Railway Science (Biology – Circulatory System)

The largest artery of the body carries blood from the heart to the circulatory system. Circulation of blood: Heart pumps oxygenated blood through the arteries to the rest of the body; Veins bring oxygen-depleted blood back to the heart to restart circulation.
Pulmonary Artery: carries deoxygenated blood from the right ventricle of the heart to the lungs for oxygenation.
Pulmonary vein: Blood vessels that carry oxygen-rich blood from lungs to the left atrium of the heart.
Vena cava: The superior and inferior vena cava are major blood vessels responsible for returning deoxygenated blood to the heart.
The superior vena cava returns deoxygenated blood from the upper portion of the body including the head, neck, arms, and chest while the inferior vena cava returns blood to the heart from the lower portion of the body including the abdomen, pelvis, legs, and feet.

Fishes like Rohu, Dogfish, Seahorse are marine and cold-blooded creatures with two chambered hearts. Amphibians such as Frogs, Toads, Salamanders have three-chambered hearts.
All mammals, Crocodiles, Blue whales and birds like Ostrich, Pigeon, Bat, whale, etc possess a four-chambered heart.
The animal with eight hearts is Barosaurus. Earthworms have five hearts. A cockroach has one heart, but the heart may have as many as 13 chambers .

Human body uses iron to make hemoglobin - A protein in red blood cells that carries oxygen from the lungs to all parts of the body. Myoglobin, A protein that provides oxygen to muscles. Deficiency of Iron causes Anaemia. Magnesium - It regulates muscle and nerve function, blood sugar levels, and blood pressure and makes protein, bone, and DNA. Cobalt - A necessary component of Vitamin B12 (Cyanocobalamin) and a fundamental coenzyme of cell mitosis. Manganese - It helps in blood clotting.

Blood groups (Inventor - Karl Landsteiner) - A blood type is a classification of blood, based on the presence and absence of antibodies and inherited antigenic substances on the surface of red blood cells.
AB⁺- are universal plasma and platelet donors. A⁺- Blood contains type-A antigens with the presence of a protein called the rhesus (Rh) factor. O⁺ - The universal donor (can donate red blood cells to anybody).

Aorta - It is the main artery that carries blood away from your heart to the rest of your body. The blood leaves the heart through the aortic valve. Vena cava - A large vein that carries blood to the heart from other areas of the body.
Renal artery - The main blood vessel that supplies blood to a kidney and its nearby adrenal gland and ureter. Pulmonary arteries - It functions to transport deoxygenated blood from the right side of the heart to the lungs for oxygenation.

It is an iron-rich protein found in red blood cells. It has less affinity for Carbon dioxide as compared to oxygen because Carbon dioxide is a larger molecule than oxygen. Melanin is a natural skin pigment.

Fish blood circulation is called venous circulation. It has a single circuit for blood flow and a two-chambered heart that has only a single atrium and a single ventricle. The atrium collects blood that has returned from the body and the ventricle pumps the blood to the gills where gas exchange occurs and the blood is reoxygenated (gill circulation).

Blood - A fluid connective tissue that consists of plasma, blood cells and platelets. It makes up 8% of our body weight. An average adult possesses around 5-6 litres of blood.
Types of Blood Cells: Red blood cells (RBC) - Carry oxygen from the lungs and transport it to all the organs of our body.
White blood cells (WBC) - Help the immune system fight off infections. Platelets - Tiny blood cells that help your body form clots to stop bleeding.

The two renal arteries - The right renal artery supplies blood to the right kidney, while the left artery sends blood to the left kidney. Coronary arteries supply oxygenated blood to the heart muscle.
Renal veins - Blood vessels that carry filtered blood to the heart from the kidney. Vena Cava - Largest vein that carries deoxygenated blood from various parts of the body back to the heart.

The Heart weighs an average of 236 to 412 gm. Its size is equal to the clenched fist. It is a muscular organ, comprising cardiac muscle tissue which rhythmically pumps blood through blood arteries and contracts repeatedly. It is the main component of the circulatory system. Weight (Brain) : 1300 to 1400 grams.