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Questions and Answers
Which layer of the heart contains connective tissue and smooth muscle fibers?
Which layer of the heart contains connective tissue and smooth muscle fibers?
What is the function of Purkinje Fibers in the heart?
What is the function of Purkinje Fibers in the heart?
Which of the following is NOT a component of the heart conducting system?
Which of the following is NOT a component of the heart conducting system?
What is the outermost layer of the heart?
What is the outermost layer of the heart?
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What type of cells are found in the Endocardium?
What type of cells are found in the Endocardium?
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What is the function of the Subendocardial layer?
What is the function of the Subendocardial layer?
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How many nuclei do Purkinje Fibers have?
How many nuclei do Purkinje Fibers have?
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What is the middle layer of the heart?
What is the middle layer of the heart?
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What is the main function of the cardiac muscle cells in the heart?
What is the main function of the cardiac muscle cells in the heart?
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Where is the SA node located?
Where is the SA node located?
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Study Notes
Cardiovascular System
- Consists of the heart, arteries, capillaries, and veins.
The Heart
- Has four chambers: two atria (right and left) and two ventricles (right and left).
- Has three layers: epicardium, myocardium, and endocardium.
Endocardium
- Innermost layer of the heart.
- Consists of a thin layer of squamous endothelium (epithelium) with connective tissue and smooth muscle fibers.
- Has a subendocardial layer that contains the sinoatrial (SA) node or pacemaker and the atrioventricular (AV) node.
Myocardium
- Thick middle layer of the heart.
- Consists mainly of cardiac muscle cells (myocytes).
- Thicker in the ventricular wall than in the atrial wall due to high pressure needed to pump out blood.
Epicardium
- Outermost layer of the heart.
- Consists of simple squamous mesothelium with connective tissue, nerves, vessels, and adipocytes.
- Mesothelium secretes pericardial fluid, which acts as a lubricant to prevent friction and covers and protects the heart.
Cardiac Skeleton
- Made up of irregular dense connective tissue located in the endocardium.
- Forms part of the interventricular and interatrial septa, anchors the valves, and surrounds the two atrioventricular canals.
- Extends into the valve cusps and the chordae tendineae.
Cardiac Valves
- The heart has four valves: two atrioventricular (mitral and tricuspid) and two semilunar (aortic and pulmonary).
- Valves possess connective tissue layers covered by endothelium on each side and are arranged into three layers: spongiosa, fibrosa, and ventricularis.
Vascular System
- Components include arteries, capillaries, and veins.
- Arteries transport blood away from the heart by branching into smaller vessels.
- Capillaries are thin-walled vessels with the smallest diameter, forming capillary beds where gases and substances are exchanged.
- Veins drain capillary beds and return blood to the heart.
Tunics or Layers of the Blood Vessels
- Wall of the blood vessels has three layers: tunica intima, tunica media, and tunica adventitia.
Tunica Intima
- Innermost layer of the blood vessel.
- Composed of simple squamous endothelium (epithelium), subendothelial connective tissue, and internal elastic lamina.
- Internal elastic lamina separates the tunica intima from the tunica media and contains elastin that allows for easy diffusion of substances.
Tunica Media
- Middle and thickest layer of the blood vessel.
- Forms the middle and thickest layer of the blood vessel.
Purkinje Fibers
- Modified cardiac muscle cells with 1-2 nuclei.
- Specialized for impulse conduction rather than contraction.
- Found at the periphery of the heart and stain more pale than contractile cardiac muscle fibers due to low myofibril content.
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Description
This quiz covers the structure and composition of the heart, including the myocardium, Purkinje fibers, and cardiac muscle fibers.
