📌𝐅𝐨𝐥𝐥𝐨𝐰 𝐨𝐧 𝐈𝐧𝐬𝐭𝐚𝐠𝐫𝐚𝐦 :- / drgbhanuprakash
Introduction to Cardiovascular System
The circulatory system, also called the cardiovascular system, is a vital organ system that delivers essential substances to all cells for basic functions to occur. The system supplies nutrients to and removes waste products from various tissues of the body.
The cardiovascular system is a network composed of the heart as a centralized pump, blood vessels that distribute blood throughout the body, blood serves as a medium of transportation, and the blood of different substances.
Blood vessels
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The blood vessels form a closed system of tubes that carry blood away from the heart to the tissues of the body and then return it back to the heart.
The blood vessels include: Arteries. Capillaries, Veins
Arteries (distributing channels) are thick-walled tubes that carry blood away from the heart. The blood leaving the heart passes through the vessels of progressively smaller diameters referred to as arteries and arterioles
Capillaries are microscopic vessels that connect arterioles and venules.
Veins (draining channels) are thin-walled tubes that carry blood from tissues of different parts of the body back to the heart. The blood returning to the heart from the capillaries passes through the vessels of progressively larger diameters, termed as veins and venules.
Except for the capillaries and the venules, the blood vessel walls consist of three layers- Tunica intima, tunica media & tunica adventitia.
End Arteries
These are the arteries whose branches do not anastomose with branches of other adjacent arteries, e.g. (a) central artery of retina, (b) arteries of spleen, liver, kidneys, metaphysis of long bones, and (c) central (medullary) branches of cerebral arteries. If these arteries are blocked, the area supplied suffers from ischemia that may lead to cell necrosis.
Anastomosis
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Anastomosis is the communication between the blood vessels forming collateral channels.
Arterial anastomosis:
o A direct anastomosis occurs where two arteries are joined directly to each other, such as in the radial and ulnar arteries via the palmar arches.
o Convergence anastomoses occur where two arteries unite to form a single artery, as in when the vertebral arteries join to form the basilar artery. A transverse anastomosis is where a small artery connects two larger arteries, for example, the anterior communicating artery connecting the right and left anterior cerebral arteries.
o Potential anastomosis takes place between terminal arterioles. In such type of anastomosis, collateral circulation cannot take place if one of the arteries is suddenly blocked. Yet, if sufficient time is given, the arterioles can dilate and establish collateral circulation, e.g. coronary arteries.
o Arteriovenous anastomoses (shunts) are a direct connection between small arteries and small veins. These occur in regions such as the skin of the nose, lips, and ears, in the mucosa of the alimentary canal, and in nasal and oral cavities.
o Portocaval anastomosis occurs where there is a connection between the systemic and portal system of veins. These occur at venous plexuses, such as around the esophagus, the umbilicus, and the rectum.
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Негізгі бет Introduction to Cardiovascular System - General anatomy
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