NCERT Gist: Transportation In Animals And Plants | Additional Study Material for UPSC PDF Download

Circulatory System

- Blood- the fluid which flows in blood vessels.
- It transports substances like digested food from the small intestine to the other parts of the body.
- It carries oxygen from the lungs to the cells of the body.
- It also transports waste for removal from the body.
- The fluid part of the blood is called plasma. One type of cells is the red blood cells (RBC) which contain a red pigment called haemoglobin.
- Haemoglobin binds with oxygen and transports it to all the parts of the body and ultimately to all the cells.
- It will be difficult to provide oxygen efficiently to all the cells of the body without haemoglobin. The presence of haemoglobin makes blood appear red.
- The blood also has white blood cells (WBC) which fight against germs that may enter our body.
- The clot is formed because of the presence of another type of cells in the blood, called platelets. Two types of blood vessels, arteries and veins are present in the body.
- Arteries cany oxygen-rich blood from the heart to all parts of the body. Since the blood flow is rapid and at a high pressure, the arteries have thick elastic walls.
- The number of beats per minute is called the pulse rate.
- A resting person, usually has a pulse rate between 72 and 80 beats per minute.
- Veins are the vessels which carry carbon dioxide-rich blood from all parts of the body back to the heart.
- The veins have thin walls. There are valves present in veins which allow blood to flow only towards the heart.
- Arteries divide into smaller vessels. On reaching the tissues, they divide further into extremely thin tubes called capillaries.
- The capillaries join up to form veins which empty into the heart.
- The heart has four chambers. The two upper chambers are called the atria (singular: atrium) and the two lower chambers are called the ventricles.
- The partition between the chambers helps to avoid mixing up of blood rich in oxygen with the blood rich in carbon dioxide.
- A doctor uses the stethoscope as a device to amplify the sound of the heart.
- It consists of a chest piece that carries a sensitive diaphragm, two ear pieces and a tube joining the parts.
- When our cells perform their functions, certain waste products are released. These are toxic and hence need to be removed from the body.
- The process of removal of wastes produced in the cells of the living organisms is called excretion. The parts involved in excretion forms the excretory system.
- The waste which is present in the blood has to be removed from the body.
- This is done by the blood capillaries in the kidneys. When the blood reaches the two kidneys, it contains both useful and harmful substances.
- The useful substances are absorbed back into the blood.
- The wastes dissolved in water are removed as urine.
- From the kidneys, the urine goes into the urinary bladder through tube-like ureters.
- It is stored in the bladder and is passed out through the urinary opening at the end of a muscular tube called urethra.
- The kindeys, ureters, bladder and urethra form the excretory system. Sometimes a person’s kidneys may stop working due to infection or injury.
- Asa result of kidney failure, waste products start accumulating in the blood.
- Such persons cannot survive unless their blood is filtered periodically through an artificial kidney. This process is called dialysis.
- Plants have pipe-like vessels to transport water and nutrients from the soil.
- The vessels are made of special cells, forming the vascular tissue.
- A tissue is a group of cells that perform specialised function in an organism.
- The vascular tissue for the transport of water and nutrients in the plant is called the xylem.
- The xylem forms a continuous network of channels that connects roots to the leaves through the stem and branches and thus transports water to the entire plant.
- Leaves synthesise food. The food has to be transported to all parts of the plant. This is done by the vascular tissue called the phloem.
- Thus, xylem and phloem transport substances in plants. Plants absorb mineral nutrients and water from the soil.
- Not all the water absorbed is utilised by the plant.
- The water evaporates through the stomata present on the surface of the leaves by the process of transpiration.