Blood is a type of tissue called complex tissue(Because it is made of cells with a specific function). it is made of Plasma, Red blood cells, White blood cells, and platelets.

There are different types of blood(A+, A-, AB+, AB-, B+, B-, O+, O-).

The function of blood is to transport oxygen and nutrients to the body cells.

90% of plasma is made of water and the other 10% of other materials. There are 3 types of proteins in plasma; One of them helps regulates the amount of water in blood; The other one produces white blood cells; The last forms blood clots with platelets.

Red blood cells take up oxygen in the lungs and deliver it to cells throughout the body.

Erythrocytes are a type of blood cell that is made in the bone marrow and found in the blood. They are disc like cells with a large and round nucleus.

The platelets are the smallest cells- are really fragments of other cells.

The red blood cells contain hemoglobin which is a protein that contains iron and binds chemically to oxygen molecules. Hemoglobin is the one that contains the iron of the blood.

They produce antibodies to destroy pathogens. (Any microorganism; Virus, bacteria, fungi, that can cause a disease)

White blood cells have something called Antigens, these protect the body from the pathogens such as bacteria and viruses.

They are bigger than red blood cells and they have an spherical nucleus. They destroy bacteria and microorganisms.