ANA 204 Heart and Genital Organs Flashcards
Describe Macrovasculature
vessels that are more than 0.1 mm in diameter (large arterioles, muscular and elastic arteries, and muscular veins). These vessels are seen grossly.
Describe Microvasculature
(arterioles, capillaries and postcapillary venules) These vessels are visible only with a microscope .
Function of microvasculature
the site of interchanges between blood and the surrounding tissues both under normal conditions and during inflammatory processes
Functions of BVS
transports oxygen and nutrients to tissues, carries carbon dioxide and waste products from the tissues,
•circulates hormones from the site of synthesis to their target cells.
Describe the heart
The heart is a muscular, highly specialized portion of the vascular system.
•it consists of 4 chambers:
•Right and Left Ventricle (RT< ventricles)
• Right and Left atria (RT< atria)
•The right and left ventricles pump blood to the lungs and the rest of the body respectively;
•right and left atria receive blood from the body and the pulmonary veins respectively.
Layers of the heart chambers
The internal endocardium
•The middle myocardium
•The external epicardium.
Describe the endocardium
•The Endocardium lines the lumen of the heart and is composed of simple squamous epithelium (endothelium) and a thin layer of loose connective tissue.
Describe the subendocardium
•Subendocardium :a connective tissue layer that contains veins, nerves, and Purkinje fibers, underlies it.
Describe the myocardium
The myocardium is the thickest of the tunics and consists of cardiac muscle cells arranged in layers that surround the heart chambers in a complex spiral.
Note: The myocardium is much thicker in the ventricles than in the atria.
Describe the epicardium
Epicardium, the outermost layer of the heart, constitutes the visceral layer of the pericardium.
•It is composed of simple squamous epithelium (mesothelium) on the external surface.
the epicardium is the site of the coronary vessels and contains considerable adipose tissue.
What is the fibrous skeleton of the heart?
•consists of thick bundles of collagen fibers oriented in various directions.
•It also contains occasional foci of fibrocartilage.
•It is the fibrous central region of the heart.
Function of fibrous skeleton
It serves as
•base of the valves.
•site of origin and insertion of cardiac muscle cells.
•Histologically, it is composed of dense irregular connective tissue, with separated nodules of fibrocartilage
What are the heart valves?
•Atrioventricular Valves
•Semilunar Valves
Describe the atrioventricular valve
Atrioventricular (AV) valves are composed of a skeleton of fibrous connective tissue arranged like an aponeurosis and lined on
both sides by endothelium.
• They are attached to the annuli fibrosi of the fibrous skeleton.
• The right AV valve is formed of three interlocking cusps (tricuspid valve) whereas the left AV valve is formed of two interlocking cusps (bicuspid or mitral valve).
Function of the atrioventricular valve
These valves prevent regurgitation of ventricular blood into the atria.
Describe the semilunar valve
Semilunar valves in the pulmonary and aortic trunks are composed of three cusps that approximate each other as
they fill with arterial blood.
• They are lined with endothelium on both sides separated by sparse strands of connective tissue.
Function of semilunar valves
These valves prevent regurgitation of pulmonary and aortic blood into the respective ventricles.