Railway Science (Biology – Circulatory System)

A thermometer is a device that measures temperature. Breathing in and out with a spirometer helps keep the lungs active and free of fluid by measuring the amount of breath.

Pulmonary veins - they carry oxygenated (oxygen-rich) blood in the body. It is part of the pulmonary circulation. Other veins (blood vessels) carry oxygen-poor blood. Similarly, pulmonary arteries are the only arteries that carry oxygen-poor blood, and the rest of arteries carry oxygen-rich blood.

When the heart beats, it contracts and pushes blood through the arteries to the body. This force creates pressure on the arteries. This is called systolic blood pressure. The Diastolic blood pressure indicates the pressure in the arteries when the heart rests between beats. High blood pressure - Hypertension, Kidney problem. Low blood pressure - Dizziness, Nausea.

Arteries carry oxygenated blood from the heart to different parts of the body. Veins carry deoxygenated blood. Pulmonary artery - deoxygenated blood. Pulmonary vein - oxygenated blood. Veins are the only blood vessels that can be seen near the surface of the skin since arteries are generally present at deeper levels.

Salamander (amphibian). Its heart has two atria and one single ventricle. Fish have two-chambered hearts (one atrium and one ventricle). The tiger and pigeon heart has 4 chambers consisting of 2 atria and 2 ventricles.
Human heart has four chambers (2 upper and 2 lower) in which blood flows. The upper chambers, the right and left atria, receive incoming blood. The lower chambers, the muscular right and left ventricles, pump blood out of the heart.

In fish the blood is pumped through the capillaries of the gills and onto the capillaries of the body tissues. Fish heart has a single pump (consisting of two chambers with an atrium and a 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; this is called gill circulation. Fish have a closed-loop circulatory system.

Fishes and Seahorses have two - chambered hearts (one auricle and one ventricle). Four-chambered heart animals (two auricles and two ventricles) - Birds and Mammals such as crocodile, ostrich, pigeon, bat, peacock and whale.

Warm-blooded animals (birds and mammals) maintain a constant body temperature by cooling themselves when in a hot environment and vice versa. To maintain their body temperature these animals require more oxygen for more cellular respiration so that they can produce more energy.
If oxygenated and deoxygenated blood mix together, the availability of oxygen for cellular respiration will be reduced and result in difficulty in maintaining the internal body temperature.

It is a fluid made up of white blood cells that attack harmful bacteria in the blood.

increases resistance and decreases blood flow which leads to increase in blood pressure. Normal blood pressure is defined as being below 120/80, where 120 represents the systolic (maximum) measurement and 80 represents the diastolic (minimum) measurement.