BLG 10A/B Chapter Notes - Chapter 18: Aortic Valve, Atherosclerosis, Qrs Complex

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31 Jan 2016

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Cardiac cycle: all events associated with the blood flow through the heart during one complete heartbeat- atrial systole and diastole followed by ventricular systole and diastole. Summary of events during the cardiac cycle: ventricular filling (mid-to-late diastole, ventricular systole (atria in diastole) Isovolumetric contraction phase: ventricular filling, atrial contraction a, ventricular ejection phase a, ventricular filling. Has three almost immediately distinguishable waves or deflections: the p wave. Lasts about 0. 008 s and results from movement of the depolarization wave from the sa node through the atria. Atria contracts 0. 1 s after this wave begins: the large qrs complex. Results from ventricular depolarization and precedes ventricular contraction. Average duration is 0. 08 s: the t wave. Caused by ventricular repolarization and typically lasts about. Repolarization is slower than repolarization so the t wave is more spread out and has a lower amplitude (height) than the. Occurs about 0. 16 s from the beginning of atrial excitation to the beginning of ventricular excitation.

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Match the following terms describing the physical/mecahnical events with the correct phases of the cardiac cycle. Each phase may be used more than once.

- A. B. C. D.	All 4 cardiac valves are closed and all 4 chambers are relaxed during this phase.
- A. B. C. D.	The maximum amount of blood is in the ventricles at the end of this phase.
- A. B. C. D.	The pressure in the ventricles is higher than in the atria, but lower than in the arteries, during this phase.
- A. B. C. D.	The semilunar valves are open and the AV valves are closed during this phase.
- A. B. C. D.	The atria contract at the end of this phase.
- A. B. C. D.	The pressure in the ventricles is higher than the pressure in both the atria and the arteries during this phase.
- A. B. C. D.	Systole begins with this phase.

A.	isovolumetric relaxation
B.	ventricular ejection
C.	isovolumetric contraction
D.	ventricular filling

1.Describe the electrical events occurring in the heart that are responsible for the P wave, QRS complex and T waves of the ECG. What is happening to the myocardium during (1) the PR interval and (2) the ST segment?

2.Question 2: Compare the effect of exercise on the IHR and the periods of ventricular systole (QT) and ventricular diastole (TQ). Which of the periods is changed more in your data and why would one period of the cardiac cycle (systole or diastole) change more than the other? In your answer, indicate what electrical characteristic of the myocardial cell determines why one of the periods changes less than the other (systole or diastole).

3Was the Bainbridge reflex initiated in the subject? In your rationale, describe the expected changes that occur as a result of the Bainbridge reflex (start with deep inhalation and end with the expected change in heart rate that characterizes the Bainbridge reflex) â how does each step in the process lead to the expected change in heart rate: include receptors and ion channels involved.

4Describe the changes in stimulation of the baroreceptor that occur during phase II and phase IV of the Valsalva maneuver. How does that change in baroreceptor activation alter heart rate (be specific for each phase of the response)?

5.What is the source of S1 and S2 detected by the phonocardiogram (what causes the valves to change in that way)? Describe how the pressure wave that travels through the vasculature is generated.

What does the velocity of that pressure pulse wave tell one about vasculature condition?

Question 1 (1 point)Save Question 1Save
Which of the following will increase blood flow to a given regionof the body?

A smaller pressure gradient between the arteries and thatregion.

Vasoconstriction of the arterioles feeding that region.

An increase in blood viscosity via dehydration.

An increase in diameter of the arterioles feeding the region.
Question 2 (1 point)Save Question 2Save
Which of the following statements pertaining to the innervation ofthe heart is TRUE?

The heart is directly activated by the somatic nervoussystem.

The heart muscle is directly activated by the autonomic nervoussystem.

NE released by sympathetic neurons binds to beta-adrenergicreceptors and increases heart rate.

ACh released by parasympathetic neurons binds to nicotinicreceptors and decreases heart rate.
Question 3 (1 point)Save Question 3Save
The prolonged depolarization in cardiac myocytes is due primarilyto which channel type?

Voltage-gated sodium channels

Voltage-gated potassium channels

Funny (F-type) sodium channels

Long-lasting (L-type) calcium channels
Question 4 (1 point)Save Question 4Save
Which of the following statements about the pacemaker potentialgenerated by the SA node is FALSE?

Its intrinsic rate is about 70 depolarizations per minute.

The rate of depolarization can be affected by autonomicinnervation.

Funny (F-type) sodium channels play a role in the gradualdepolarization.

In the complete absence of extrinsic input (hormones or neurons),the SA node will continue to depolarize
Question 5 (1 point)Save Question 5Save
Match the description in the left hand column with the terms in theright hand column that BEST correspond (one match per term, allselections are used).

The period of the cardiac cycle when the heart is contracting

The period during diastole when the pressure in the atria exceedsthe pressure in the ventricles.

The period during systole when all heart valves are closed.

The difference between end-diastolic volume and end-systolicvolume.

The period of the cardiac cycle when the heart is relaxing.

1.
Systole
2.
Diastole
3.
Stroke volume
4.
Isovolumetric contraction
5.
Ventricular filling

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BLG 10A/B Chapter Notes - Chapter 18: Aortic Valve, Atherosclerosis, Qrs Complex

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