergency room of a hospital.He begins to exhibit tachycardia and as a result loses consciousness.His anxious wife asks you why he has lost consciousness.What would you tell her?

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Question 8

You are constructing working models of the heart for extra credit.Your first attempt failed because the cells separated from each other during beating.What structures did you omit,and why did this allow the heart to fall apart? You omitted the gap junctions in your second attempt.How would a real heart fail to function normally without gap junctions?

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Question 9

Explain why a heart can keep beating after it has been removed from a living body.

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Question 10

How many liters of blood are distributed between the pulmonary and systemic circuits in a "typical" person? Assume 20% of the blood is in the lungs at any moment.If the cardiac output is 5 L/min,how long will it take a drop of blood to flow from the right ventricle to the left ventricle?

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Question 11

A chronotropic agent is one that affects the heart rate.Compare and contrast this term with an inotropic agent.Give specific examples of each.

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Question 12

Amy is a premed student with a summer job as an animal research technician.One of her duties is to withdraw blood by syringe from the anterior vena cava of pigs,to be analyzed for various hormones.During her training she noticed that most blood samples were very dark in color,but occasionally a sample was bright red.Propose an explanation.

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Question 13

Compare the flow rates (Q)of tubes one and two,assuming the following parameters:
Tube one: ΔP = 30,r = 3,L = 20.Tube two: ΔP = 60,r = 4,L = 10.

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Question 14

Name four questions related to heart function that you could answer by examining an ECG and one abnormal condition that may be indicated by each function.

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Question 15

Explain how Ca²⁺ levels inside myocardial cells are altered.

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Question 16

What is a normal heart rate for healthy adults at rest,and what neural inputs contribute to the achievement of that range? How is heart rate affected when all nervous system input to the heart is blocked,and why is this effect seen?

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Question 17

Atropine inhibits parasympathetic activity.Discuss the effects of atropine on the heart and describe common expected side effects.

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Question 18

Acetylcholine is excitatory at the neuromuscular junction,but inhibitory at the SA node.Explain why this is true.

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Question 19

Sonja is pregnant during the year she is taking human physiology.At each check-up,she expects to be told that her blood pressure has increased.Yet into the final weeks of her pregnancy,her blood pressure is unchanged from its pre-pregnancy value.Why did she expect her blood pressure to increase? Propose some explanations for why it didn't.(Hint: Sometimes women adopt healthier habits during pregnancy,there are large blood-filled sinuses in the maternal portion of the placenta,and there are many hormonal effects that are unique to pregnancy.)

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Question 20

Sonja is pregnant.Over the next 40 weeks,her uterus will enlarge as the placenta develops and the fetus grows,her abdomen will add skin to accommodate distension,her breasts will grow,her blood volume will increase,and many other changes will occur.Using what you have learned about basic cardiovascular physiology,predict how parameters such as blood pressure and cardiac output will change.(Note that the fetus has a separate cardiovascular system,which does not need to be considered.)Explain your answer.

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Quiz 14: Cardiovascular Physiology