The organ system of the body that is responsible for the 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.
- 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
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 which 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.
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.
- 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.