CBSE CLASS 7-Respiration in Organisms -CHAPTER NOTE

Respiration in Organisms

RESPIRATION:-

·         Respiration is a process in which organisms takes in air and uses it to break down glucose to release energy.

·         There two types of respiration: - Aerobic and Anaerobic Respiration.

Aerobic Respiration:-

·         The respiration which occur in presence of oxygen is called as aerobic respiration.

·          The breakdown of glucose happens in cells.

·         Cellular respiration process of break down of food in the cell with the release of energy is called cellular respiration. Cellular respiration takes place in the cells of all organisms.

·          The food (glucose) is broken down into carbon dioxide and water using oxygen inside the cell.

        Glucose + Oxygen → Carbon dioxide + Water + Energy

        C₆H₁₂0₆ + 6O2 → 6C0₂ + 6H20 + Energy

Anaerobic Respiration:-

• The respiration which occur without oxygen is called anaerobic respiration.
•  Some organisms such as yeast that can survive in the absence of air, They are called anaerobes.
•       They get energy through anaerobic respiration.  Glucose breaks down into alcohol and carbon dioxide in the absence of oxygen,.

• Anaerobic Respiration also takes place in our body through cell and we produce lactic acid in our muscles.
• Muscle cells can also respire anaerobically, but only for a short time, when there is a temporary & happens deficiency of oxygen.
• Anaerobic Respiration happens during heavy exercise, fast running, cycling, walking for many hours or heavy weight lifting, the demand for energy is high.

•  We get relief from cramps after a hot water bath or a massage. Massage or  hot water bath improves circulation of blood. Due to this the supply of oxygen to the muscle cells increases.
•  The increase in the supply of oxygen results in the complete breakdown of lactic acid into carbon dioxide and water.

Breathing

•      Breathing is taking in of air and giving it out.

  ·         Breathing is a part of Respiration.

  ·         The taking in process of air rich in oxygen into the body is called inhalation and giving out of air rich in carbon dioxide is known as exhalation.

  ·         It is a continuous process which goes on all the time and throughout the life of an organism.

  ·        Breathing rate means number of times a person breathes in a minute is termed as the breathing rate.

  ·         During breathing inhalation and exhalation take place one by one .

  ·         A breath means one inhalation plus one exhalation.

  ·         Whenever a person needs extra energy, he/she breathes faster.

          gets more oxygen is supplied to our cells.

  ·          More oxygen is supply speeds up the breakdown of food and more energy is released.

  ·         We breathe 16-18 times per minute.

  Human Respiratory System

  ·         Inhale air passes through our nostrils into the nasal cavity. then

          air moves in our lungs through the windpipe.

  ·          Lungs are present inside the chest cavity.

  ·         This cavity is surrounded by ribs on the sides.

  ·         A large, muscular sheet known as  diaphragm forms the floor of the chest cavity. 

Trachea:-

•  Trachea is also known as wind pipe.
•  It is connected from Pharynx to lungs.
• The Trachea divides into two  branches called as Bronchi.

Bronchi:-

• Bronchi connects Trachea to lungs.
• They get air passed by Trachea.
•  They further divide into Bronchioles.

Bronchioles:-

• Bronchioles connects Bronchi to inner lungs.
•   They pass on the air they get from bronchi.
•  They are further divided into alveoli.

Alveoli:-

• In Alveoli the exchange of gases take place.
• They are also called as air sacs.
• They are covered with capillaries.
•  When they receive air they take in carbon dioxide and give out oxygen in blood.
• We breathe out carbon dioxide rich air.    
•   They then mix the oxygen rich blood with hemoglobin and make oxy hemoglobin.

Inhalation and Exhalation

·         When we breathe in air rich in oxygen then our diaphragm moves down and out ribs goes outwards and we breathe in.

·         When we breathe out air rich in carbon dioxide then our ribs goes inwards and diaphragm moves up and we breathe out.

·         Inhaled air has 21% oxygen and 0.04% carbon dioxide.

·         Exhaled air has 16.4% oxygen and 4.4% carbon dioxide.

Breathing in Other Animals

COCKROACH:-

·       Cockroachs have small openings on the sides of its body. Other insects also have similar openings.

·         These openings are known as spiracles.

·         Insects have a network of air tubes called tracheae for gas exchange.

·         Oxygen rich air passed through spiracles into the tracheal tubes, diffuses into the body tissue, and reaches every cell of the body.

·         Carbon dioxide from the cells goes into the tracheal tubes and moves out through spiracles.

·         These air tubes or tracheae are found only in insects .It is not in any other group of animals.

EARTHWORM:-

·         Earthworms breathe through their skins.

·         The skin of an earthworm feels moist and slimy on touching.

·         Gases can easily pass through them.

·         Though frogs have a pair of lungs like human beings, they can also breathe through their skin, which is moist and slippery.

Breathing Under water

FISH:-

·         That gills in fish help them to use oxygen dissolved in water.

·         Gills are projections of the skin.

·         Gills are well supplied with blood vessels for exchange of gases.

Respiration in Plants

·         They also take in oxygen from the air and give out carbon dioxide.

·         In the cells oxygen is used to break down glucose into carbon dioxide and water as in other organisms.

·         In plants each part can independently take in oxygen from the air and give out carbon dioxide.

·         The leaves of the plants have tiny pores called stomata for exchange of oxygen and carbon dioxide.

·         Roots take up air from the air spaces present between the soil particles.

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