Textbook Question
Describe the location and position of the heart in the body.
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Ch. 18 The Cardiovascular System: The Heart
Marieb, Hoehn11th EditionHuman Anatomy & PhysiologyISBN: 9780136874034
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Table of contents
- Ch. 1 The Human Body: An Orientation24
- Ch. 2 Chemistry Comes Alive25
- Ch. 3 Cells: The Living Units21
- Ch. 4 Tissue: The Living Fabric20
- Ch. 5 The Integumentary System11
- Ch. 6 Bones and Skeletal Tissues19
- Ch. 7 The Skeleton14
- Ch. 8 Joints7
- Ch. 9 Muscles and Muscle Tissue26
- Ch. 10 The Muscular System26
- Ch. 11 Fundamentals of the Nervous System and Nervous Tissue19
- Ch. 12 The Central Nervous System26
- Ch. 13 The Peripheral Nervous System and Reflex Activity32
- Ch. 14 The Autonomic Nervous System19
- Ch. 15 The Special Senses26
- Ch. 16 The Endocrine System23
- Ch. 17 Blood25
- Ch. 18 The Cardiovascular System: The Heart24
- Ch. 19 The Cardiovascular System: Blood Vessels27
- Ch. 20 The Lymphatic System and Lymphoid Organs and Tissues14
- Ch. 21 The Immune System: Innate and Adaptive Body Defenses27
- Ch. 22 The Respiratory System21
- Ch. 23 The Digestive System31
- Ch. 24 Nutrition, Metabolism, and Energy Balance26
- Ch. 25 The Urinary System26
- Ch. 26 Fluid, Electrolyte, and Acid-Base Balance24
- Ch. 27 The Reproductive System24
- Ch. 28 Pregnancy and Human Development25
- Ch. 29 Heredity11
Marieb, Hoehn11th EditionHuman Anatomy & PhysiologyISBN: 9780136874034Not the one you use?Change textbook
Chapter 18, Problem 12
Define cardiac cycle, and follow the events of one cycle.
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Begin by defining the cardiac cycle as the sequence of mechanical and electrical events that repeat with every heartbeat, including the contraction and relaxation of the atria and ventricles.
Explain that the cardiac cycle consists of two main phases: systole (contraction) and diastole (relaxation), which occur in both the atria and ventricles but at different times.
Describe the first event: atrial systole, where the atria contract to push blood into the ventricles, completing ventricular filling.
Next, outline ventricular systole, where the ventricles contract, causing the atrioventricular (AV) valves to close (producing the first heart sound) and the semilunar valves to open, allowing blood to be ejected into the arteries.
Finally, explain ventricular diastole, where the ventricles relax, the semilunar valves close (producing the second heart sound), and the AV valves open to allow passive filling of the ventricles, completing the cycle.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Cardiac Cycle
The cardiac cycle refers to the complete sequence of events in the heart from the beginning of one heartbeat to the start of the next. It includes phases of contraction and relaxation that enable blood to be pumped throughout the body.
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Events in the Cardiac Cycle
Phases of the Cardiac Cycle
The cardiac cycle consists mainly of systole (contraction) and diastole (relaxation). During atrial systole, atria contract to fill ventricles; ventricular systole follows, pumping blood out; diastole allows chambers to relax and refill.
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3:55Cardiac Cycle Example 3
Heart Valve Function During the Cycle
Heart valves regulate blood flow direction during the cardiac cycle. The atrioventricular valves open during diastole to allow ventricular filling and close during systole to prevent backflow, while semilunar valves open during ventricular systole to eject blood.
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7:54Sounds in the Cardiac Cycle
Related Practice
Textbook Question
What is cardiac output, and how is it calculated?
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Textbook Question
The refractory period of cardiac muscle is much longer than that of skeletal muscle. Why is this a desirable functional property?
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Textbook Question
The activity of the heart depends on intrinsic properties of cardiac muscle and on neural factors. Thus:
a. Vagus nerve stimulation of the heart reduces heart rate
b. Sympathetic nerve stimulation of the heart decreases time available for ventricular filling
c. Sympathetic stimulation of the heart increases its force of contraction
d. All of the above
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Textbook Question
As Cara worked at her dissection, she became frustrated that several of the structures she had to learn about had more than one common name. Provide another name for each of these structures:
a. Atrioventricular groove
b. Tricuspid valve
c. Bicuspid valve (give two synonyms)
d. Atrioventricular bundle
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Textbook Question
Draw a normal ECG pattern. Label and explain the significance of its deflection waves.
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