Quick Revision Notes & Formula Sheet

Class 7 Science: Respiration in Organisms (MP Board)

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### 1. Important Definitions (मुख्य परिभाषाएँ)

• Respiration (श्वसन): The process of breakdown of food in the cells with the release of energy is called respiration. It is essential for all living organisms.
• Breathing (श्वास लेना): The process in which a person takes in oxygen-rich air and gives out carbon dioxide-rich air using respiratory organs.
• Aerobic Respiration (वायवीय श्वसन): Breakdown of food (glucose) with the use of oxygen to release energy, carbon dioxide, and water.
• Anaerobic Respiration (अवायवीय श्वसन): Breakdown of food without using oxygen to release energy, alcohol (or lactic acid), and carbon dioxide. Occurs in yeast and temporarily in human muscles.
• Inhalation (अन्त:श्वसन): Taking in of air rich in oxygen into the body.
• Exhalation (उच्च्वास): Giving out of air rich in carbon dioxide from the body.
• Breathing Rate (श्वसन दर): The number of times a person breathes in and out in a minute.
• Spiracles (श्वासंध्र): Small openings on the sides of the body of insects through which air enters.
• Gills (क्लोम / गिल्स): Special respiratory organs in aquatic animals (like fish) that help them use oxygen dissolved in water.
• Stomata (रंध्र): Tiny pores on the surface of leaves used for the exchange of gases.

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### 2. Key Word Equations (रासायनिक समीकरण / शब्द समीकरण)

• Aerobic Respiration: Glucose + Oxygen -> Carbon dioxide + Water + Energy

• Anaerobic Respiration (in Yeast): Glucose -> Alcohol + Carbon dioxide + Energy

• Anaerobic Respiration (in Human Muscles during heavy exercise): Glucose -> Lactic Acid + Energy (Accumulation of lactic acid causes muscle cramps).

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### 3. Respiratory Organs in Different Animals (विभिन्न जीवों में श्वसन अंग)

S.No.	Animal / Organism (जीव)	Respiratory Organ (श्वसन अंग)
1.	Humans, Mammals, Birds, Reptiles	Lungs (फेफड़े)
2.	Earthworms, Frogs (skin)	Moist Skin (नम त्वचा)
3.	Insects (Cockroach, Grasshopper)	Trachea and Spiracles (श्वासनली और श्वासंध्र)
4.	Fish, Tadpoles	Gills (गिल्स / क्लोम)
5.	Plants	Stomata (रंध्र) and Root hairs

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### 4. Human Respiratory System & Mechanism (मानव श्वसन तंत्र और क्रियाविधि)

• Path of Air: Nostrils -> Nasal cavity -> Windpipe (Trachea) -> Lungs -> Chest cavity
• Diaphragm (डायफ्राम): A large, muscular sheet that forms the floor of the chest cavity. It helps in breathing movements.
• During Inhalation (श्वास अंदर लेते समय):
  • Ribs move up and outwards.
  • Diaphragm moves down.
  • Chest cavity increases in size, and air rushes into the lungs.
• During Exhalation (श्वास बाहर छोड़ते समय):
  • Ribs move down and inwards.
  • Diaphragm moves up to its original position.
  • Chest cavity decreases in size, and air is pushed out of the lungs.

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### 5. Important Facts to Remember (महत्वपूर्ण तथ्य)

• Normal Breathing Rate: An adult human breathes 15 to 18 times per minute at rest. During heavy exercise, it can rise up to 25 times per minute.
• Composition of Inhaled vs Exhaled Air:
  • Inhaled air contains 21% Oxygen and 0.04% Carbon dioxide.
  • Exhaled air contains 16.4% Oxygen and 4.4% Carbon dioxide.
• Why do we get muscle cramps after heavy exercise? Due to temporary anaerobic respiration in muscles, partial breakdown of glucose produces lactic acid. The cramp relieves after hot water bath or massage (which improves blood circulation and oxygen supply).
• Why do plants need respiration? Plants respire just like other living organisms to get energy from food. Roots take in oxygen from the air spaces present between soil particles.