Edunes Online Education
Edunes Online Education
Study Notes: Respiration in Organisms
All living organisms are made of microscopic units called cells, which are the smallest structural and functional units of life. Every cell performs specific vital functions, such as nutrition, transport, excretion, and reproduction. To carry out these activities—and even for passive tasks like reading, sleeping, or eating—the cell requires a constant supply of energy. This energy is stored in food and is released during the process of respiration.
Key Concept: Cellular Respiration
Cellular respiration is the process of breaking down food (glucose) within the cells of an organism to release energy. Since this process occurs inside the cells of all living beings, it is the fundamental mechanism by which life is sustained.
Respiration is categorized into two types based on whether oxygen is utilized in the breakdown of food.
When the breakdown of glucose occurs with the use of oxygen, it is called aerobic respiration. This is the most common form of respiration in higher organisms, resulting in the production of carbon dioxide, water, and energy.
\( C_6H_{12}O_6 + O_2 \rightarrow CO_2 + H_2O \) + Energy
Food can also be broken down without using oxygen; this is known as anaerobic respiration.
1. Yeast (Anaerobes): Yeasts are single-celled organisms that can survive in the absence of air and are known as anaerobes. During anaerobic respiration, they convert glucose into alcohol and carbon dioxide. This process is utilized industrially to produce wine and beer.
Glucose (in the absence of oxygen) --> Alcohol + Carbon dioxide + Energy
Glucose (in the absence of oxygen) --> Alcohol + Carbon dioxide + Energy
2. Human Muscle Cells: Our muscles can respire anaerobically, but only for a short duration when there is a temporary deficiency of oxygen. This typically happens during heavy exercise, fast running, or weight lifting, where the demand for energy is high but the oxygen supply is insufficient.
Glucose (in muscle, in the absence of oxygen) --> Lactic acid + Energy
Muscle Cramps: The partial breakdown of glucose produces lactic acid. The accumulation of lactic acid in the muscle tissues causes cramps.
Relief and Synthesis: Relief from cramps is achieved through a hot water bath or a massage.
These treatments improve blood circulation, which increases the supply of oxygen to the muscle cells. This increased oxygen results in the complete breakdown of lactic acid into carbon dioxide and water, thereby eliminating the cause of the cramp.
Glucose (in muscle, in the absence of oxygen) --> Lactic acid + Energy
Muscle Cramps: The partial breakdown of glucose produces lactic acid. The accumulation of lactic acid in the muscle tissues causes cramps.
Relief and Synthesis: Relief from cramps is achieved through a hot water bath or a massage.
These treatments improve blood circulation, which increases the supply of oxygen to the muscle cells. This increased oxygen results in the complete breakdown of lactic acid into carbon dioxide and water, thereby eliminating the cause of the cramp.
Breathing is the physical act of exchanging gases with the environment. It consists of inhalation (taking in air rich in oxygen) and exhalation (giving out air rich in carbon dioxide).
The Pathway of Air:
The Pathway of Air:
- Air is taken in through the nostrils.
- It enters the nasal cavity, where it is filtered.
- The air passes through the pharynx and travels down the trachea (commonly known as the windpipe).
- Finally, it reaches the lungs, which are located in the chest cavity. The lungs are surrounded by ribs on the sides, and a large muscular sheet called the diaphragm forms the floor of the chest cavity.
| Feature | Inhalation | Exhalation |
|---|---|---|
| Ribs | Move up and outwards | Move down and inwards |
| Diaphragm | Moves down (contracts) | Moves up to its former position |
| Chest Cavity Volume | Increases | Decreases |
| Air Pressure & Flow | Volume increase leads to a decrease in air pressure; air rushes into the lungs. | Volume decrease leads to an increase in air pressure; air is pushed out of the lungs. |
A breath is defined as one inhalation plus one exhalation. The number of times a person breathes in a minute is termed the breathing rate.
- Average Adult at Rest: 15–18 breaths per minute.
- During Heavy Exercise: The rate can increase up to 25 breaths per minute as the body works to supply more oxygen to speed up the breakdown of food for energy.
| Gas | Inhaled Air | Exhaled Air |
|---|---|---|
| Oxygen | 21% | 16.4% |
| Carbon Dioxide | 0.04% | 4.4% |
The organs for gas exchange vary significantly across the animal kingdom.
Cockroaches: Insects have small openings on the sides of their bodies called spiracles. These openings lead to a network of air tubes called tracheae. Oxygen enters through the spiracles, travels through the tracheae, and diffuses directly into the body tissues. Carbon dioxide follows the same path in reverse.
Earthworms: Earthworms breathe through their skin. The skin is moist and slimy to the touch, allowing gases to pass through it easily.
Frogs: Frogs are unique in their dual breathing capability. Like humans, they possess a pair of lungs for breathing on land, but they can also perform gas exchange through their skin , which is kept moist and slippery.
Fish: Fish utilize gills for respiration. Gills are projections of the skin that are richly supplied with blood vessels. They allow the fish to absorb oxygen that is dissolved in the water.
Cockroaches: Insects have small openings on the sides of their bodies called spiracles. These openings lead to a network of air tubes called tracheae. Oxygen enters through the spiracles, travels through the tracheae, and diffuses directly into the body tissues. Carbon dioxide follows the same path in reverse.
Earthworms: Earthworms breathe through their skin. The skin is moist and slimy to the touch, allowing gases to pass through it easily.
Frogs: Frogs are unique in their dual breathing capability. Like humans, they possess a pair of lungs for breathing on land, but they can also perform gas exchange through their skin , which is kept moist and slippery.
Fish: Fish utilize gills for respiration. Gills are projections of the skin that are richly supplied with blood vessels. They allow the fish to absorb oxygen that is dissolved in the water.
Plants perform respiration to obtain energy, just like other living organisms. Each part of a plant can independently take in oxygen from the air and give out carbon dioxide.
In the leaves, gas exchange occurs through tiny pores called stomata. Below the ground, root cells also require oxygen to generate energy. They absorb air from the small air spaces present between soil particles. A critical concern for plant health is overwatering; if a potted plant is overwatered, the air spaces in the soil are filled with water, preventing the roots from taking in the oxygen they need to respire.
In the leaves, gas exchange occurs through tiny pores called stomata. Below the ground, root cells also require oxygen to generate energy. They absorb air from the small air spaces present between soil particles. A critical concern for plant health is overwatering; if a potted plant is overwatered, the air spaces in the soil are filled with water, preventing the roots from taking in the oxygen they need to respire.
Glossary of Key Terms
Diaphragm: A large, muscular sheet forming the floor of the chest cavity that aids in breathing.
Tracheae: A network of air tubes in insects used for gas exchange.
Spiracles: Small openings on the sides of an insect's body through which air enters.
Gills: Respiratory organs in fish that facilitate the exchange of gases dissolved in water.
Stomata: Microscopic pores on the surface of plant leaves used for gas exchange.
Tracheae: A network of air tubes in insects used for gas exchange.
Spiracles: Small openings on the sides of an insect's body through which air enters.
Gills: Respiratory organs in fish that facilitate the exchange of gases dissolved in water.
Stomata: Microscopic pores on the surface of plant leaves used for gas exchange.
Health Note:
Smoking: Smoking seriously damages the lungs and is directly linked to cancer. It must be strictly avoided.
Pranayama: Regular practice of traditional breathing exercises (Pranayama) can increase the capacity of the lungs to take in more air. This provides more oxygen to the body's cells, leading to increased energy release and better overall health.
Pranayama: Regular practice of traditional breathing exercises (Pranayama) can increase the capacity of the lungs to take in more air. This provides more oxygen to the body's cells, leading to increased energy release and better overall health.
