Wednesday, September 18, 2019

Heart Structure | Blood Flow through the Heart Step by Step

Position of Heart:
The heart is situated in the middle mediastinum of the thoracic cavity. It is placed obliquely behind the sternum and adjoining parts of the costal cartilages. So, one-third of it lies to the right of the median plane and two-thirds to the left of the median plane. 
Human heart
Fig: Human heart
Shape and Measurement of heart:

Shape: pyramidal or conical,
Length: 12cm,
Width: 9cm.
Weight:
Adult males: 280-340gm,
Adult females: 230-280gm.

Order of Blood Flow Through the Heart:
Blood flow process through the heart has presented in the below:
  • Through the two largest veins of the body, the superior vena cava, and inferior vena cava, the right atrium receives deoxygenated blood from the whole body.
  • This blood flows from the right atrium into the right ventricle through the right atrioventricular orifice.
  • From the right ventricle, blood is pumped into the pulmonary trunk (pulmonary arteries).
  • Finally, the left and right pulmonary arteries carry the deoxygenated blood to the lungs where blood is oxygenated (exchanges of gases: Carbon dioxide is excreted and oxygen is absorbed).
  • Two pulmonary veins from each lung carry oxygenated blood back to the left atrium.
  • The blood from the left atrium flows into the left ventricle through the left atrioventricular orifice.
  • From the left ventricle, the blood is pumped into the ascending aorta and then into the systematic circulation.
(Note: from the sequences of events just described above it can be seen that the blood passes from the right to the left side of the heart via the lungs or pulmonary circulation).

Blood Supply of the Heart:
It is discussed in the following:

Arterial Supply:

The heart is supplied with arterial blood by the two coronary arteries (right and left) which arise from the ascending aorta immediately above the aortic valve. The right and left coronary arteries from a vast network of arteries and capillaries throughout the heart.

Blood Drainage:
Most of the venous blood is collected into several small veins that join to form the coronary sinus, which opens into the right atrium.

More questions related to this article:

  1. What is the position of the heart?
  2. What is the size of the heart?
  3. What is the weight of the heart?
  4. What is the shape of the heart?
  5. What is the flow of blood through the heart in order?
  6. How does a heart work step by step?
  7. How does blood flow through the 4 chambers of the heart?
  8. How does the blood flow through the heart step by step?