The organ system of the body that is responsible for the transport of material throughout the body is called the circulatory system.
- The materials transported are nutrients, oxygen, carbon dioxide, cells, etc
- The medium of transportation is blood.
- The primary parts of the circulatory system are heart, arteries and veins.
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- Blood is a fluid tissue that transports nutrients and oxygen to the cells and carries away carbon dioxide and other waste products in our body.
- The fluid part of blood is called plasma and has various salts and nutrients dissolved in it.
- Blood cells are suspended in plasma and they are Red Blood Cells (RBCs), White Blood Cells (WBCs) and Platelets.
- Plasma is the liquid component of the blood in which most of the blood cells are suspended.
- It is mostly made up of water (up to 95%) and contains dissolved nutrients, carbon dioxide and oxygen.
- Red blood cells (RBC) present in the blood are responsible for the transport of oxygen throughout the body.
- They contain a red pigment called haemoglobin, which binds with the oxygen.
- The reddish colour of the blood is due to haemoglobin.
- The blood contains white blood cells (WBC), which are part of the immune system.
- They are like soldiers, which fight and kill germs that may enter the body.
- Platelets are the smallest cells in the blood.
- By clumping together, they form a blood clot, preventing loss of blood due to bleeding.
- They prevent excessive damage to the blood vessels by binding together at the site of damage.
- Blood vessels are tubes that carry blood all over the body.
- Arteries, veins and capillaries are collectively called as blood vessels.
- Arteries are blood vessels that carry oxygenated blood to the cells and tissues of our body.
- They carry blood from the heart to the tissues.
- Veins are blood vessels that carry away deoxygenated blood from the cells and tissues of our body.
- They carry blood from tissues to the heart.
- Capillaries are the smallest of the body’s blood vessels.
- It serves the most important task of the circulatory system: exchange of material between circulation and cells.
- The fine network makes it easy for the process of diffusion of materials due to the increase in surface area.
- The heart is a muscular organ in animals that pumps blood through blood vessels to all the parts of the body.
- The heart consists of four chambers that prevent the oxygenated and deoxygenated blood from mixing.
- The upper chambers are called as atria and the lower chambers are called as ventricles.
- Valves are present in the heart as well as in veins.
- In the heart, they are present between atria and ventricles and at the base of big vessels leaving the heart.
- Valves are responsible for the unidirectional flow of blood in the body.
- Opening and closing of the valves present in the heart is responsible for the lub-dub sound of the heart.
- It is the network of arteries and veins connecting the heart and lungs.
- Deoxygenated blood is pumped from the blood to the lungs for oxygenation.
- The oxygenated blood returns to the heart to be pumped to the rest of the body.
Oxygenation of Blood
- Oxygenation of blood occurs at the alveoli in the lungs.
- The alveoli have blood vessels wrapped around it and the blood is oxygenated by diffusion.
- The heart periodically expands and contracts to pump blood into the arteries, which also expands and contracts as the blood flows through them. This is called pulsation.
- This pulsation of the arteries can be felt at certain places of the body such as the wrist.
- Pulsation is measured as the number of heartbeats per minute, which is nothing but pulse rate
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The process of removal of waste products from the cells of living organisms is called excretion.
- For human beings, the waste products are in the form of carbon dioxide, urine and faeces.
- Our body’s main excretory organs are the kidneys.
- There is a pair of kidneys present on either side of the spine.
- Each kidney is a bean-shaped organ, reddish in colour.
- It contains millions of tiny tubules that act as microscopic filters and filter out the useful and harmful substances from the blood.
- The useful substances are again reabsorbed back into the blood and only harmful substances are concentrated.
- These harmful substances are present in a dissolved state in water and now it is called as urine.
- Urine is excreted out of the body.
- Thus, kidneys act as filters of our body.
- Urine is sent from the kidneys to the urinary bladder through tubes called ureters.
- The urinary bladder is a muscular bag where urine is accumulated and excreted from the body through the urethra.
- It can hold about 300-500 mL urine for a while before the urge to empty occurs.
- Dialysis is the filtering of blood outside the human body using a machine, when both the kidneys fail.
Excretion in Other Animals
- Excretion in different animals differs based on the excretory material.
- Ammonia, urea and uric acid are the commonly excreted material.
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Transportation in Plants
Osmosis is the movement of solvent molecules from a region of lower solute concentration to a region of higher solute concentration through a semi-permeable membrane.
- Root hairs are elongated extensions of the roots that are comparable to hairs on animals.
- They increase the surface area for increased exchange of water and minerals.
- Phloem is the plant tissue that transports the soluble organic material created during photosynthesis from the leaves to the other parts of the plant.
- Xylem is the plant tissue that transports the water and other nutrients from the roots to other parts of the plant.
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- Transpiration is the loss of water in the form of water vapour from stomata present on leaves.
- This process also helps the plants absorb and distribute water through their roots.
- Transpiration exerts a straw-like effect and the water moves up against gravity in tubes made of xylem cells.
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