RESPIRATION

Breathing is vital for all living things since it provides them with the energy they need to carry out their daily tasks.

The respiratory system’s principal duty is to transport oxygen to the cells of the body’s tissues while also removing carbon dioxide. The nasal cavity, trachea, and lungs are the primary components of the human respiratory system. All aerobic organisms require oxygen to carry out their metabolic processes.

Breathing is exchanging O2 from the atmosphere with CO2 generated by the cell. It is divided into two parts: inspiration and expiry. Air enters the lungs from the atmosphere during inspiration and exits the lungs during expiration.

Breathing is simply the act of taking in the fresh air and exhaling stale air.

1. It is a bodily function.
2. There is no energy released.
3. It is a process that occurs outside of the cell.

Respiration is the process of breaking down food into carbon dioxide, water and energy.

4. ATP is used to liberate energy.
5. It is a process that occurs within the cell.

Respiratory Organs

Varied organisms have different breathing mechanisms depending on their body form and environment.

The Respiratory System of Humans

1. The human respiratory system comprises a set of nostrils, a pharynx, bronchi, bronchioles and lungs.
2. The nasal cavity opens into the pharynx, which leads to the larynx
3. Each bronchiole ends in an alveolus, a vascularized bag-like structure with an uneven wall
4. The lungs are composed of a branching network of bronchi, bronchioles, and alveoli
5. To decrease friction on the lung surface, two lungs are covered by a double-layered pleura with pleural fluid between them
6. The nose, throat, larynx, and trachea are all conducting components
7. Transport of atmospheric air to alveoli is one of the main tasks
8. Removing foreign particles from the air, humidifying it, and bringing it to body temperature are steps in the process
9. Alveoli are the exchanging portions. It is the actual location of C and D diffusion between blood and ambient air.

Respiration Procedures

1. Diffusion of oxygen-rich atmospheric air into the lungs and CO2-rich alveolar air out of the lungs.
2. Gas diffusion over the alveolar membrane.
3. Gas transport through the blood.
4. The exchange of and C between blood and tissues.
5. Cells’ used to obtain energy and the release of  CO2 (cellular respiration). 

Breathing Mechanism

1. Inspiration and expiration are two aspects of breathing. Atmospheric air is sucked in during inspiration, while alveolar air is expelled during expiration.
2. Air movement in and out occurs due to a pressure gradient difference.
3. Inspiration happens when the pressure inside the lungs is lower than the outside pressure, and expiration occurs when the pressure inside the lungs is higher than the external pressure.
4. The diaphragm and the external and internal intercostal muscles between the ribs aid in developing a pressure gradient as a result of volume changes.

Intercostal muscle contractions raise the ribs and sternum, increasing the thoracic cavity volume and lowering the pressure below atmospheric pressure. This is the source of inspiration.

1. Expiration occurs when the diaphragm and intercostal muscles relax, reducing thoracic volume and increasing pressure.
2. For clinical examination of pulmonary functions, the amount of air involved in breathing motions is evaluated using a spirometer.

Respiratory Volume and Capacities

The volume of air inhaled or exhaled during typical respiration is the tidal volume (TV). In a healthy male, this amount is around 500mL.

IRV stands for Inspiratory Reserve Volume, the extra volume of air a person may inhale when they forcefully inhale. 2500 mL to 3000 mL is the approximate volume.

Expiratory Reserve Capacity (ERV) is the amount of air that a person may forcefully exhale in addition to their average breathing volume. 1000 mL to 1100 mL is the approximate volume.

RV (Residual Volume) is the amount of air in the lungs that remains following a forced expiration. 1100mL to 1200mL is the approximate volume.

IC – TV + IRV = Inspiratory Capacity

EC = TV + ERV = Expiratory Capacity

FRC (Functional Residual Capacity) = ERV + RV

Vital Capacity (VC) – the greatest amount of air a person can inhale following a strong exhalation. ERV+ TV+ IRV is a combination of ERV and television.

Total Lung Capacity (TLC) – the total volume of air that can be held in the lungs after forceful inspiration. RV+ ERV+ TV+ IRV stands for Residual Volume + Vital Capacity.

Respiration and Gaseous exchange

1. Gas exchange takes place at two locations.

Between the blood and the tissues are the alveoli.

2. Gas exchanges occur by simple diffusion due to pressure,concentration gradients, gas solubility, and membrane thickness.
3. Partial pressure, denoted by the letters p, is the pressure exerted by separate gases in a mixture of gases.
4. The partial pressure of oxygen and carbon dioxide at various parts of the diffusion process fluctuates from one portion to the next, moving from higher to lower partial pressure.
5. Because CO2 has a solubility of 20-25 times O2, it diffuses considerably quicker across the membrane.
6. The alveolar squamous epithelium, endothelium of alveolar capillaries, and basement material between them make up the diffusion membrane, which is three layers thick. 

Gases Transportation

CO2 and O2 use blood as a mode of transportation. RBC transports 97 percent of oxygen, whereas blood plasma transports the remaining 3%.

RBC transports 20-25 percent of carbon dioxide, 70 percent as bicarbonate, and the remaining 7% as dissolved carbon in blood plasma.  

Oxygen transportation

1. Oxyhaemoglobin is formed when haemoglobin in RBC mixes with oxygen. Each haemoglobin molecule combines with four oxygen molecules to form haemoglobin.
2. Oxygen binding is affected by partial pressures of oxygen and carbon-dioxide hydrogen ions, as well as temperature.
3. A sigmoid curve is formed by the percentage saturation of haemoglobin and the partial pressure of oxygen (oxygen dissociation curve).
4. In the alveoli, pO2 is higher, pCO2 is lower; fewer H+ ions are present, and the temperature is lower, favouring O2 binding to haemoglobin. Oxyhaemoglobin dissociation is favoured in tissues with opposing conditions. 

Carbon dioxide transport

1. Carbon dioxide is delivered as carbamino-haemoglobin by haemoglobin. In tissues, pCO2 is high, and pO2 is low, allowing carbon dioxide to bind to haemoglobin. The opposite circumstance aids the dissociation of carbamino-haemoglobin in alveoli.
2. The carbonic anhydrase enzyme aids in the synthesis of carbonate ions, which are used to transport carbon dioxide. 

Respiratory Regulation

1. Humans can maintain and adjust their rate of breathing to meet the brain system’s requirement for body tissues.
2. The medulla area of the hindbrain houses the respiratory rhythm centre. The pneumatic centre regulates the function of the respiratory rhythm centre in the pons.
3. The chemo-sensitive region in the rhythm centre is susceptible to carbon dioxide  and H+ ions, which regulate the respiratory rate. Oxygen does not have a significant function in controlling the rate of respiration. 

Respiration’s Functions 

1. Energy Production
2. Acid-base equilibrium is maintained.
3. Temperature regulation
4. The return of blood and lymphatic fluid.

Mountain sickness is a condition characterised by the adverse effects of hypoxia (lack of oxygen) in the tissues at high altitudes, which is most typically experienced by those visiting high altitudes for the first time.Symptoms of Mountain sickness:

1. The expansion of gases in the digestive tract causes loss of appetite, nausea, and vomiting.
2. Pulmonary oedema is the cause of breathlessness.
3. Headache, sadness, confusion, sleep deprivation, weakness, and exhaustion.

Disorder of Respiratory System

1. Asthma – This condition is caused by an allergic response to foreign particles in the respiratory tract. Coughing, wheezing, and trouble breathing are some of the symptoms. This is caused by an overabundance of mucus in the respiratory tract’s wall.
2. The inflating or abnormal distension of the bronchioles or alveolar sacs of the lungs is referred to as emphysema. The septa between alveoli are destroyed because of smoking and inhalation of other smoke. Exhalation becomes difficult, and the lung continues to swell.
3. Occupational Respiratory Disorders– arises from an individual’s profession. Inhalation of gas, fumes, or dust prevalent in the work environment causes this. This comprises Silicosis and Asbestosis caused by silica and asbestos exposure. The proliferation of fibrous connective tissue in the upper region of the lung causes inflammation as a symptom.
4. Pneumonia – caused by the bacteria Streptococcus pneumoniae. Pneumonia is an acute infection or inflammation of the alveoli of the lungs. 

Conclusion

Although the lungs have a considerable capacity for holding air, they are rarely full to maximum. Tidal volume, expiratory reserve volume, inspiratory reserve volume, and residual volume are all metrics used to determine the volume of the lungs. The total lung capacity is the sum of these numbers. The pressure of the gas determines how much it moves into or out of the lungs. Since air is a combination of gases, the partial pressure of each gas may be computed to estimate how the gas will flow through the lungs. The partial pressure of the gas in the air causes oxygen to flow into the tissues and carbon dioxide to exit the body.