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Ch. 20 The Heart
Martini - Fundamentals of Anatomy and Physiology 12th Edition
Martini, Nath, Bartholomew12th EditionFundamentals of Anatomy and PhysiologyISBN: 9780137854011Not the one you use?Change textbook
Chapter 20, Problem 11

During the cardiac cycle, the amount of blood ejected from the left ventricle when the semilunar valve opens is the:
(a) Stroke volume (SV)
(b) End-diastolic volume (EDV)
(c) End-systolic volume (ESV)
(d) Cardiac output (CO)

Verified step by step guidance
1
Step 1: Understand the key terms related to the cardiac cycle. The End-Diastolic Volume (EDV) is the volume of blood in the left ventricle at the end of diastole (just before contraction).
Step 2: Recognize that the End-Systolic Volume (ESV) is the volume of blood remaining in the left ventricle after systole (after contraction).
Step 3: Define Stroke Volume (SV) as the amount of blood ejected from the left ventricle during one contraction, which is the difference between EDV and ESV. Mathematically, this is expressed as: \(\text{SV} = \text{EDV} - \text{ESV}\).
Step 4: Understand that Cardiac Output (CO) is the total volume of blood pumped by the left ventricle per minute, calculated as \(\text{CO} = \text{SV} \times \text{Heart Rate}\).
Step 5: Since the question asks for the amount of blood ejected when the semilunar valve opens (which occurs during ventricular systole), the correct term describing this volume is Stroke Volume (SV).

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Stroke Volume (SV)

Stroke volume is the amount of blood ejected by the left ventricle during each heartbeat, specifically when the semilunar valve opens. It is calculated as the difference between end-diastolic volume and end-systolic volume, reflecting the effective blood pumped into circulation per beat.
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End-Diastolic Volume (EDV)

End-diastolic volume is the total volume of blood in the left ventricle at the end of diastole, just before contraction. It represents the maximum filling of the ventricle and serves as the starting point for stroke volume calculation.
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End-Systolic Volume (ESV)

End-systolic volume is the amount of blood remaining in the left ventricle after contraction, once the semilunar valve closes. It indicates the volume not ejected during systole and is used alongside EDV to determine stroke volume.
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