Respiration in Organisms - Chapter Notes
- The cells in our body perform functions like growth, excretion, reproduction, etc.
- The cells in our body perform functions like growth, excretion, reproduction, etc. A cell needs energy to perform these functions. The food we take in is converted into glucose by the digestive system.
Glucose reaches the cells through the blood
- In the presence of oxygen, glucose is broken down into energy, water and carbon dioxide. Anaerobic respiration takes place in the muscle cells if enough oxygen is not present in the cell.
- Glucose is converted into lactic acid and carbon dioxide in the absence of oxygen. Accumulation of lactic acid inside the cells leads to muscle cramps. Oxygen will break down lactic acid into carbon dioxide and water.
Yeast respires in the absence of oxygen
- Glucose is converted into alcohol and carbon dioxide by yeast in the absence of oxygen. Yeast is used in beverage industries to produce beer and wine.
- During day time, plants utilise oxygen to perform photosynthesis.
- During the night, plants release carbon dioxide and take in oxygen for respiration.
- In plants, the exchange of gases takes place through a special structure, called the stomata. The process of respiration in plants breaks down glucose and releases energy.
- The energy released from food is useful in activities like growth, excretion, reproduction, running, reading and sleeping.
- The food we eat has to be converted into glucose for releasing energy. Digestive juices convert complex carbohydrates into glucose.
- The breakdown of glucose in a cell to release energy is called cellular respiration. Blood absorbs glucose and transports it to the cells. In the cells, this glucose is broken down to release energy.
- The breakdown of glucose in the presence of oxygen is called aerobic respiration.
- Cells use oxygen to break down glucose and release energy.
- When we inhale air, oxygen goes into the lungs. From the lungs, the oxygen is absorbed by the red blood cells and supplied to all the cells in the body. Our cells use this oxygen to break down glucose to release energy. Carbon dioxide and water are also formed.
- The breakdown of glucose in the cell in the absence of oxygen is called anaerobic respiration.
- Muscle cells require a lot of energy to perform exercises. Muscle cramps occur when strenuous exercises like cycling, running, speed walking, etc. are done for a long time. The accumulation of lactic acid in the muscles causes muscle cramps.
- During anaerobic respiration, lactic acid is formed in the muscles. A massage or a hot bath can ease a muscle cramp by improving the circulation of blood in the affected muscles.
- Anaerobic respiration can be seen in yeast.
- The breakdown of glucose in the absence of oxygen in yeast forms alcohol, energy and carbon dioxide. Yeasts and other organisms that respire in the absence of oxygen are also known as anaerobes.
- Plants utilise oxygen for respiration released through photosynthesis during the day, and at night, they take in oxygen from the atmosphere and give out carbon dioxide and water vapour.
- The stomata are involved in the entry and exit of gases in plants.
The cells of living organisms require a constant supply of oxygen to release energy.
The cells of living organisms require a constant supply of oxygen to release energy. This is done by a process called breathing.
Breathing involves two steps - one inhalation and one exhalation.
- The breath rate of human beings is 15 - 18 breaths a minute. Air passes through the tiny hair in the nasal cavity, and then through the pharynx, larynx and windpipe before reaching the lungs.
- The hairs in the nasal cavity prevent the entry of dust particles and pollen. The mucous lining is present from the nasal cavity to the lungs. Lungs are situated inside the chest cavity, and they rest on a large muscular sheet called the diaphragm, which forms the floor of the chest cavity. Fig: Inhalation and exhalationWhen you breathe in, your diaphragm and rib cage get into action. The diaphragm is protected by the rib cage. The diaphragm plays an important role in inhalation and exhalation.
- An insect does not have any respiratory organs. For respiration, they have special organs called spiracles. Oxygen reaches to the cells directly through the spiracles by means of diffusion.
- The skin is the respiratory organ in animals like frogs and earthworms. The skin in these animals is moist and slimy, which makes it easier for oxygen to diffuse in and carbon dioxide to diffuse out of the body.
- However, frogs are special animals. They can breathe through their skin in water, while on land they can breathe through their skin as well as their lungs. The respiratory organs in fish are the gills. Fishes take in oxygen in dissolved form.
- During respiration, water enters the body through the mouth, and then passes through the gills and comes out of the operculum. The gills take in the oxygen dissolved in the water and give out carbon dioxide.
Breathing is a mechanical process that involves two steps - taking in oxygen from the air and giving out carbon dioxide to the air.
- The action of taking in air rich in oxygen is termed as inhalation.
- The action of giving out air rich in carbon dioxide is called exhalation.
- One inhalation and one exhalation make up one breath.
- The number of times you breathe in one minute is called the breathing rate.
After air enters the nostrils, it passes through the nasal cavity, where tiny hair present inside the cavity trap unwanted particles such as smoke, dust and pollen. From the nasal cavity, air travels through the pharynx, larynx, and windpipe before it reaches the lungs located in the chest cavity.
- The lungs rest on a large muscular sheet, called the diaphragm, which forms the floor of the chest cavity.
- When inhaling, the rib cage moves outwards, and the diaphragm contracts and moves downwards. The rib cage expands and this increases the space in the chest cavity. Air rich in oxygen is pulled into the lungs.