The cardiovascular system is a complex network for transporting blood to the whole body. This system coordinates all the heart, blood vessels, and blood to circulate important substances such as oxygen, nutrients, and hormones into tissues and organs. In addition, it promotes removal of metabolic waste such as carbon dioxide and urea. The heart functions as a pump, and blood vessels (arteries, veins, capillaries) form a blood transport route. Blood movements and pressure in the cardiovascular system are strictly adjusted to ensure constant.
Blood vessels and their functions
Blood vessels are cardiovascular highways, where blood flow is turned to various parts of the body, and gas, nutrients, and waste are replaced between blood and tissue. The main functions include the following:
- transportation: Blood vessels guarantee that oxygenized blood from the lungs reaches the tissue, and the blood that has been dioxigen returns to the heart and lungs for reinxia.
- Regulation: Blood vessels regulate blood flow by contracting or expanding to secure the appropriate distribution of blood to active tissues.
- Blood pressure control: Blood vessels play an important role in controlling blood pressure by changing the diameter according to physiological needs.
- Chemical secretion: Blood vessels can secrete hormones and other substances that affect blood pressure and volume.
Circulating route
Blood circulates two major circuits.
- Pulmonary circuit: This circuit carries blood between the heart and lungs. Oxygen depleted blood is pumped into the lungs from the right side of the heart, picking up oxygen and releasing carbon dioxide. Next, the oxygen blood is returned to the left side of the heart.
- Whole body circuit: This circuit transports an oxygenized blood from the heart to the rest of the body, and supplies nutrients and oxygen to the tissue. Next, return the blood that has been deoxygen to the heart to re -oxygen of the lungs.
These routes are composed of three major types of blood vessels: arteries, veins, and capillaries.
Type of blood vessels
artery
The artery is a blood vessel that transports blood from the heart to the body tissue. They usually carry oxygen -rich blood, except for the lungs and fetal circulation that usually carry a deoxygen. The artery has a thick and muscular wall to withstand high pressure that blood is pumped from the heart.
Characteristics of the artery
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- Thick muscle wall Because it is necessary to withstand high pressure from the heart pumping action.
- Small inner cavity (inner diameter) Compared to the vein.
- There is no valve: The arteries do not contain valves to prevent the heart from reflux.
- Elasticity: The artery has a more elastic organization so that blood can be pumped at the easing stage of the heart, and to maintain pressure and maintain pressure.
Arteries can be classified into three types based on sizes, structures and functions.
- Elastic artery: These are the largest arteries such as aorta and lung trunk. These functions are to conduct blood from the heart to a small artery. The elastic tissue on the wall can be extended under pressure, reaction, and pushes the blood forward.
- Muscle artery: These arteries are medium size and have sufficiently developed smooth muscle layers. They distribute blood to various organs and tissues. An example includes the femoral artery and the coronary artery.
- Artery: These are the smallest arteries and lead to capillaries. The pharmic role plays an important role in adjusting blood flow and pressure by contracting or expanding various organs to adjust blood content.
vein
The vein is responsible for returning blood to the heart. They usually transport deeoxigenized blood, except for the lungs and fetal circulation of oxygen rich in oxygen. The pressure of the vein is much lower than the artery, and the veins relies on muscle contraction, gravity, and valve to return blood to the heart.
Characteristics of vein:
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- Thin wall This is because the pressure in the vein is much lower than that of the artery.
- Large inner cavity To support low -pressure blood flow and maintain more blood.
- valveMany veins contain the valve of legs, especially when blood returns to the heart, prevents blood backflow.
- Low elastic tissue and smooth muscle The vein does not need to withstand the same high pressure than the artery.
The veins are divided into two major types.
- vein: These are small veins that collect blood from capillaries and combine them to form a large vein.
- Large vein: These veins are responsible for returning blood to the heart. The example includes the upper and lower Vena cavae, which brings the oxygenized blood to the right core of the heart.
Capillaries
Capillaries are the smallest and most blood vessels that connect the artery to the vein. They are places where gas, nutrients and waste are replaced. Capillaries have very thin walls made in a single layer of endothelial cells to promote rapid replacement between blood and organizations.
Characteristics of capillaries:
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- Single layer of endothelial cells: This structure enables efficient replacement of oxygen, carbon dioxide, glucose, and other substances between blood and surrounding tissues.
- Wide network: Capillaries form a vast network in the tissue and provide a huge surface area for diffusion.
There are three major types of capillaries.
- Continuous capillaries: These are the most common types of muscles, skin and nervous system. They enable small molecules such as water and ions, but restricts larger molecules.
- Power generated capillaries: These capillaries include small pores (windows) that enable larger molecules and larger liquid amounts. They are found in areas such as kidney, small intestine, and endocrine glands.
- Sinus eyelid blood vessels: These are the most leaked capillaries and have a larger gap between endothelial cells. They are found in liver, spleen, and bone marrow -like organs. There, you need to replace large molecules and cells.
Blood pressure and circulation dynamics
Blood flow is mainly driven by pressure gradient in the blood vessels. The heart generates a high -pressure pulse of blood. Blood is transmitted through the artery, and when the blood moves to the artery and capillaries, it gradually deviates. The amount of blood that always flows through the body is adjusted by various factors such as resistance and cross -sectional area of ​​blood vessels.
blood pressure
Blood pressure is the power of blood on the walls of blood vessels. It is the highest in the large artery near the heart, and decreases as the blood moves through small arteries, arteries, and capillaries. Blood pressure is expressed in millimeter (MM HG) and is usually measured using two values.
- Controlting phase pressure: Pressure when the heart contracts and sending blood into the artery.
- Pressure of the expansion period: Pressure when the heart is relaxed and filled with blood.
The normal blood pressure measurement is about 120/80 mm HG. Hypertension, that is, hypertension, occurs when the pressure of the shrinkage period exceeds 140 mm HG or the expansion phase exceeds 90 mm HG. Conversely, hypotension or hypotension is when the contraction period is less than 90 mm HG or the pressure during the expansion period is less than 60 mm HG.
resistance
Resistance is mainly the opposite of the blood flow of the circulatory system due to friction between blood vessels and blood vessels. Several factors, such as blood vessels, the viscosity of the blood, and the total length of the blood vessels, contribute to the resistance. Resistance is inversely proportional to the diameter of blood vessels. Blood vessels cause more resistance and increase blood pressure, but extended containers have low resistance and blood pressure.
Control of blood pressure
Blood pressure is regulated by both short and long -term mechanisms. Short -term restrictions occur especially through the nervous system. Pressure RO receptor reflection。 The overwhelming device is a stretch receptor in large arteries such as aorta and cervical arteries. When a change in blood pressure is detected, a signal is sent to the brain to adjust the heart rate and the diameter of the container.
Long -term regulations are managed by kidneys and endocrine systems. Hormones such as Epinephrine,, Angiotensin IIand Aldosterone It is helpful to adjust blood pressure by causing blood vessels or liquid retention. Conversely, it looks like a hormone Atrial sodium urgent peptide (ANP) It causes blood vessels and helps to lower blood pressure.
Atheromic arteriosclerosis and its effects
Atheromic arteriosclerosis is a state in which a fat deposits (plaque) accumulate inside the arterial wall, leading to blood vessels and curing. This state can mainly affect medium and large arteries, and may increase the risk of heart attacks, stroke, and other cardiovascular diseases. Plaque tends to be formed in areas where blood flow is turbulent, such as junctions and arterial curves.
Ateromic arteriosclerosis is often caused by high cholesterol, smoking, hypertension, and diabetes. As time goes on, plaque can burst, causing blood clots, which can completely block blood flow, causing tissue damage or organ failure.
Venous disorder
Varicose veins It is usually a general vein disorder that is characterized by swollen twisted veins. This condition occurs when the valve in the vein becomes weaker or damaged, leading to the expansion of blood pools and veins. Vicarial aneurysms are often caused by long -term standing, pregnancy, obesity, or aging. The veins grow and become like a rope, which can be painful in some cases.
Conclusion
The cardiovascular system is an important factor in human physiology and is in charge of transporting blood, nutrients and waste throughout the body. Blood vessels containing arteries, veins, and capillaries work all at once to guarantee that blood is efficiently and effective. In order to maintain constant, it is essential to adjust the blood pressure, blood flow, and resistance. Disorders such as atherosclerosis, hypertension, and varicose veins need to be paid to prevent serious health impact on cardiovascular systems.
Understanding the structure and functions of cardiovascular systems is essential for diagnosis, treatment, and prevention of cardiovascular diseases that continue to be a major cause of death around the world.
