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Module 1: Módulo 2: Os vasos sanguíneos e o coração

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Os recipientes de sangue e o Resumo de Pulsação-Lição

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In general, there are three types of blood vessels - arteries, veins, and capillaries.

Blood vessels are generally composed of three layers - the intima, the media and the adventitia.

For protection, arteries tend to be located deep within the structures of the body.

Veins can be located at both deep and cutaneous levels.

The capillaries are located throughout all tissues of the body.
The exchange of materials between the blood and the cells of the body takes place in the capillary beds.

Some special situations which arise in the blood vascular system include:

nutrient versus functional blood supply

collateral circulation

end arteries

portal veins

The heart comprises two upper chambers - the atria - and two lower chambers - the ventricles.

The walls of the chambers of the heart consist of three layers - the endocardium, the epicardium and the myocardium.

There are two sets of cardiac valves the atrioventricular (AV) valves and the semilunar valves.

The fibrous skeleton of the heart provides sites of attachment for muscle tissues and supporting structures for the cardiac valves.

The heart is enclosed in a protective sac called the pericardium.

Heart function is governed by extrinsic controls, intrinsic controls and humoral control.

Blood is supplied to the heart by the coronary arteries, cardiac veins, coronary sinus and thebesian veins.

Arterial blood flow is driven by the contraction of the ventricular walls, the elastic recoil of the arterial walls, vasoconstriction and gravity.

Venous blood flow is driven by the pump effect from venous valves, pressure from arteries, pressure from muscular contractions and gravity.