Cardiovascular system: heart, blood vessels and blood

The cardiovascular system is a complex network that is responsible for transporting blood throughout the human body. The system includes the heart, blood vessels and blood, all of which cycle important substances such as oxygen, nutrients and hormones to tissue and organs. In addition, it helps remove metabolic waste products such as carbon dioxide and urea. The heart acts as a pump, blood vessels (arteries, veins, and capillaries) formed a blood transportation route. The exercise and pressure of blood in the cardiovascular system are strictly adjusted to ensure the balance in the body.

Blood vessels and their functions

Vascular is a highway of the cardiovascular system, and the blood is guided to all parts of the human body, where the gas, nutrients and waste are exchanged between blood and tissue. Their main functions include:

1. transportation: Blood vessels ensure that oxygen -containing blood from the lungs reaches tissue, and the blood that is dehydrated returns to the heart and lungs for oxygen.
2. Regulation: Blood vessels can regulate blood flow by contraction or dilation to ensure the correct distribution of blood to active tissues.
3. Blood pressure control: Blood vessels change diameter to control blood pressure by responding to physiological needs.
4. Chemical secretion: Blood vessels can secrete hormones and other substances that affect blood pressure and volume.

Circular pathway

Blood circulation through two main circuits:

1. Pulmonary circuit: This circuit conveys blood between the heart and the lungs. The exhaustion of oxygen blood is pumped from the right side of the heart to the lungs, where it picks up oxygen and releases carbon dioxide. Then return the blood -containing blood to the left side of the heart.
2. Systemic circuit: The circuit transmits oxygen -containing blood from the heart to the rest of the human body, and the nutrition and oxygen are transmitted to the tissue. Then return the dehydrated blood to the heart to make the lungs in the lungs.

Each of these circuits consists of three main vascular composition: arteries, veins and capillary.

Vascular type

artery

The arteries are blood vessels, bringing blood from the heart to human tissue. They usually carry oxygen -rich blood, except for the lungs and fetal circulation, where they carry deoxymal blood. The arteries are thick, muscle and elastic walls to withstand high pressure applied when blood pumping from the heart.

Features of the artery

• • Thick muscle wall Due to the need to endure high pressure from the pumping action of the heart.
  • Small cavity (inner diameter) Compared with intravenous veins.
  • No valve: The artery does not contain valve, because the pressure from the heart prevents the return.
  • elasticity: The arteries have more elastic tissues, which can be pumped and stretched when recoil to keep pressure at the stage of relaxation.

The arteries can be divided into three types according to their size, structure and function:

1. Elastic artery: These are the largest arteries, such as aorta and lung trunk. Their function is from the heart to small arteries from the heart. The elastic tissue in the wall enables them to stretch under pressure and recoil to push the blood forward.
2. Muscle artery: These arteries are medium -sized and have developed smooth muscle layers. They allocate blood to various organs and tissues. Examples include femoral artery and coronary arteries.
3. Arterial artery: These are the smallest arteries that lead to capillaries. In terms of regulating blood flow and pressure, small arteries play a key role in regulating the blood capacity of different organs.

vein

Intravenous is responsible for returning blood to the heart. Except in the lungs and fetal cycles, veins contain oxygen -rich blood, and they usually transport deoxygenic blood. The pressure of the vein is much lower than the arteries, and the vein relies on muscle contraction. Gravity and valve restore blood to the heart.

Featured featuresThe

• • Thin wall Compared with arteries, the pressure inside the vein is much lower.
  • Larger lumen To adapt to low -pressure blood flow and maintain a large amount of blood.
  • valve: Many veins contain valve, especially in the legs to prevent blood flow from returning to the heart.
  • Elastic tissue and less smooth muscles Not the arteries, because the vein does not need to bear the same high pressure.

Variable veins are divided into two main types:

1. vein: These are small veins collected from the capillaries and combine it to form a larger vein.
2. Vein: These veins are responsible for restoring blood to the heart. Examples include the upper and lower cavity, bringing off deoxy blood into the right heart room of the heart.

Capillary

The capillaries are the smallest and most of the blood vessels are connected to the vein. They are places where gas, nutrients and waste. The wall of the capillaries is very thin and is made of single -layer endothelial cells to promote rapid exchange between blood and tissue.

Features of capillariesThe

• • Single -layer endothelial cell: This structure allows effective exchange of oxygen, carbon dioxide, glucose and blood and surrounding tissues.
  • Wide network: The capillaries form a huge network in the tissue, providing a huge surface area for diffusion.

There are three main types of capillaries: three main types:

1. Continuous capillary: These are the most common types found in muscle, skin, and nervous system. They allow small molecules (such as water and ions) to pass, but limited large molecules.
2. Capillary: The pores of these capillaries are small, which can exchange larger molecules and larger liquid volumes. They are found in areas such as kidney, small intestines and endocrine glands.
3. Sine capillaries: These are the most leaked capillaries, and there is a large gap between endothelial cells. They found in the liver, spleen, and bone marrow, where there are macromolecules or even cells.

Blood pressure and cyclic dynamics

Blood flow is mainly driven by pressure gradient in the blood vessels. The heart can cause high pressure blood. The blood spreads through the arteries and gradually disappears as the blood moves into the arteries and capillary. At any given time, the blood volume flowing through the body is adjusted by various factors, including drug resistance and cross -section area of ​​blood vessels.

blood pressure

Blood pressure is the force of blood on the blood vessel wall. It is the highest among the great arteries near the heart, and it decreases as the blood moves through smaller arteries, arteries and capillaries. The blood pressure is expressed in millimeters of mercury (MM HG), and two values ​​are usually used for measurement:

• Systolic blood pressure: Heart shrinkage and pump blood into the pressure of the arteries.
• Diastolic pressure: When the heart is relaxed and full of blood.

The number of normal blood pressure is about 120/80 mm Hg. When the systolic blood pressure is always higher than 140 mm Hg or the diastolic pressure is higher than 90 mm HG, hypertension or hypertension occurs. In contrast, hypotension or hypotension is when the systolic blood pressure is lower than 90 mm Hg or the diastolic pressure is less than 60 mm HG.

Resist

Resistance is the opposition of blood flow in the circulatory system, mainly due to the friction between blood and walls of blood vessels. Several factors lead to anti -medicinal properties, including the size of the vascular, the viscosity of blood and the overall length of the blood vessels. Anti-vascular diameter-responding-shoulder-based protector can cause more resistance, thereby improving blood pressure, and the dilated blood vessels reduces drug resistance and blood pressure.

Blood pressure regulation

Blood pressure is adjusted by short -term and long -term mechanisms. Short -term regulation occurs through the nervous system, especially through Pressure sensor reflectionEssence The pressure sensor is stretch receptor in large arteries such as aorta and carotid artery. When they detect blood pressure changes, they send signals to the brain to regulate heart rate and blood vessel diameter.

Long -term regulation is managed by kidney and endocrine systems. Hormone, such as Adrenaline,,,,, Vascular tension IIand Aldehyde solid ketone Help blood pressure by causing vascular contraction or liquid retention. On the contrary, hormones like Atrial sodium peptide (ANP) Causes blood vessels to relax and help reduce blood pressure.

Atherosclerosis and impact

Atherosclerosis is a condition for fat deposition (plaques) to accumulate in the arterial wall, leading to narrowing and hardening blood vessels. This situation mainly affects medium and large arteries, which can increase the risk of heart disease, stroke and other cardiovascular diseases. Parats tend to be formed in the area where blood flow turbulence, such as branch points or arterial curves.

Atherosclerosis is usually caused by high cholesterol, smoking, hypertension and diabetes. Over time, the plaques will break, causing blood condens to completely block blood flow, which will cause tissue injury or organ failure.

Intravenous disease

Varicose veins It is a common venous disease, which is characterized by the veins of leg swelling and distorted. This happens when the valve in the vein becomes weakened or damaged, which will cause blood agglomeration and vein to increase. Varic veins are usually caused by long -term standing, pregnancy, obesity or aging. The vein becomes stretched and like a rope, in some cases, they may be painful.

in conclusion

Cardiovascular system is a key component of human physiology and is responsible for transporting blood, nutrition and waste in the entire human body. Including the consistent vascular work in the arteries, veins, and capillary to ensure effective blood circulation. Properly regulating blood pressure, blood flow and drug resistance are essential for maintaining the balance in the body. Paths such as atherosclerosis, hypertension and varicose vein tension can have a significant impact on the cardiovascular system, and need to pay attention to prevent serious health consequences.

Understanding the structure and function of the cardiovascular system is critical for diagnosis, treatment and prevention of cardiovascular disease, which is still the main cause of global death.