Mace Cardiac Lectures 5a-5d Flashcards
T or F? When the ventricles relax, blood in the aorta flows back towards the heart, filling the coronary arteries?
True! At this point, during isovolumetric relaxation, both the semilunar vales and aortic valves are closed so the blood drains into the coronary arteries instead of back into the heart.
During a normal cardiac cycle, which phase has the longest duration?
a. atrial systole
b. ventricular systole
c. quiescent period
d. valvular period
quiescent period
What is the average cardiac output of a person ?
5-6 L/min
Exercise will increase CO. This is because there is a ___ in HR and a ____ in stroke volume.
increase in HR and also an increase in SV
Assume that the left ventricle of a child’s heart has an EDV= 90mL, ESV= 60mL, and a cardiac output of 2,400 mL/min. His SV and HR are ?
SV= EDV-ESV
= 90-60
SV = 30 mL
CO = (SV)(HR) 2,400 = (30)(HR) HR = 80 bpm
Sympathetic NS innervates AV and SA node leading to ______ in the myocardium, also affecting contractility/inotropy
tachycardia
Parasympathetic NS innervates AV and SA nodes leading to ____.
bradycardia, surprise, surprise
One degreee of temperature change (celsius) increases heart rate by __ beats
10 beats
All of the following are heart rate stimulants except
a. epinephrine
b. caffeine, nicotine, and chocolate
c. thyroid hormone
d. potassium (and calcium ions)
D. potassium (and calcium ions)
Increased venous return occurs with (LESS/MORE) ___ venous pressure or (FASTER/SLOWER)____ heart rate.
Increased venous return occurs with MORE venous pressure or SLOWER heart rate
What effect does increased preload (stretch of the heart wall) have on stroke volume?
Stroke volume increases.
What effect does atherosclerosis have on stroke volume?
Stroke volume decreases.
What effect do inotropic agents (substances that act on contractility of the heart) have on stroke volume?
Stroke volume increases.
What effect does hemorrhage or an extremely rapid heart rate have on stroke volume?
Stroke volume decreases.
What effect do calcium channel blockers have on stroke volume?
Stroke volume decreases. Calcium channel blockers are negative inotropic agents.
Which of the following increases stroke volume proportionally?
a. increased venous return
b. increased Ca2+ in the sarcoplasm
c. increased after load
d. A and B
e. all of the above
d. A and B
Death of heart muscle from lack of oxygen is known as a myocardial infarction (MI), but what is temporary myocardial ischemia called ?
a. cardiac stenosis
b. cardiac defibrillation
c. angina pectoris
d. cardiac arrest
Answer: C.
explanation: cardiac stenosis is a form of fibrosis of the heart. Cardiac defibrillation is voltage used to get the heart back in rhythm and cardiac arrest is a permanent STOP in the heart beat.
When left ventricular output exceeds right ventricular output, where will fluid accumulate?
In the systemic tissue
When right ventricular output exceeds left ventricular output, where will fluid accumulate?
In the pulmonary tissue
What effect will hormones such as epinephrine or thyroxine have on cardiac output?
These hormones increase heart rate, thus increasing cardiac output (CO= SV X HR)
During heart surgery, your body temperature may be lowered. What effect will this have on your cardiac output?
Heart rate will be decreased at lower temperatures. Therefore, CO will decrease!
What happens to cardiac output if no other compensating mechanisms occur: increased blood volume?
increases CO due to increase MAP linear relationship/ CO increases due to increase in stroke volume from increase preload from venous return w/ increased volume
What happens to cardiac output if there is loss of myocardial tissue?
CO decreases due to loss of contractility i.e. stroke volume
What happens to cardiac output if there is administration of verapamil?
Decreased CO secondary to decreased SVR
What happens to cardiac output if there is administration of Digoxin?
Increased CO due to increased SV secondary to increased contractility
What happens to cardiac output if there is an increased EDV?
Increased CO due to increased SV
What happens to cardiac output with administration of a beta blocker?
Decreased CO secondary to decreased HR
What happens to cardiac output in response to increased ESV?
Decreased CO secondary to decreased SV
What happens to cardiac output in response to muscular contraction in the legs ?
Increased CO secondary to increased preload from increased venous return
What happens to cardiac output in response to inversion of the body?
Increases CO due to increase SV secondary to increase venous return
What happens to cardiac output in response to calcified aortic valve?
decreased CO to do increased afterload
What happens to cardiac output in response to new prescription of HCTZ with dose too high?
decrease CO due to decrease SV secondary to decrease venous return i.e. volume loss
What effect does HTN have on cardiac output?
CO decreases
Which portion of an EKG represents the quiescent period?
T-P
What does the P-Q segment on an EKG represent?
atrial contraction (delay of the AV node)
What does the QRS segment on an EKG represent?
ventricle depolarization overlapping with atrial repolarization
What does the S-T segment on an EKG represent?
ventricular contraction
What does the T wave on an EKG represent?
ventricular repolarization
What does increased preload do to the heart pressure volume loop?
P is shifted to the right, EDV shifts right, ESV is the same and SV is increased
T or F? There is a change in height to the pressure volume loop when there is an increase in preload.
False
