Introduction:
As you know that how cells (living things) produce adenosine triphosphate-ATPs (the currency of energy) from organic food and photosynthesis. As we know all organisms need energy to perform various daily activities and growth.
In this article you will go through the mechanism of gaseous exchange in plants and human. You will also study some respiratory disorders of human.
“Optimize Breathing: Efficient Gaseous Exchange & Cellular Respiration”
Breathing is taking of air in and out of lungs (respiration surface). Gaseous exchange is intake of oxygen and removal of CO2 at the lungs surface (Oxygen moves into the blood and CO2 move out of the blood). Cellular respiration is the process that release energy from the organic food.
Cellular respiration is the process in which food is broken down by oxidation-reduction reactions (redox) and energy is stored and transformed in the form of ATPs. The oxygen is used and CO2 is produced during cellular respiration which is taken out of the cells and body through gaseous exchange. The respiration is used to explain the diffusion of respiratory gases from an area of higher concentration to an area of lower concentration. The autotrophs like plants beside respiration, they also perform gaseous exchange during the process of photosynthesis. Process of respiration is similar between plants and animals. The animals possess more efficient way of gaseous exchange due to need of more energy for active life.
Gaseous exchange in plants
All plants need exchange of gases for both respiration and photosynthesis, In contrast to animals, they have no organ system for gaseous exchange as that exist in most animals. Thus each cell of plants part carries out exchange of gases according to its need which occurs only by diffusion
The process of respiration occurs constantly day and night while photosynthesis takes place mostly during day time in chlorophyll containing cells.
Gaseous exchange in lower plants, especially aquatic plants takes place by diffusion across wet body surface while in higher land plants through stomata and lenticels. The leaves and young-stems have numerous pores known as stomata (singular stoma) for exchange of gases as well as transpiration. Their inner cells (mesophyll) have large air spaces. These air spaces are directly involved in gaseous exchange.
Interesting Information
In young stems and leaves, some gaseous exchange also occurs through the cuticle which is present over their eqidermis.
During the day time, mesophyll cells are involved in both photosynthesis and respiration. During photosynthesis plants get CO2 from air through stomata. The oxygen is generated in photosynthesis which is either used in cellular respiration or removed through stomata, while CO2 produced during respiration is utilized for photosynthesis. However, at night when photosynthesis is not taking place, the stomata of leaf and lenticels of stem get oxygen from the environment and remove CO2 through same openings.
Interesting Information
Lenticels appears as small dots to the naked eye, but on microscopic examination they can be seen that they are cluster of loose cells in the cork (layer of bark)
In higher or woody plants the stem and roots are mostly covered by dead bark, which is impervious for bath water and gases. Thus these parts possess special pores for gaseous exchange known as lenticels.
The young root cells exchange gases by diffusion through general body surface from surrounding moist soil.
| No | Photosynthesis | Respiration |
| i) | It is anabolic process, in which plants absorb solar energy and synthesize food. | It is catabolic process, in which organism’s breakdown the synthesize food. |
| ii) | The raw material for photosynthesis are CO2 and H2O while O2 is released. | The raw material for respiration are organic substance mainly glucose (C6 H12 O6), which is broken down either in the presence (aerobic) or absence (anaerobic) of O2 and CO2 while H2O is released |
| iii) | It occurs in green cells containing chlorophyll. | It occurs in cytoplasm and mitochondria. |
Gaseous Exchange in Human
Human and all mammals are homeotherms (i.e. warm blooded). Therefore, by possessing high metabolic rate they consume large amount of energy to maintain their body temperature at a constant level (i.e. in human 36.8oC or 98.6o F).
Thus the human respiratory system is efficient for readily exchange of gases.
The respiratory system of human is divided into two main parts; i.e. the air passage ways and lungs.
Interesting Information
The membranous septum, which separates both lungs from each other, is called mediastinum
The Air Passage Ways and Lungs
Air Passage Ways
The air passage ways of human consist of nostrils, nasal cavities, pharynx, larynx, trachea, bronchi, bronchioles and alveolar ducts.
The external openings of nasal cavities are called nostrils. The nasal cavity is subdivided into three passage ways by projection of bones from wall of internal nose. The nasal cavities are lined with hairs and mucus membrane of ciliated epithelium (i.e. thin layer of cells), which traps foreign dust particles thus filters the air. It also moistens the dry air and beings the air temperature near to body temperature.
The nasal cavities lead into muscular pharynx through two internal nostrils. It is common passage for both air and food. The air is passed from the pharynx into the larynx or sound box. Larynx is a cartilaginous structure situated above the trachea, its cavity is called glottis. One of the cartilages known as epiglottis is controlled by muscles and serving as a lid having hinge like action. The epiglottis automatically covers the opening of larynx during the act of swallowing so as to prevent the entry of food or liquids into the larynx.
The glottis contains two pairs of fibrous bands known as vocal cords; their vibration during expiration produces voice.
Trachea is a tubular structure placed ventral to the esophagus and extends to the chest cavity (thorax) where it is divided into right and left bronchi, each leading to the lungs of its side. The wall of the trachea is membranous and ciliated, which secretes mucus that helps to filter, moisten and warm the incoming air. The trachea is supported by a series of C-shapes cartilaginous rings (about 16-22 rings) in adult which prevent the trachea from blocking by kink (twist) any time, when the neck bends during movement. It also prevents collapsing and provides an open passage way for the air to pass.
Each bronchus when enters the lungs divides and subdivides progressively into smaller bronchi, which is cartilaginous. Each smaller bronchus divides to form small branches known as bronchioles, which have diameter of one mm, made up of circular involuntary smooth muscles, lack cartilaginous rings.
The bronchioles end into fine thin walled tubules called alveolar ducts, which end into tiny hollow bag like structure called air sacs or alveoli (singular alveolus).
The alveolus is the functional unit of the lungs where exchange of gases take place. They are surrounded by blood capillaries of pulmonary arteries which carry deoxygenated blood from right side of heart that is from right ventricle. These capillaries join together to form the pulmonary veins which bring back oxygenated blood to left side of heart (i.e. to left atrium).
Lungs
Lungs are paired and located in the chest cavity, one on either side of the heart.
These are extended from the base of the neck to the diaphragm. Both lungs are radish yellow in color, conical in shape. The right lung is broader than the left lung while the left lung is 2.54 cm longer than the right lung.
Each lung is enclosed in a double membrane called pleura. There is a fluid named pleural fluid between the two pleural membranes, which protects the lungs from friction during its contraction and expansion.
The Mechanism of Breathing
Breathing is a physical process which helps in gaseous exchange between lungs and external environment. It consists of two phases, i.e. inspiration (inhalation) and expiration (exhalation).
Adult humans normally, at rest breathe 15-20 times per minute. It increases during hard work and exertion (about 30-40 times per minute). The rate and depth of breathing is controlled by medulla of brain, which is sensitive to the concentration of CO2 in the blood.
Interesting Information
Diaphragm is a sheet of skeletal muscle which separate chest cavity from abdomen.
Inspiration (Inhalation)
The intake of fresh air into the lungs is called inspiration. During inspiration the space inside the chest cavity is increased by two ways:
1) The muscles of diaphragm contract, thus it becomes flat rather than dome shaped and chest cavity is increased.
2) The intercostal muscles (i.e. muscles around ribs) contract, thus pull the ribs upward, forward and outward.
Interesting Information
The breathing movements are involuntary to a large extent. However, we can control the rate of breathing but not for a long time.
The above explained mechanism increases the volume of chest cavity, the pressure from the lungs is released and they expend. The atmospheric air rushes into the lungs through the air passage ways.
Expiration (Exhalation)
The expelling (removal) of stale or deoxygenated air from lungs is called expiration. During expiration the volume of thorax increases by two ways:
1) The muscles of diaphragm relaxed thus it again become dome-shaped.
2) The intercostal muscles relax thus ribs again pull downward and inward.
The chest cavity decreases thus pressure on lungs increases which helps to expel the air out
Comparison Between Inspired and Expired Air
| NO | Inspired Air | Expired Air |
| i) | Oxygen 21% | Oxygen 16% |
| ii) | Carbon dioxide 0.04% | Carbon dioxide 4% |
| iii) | Nitrogen 79% | Nitrogen 79% |
| iv) | Water vapours variable | Water vapours saturated |
| v) | Temperature: variable | Temperature: near to body temperature |
Respiratory Disorders
Many problems in respiratory system of human can take place due to irritation in the inside lining of air passage and lungs. Some common respiratory disorders are bronchitis, emphysema, pneumonia, asthma, and lung cancer.
Bronchitis
It is the inflammation of air passage ways, especially bronchi and bronchioles.
The cause of bronchitis is mainly unhealthy air (smoke), bacterial and viral infection, which result in excessive secretion of mucus or phlegm into the air passage ways. This reduce the diameter of air tubules thus during breathing amount of air decreases. Symptoms of this disorder are cough, fever chill and shortness of breath etc.
Two main types of bronchitis:
1) Acute bronchitis lasts about two weeks, mostly do not damage the respiratory passage.
2) Chronic bronchitis damages the respiratory passage and lasts for three months to two years.
Emphysema
In this lung disorder the alveoli are degenerated, which results to from large sacs. Thus number of alveoli decreases, volume increases but with less surface area for gaseous exchange. Patient faces difficulty in walking, lung loses elasticity, so it becomes for difficult to exhale air. The causes of emphysema are long term irritation of the lungs by smoking and polluted air. There is no complete treatment or cure of emphysema but some preventive measures i.e. avoid smoking and doing regular exercises to avoid respiratory infections.
Pneumonia
Pneumonia is respiratory disorder of one or both lungs. If both lungs are infected then it is called double pneumonia. It is mainly caused by bacteria, viral or fungal infection.
Chronic Obstructive Pulmonary Disease (COPD)
It refers to disorders that impair movement of the air in the respiratory system. Bronchitis and emphysema are two common COPD disorders that are most frequently caused by cigarette smoking.
These microorganisms settle and grow in alveoli damage the lungs tissues and ultimately lungs are filled with fluid and pus. The symptoms of pneumonia include cold, that is followed by fever and cough with sputum production, sneezing and sore throat.
Vaccines for the prevention of bacterial pneumonia is available, while antibiotic is used as its treatment.
Tuberculosis
Tuberculosis (TB) is caused by a bacterium called Mycobacterium tubercule. The bacteria usually attack the lungs, but TB bacteria can attack any part of the body such as the kidney, spine, and brain. Not everyone infected with TB bacteria becomes sick. As a result, two TB-related conditions exist: latent TB information (LTBI) and TB disease can be fatal.
Asthma
In this respiratory disorder, patients faces difficulty in breathing, associated with sudden attack of coughing. It is usually followed by a brief period of relief with recurrence (repetition) attack at most or less frequent intervals
The symptoms of asthma in both expiration and inspiration. A characteristic whistling sound produces during breathing. The cause of asthma is an over allergic reaction to pollens, household dust which may contain spores of fungi and small arthropods known as mite. The inflammation produces more mucus production and narrowing of the bronchi and bronchioles.
Anti-inflammatory drugs help in controlling asthma. Bronchiole dilator inhalants from aerosol cans are helpful in relaxing the muscles of the bronchioles.
Effect of Smoking on Lungs
Smoking is harmful due to the chemical in cigarettes and smokes (more than 4000 different types of chemicals). Many smoke chemicals are cancer causing that is carcinogenic. Smoke besides causing lung cancer, if also creates many bad effects on the body from head to toe.
Tar is a carcinogen and cancerous tumor initiator. In solid form; it is the component that stains the teeth and fingers of smokers. Tar also increases the secretion of mucus.
Interesting Information
Nicotine also increases the production of blood platelets, which make the blood viscous and it leads to blockage of blood vessels in heart and brain etc.
Nicotine and other chemicals, present in smoke lead to the cancer in larynx, oral cavity, breast, kidney and urinary bladder etc.
The carbon monoxide present in
smoke, more easily combine with
hemoglobin than oxygen. Thus reduces
the oxygen carrying capacity of
hemoglobin. Smoke increases the risk
of respiratory diseases such as
tuberculosis by two to four times while
pneumonia by four times.
Nitrogen oxides are found in large amount in smoke of cigarette, responsible for emphysema. Hydrogen cyanide destroy cilia in respiratory passage thus lungs cleaning system is badly affected.
Lung Cancer
Lung cancer is one of most serious disorder of respiratory system. It can stop air passage ways as the tumor replaces the lung tissue due to uncontrolled cell division. The respiratory passage is blocked and cutting of supply of air occurs to lungs. The most common cause is smoking and inhalation of polluted air.
The chances of lung cancer are ten times more in those people who smoke or live in polluted areas. It is estimated that 90% of lung cancer is caused by smoking. The only treatment of lung cancer is to remove the tumor or to cut cancerous portion of lungs before cellular growth invade adjacent tissues beyond the lungs.
Artificial Ventilators
If lungs of a person do not function properly than artificial ventilator is used. This breathing machine pushes air into the lungs to ensure enough supply of gaseous exchange. Artificial ventilator can adjust the rate and size of each breath. It moistens and maintains the temperature of air close to the body temperature. Artificial ventilator can be used as an alternative of natural breathing or to assist breathing process e.g. during surgery due to some other reason when the patient goes in coma. In such cases the artificial ventilator is used as life-saving apparatus.
Extra Reading
The Coronavirus was first identified in December, 2019. Therefore, it was given name COVID-19 (Coronavirus Disease 2019). The word corona is a Latin word meaning crown or halo. It is a +ve strand RNA enveloped virus. It causes flu like respiratory tract infection. It is a contagious disease and spreading with a high speed throughout the world. So far thousands of people worldwide have died due to COVID-19 infection. More than 2 million people have been infected from this viral infection. According to WHO, signs of Infection include fever, cough, shortness of breath and breathing problems. In more severe cases it can lead to pneumonia, multiple organ failure and death. Some infected patients may be asymptomatic.
The mortality rate is 3.4% according to the WHO. The virus has spread from Wuhan City of China and spread almost all over the world prompting the WHO designate the COVID-19 outbreak as pandemic. Most of the death cases are found to in Italy, USA, Spain, France, UK, Iran, China. In Pakistan thousands are infected and many deaths cases are reported.
Conclusion
Understanding gaseous exchange is essential for sustaining life in both plants and humans. Efficient gaseous exchange in humans involves the respiratory system, including air passageways and lungs, to ensure proper oxygen intake and carbon dioxide removal. Respiratory disorders like bronchitis, emphysema, pneumonia, COPD, tuberculosis, and asthma can impair gaseous exchange, highlighting the need for a healthy respiratory system. Smoking also negatively affects gaseous exchange, further emphasizing lung protection.
In plants, gaseous exchange occurs through stomata and lenticels, supporting respiration and photosynthesis. This understanding can enhance agricultural practices and plant health. Optimizing our knowledge of gaseous exchange benefits human health and plant biology, making it a critical focus for research and education. Prioritizing gaseous exchange research will continue to benefit both medical and agricultural fields.
Optimizing gaseous exchange improves both human health and plant vitality. Prioritizing gaseous exchange research is essential.
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2 thoughts on “Boost Health: Efficient Gaseous Exchange & Respiration”
This article is fantastic! I thoroughly enjoyed reading it. The author covers everything about gaseous exchange and even includes information on respiration disorders, which is amazing. I’m thrilled after reading this insightful piece.
Thanks Brother