The human heart is a hollow muscular organ that represents the central part of the circulatory system. It measures about 12 cm long and 9 cm wide. It weighs, on average, 250 to 300 g in adults.
The human heart is located in the central part of the rib cage, slightly tilted to the left. It lies between the lungs and behind it are the esophagus and the aorta artery.
The heart occupies the central portion of the chest cavity
Anatomy
The human heart is internally divided into four cavities:
- Two atriums: Upper cavities where blood reaches the heart;
- Two ventricles: Lower cavities where blood exits the heart.
heart parts
The right atrium communicates with the right ventricle and the left atrium communicates with the left ventricle.
Between the atria and the ventricles there are valves that regulate the flow of the blood and prevent its reflux, that is, the return of blood from the ventricles to the atria. These are called the right atrioventricular valves and the left atrioventricular valve.
For a long time, atrioventricular valves were called tricuspid (right) and bicuspid or mitral (left).
Structure
The cardiac wall is formed by three tunics: pericardium, endocardium and myocardium.
walls of heart
Pericardium
The pericardium is the serous membrane that surrounds the heart. It is formed by two types of membranes with different constitutions:
- Parietal or fibrous pericardium: Outer layer formed by a layer of collagen bundles.
- Visceral or serous pericardium: Inner layer formed by a serous membrane.
The pericardium has a protective function and helps the heart to remain in the correct position.
endocardium
The endocardium is the thin, smooth membrane that lines the heart's cavities. It is formed by flat endothelial cells, arranged in a single layer.
Myocardium
O myocardium it is the middle and thickest layer of the heart. It is formed by striated muscle tissue and is responsible for the heart's contractions. This condition allows the heart to carry out its blood-propelling function.
Also know about the Muscle tissue.
What is the function of the heart?
The primary function of the heart is pump blood throughout the body.
For this, it works as a double pump, its left side pumping oxygenated blood (arterial) to different parts of the body. Meanwhile, the right side pumps venous blood to the lungs.
Read too:
- Circulatory system
- Cardiovascular system
- Blood vessels
- veins
Heart beats
The heart works by pushing the blood through two movements:
- Systole: Contraction movement, in which blood is pumped into the body;
- Diastole: Relaxation movement, in which the heart fills with blood.
When they are filled with blood, the atria contract (systole), valves open, and blood is pumped to ventricles that are relaxed (diastole).
Then the ventricles contract (systole) and press the blood into the vessels. At that moment, the atria in diastole fill with blood. This set of movements is called cardiac cycle.
The noise we hear from the heartbeat corresponds to the movement of the valves, which happens in a rhythmic way.
- In a adult person at rest the heart beats about 70 times a minute;
- In a kid the heart normally beats about 120 times a minute;
- On a drink the heart beats normally 130 times per minute.
Blood pressure
Each time the ventricles contract, they propel blood into the arteries.
As the blood is pumped, it puts pressure on the walls of the blood vessels, which expands and contracts.
This pulse is called pressure or arterial pulse, through which you can check the frequency of heartbeats.
Hypertension occurs when pressure reaches high values and remains so for a long period.
It usually does not cause symptoms, but it increases the risk of stroke (stroke), heart attack, and other problems with the cardiovascular system.
Also read about:
- Blood pressure
- Hypertension
- hypotension
Curiosities
- In the human body, only the corneas do not receive blood supplies.
- The blue whale is the living being with the biggest heart, weighing up to 680 kg.
- If the heart has a sufficient supply of oxygen, it can continue to beat even outside the body. This condition allows the performance of transplants.
Learn more, see also:
- Human Body
- Organs of the Human Body
- Exercises on the cardiovascular system
