**Physiological Functions of Blood:**
– Supply of oxygen to tissues through hemoglobin
– Supply of nutrients like glucose, amino acids, and fatty acids
– Removal of waste such as carbon dioxide, urea, and lactic acid
– Immunological functions, including circulation of white blood cells
– Coagulation to stop bleeding and detect tissue damage
**Composition of Blood:**
– Blood accounts for 7% of human body weight
– Average adult has a blood volume of roughly 5 litres
– Composed of plasma and formed elements (red blood cells, white blood cells, platelets)
– Red blood cells make up about 45% of whole blood
– Plasma, cells, and formed elements exhibit non-Newtonian fluid dynamics
**Physiological Processes Involving Blood:**
– Cell production and degradation
– Oxygen transport through hemoglobin
– Carbon dioxide transport and its effects on oxygen binding
– Transport of hydrogen ions
– Lymphatic system functioning and equilibrium with blood
**Blood Circulation and Regulation:**
– Circulatory system and the role of blood vessels and the heart
– Homeostatic mechanisms controlling blood pH and gases
– Thermoregulation through blood flow adjustments
– Rate of blood flow to various organs and tissues
– Hydraulic functions like blood flow restriction and engorgement
**Blood-related Disorders and Treatments:**
– Blood loss, clotting issues, shock, atherosclerosis, and vessel blockages
– Hematological disorders like anemia, leukemia, and hemophilia
– Carbon monoxide poisoning and its effects on oxygen transport
– Various treatments including blood transfusions, medications, and plasma expanders
– Historical practices like bloodletting and cultural beliefs surrounding blood
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Blood is a body fluid in the circulatory system of humans and other vertebrates that delivers necessary substances such as nutrients and oxygen to the cells, and transports metabolic waste products away from those same cells.
| Blood | |
|---|---|
 Venous (darker) and arterial (brighter) blood | |
| Identifiers | |
| MeSH | D001769 |
| TA98 | A12.0.00.009 |
| TA2 | 3892 |
| FMA | 9670 |
| Anatomical terminology | |
Blood is composed of blood cells suspended in blood plasma. Plasma, which constitutes 55% of blood fluid, is mostly water (92% by volume), and contains proteins, glucose, mineral ions, and hormones. The blood cells are mainly red blood cells (erythrocytes), white blood cells (leukocytes), and (in mammals) platelets (thrombocytes). The most abundant cells are red blood cells. These contain hemoglobin, which facilitates oxygen transport by reversibly binding to it, increasing its solubility. Jawed vertebrates have an adaptive immune system, based largely on white blood cells. White blood cells help to resist infections and parasites. Platelets are important in the clotting of blood.
Blood is circulated around the body through blood vessels by the pumping action of the heart. In animals with lungs, arterial blood carries oxygen from inhaled air to the tissues of the body, and venous blood carries carbon dioxide, a waste product of metabolism produced by cells, from the tissues to the lungs to be exhaled. Blood is bright red when its hemoglobin is oxygenated and dark red when it is deoxygenated.
Medical terms related to blood often begin with hemo-, hemato-, haemo- or haemato- from the Greek word αἷμα (haima) for "blood". In terms of anatomy and histology, blood is considered a specialized form of connective tissue, given its origin in the bones and the presence of potential molecular fibers in the form of fibrinogen.[citation needed]