Basics of the cardiovascular system

Basics of the cardiovascular system

The heart

A septum separates the human heart into the left and right halves of the heart, each of which consists of a chamber (ventricle) and an atrium (atrium). Heart valves are used as check valves between the atria and the rooms and between the rooms and the adjacent large vessels so that the blood can only flow in one direction. healthandbeautytimes  

 

The bloodstream

The heart works like pressure and suction pump. With each contraction of the muscular left ventricle - which happens about 60 to 80 times per minute under physiological conditions - the oxygen-enriched blood is pumped via the large artery (aorta) and further via elastic arteries, arterioles, and capillaries to the organs and tissues. In the body tissues, gas exchange occurs at the capillary walls, with oxygen being taken up by the cells and carbon dioxide being released into the capillary blood. The oxygen-poorer and more carbon dioxide-enriched blood then flow back into the heart's right atrium via the vena cavae. themarketingguardian

 

In the pulmonary circulation, the blood leaves the right ventricle via the pulmonary artery (Truncus pulmonalis) and flows to the two lungs, where oxygen is enriched. Via the pulmonary vein (pulmonary vein), the oxygen-enriched blood is pumped through the left atrium into the left ventricle and then returned to the circulatory system through the aorta.

 

The blood pressure

The arterial blood pressure is given as a pair of systolic and diastolic pressures in mm Hg. The systolic arterial pressure is the maximum pressure created by the heart muscle contraction during the ejection phase. Diastolic bp is the lowest pressure during the heart's relaxation phase when the heart chambers fill with blood from the atria. imtechies 

 

The specification in millimeters of mercury (mm Hg) describes that 1 mm Hg corresponds to the pressure generated by a 1 mm high column of mercury. While the blood pressure in the heart when the blood is ejected (systole) is around 160 mm Hg, 100-130 mm Hg is still measured in humans' arm artery. The pressure in the capillaries is only about 20 mm Hg. techiesguardian 

 

Blood pressure is a variable and depends on the performance that the cardiovascular system has to provide. Among the factors that determine blood pressure, the blood volume that the heart ejects per minute and the total peripheral vascular resistance is central. healthsunlimited 

 

Cardiac output (HMV) or cardiac output (CO)

The cardiac output agrees to the blood volume that the heart pumps into the bloodstream via the aorta per minute. Under physiological conditions, this corresponds to about 4.5-5 liters. The HMV increases with physical exertion and anemia or an overactive thyroid. In contrast, it is reduced in hypothyroidism or diseases that reduce the heart's pumping capacity.

 

Peripheral vascular resistance

All blood vessels put up physical resistance to the blood flow through wall tension. The various sections of the circuit's resistances differ significantly from one another. The most significant opposition comes from the small arteries and arterioles. The sum of the individual vessel resistances is called the total peripheral resistance.

 

The vascular resistance is determined by:

 

·        active contraction of the vascular wall muscles (regulated by vasoconstrictive and vasodilatory signals such as hormones or nerve messengers)

·        Vessel diameter

·        The viscosity of the blood

Structure of the blood vessels

The circulatory system is divided into:

 

·        Arteries that carry oxygen-rich blood to organs, tissues, and the heart,

·        Veins that carry oxygen-depleted, carbon-dioxide-enriched blood away from tissues and

·        Capillaries enable the exchange of substances in the blood in the body tissues.

Regardless of their size, all blood vessels have roughly the same three-layer wall structure:

 

The intima layer (tunica interna) lines the blood vessels' inside. This consists of a layer of flattened endothelial cells, which enables smooth blood flow in the intact blood vessel and prevents the undesired attachment of blood particles.

 

Various messenger substances involved in blood pressure regulation are formed in the endothelial cells. Of particular importance is nitric oxide (NO) obtained from arginine and causes vasodilation (vasodilation).

 

The media layer (tunica media) consists of smooth muscle fibers running in a ring around the vessel, traversed by a network of collagenous and elastic fibers. In the arteries close to the heart, this layer provides the necessary elasticity to regulate blood pressure.

 

The media is traversed by sympathetic nerve fibers that regulate the vessels via adrenaline and noradrenaline. Noradrenaline and high doses of adrenaline have a vasoconstrictive effect (vasoconstrictive).

 

The adventitia layer (tunica adventitia) consists of connective tissue that anchors the blood vessel to the environment. While smaller vessels are supplied by the blood flowing through, the large vessels' adventitia is permeated with tiny blood vessels. In arteriosclerotic vascular changes, these blood vessels can grow into the intima.

webtechradar


 


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