BPK 105 Study Guide - Final Guide: Smooth Muscle Tissue, Cardiac Muscle, Elastic Fiber
27 Apr 2018
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Modules 7 & 8 - Objectives - Part 4
● Explain the structure and function of the electrical conduction system of the
heart.
Refer to figure 12.15 in textbook.
● Describe the cardiac cycle including the contraction of each chamber, the
pressure in each chamber, the phases of the electrocardiogram (ECG), and the
sounds of the heart.
Refer to figure 12.17 in textbook.
● Describe the intrinsic and extrinsic regulation of heart function
(chemoreceptor reflex will be discussed in Module 10: Respiratory System
Physiology).
Intrinsic Regulation of the Heart
Intrinsic regulation refers to mechanisms contained within the heart itself. The force of
contraction produced by cardiac muscle is related to the degree of stretch of cardiac muscle
fibers. The amount of blood in the ventricles at the end of ventricular diastole determines the
degree to which cardiac muscle fibers are stretched. Venous return is the amount of blood that
returns to the heart, and the degree to which the ventricular walls are stretched at the end of
diastole is called preload. If venous return increases, the heart fills to a greater volume and
stretches the cardiac muscle fibers, producing an increased preload. In response, cardiac
muscle fibers contract with a greater force. The greater force of contraction causes an increased
volume of blood to be ejected from the heart, resulting in an increased stroke volume. As
venous return increases, resulting in an increased preload, cardiac output increases.
Conversely, if venous return decreases, resulting in a decreased preload, the cardiac output
decreases. The relationship between preload and stroke volume is called Starling’s law of the
heart.
After completing Chapter 13 you will be able to:
● List the functions of the peripheral circulation.
Regulate blood flow, exchange substances, direct blood flow, carry blood and transport
substances.
● Compare and contrast the structure and function of elastic arteries, muscular
arteries and capillaries.
The three main types of blood vessels are arteries, capillaries, and veins. Arteries (ar′ter-̄z)
carry blood away from the heart; usually, the blood is oxygen-rich. Blood is pumped from the
ventricles of the heart into large, elastic arteries, which branch repeatedly to form progressively
smaller arteries. As they become smaller, the artery walls undergo a gradual transition from
Document Summary
Modules 7 & 8 - objectives - part 4. Explain the structure and function of the electrical conduction system of the heart. Describe the cardiac cycle including the contraction of each chamber, the pressure in each chamber, the phases of the electrocardiogram (ecg), and the sounds of the heart. Describe the intrinsic and extrinsic regulation of heart function (chemoreceptor reflex will be discussed in module 10: respiratory system. Intrinsic regulation refers to mechanisms contained within the heart itself. The force of contraction produced by cardiac muscle is related to the degree of stretch of cardiac muscle fibers. The amount of blood in the ventricles at the end of ventricular diastole determines the degree to which cardiac muscle fibers are stretched. Venous return is the amount of blood that returns to the heart, and the degree to which the ventricular walls are stretched at the end of diastole is called preload.
