Human Circulatory system HCS Types of circulation

Human Circulatory system (HCS) – Types of circulation and blood tissue

Pulmonary circulation - малый круг кровообращения • Occurs between the heart and the lungs • It is initiated with the contraction of the right ventricle and the pumping of deoxygenated blood into the pulmonary artery.

Pulmonary circulation • Branches of the pulmonary artery transport blood into both lungs. • In the lungs, CO 2 passes out of the blood into the lungs, while oxygen passes in. • The oxygen-rich blood is then carried into the left atrium by the pulmonary veins.

Systemic circulation - большой круг кровообращения • Occurs between the heart and all other parts of the body (except the lungs) where materials and gases are exchanged.

Systemic circulation • It begins with the contraction of the left ventricle and the transport of oxygenated blood to the tissues via the aorta. • The aorta then branches into the main vessels which carry blood into different parts of the body.

Systemic circulation • Nutrients and oxygen pass into the tissues while wastes and CO 2 diffuse into the blood. • The deoxygenated blood is then transported by the superior and inferior vena cava into the right atrium.

BLOOD • Blood is a connective tissue • It consist of 45% blood cells and 55% plasma

Functions of the Blood • • • Nutrient Transport Hormone Transport Homeostasis Immune response Clotting

Plasma • Plasma constitutes 55% of the blood, of which 90 -92 % is water, 7 -9% plasma proteins, and the remaining 1% is amino acids, carbohydrates, lipids, hormones, urea, minerals and other substances

Plasma proteins • There are more than 70 different types of plasma proteins. • Fibrinogen is involved in blood clotting • Albumin regulates water level • Globulins participate in the structure of antibodies and protects body from pathogens

Erythrocytes – red blood cells • There approximately 4. 5 to 5. 5 million per mm 3 in the adults. • Mature erythrocytes in mammals lack a nucleus and disk shaped. • They have a protein which is called hemoglobin

Hemoglobin It consists of A heme group A globin group The heme group is an iron containing complex, whereas the globin group is composed of globular proteins. • Oxygen molecules bind weakly to the iron of the heme group. • •

HEMOGLOBIN • The transport of oxygen and carbon dioxide are carried out by hemoglobin.

• Erythrocytes are produced by the red bone marrow and the spleen. • The most important vitamin in erythrocyte production is vitamin B 12. • Erythrocytes live for approximately 80 -120 days in the circulatory system and are destroyed in liver and spleen. Erythrocytes

Leucocytes - White Blood Cells • Leucocytes are nucleated, spherical, white cells. • The number of leucocytes in a healthy person is approximately 6 -8 thousand per mm 3. • They are produced by spleen and lymph nodes and life span is about 2 -4 days. • They have pseudopodia by which they move

Leucocytes • Their main function – protect body against pathogens. • I. I. Mechnikov had discovered the process which is called phagocytosis • Phagocytes (type of leucocyte) eat the pathogen and break down into small particles.

Thrombocytes - Platelets • Blood platelets, or thrombocytes, number approximately 250, 000/mm 3 of blood. • They are 2 -4 μm in diameter, non-nucleated. • Thrombocytes are produced in the bone marrow and are broken down in the lungs and spleen. • Their life span is only approximately 8 days.

Thrombocytes • They play a vital role in preventing blood loss from the body and maintain hemostasis by blood clotting, thus helping to prevent the loss of large volumes of blood.

Blood typing • Blood typing involves two types of molecules called antigens and antibodies. • When antigens enter the bodies of other organisms, they are not recognized, and special molecules, called antibodies, are produced to destroy the foreign antigens. • The membrane of red blood cells contains antigens.

ABO System • On the membrane of a red blood cell, only antigen A, only antigen B, both antigen A and B, or no antigen may be found. • In the simplified ABO system there are four possible blood types

A blood group • Red blood cells carry only antigen A. • The plasma of a such person has antibody b.

B blood group • Red blood cells carry only antigen B. The plasma of a such person has antibody a.

AB blood group • Red blood cells carry both antigen A and antigen B. • Since both of the antigens are present, there is no antibody in the plasma.

O blood group • Red blood cells carry none of the antigens. • Since both of the antigens are foreign to the organism, plasma has both antibody a and antibody b.