$$CO = 80 \times 65 = 5200 mL/$$min $$= 5.2 L/$$min

Question 1

Which pacemaker takes over when the SA node is nonfunctional, and what is the expected heart rate?

Accepted Answer

The AV node; 40-60 beats/min

Question 2

A patient’s EKG shows a prolonged P-R interval longer than 200 ms. Which condition does this most likely indicate?

Accepted Answer

First-degree heart block

Question 3

Which formula correctly calculates cardiac output ($$CO) in $$terms of heart rate ($$HR) $$and stroke volume ($$SV$$)?

Accepted Answer

$$CO = HR 	imes SV$$

Question 4

If a patient’s heart rate is 80 beats/min and their stroke volume is 65 mL/beat, what is their cardiac output in liters per minute?

Accepted Answer

$$CO = 80 	imes 65 = 5200 mL/$$min $$= 5.2 L/$$min

Question 5

Which of the following is TRUE regarding the regulation of stroke volume?

Accepted Answer

Stroke volume increases with increased venous return due to greater sarcomere stretch

Question 6

A patient with high blood pressure is likely to have which change in their cardiac function?

Accepted Answer

Increased afterload, leading to increased end systolic volume and reduced stroke volume

Question 7

Which statement best describes the difference between single-unit and multi-unit smooth muscle?

Accepted Answer

Single-unit smooth muscle cells are electrically coupled by gap junctions and often contract synchronously

Question 8

Which of the following is NOT a feature of smooth muscle contraction?

Accepted Answer

Requires troponin for calcium binding

Question 9

What is the correct formula for stroke volume ($$SV$$)?

Accepted Answer

$$SV = EDV - ESV$$

Question 10

Which of the following would most likely result in a heart sound described as a 'creaking' noise heard with a stethoscope?

Accepted Answer

Pericarditis

Question 11

A patient presents with a heart rate of 45 beats/min and absent P waves on their EKG. Which is the most likely explanation?

Accepted Answer

SA node failure with AV node pacing the heart

Question 12

Which of the following is a direct effect of increased sympathetic stimulation on the heart?

Accepted Answer

Increased contractility due to greater Ca$$^{2+}$$ influx

Question 13

Which condition is characterized by rapid, irregular contractions that render the heart useless for pumping blood?

Accepted Answer

Fibrillation

Question 14

Which of the following is TRUE about the excitation-contraction coupling in smooth muscle?

Accepted Answer

Calcium binds to calmodulin, which activates myosin light chain kinase

Question 15

Which of the following would most likely increase venous return and thus stroke volume during exercise?

Accepted Answer

Increased heart rate and blood pressure

Question 16

Which statement best describes the function of the chordae tendineae and papillary muscles?

Accepted Answer

They prevent AV valve flaps from everting into the atria during ventricular contraction

Question 17

Which of the following is a feature of multi-unit smooth muscle?

Accepted Answer

Graded contractions in response to neural stimuli

Question 18

A patient with a leaky (incompetent) heart valve is likely to experience which of the following?

Accepted Answer

Blood backflows, causing the heart to re-pump the same blood repeatedly

Question 19

Which of the following is a correct statement about smooth muscle relaxation?

Accepted Answer

Relaxation requires removal of phosphate from myosin light chain by myosin light chain phosphatase

Lecture #23

Guida di studio - Domande di pratica