Respiratory System - NCLEX-PN

Gas exchange in the lung occurs exclusively in the alveoli, the tiny grape-like clusters of sacks at the terminus of the bronchioles of the lung. The gas contained in the larger structures of the lung - the trachea, bronchi, and bronchioles, is termed "dead space" as it does not participate in gas exchange.

Gas exchange in the alveoli occurs by the process of simple diffusion. The blood that enters the lung capillaries is relatively low in oxygen and high in , in comparison to the room air that is drawn into the alveoli during respiration. The separation between the capillaries and the alveolar epithelium is thin enough that these gasses can exchange across their pressure gradients by the process of simple diffusion.

The main trigger for the impulse to breathe is high carbon dioxide (decreased blood pH). In response to a decrease in blood pH, the medullary respiratory center triggers the diaphragm and the external intercostal muscles to increase breathing rate.

Myoglobin, an oxygen-binding protein in the muscle tissue, can bind with one molecule of oxygen. Hemoglobin, the main oxygen-binding metalloprotein in red blood cells, can bind four molecules of oxygen.

While hyperventilation or tachypnea may be triggered by various forms of acidosis, they will not cause a decrease in blood pH, but rather push the blood into a more alkaline state. This occurs due to loss of carbon dioxide during respiration, followed by a compensatory decrease in bicarbonate ions. The result is in an elevation in the pH of the blood. This condition is known as respiratory alkalosis.

Many gases, such as room air, are composed of several gasses (in the case of room air, primarily nitrogen, oxygen, and several trace gasses). Partial pressure is the amount of pressure that each gas contributes. To find the total pressure of a gas mixture, one would find the sum of all partial pressures of each individual gas.

Gas exchange in the lung occurs exclusively in the alveoli, the tiny grape-like clusters of sacks at the terminus of the bronchioles of the lung. The gas contained in the larger structures of the lung - the trachea, bronchi, and bronchioles, is termed "dead space" as it does not participate in gas exchange.

Gas exchange in the alveoli occurs by the process of simple diffusion. The blood that enters the lung capillaries is relatively low in oxygen and high in , in comparison to the room air that is drawn into the alveoli during respiration. The separation between the capillaries and the alveolar epithelium is thin enough that these gasses can exchange across their pressure gradients by the process of simple diffusion.

The main trigger for the impulse to breathe is high carbon dioxide (decreased blood pH). In response to a decrease in blood pH, the medullary respiratory center triggers the diaphragm and the external intercostal muscles to increase breathing rate.

Myoglobin, an oxygen-binding protein in the muscle tissue, can bind with one molecule of oxygen. Hemoglobin, the main oxygen-binding metalloprotein in red blood cells, can bind four molecules of oxygen.

While hyperventilation or tachypnea may be triggered by various forms of acidosis, they will not cause a decrease in blood pH, but rather push the blood into a more alkaline state. This occurs due to loss of carbon dioxide during respiration, followed by a compensatory decrease in bicarbonate ions. The result is in an elevation in the pH of the blood. This condition is known as respiratory alkalosis.

Dead space is the volume of air that remains in the trachea, bronchi, and bronchioles during respiration. It does not enter the alveoli and so does not participate in gas exchange. In the average adult, the amount of air left in the dead space after expiration is .

Tidal breathing is the term for relaxed inhalation and exhalation (as opposed to maximum inspiration and forced exhalation). The average volume of air breathed into and out of the respiratory system during tidal breathing is .

Carbon dioxide has paracrine effects in the airway, causing the smooth muscle of bronchioles to relax. When the partial pressure of carbon dioxide in the alveoli increases, the bronchioles dilate. This allows for increased ventilation.

There are many factors that can cause bronchioconstriction. Some of them are normal physiological responses, such as parasympathetic input or decreased partial pressure of carbon dioxide in the alveoli. Other causes are pathological, such as allergic bronchioconstriction or asthma triggered by cold air.

The diaphragm is innervated by the phrenic nerve. This nerve exits the spine at C3-C5. In the case of spinal cord trauma, if injury occurs above C3, the diaphragm is no longer able to function on its own and breathing assistance is generally required.

Vital capacity is the maximum volume of air a person can exhale after maximum inhalation. Residual volume is the air that remains in the lung after forced exhalation, while functional residual capacity is the volume of air that remains in the lung after a relaxed exhalation.

There are five lobes total in the human lungs: the right lung has three lobes (the upper lobe, the middle lobe, and the lower lobe) while the left lung has two lobes (the upper lobe and the lower lobe).

The topmost part of the lungs is the apex. This area extends into the neck above the 1st rib and is the location auscultated for a diagnosis of a pancost tumor. The lingula of the lung is a small flap of the lowest part of the upper lobe of the left lung. The hilum is the entry point of the lung for the bronchi, pulmonary artery and vein, and nerves. The trachea is not a part of the lung at all; it is the cartilaginous tube that connects the pharynx and larynx to the lung.