7. Transportation in Animals and Plants

Circulation in Human body:

Blood flow in heart, lungs & body:

Excretory system in humans:

Circulation in plants:

Quick revision notes

1. Human circulatory system consists of:

• Blood: It is the fluid that carries oxygen & nutrients to all the parts of body and carries waste products to be removed.
• Heart: It is the organ which beats continuously to act as a pump for the transport of blood.
• Blood vessels: They are arteries, veins & capillaries.

2. Blood consists of:

• Plasma: Blood is composed of a yellowish fluid called plasma that carries nutrients & waste.
• Red blood cells (RBC): They contain a red pigment called haemoglobin which helps in transportation of oxygen. 
• White blood cells (WBC): They fight against germs, diseases, bacteria or any infection in the body.
• Platelets: Help the blood to clot.

3. Functioning of Heart:

• The heart is made of four chambers.
• Upper two chambers are called atrium & lower two chambers are called ventricles.
• Deoxygenated blood enters the right atrium through the vena cava.
• This deoxygenated blood goes to the right ventricle from there it is transported to the lungs through the pulmonary artery.
• In the lungs carbon dioxide is removed and the blood is oxygenated and sent to the left atrium of the heart through pulmonary vein.
• This oxygenated blood is transported from the left ventricle of the heart to the body through the aorta.

4. Stethoscope:

• The stethoscope consists of two ear pieces and one chest piece having a sensitive diaphragm.
• A tube connects both these pieces.
• The stethoscope amplifies the sound of our heart.
• This helps the doctors to know the condition of the heart.

5. Blood vessels:

• Arteries carry oxygenated blood from the heart to all the parts of the body. They have thick elastic walls.
• Veins carry deoxygenated blood from all the parts of the body back to the heart. They have thin walls & valves.
• On reaching the tissues arteries divide into capillaries which in turn join to form veins.

Exception:

• Pulmonary artery carries deoxygenated blood from the heart to the lungs.
• Pulmonary vein carries oxygenated blood from the lungs to the heart.

6. Excretory system in humans:

• The blood containing both useful and harmful substances reaches the kidneys.
• The blood capillaries in the kidneys filter this blood.
• The useful substances are absorbed back into the blood.
• The wastes are dissolved in water are removed as urine.
• Then tubes called ureters pass the urine from into the urinary bladder.
• Urine is stored in the bladder and is passed out through the urinary opening at the end of a muscular tube called urethra.
• Thus, the kidneys, ureters, bladder and urethra form the excretory system.

7. Waste in different organisms:

• Human - urine ( 95% water, 2.5% urea and 2.5% other waste)
• Aquatic animals -  ammonia 
• Birds, lizards & snakes - uric acid (semi-solid, white coloured compound).

8. Dialysis:

• Sometimes a person’s kidneys 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.

9. Circulation in plants:

• The plants have pipe-like vessels made of special cells, forming the vascular tissue. 
• 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. 
• The food is transported to all parts of the plant through the vascular tissue called the phloem.
• Thus, xylem and phloem transport substances in plants & form the circulatory system.

10. Transpiration in plants:

• Out of the water absorbed by the plants, some of it evaporates from the stomata by the process of transpiration.
• This creates a suction pull which enables the roots to absorb more water from the soil.
• It also keeps the plant cool.