Table of contents

1. Introduction to Anatomy & Physiology5h 43m
2. Cell Chemistry & Cell Components12h 36m
3. Energy & Cell Processes10h 6m
4. Tissues & Histology10h 3m
5. Integumentary System2h 20m
6. Bones & Skeletal Tissue2h 16m
7. The Skeletal System2h 35m
8. Joints2h 17m
9. Muscle Tissue2h 33m
10. Muscles1h 11m
11. Nervous Tissue and Nervous System1h 35m
12. The Central Nervous System1h 6m
- Introduction to the Central Nervous System
  18m
- The Cerebrum
  48m
13. The Peripheral Nervous System1h 26m
14. The Autonomic Nervous System1h 38m
15. The Special Senses2h 41m
16. The Endocrine System2h 48m
17. The Blood3h 22m
18. The Heart3h 42m
19. The Blood Vessels3h 35m
20. The Lymphatic System3h 16m
21. The Immune System14h 37m
22. The Respiratory System3h 20m
23. The Digestive System2h 5m
24. Metabolism and Nutrition4h 0m
25. The Urinary System2h 39m
26. Fluid and Electrolyte Balance, Acid Base Balance37m
27. The Reproductive System2h 5m
28. Human Development1h 21m
29. Heredity3h 32m

18. The Heart

Cardiac Cycle

Anatomy & Physiology

18. The Heart

Cardiac Cycle

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2:14 minutes

Problem 29

Textbook Question

Mrs. Hamad, a middle-aged woman, is admitted to the coronary care unit with a diagnosis of left ventricular failure resulting from a myocardial infarction. Her chart indicates that she was awakened in the middle of the night by severe chest pain. Her skin is pale and cold, and moist sounds of pulmonary edema are heard over the lower regions of both lungs. Explain how failure of the left ventricle might cause these signs and symptoms.

Verified step by step guidance

Understand the role of the left ventricle: The left ventricle is responsible for pumping oxygenated blood from the heart to the systemic circulation (the rest of the body). When the left ventricle fails, it cannot effectively pump blood forward, leading to a backup of blood in the pulmonary circulation.

Explain pulmonary edema: The backup of blood in the pulmonary circulation increases pressure in the pulmonary capillaries. This elevated pressure forces fluid out of the capillaries and into the alveoli (air sacs) of the lungs, causing pulmonary edema. This explains the moist sounds heard in the lower regions of the lungs.

Discuss the pale and cold skin: Left ventricular failure reduces the amount of oxygenated blood reaching the systemic circulation. As a result, tissues receive less oxygen, leading to vasoconstriction (narrowing of blood vessels) in the skin to preserve blood flow to vital organs. This causes the skin to appear pale and feel cold.

Relate chest pain to myocardial infarction: A myocardial infarction (heart attack) occurs when blood flow to a portion of the heart muscle is blocked, causing damage to the muscle. This damage impairs the left ventricle's ability to pump blood effectively, leading to the symptoms described. Severe chest pain is a hallmark symptom of myocardial infarction due to ischemia (lack of oxygen) in the heart muscle.

Summarize the connection: The failure of the left ventricle due to myocardial infarction leads to reduced forward blood flow, increased pulmonary pressure causing pulmonary edema, and systemic effects such as pale and cold skin. These symptoms are interconnected and stem from the impaired function of the left ventricle.

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Key Concepts

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

Left Ventricular Failure

Left ventricular failure occurs when the left ventricle cannot effectively pump blood to the body, leading to inadequate circulation. This can result from conditions like myocardial infarction, where heart muscle damage impairs its ability to contract. Symptoms often include fatigue, shortness of breath, and fluid accumulation due to increased pressure in the pulmonary circulation.

Myocardial Infarction

A myocardial infarction, commonly known as a heart attack, occurs when blood flow to a part of the heart is blocked, causing damage to the heart muscle. This blockage is often due to atherosclerosis, where plaque builds up in the coronary arteries. The resulting damage can lead to left ventricular failure, as the heart struggles to pump effectively.

Pulmonary Edema

Pulmonary edema is a condition characterized by excess fluid in the lungs, often resulting from left ventricular failure. When the left ventricle fails, blood backs up into the pulmonary circulation, increasing pressure and causing fluid to leak into the lung tissues. This can lead to symptoms such as difficulty breathing, coughing, and the moist sounds heard during auscultation.