Transportation in animals and plants
The blood is made up primarily of 3 types of cells and a fluid medium:
- Red blood cells
- White blood cells
- Plasma (the fluid part)
Transport in Blood
- The red blood cells (RBC) contain a red pigment called haemoglobin
- Haemoglobin binds with oxygen and transports it to all the parts of the body
- White blood cells (WBC) fight against germs
- A clot is formed because of the presence of platelets.
There are different types of blood vessels in the body
- Arteries – Carry oxygen-rich blood from the heart to all parts of the body
- Veins – Carry carbon dioxide-rich blood from all parts of the body back to the heart
- Capillaries – They form the junction where the arteries and veins meet
Pulse and pulse rate
- The throbbing of blood vessels is called the pulse
- 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
The heart has 4 chambers:
- The two upper chambers are called the atria
- The two lower chambers are called the ventricles
The partition between the chambers helps to avoid mixing up of blood rich in O2 with the blood rich in CO2
- The rhythmic contraction followed by its relaxation constitute a heartbeat
- An instrument called a stethoscope is used to amplify the sound of the heart
Do all organisms have a circulatory system?
- Animals such as sponges and Hydra do not posses any circulatory system.
- The water in which they live brings food and oxygen as it enters their bodies
- The water carries away waste materials and carbon dioxide as it moves out
- The process of removal of wastes produced in the cells of the living organisms is called excretion
- The waste which is present in the blood (urea) has to be removed
- This is done by the blood capillaries in the kidneys
- 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
- The urine is passed out through the urinary opening at the end of a muscular tube called urethra
- The urine consists of 95% water, 2.5% urea and 2.5% other waste products
Excretion in other animals
- Aquatic animals like fishes, excrete cell waste as ammonia which directly dissolves in water
- Land animals like birds, lizards, snakes excrete a semi-solid, white coloured compound (uric acid)
- Sometimes a person’s kidney may stop working due to infection or injury
- As a 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
Transport of substances in Plants
Tissue & Vascular tissue
- A group of cells that perform specialised function in an organism
- Plants have pipe-like vessels to transport water and nutrients from the soil.
- The vessels are made of special cells, forming the vascular tissue
Xylem & Phloem
- Vascular tissues called Xylem and phloem transport substances in plants
- Xylem helps in the transport of water and nutrients in the plant,
- They form a continuous network of channels that connects all parts of the plant
- Phloem helps in the transportation of food from the leaves to all parts of the plant
- Water evaporates through the stomata present on the leaves by the process of transpiration.
- Evaporation of water from leaves generates a suction pull which can pull water to great heights in the tall trees
- Transpiration also cools the plant.
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