Same-type antigens and antibodies should not meet in the recipient’s blood, Knowing the blood group of the donor and of the recipient is mandatory, A 0-group donor can donate blood to all the other blood groups, An AB-group recipient can receive blood from groups A and B

Their primary role is to protect tissues against infections and foreign substances in the body, They have a nucleus which can have two or more lobes or can have different sizes and shapes, Enter the blood stream by diapedesis and leave the blood stream in the same way

Depending on the presence of cytoplasmic granules, they can be classified into granulocytes and agranulocytes, Depending on their type, they can remain in the blood stream for a few hours up to a few months, Neutrophils belong to granulocytes

They migrate from the blood into the tissues by diapedesis, Once in the bloodstream, certain types of leukocytes finish their maturation process in the thymus (T lymphocytes), Neutrophils, eosinophils and basophils contain granules in their cytoplasm (they are granulocytes)

They represent about 30% of the total number of leukocytes and they are of two types, B lymphocytes and T lymphocytes, Both lymphocyte types can be found in the lymph nodes and in the blood, B lymphocytes, stimulated by the body’s antigens during the immune response, proliferate and turn into plasmocytes

They are formed in the red bone marrow from megakaryocytes, Their approximate number is of 300000/mm3 blood, They are involved in haemostasis by forming platelet aggregation

The cardiovascular system consists of the heart and blood vessels, The cardiovascular system includes a set of tubes which transport blood (blood vessels), The heart is the organ which acts like a pump in the cardiovascular system

It is situated in the mediastinum, in the thoracic cavity, It is bordered by the lungs, which overlap on it, It is a four-cavity organ (two atria and two ventricles)

They are two cavities, situated superior to the ventricles, Both have a flat, wrinkly, projection called atrial appendage or auricle, They are cavities which serve to fill the heart with blood

There are two ventricles situated inferior to the atria, They are heart cavities acting as a pump, The left ventricle pumps oxygenated blood into the aorta

It begins in the left heart, The left ventricle receives, through the bicuspid valve, oxygenated blood from the left atrium, The arteries of the systemic circulation take the blood to the head, thorax, abdominal region and other parts of the body

They ensure the unidirectional flow of the blood, preventing its reflux, Two of the heart valves are called atrioventricular valves, the other two being called semilunar valves, Atrioventricular valves let blood flow from the atria into the ventricles, preventing it to return into the atria when the ventricles contract

It represents a mass of cardiac muscle cells and is situated in the superior wall of the right atrium, It is characterised by auto-rhythmicity thus determining the rhythm of cardiac contractions (pacemaker), It depolarizes without nerve involvement approximately 70-80 times/minute

It records the transmission of the nerve impulse through the heart’s cardiac conduction system, A normal ECG recording shows the following succession: P wave, QRS complex and T wave, which appear in every cardiac cycle, The P wave shows atrial depolarisation

Atrial depolarisation wave – ascending wave – P wave, Ventricular depolarisation complex – QRS complex, Ventricular repolarisation wave – rounded deflection – T wave

The term „systole” refers to the heart’s contractions, The term „diastole” refers to the heart’s relaxation periods, Consists of systole and diastole

They form a network of tubes which transport blood from the heart to the body’s tissues and back, Veins result from the union of venules (small veins) and carry blood back to the heart, Arteries are divided into small vessels called arterioles and the latter are subdivided into capillaries

They are vessels that carry high-pressure blood from the heart to the arterioles, They have a three-layered thick and tough wall, They have an empty central space, called lumen

Their function is to facilitate the exchange between blood and tissues, The passage of blood into the capillary bed is regulated by the precapillary sphincter, The exchanges between blood and cells in the body take place in a transendothelial manner according to Starling’s law of fluid movements

They carry low-pressure blood from the venules to the heart, Hold approximately 60% of the blood volume (they act as the body’s blood reservoirs)

It represents a pressure wave in the arteries, due to the contractions of the left ventricle, It is normally measured at the radial artery at wrist level, It has the same rate as the heart rate, an average of 70 – 75 beats/minute

It can be coordinated by the regulating centres in the encephalon or other areas of the nervous system, It is coordinated by the vasomotor centre in the medulla oblongata, It can also be carried out by baroreceptors which are indirectly involved by vasoconstriction or vasodilation

The right axillary artery (for the right upper limb), The brachial, radial and ulnar arteries (for the arm and forearm), The femoral, popliteal, anterior tibial, posterior tibial and the dorsal arch (for the lower limb)

It carries blood from the gastrointestinal tract and spleen to the liver, It carries nutrients to the liver in order to be processed, the main vessel being the portal vein, It carries low-oxygen blood as it has supplied the gastrointestinal tract