Carbonic anhydrase is an enzyme that facilitates the conversion of carbon dioxide and water into bicarbonate and protons, and vice versa, playing a crucial role in gas exchange in the blood.
The total thickness of the diffusion membrane is much less than a millimeter.
Alveoli are very thin, irregular-walled, vascularized bag-like structures that arise from terminal bronchioles and are involved in gas exchange.
The pleura are double-layered membranes that cover the lungs and contain pleural fluid, which reduces friction on the lung surface during respiration.
The trachea is a straight tube that extends to the mid-thoracic cavity and divides into the primary bronchi, facilitating the passage of air.
Expiratory Reserve Volume (ERV) is the additional volume of air a person can expire by a forcible expiration, averaging 1000 mL to 1100 mL.
During expiration, the diaphragm and inter-costal muscles relax, reducing thoracic and pulmonary volume, which increases intra-pulmonary pressure, forcing air out of the lungs.
The maximum volume of air a person can breathe in after a forced expiration, including expiratory reserve volume, tidal volume, and inspiratory reserve volume (ERV + TV + IRV).
Inspiration is the process of taking in atmospheric air into the lungs, which is the first step in respiration.
An increase in CO2 and H+ concentration activates a chemosensitive area adjacent to the respiratory rhythm centre, which signals for necessary adjustments in the respiratory process to eliminate these substances.
The respiratory centre in the medulla maintains respiratory rhythm and can be altered by the pneumotaxic centre in the pons and chemosensitive areas.
The volume of air remaining in the lungs after a normal breath is known as the functional residual capacity.
The site of gaseous exchange in an insect is throughout the body via a network of tracheae that deliver oxygen directly to tissues.
The diffusion membrane is made up of three major layers: the thin squamous epithelium of alveoli, the endothelium of alveolar capillaries, and the basement substance, which supports the squamous epithelium and surrounds the endothelial cells of capillaries.
All the factors in the body are favorable for the diffusion of O2 from alveoli to tissues and CO2 from tissues to alveoli.
Volume of air remaining in the lungs even after a forcible expiration, averaging 1100 mL to 1200 mL.
Total volume of air a person can expire after a normal inspiration, including tidal volume and expiratory reserve volume (TV + ERV).
Cellular respiration is the process by which cells utilise oxygen and produce energy, along with carbon dioxide.
Alveoli are the primary sites of exchange of gases, where O2 and CO2 are exchanged mainly by simple diffusion based on pressure/concentration gradients.
Lower invertebrates, such as sponges and flatworms, exchange O2 with CO2 by simple diffusion over their entire body surface.
The gradient for CO2 follows the direction from tissues to blood and from blood to alveoli.
Tidal Volume (TV) is the volume of air inspired or expired during a normal respiration, approximately 500 mL.
At the tissue site where partial pressure of CO2 is high, CO2 diffuses into the blood and forms bicarbonate (HCO3–) and protons (H+).
The pneumotaxic centre, located in the pons, moderates the functions of the respiratory rhythm centre by altering the duration of inspiration and affecting the respiratory rate.
Intercostal muscles assist in breathing by creating pressure gradients between the atmosphere and the alveoli.
Occupational Respiratory Disorders are conditions, such as lung damage from long exposure to dust in industries like grinding, resulting in inflammation and fibrosis.
The major transport mechanisms for CO2 are as bicarbonate ions in plasma, bound to hemoglobin, and dissolved in blood plasma.
The solubility of CO2 is 20-25 times higher than that of O2, allowing for a greater amount of CO2 to diffuse through the diffusion membrane per unit difference in partial pressure.
The conducting part transports atmospheric air to the alveoli, clears it from foreign particles, humidifies it, and brings it to body temperature.
The exchange part is the site of actual diffusion of O2 and CO2 between blood and atmospheric air.
The respiratory rhythm centre is a specialized brain area in the medulla responsible for regulating and moderating the respiratory rhythm according to the body tissues' demands.
Asthma is a respiratory condition characterized by difficulty in breathing, causing wheezing due to inflammation of the bronchi and bronchioles.
Total volume of air accommodated in the lungs at the end of a forced inspiration, including residual volume, expiratory reserve volume, tidal volume, and inspiratory reserve volume (RV + ERV + TV + IRV).
In the tissues, where there is low pO2, high pCO2, and high H+ concentration, conditions favor the dissociation of oxygen from oxyhaemoglobin, allowing oxygen to be delivered to cells.
Inspiration involves the diaphragm contracting and moving downwards, increasing thoracic volume and drawing air into the lungs.
Hypoxia is a condition characterized by insufficient oxygen levels in the tissues, leading to various physiological responses.
During inspiration, the diaphragm contracts, increasing the volume of the thoracic chamber, which decreases intra-pulmonary pressure and allows air to move into the lungs.
Expiration is the release of alveolar air from the lungs, which is the second step in respiration.
The diaphragm and external and internal intercostal muscles help generate pressure gradients for breathing.
Oxyhaemoglobin is the complex formed when oxygen binds with haemoglobin in the red blood cells, allowing for the transport of oxygen in the blood.
The binding of oxygen to haemoglobin is influenced by the partial pressure of oxygen (pO2), partial pressure of carbon dioxide (pCO2), hydrogen ion concentration, and temperature.
Gills are special vascularised structures used by most aquatic arthropods and molluscs for gas exchange.
The steps include pulmonary ventilation, diffusion of gases across the alveolar membrane, transport of gases by blood, diffusion between blood and tissues, and utilization of O2 by cells.
Inspiration occurs when the intra-pulmonary pressure is less than atmospheric pressure, creating a negative pressure in the lungs.
Haemoglobin is a red colored iron-containing pigment in red blood cells that binds oxygen and carbon dioxide, facilitating their transport in the bloodstream.
Every 100 ml of oxygenated blood can deliver around 5 ml of O2 to the tissues under normal physiological conditions.
The larynx is a cartilaginous box that helps in sound production, commonly referred to as the sound box.
The epiglottis is a thin, elastic cartilaginous flap that covers the glottis during swallowing, preventing food from entering the larynx.
Inspiratory Reserve Volume (IRV) is the additional volume of air a person can inspire by a forcible inspiration, averaging 2500 mL to 3000 mL.
Total volume of air a person can inspire after a normal expiration, including tidal volume and inspiratory reserve volume (TV + IRV).
A spirometer is used to estimate the volume of air involved in breathing movements, aiding in the clinical assessment of pulmonary functions.
Partial pressure gradients refer to the difference in pressure of gases like O2 and CO2, which influences their diffusion across alveoli and tissues.
Oxygen is primarily transported in the blood as oxyhaemoglobin, which forms when oxygen binds to haemoglobin in the alveoli.
The Oxygen dissociation curve is a sigmoid curve that illustrates the percentage saturation of haemoglobin with oxygen plotted against the partial pressure of oxygen (pO2), showing how factors like pCO2 and H+ concentration affect oxygen binding.
Diffusion of gases occurs in the alveolar region only because the alveoli provide a large surface area and thin walls, which facilitate efficient gas exchange.
In atmospheric air, pO2 is higher and pCO2 is lower compared to alveolar air.
The oxygen dissociation curve is a graph that illustrates the relationship between the saturation of hemoglobin with oxygen and the partial pressure of oxygen, showing a sigmoidal pattern due to cooperative binding.
Pulmonary respiration refers to the process of gas exchange in vascularised bags called lungs, primarily used by terrestrial animals.
The thoracic chamber is an air-tight chamber that houses the lungs and allows changes in volume to be reflected in the pulmonary cavity, essential for breathing.
Breathing involves inspiration, where atmospheric air is drawn in, and expiration, where alveolar air is released out, dependent on pressure gradients.
Volume of air that remains in the lungs after a normal expiration, including expiratory reserve volume and residual volume (ERV + RV).
Carbon dioxide is transported in the blood primarily as bicarbonate (70%), with about 20-25% bound to haemoglobin as carbamino-haemoglobin, and the remaining 7% dissolved in plasma.
Oxygen utilisation refers to the process by which cells use oxygen for metabolism to produce energy and other substances, such as carbon dioxide.
A healthy human breathes approximately 12-16 times per minute.
Emphysema is a chronic respiratory disorder in which the alveolar walls are damaged, resulting in decreased respiratory surface area; one major cause is cigarette smoking.
Bicarbonate (HCO3–) is responsible for transporting nearly 70 percent of carbon dioxide from tissues to the lungs, facilitated by the enzyme carbonic anhydrase.
About 97 percent of O2 is transported by red blood cells (RBCs) in the blood.
Respiration is regulated by the respiratory center in the brainstem, which responds to levels of CO2, O2, and pH in the blood.
Pressure contributed by an individual gas in a mixture of gases, represented as pO2 for oxygen and pCO2 for carbon dioxide.
Vital capacity is the maximum amount of air a person can expel from the lungs after maximum inhalation. It is significant as it indicates the strength and efficiency of the respiratory system.
An increase in pCO2 enhances the release of oxygen from hemoglobin (Bohr effect), facilitating oxygen delivery to tissues.
At the alveoli, conditions are favorable for the formation of oxyhaemoglobin due to high pO2, low pCO2, lower H+ concentration, and lower temperature.
As a man goes up a hill, the respiratory rate increases to compensate for lower oxygen availability at higher altitudes.
Tidal volume is the amount of air inhaled or exhaled during normal breathing, and for a healthy human, it is approximately 500 mL.
Breathing, commonly known as respiration, is the process of exchanging O2 from the atmosphere with CO2 produced by the cells.
The pharynx is a portion of the human respiratory system that serves as a common passage for food and air.
Cutaneous respiration is a method of gas exchange where some organisms, like amphibians, can respire through their moist skin.
