Body Fluids and Circulation Test - 19

The bone marrow produces the cellular elements of the blood, including platelets, red blood cells and white blood cells. Red marrow is found in the flat bones, such as the pelvis, sternum, cranium, ribs, vertebrae and scapulae, and in the cancellous material at the epiphyseal ends of long bones such as the femur and humerus. Platelets which are a part of blood are produced in the red bone marrow along with many other cells. 

Polycythemia is a disease state in which the proportion of blood volume that is occupied by red blood cells increases. Blood volume proportions can be measured as hematocrit level. It can be due to an increase in the number of red blood cells or to a decrease in the volume of plasma.

Maintaining a steady internal environment by maintaining equilibrium within the body, for its proper functioning is called homeostasis. Human blood plays multiple functions in maintaining homeostasis. Blood acts as the vehicle that carries messengers, nutrients and essential elements like glucose, potassium, sodium, proteins, hormones, and enzymes for organs to function at a normal level. It helps in transport and exchange of respiratory gases. It carries cellular wastes, in particular, carbon dioxide and lactic acid away from the cells. It regulates body temperature through vasodilation and vasoconstriction. It plays a major role in maintaining acid-base balance (pH) in the body through red blood cells, and bicarbonate ions, by regulating the amount of $${CO_{2}}$$. 

ECG is a graphical representation of the electrical activity of the heart during a cardiac cycle. Each peak in the ECG is identified with a letter from P to T that corresponds to a specific electrical activity of the heart. The P-wave represents the electrical excitation (or depolarisation) of the atria, which leads to the contraction of both the atria. The T-wave represents the return of the ventricles from excited to normal state (repolarisation). The end of the T-wave marks the end of systole.

All of them are anticoagulant. 'Citrate' is in liquid form and is used for coagulation tests, as well as in blood transfusion bags. It binds with the calcium ion, preventing the coagulation proteins from using them and thus prevent blood from clotting and this can be reversed with the addition of calcium. It can be in the form of sodium citrate or acid-citrate-dextrose.
'Oxalate' is an anticoagulant, which has a mechanism similar to that of citrate. It is used in fluoride oxalate tubes, used to determine glucose and lactate levels.
'Dicoumarol' is a naturally occurring anticoagulant that functions as a functional vitamin K depleter. It is also used in biochemical experiments as an inhibitor of reductases.
'Heparin' is widely used anticoagulant. It works by activating antithrombin III, which blocks thrombin from clotting blood. It can be used in vivo as an injectable anticoagulant. It can also be used to form an inner anticoagulant surface on various experimental and medical devices such as test tubes and renal dialysis machines.

During an injury, the platelets aggregate at the site of injury and get transformed. The transformed platelets release thromboplastin which converts the prothrombin into thrombin. Thrombin is the proteolytic enzyme that converts the fibrinogen into the thin filaments of fibrin which makes the insoluble network of the fibril and forms the clots of the blood containing the red blood cells, pathogens, platelets, factors, etc.

• Humans have four-chambered hearts with complete separation between oxygenated and deoxygenated blood. 
• The auricles receive the blood and ventricles pump the blood. 
• Right auricles receive deoxygenated blood from the body and pass it to the right ventricle. 
• At the same time, the left auricle receives oxygenated blood from the lungs. 
• The right ventricle pumps deoxygenated blood to the lungs for oxygenation and at the same time, the left ventricle pumps oxygenated blood to the body. 
• Pulmonary circulation is the circulation of deoxygenated blood from the right ventricle to the lungs and from the lungs, the oxygenated blood comes to the left auricle.

Acid citrate dextrose solution (anticoagulant citrate dextrose solution) is a solution of citric acid, sodium citrate and dextrose in water. It is mainly used as an anticoagulant to preserve blood specimens required for tissue typing because it removes the calcium ion which plays an important role in blood clotting reaction.

An electrocardiogram (ECG) is a medical test that detects cardiac (heart) abnormalities by measuring the electrical activity generated by the heart as it contracts. The ECG can help diagnose a range of conditions including heart arrhythmias, heart enlargement, heart inflammation (pericarditis or myocarditis) and coronary heart disease.