Biology Kenya
Gaseous Exchange
Gaseous Exchange
Gaseous Exchange
Gaseous exchange in living organisms (necessity)
Organs responsible for gaseous exchange in living organisms include the following:
| ORGANISM | RESPIRATORY SURFACE |
| Amoeba | Cell membrane |
| Insects | Tracheal system |
| Spider | Book lung |
| Fish | Gills |
| Plants | Leaves, stems, roots |
| Amphibians | Skin, gills and lungs |
| Mammals | Lungs |
| Birds | Lungs |
| reptiles | Lungs |
Features of Respiratory Surface
- They are thin to reduce diffusion distance
- They are moist to dissolve gaseous so that they dissolve and diffuse in solution form
- They are highly braced, folded or flattened in order to increase the surface area for gaseous exchange
- They are close to efficient transport and exchange easily by the cells
- They are well ventilated so that gaseous passes easily
Gaseous exchange in plants
In plants gaseous exchange takes place through the stomata on the leaves and lenticels on the stem. But some plants such as mangrove also carry out gaseous exchange through breathing roots.Parts of Plant Responsible for Gaseous ExchangeIdentify parts of plant responsible for gaseous exchangeIn plants gaseous exchange takes place through the stomata on the leaves and lenticels on the stem. But some plants such as mangrove also carry out gaseous exchange through breathing roots.The Process of Gaseous Exchange in PlantsDescribe the process of gseous exchange in plantsGaseous exchange in leaves: Through stomata, atmospheric air moves in and out of the leaf. Gaseous exchange mostly takes place in the air spaces in the spongy mesophyll.
During the day, green plants carry out photosynthesis to produce glucose and this takes place within the guard cells that surround the stomata then the cell sap of the guard cells becomes hypertonic and draws in water from the neighboring cells by osmosis.The guard cells become turgid and the stomata open whereby the air from the atmosphere such as carbon dioxide enters into the air spaces in the spongy mesophyll.In this case carbon dioxide (CO2) is more in the air within the air space but oxygen is less. Then the carbon dioxide and oxygen diffuse in opposite direction depending on their concentration gradients (such as oxygen out and carbon dioxide in). The carbon dioxide diffuses into neighboring cells until it reaches the site for photosynthesis and oxygen moves out through the open stomata to the atmosphere.During the night there is no light so that photosynthesis ceases and there is no production of glucose. Therefore the guard cells do not absorb water by osmosis hence the stomata remain partially closed.However respiration process takes place at night in plants. The partially open stomata allow small amount of air to enter and accumulate in the air spaces. In this case there is more oxygen and less carbon dioxide in the air spaces compared to plant cells.Oxygen moves into the plant cells while carbon dioxide moves into the air spaces and eventually into the atmosphere through the partially open stomata. This explains why green plants produce carbon dioxide at night and oxygen during the day.
Mechanisms of opening and closing of stomata
The process of gaseous exchange in root, stem and leaves of both aquatic (floating) and terrestrial plants
Gaseous Exchange in Animals
Types and characteristics of respiratory surfaces - cell membrane, gills, buccal cavity, skin and lungs
The Features of Different Parts of the Respiratory System include the following:
- Nose and nasal cavity: It has mucus and hair which trap dust and microorganisms
- Glottis: It is situated in the epiglottis which closes the trachea during swallowing to prevent food from entering the respiratory system
- Trachea, Bronchus, and Bronchioles: They have blood vessel which have ring cartilage and mucus which warm hair and prevent collapse of respiratory track also they trap and fitter dust and micro organisms
- Lungs:They are sponge with air space (alveoli) which is the main organ of mammalian gaseous exchange
- Ribs: They are made up of hard bone tissues which protect the lungs from injury.
- Intercostal muscles: They more antagonistically to allow expansion and relaxation of the thoraic cavity
- Diaphragm: is the muscular sheet of tissue which separate thorax from abdomen
- Alveoli: they are numerous in number; they are moist and thin membranes
Mechanism of gaseous exchange in:Protozoa - amoeba
Mechanism of gaseous exchange in:Insect - grasshopper
Mechanism of gaseous exchange in:Fish - bonyfish
Mechanism of gaseous exchange in:Amphibia - frog
Mechanism of gaseous exchange in:Mammal - human
Factors affecting rate of breathing in humans
Respiratory diseases: Asthma, Bronchitis, Pulmonary tuberculosis, Pneumonia and whooping cough
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