Human blood is a fluid connective tissue that circulates throughout the body, carrying oxygen and nutrients to cells while removing waste products; it primarily consists of plasma (liquid component), red blood cells (oxygen transport), white blood cells (immune function), and platelets (clotting mechanism) which all originate in the bone marrow.
Key components:
Plasma:
The liquid part of blood, primarily composed of water, proteins, electrolytes, nutrients, and hormones.
Red blood cells (erythrocytes):
Small, biconcave cells that carry oxygen from the lungs to tissues and carbon dioxide back to the lungs.
White blood cells (leukocytes):
Cells involved in immune response, fighting infections by attacking bacteria and viruses.
Platelets (thrombocytes):
Cell fragments crucial for blood clotting at injury sites.
Functions of blood:
Oxygen delivery: Transporting oxygen from the lungs to tissues throughout the body.
Nutrient transport: Carrying nutrients absorbed from the digestive system to cells.
Waste removal: Carrying carbon dioxide and other waste products from cells to the excretory organs.