Respiration & Transportation in Humans class 10th science

Respiration & Transportation in Humans


  • Air enter through the nostrils. The hairs and mucous traps the dust particles. It then passes through the phraynx, larynx, trachea, bronchi and enters the lungs. The trachea has rings of cartilage which prevents it from collapsing when there is no air in the trachea. The bronchi divides into smaller tubes called bronchioles which ends in tiny air sacs called alveoli. The alveoli is supplied with blood vessels through which exchange of gases takes place. The alveoli helps to increase the surface area for the exchange of gases.

Mecahanism of breathing :-

  • When we breathe in air, the muscles of the diaphragm contracts and moves downward and the chest cavity expands and air enters into the lungs.
  • When we breathe out air, the muscles of the diaphragm relaxes and moves upward and the chest cavity contracts and air goes out of the lungs.
  • Transportation :-

    • a) Transportation in Human beings :-
    • The main transport system in human beings is the circulatory
    • system. It consists of blood, arteries, veins capillaries and heart.
    • i) Blood :- transports food, oxygen and waste products. It consists of
    • plasma, red blood cells (RBC), white blood cells (WBC) and platelets.
    • Plasma transports food, water, carbondioxide, nitrogenous waste etc.
    • Red blood cells transports oxygen. White blood cells kills harmful
    • microbes and protects the body. Platelets help in clotting of blood and
    • prevents loss of blood during injury.
    • ii) Arteries :- carry pure blood from the heart to all parts of the body.
    • They are thick walled and do not have valves.
    • ii) Arteries :- carry pure blood from the heart to all parts of the body.
    • They are thick walled and do not have valves
    • Heart :- is a muscular organ which pumps blood to all parts of the body. It has four chambers. The upper chambers are called atria and the lower chambers are called ventricles. Since the ventricles pump blood to the different organs its walls are thicker than the atria. The right and left chambers are separated by a septum. It prevents the mixing of oxygenated and deoxygenated blood The atria and ventricles have valves between them to prevent blood flowing backward
    • Working of the heart ( Circulation of blood ) :-
    • When the left atrium relaxes oxygenated blood from the lungs flows into it through the pulmonary vein. When it contracts, the left ventricle expands and the blood flows into it. Then the left ventricle contracts and the oxygenated blood is pumped out through the aorta to all parts of the body. After circulating through all parts of the body the deoxygenated blood enters the right atrium through the vena cava. When the right atrium contracts, the right ventricle expands and the blood flows into it. Then the right ventricle contracts and the blood is pumped to the lungs through the pulmonary artery. In the lungs carbon dioxide is removed and oxygen is absorbed and the oxygenated blood again enters the left atrium and the process repeats.
    • Since blood flows through the heart twice in one cycle, it is called double circulation.

    • Lymph :- is a colourless fluid present in intercellular spaces. It is formed from the plasma which escapes from the capillaries. Lymph drains into lymphatic capillaries which forms lymph vessels and joins into large veins.
    • Lymph transports digested fats and drains excess fluids from intercellular spaces back into the blood. It contains lymphocytes which kills germs and protects the body

    Hearts of mammals, birds, amphibians, reptiles, and fishes :-

    • i) The heart in mammals :- and birds have four chambers and the right and left sides of the heart is separated by a septum. This prevents mixing of oxygenated and deoxygenated blood and provides efficient supply of oxygen. This is necessary because they need more energy to maintain their body temperature.
    • ii) The heart in amphibians and reptiles :- have three chambers and allows some mixing of oxygenated and deoxygenated blood because the do not use energy to maintain their body temperature. Their body temperature is the same as the temperature of the surroundings.
    • iii) The heart in fishes :- have only two chambers and blood is oxygenated in the gills.

    Transportation in plants :-

    • In plants, transportation of materials like food, water and minerals takes place through conducting tissues called xylem and phloem.
    • i) Xylem :- transports water and minerals from the roots to all parts of the plant. It consists of xylem vessels and tracheids. Water and minerals enter the roots by diffusion. Then due to transpiration, the suction force helps in the upward movement of water an minerals.
    ii) Phloem :- transports food from the leaves to the other parts of the plant. This process is called translocation. The phloem consists of sieve tubes and companion cells. Food from the leaves is transferred to the xylem by the energy of ATP molecules. Due to osmotic pressure water enters the phloem and helps in the transport of food.

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