Body Fluids and Circulation

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ÇÏRÇÜLÅTØRÝ SÝSTËM

HÜMÅÑ ÇÏRÇÜLÅTØRÝ SÝSTËM

Muscular chambered heart

A network of closed branching blood vessels

Fluid which is circulated

Components of Human

Circulatory System

BLØØD VËSSËLS

Blood vessels are of 3 types: Arteries, Veins & Capillaries.

01

ARTERIES: They carry blood from heart to other tissues.

They contain oxygenated blood (except pulmonary artery).

Their smaller branches are called arterioles. Arteries are

3-layered- inner tunica intima (squamous endothelium),

middle tunica media (smooth muscles & elastic fibres)

and outer tunica externa (fibrous connective tissue). They

have thick wall and narrow lumen. (MAINS 2010)

02

VEINS: They carry blood towards heart. They contain

deoxygenated blood (except pulmonary vein). Their

smaller branches are called venules. Veins are also

3-layered but tunica media is comparatively thin. Valves

are present to check backward flow of blood. (AIPMT 1995)

03

CAPILLARIES: In tissues, arterioles divide into thin

walled and single layered vessels. They are called

capillaries. They unite into venules

STRÜÇTÜRË ØF HËÅRT

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Heart is a mesodermally derived organ located in mediastinum and

protected by double-layered pericardium.

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The pericardial space (between pericardial membranes) is filled with

pericardial fluid. It reduces the friction between the heart walls and

surrounding tissues.