Human Circulatory System

Platelets are produced in the bone marrow, the same as the red cells and most of the white blood cells. Platelets are produced from very large bone marrow cells called megakaryocytes.

Thromboplastin is a plasma protein aiding blood coagulation through catalyzing the conversion of prothrombin to thrombin.

 The tricuspid valve, or right atrioventricular valve, is on the right dorsal side of the mammalian heart, between the right atrium and the right ventricle. The function of the valve is to prevent back flow of blood into the right atrium.

In open circulatory systems (found in arthropods and mollusks), the circulating fluid is called hemolymph, which is analogous to blood in closed systems. Hemolymph directly bathes the tissues in body cavities called sinuses. Blood (D) is specific to closed circulatory systems. Perilymph relates to the inner ear, and lymphatic fluid is part of the lymphatic system.

Pulmonary veins are the only veins in the body that carry oxygenated blood, transporting it from the lungs back to the left atrium of the heart. This oxygen-rich blood is then pumped to the rest of the body through the systemic circulation.

Coronary veins drain deoxygenated blood from the heart muscle (myocardium). Coronary arteries supply oxygenated blood TO the heart. Pulmonary veins carry oxygenated blood from lungs to heart, while pulmonary arteries carry deoxygenated blood to lungs.

Prawns have an open circulatory system where hemolymph (not true blood) is pumped by the heart into body cavities (sinuses). The heart receives and pumps mixed hemolymph containing both oxygenated and deoxygenated components, as there's no complete separation like in closed circulatory systems.

Insects have an open circulatory system where hemolymph (blood) is pumped into body cavities called hemocoel, directly bathing the organs. Unlike closed systems, the blood is not confined to vessels throughout most of the body. Reptiles have closed circulation, man has a closed circulatory system, and 'animals' is too broad since most vertebrates have closed systems.

The internal pudendal arteries serve as the penile blood supply by entering the penis dorsally and running deep into the tissues of the corpora cavernosa. The internal pudendal artery becomes the penile artery.

In mammals, deoxygenated blood from the right atrium (auricle) enters the right ventricle, then is pumped to the lungs via the pulmonary artery (pulmonary aorta). This is part of pulmonary circulation. The systemic aorta carries oxygenated blood from the left ventricle.

Lymph glands primarily filter lymph, produce lymphocytes and antibodies, and help fight infections by trapping pathogens. The destruction of red blood cells occurs mainly in the spleen and liver, making this the correct choice as it is NOT a primary function of lymph nodes.

Haemoconia refers to small, granular particles occasionally observed in blood plasma, distinct from platelets which are cellular components involved in clotting. Chylomicrons are lipoprotein particles transporting dietary lipids, and chyluria indicates a milky appearance of urine due to lymph presence.

The liver synthesizes major plasma proteins including albumin (maintains oncotic pressure), fibrinogen (essential for clotting), and prothrombin (a clotting factor). This protein synthesis function is exclusive to hepatocytes, distinguishing the liver from other organs listed.

Heparin, produced by mast cells and basophils, acts as a natural anticoagulant by enhancing antithrombin III activity, which inhibits thrombin and factor Xa. This prevents inappropriate clotting in intact blood vessels during normal circulation.

The pulmonary vein uniquely carries oxygenated blood from the lungs to the left atrium. All other options carry deoxygenated blood: renal vein (A) from kidneys, hepatic portal vein (B) from GI tract to liver, and pulmonary artery (C) from heart to lungs.