Respiratory System Overview

The amount of air inhaled or exhaled during a normal breath.

The extra air that can be inhaled after a normal breath.

The amount of air that can be forcefully exhaled after a normal breath.

The air remaining in the lungs after maximal exhalation.

The total volume of air in the lungs after a maximal inhalation.

The maximum amount of air that can be exhaled after a maximal inhalation.

The amount of air remaining in the lungs after a normal exhalation.

The maximum amount of air that can be inhaled after a normal exhalation.

The exchange of oxygen (O2) and carbon dioxide (CO2) between the alveoli of the lungs and the blood in the pulmonary capillaries.

Another name for pulmonary respiration, emphasizing the gas exchange happening outside of the body's cells.

The exchange of oxygen (O2) and carbon dioxide (CO2) between the blood in the capillaries and the body's cells.

Another name for tissue respiration, emphasizing the gas exchange happening inside the body's cells.

The process by which oxygen is carried from the lungs to the body's tissues.

A protein in red blood cells that binds to oxygen, allowing blood to carry a lot more oxygen.

Hemoglobin that is bound to oxygen, making it oxygen-rich.

Hemoglobin that has released its oxygen, making it oxygen-poor.

The process of moving air in and out of the lungs. This involves two phases: inspiration (air in) and expiration (air out).

Changes in the volume of the thorax, which in turn influence the air pressure in the lungs, drive air movement.

The process of drawing air into the lungs. This occurs when the diaphragm contracts and moves downwards, and the rib cage expands due to external intercostal muscle contraction.

The process of expelling air from the lungs. This usually occurs passively, as the intercostals muscles relax and the diaphragm returns to its dome shape, reducing the thoracic cavity volume and increasing pressure.

During exercise, expiration becomes more active. Internal intercostals and abdominal muscles contract, speeding up and intensifying the process of air expulsion.

These muscles are responsible for bringing air into the lungs. Key inspiratory muscles include the diaphragm, external intercostals, and accessory muscles like the sternocleidomastoids and scalenes.

These muscles help you exhale air from the lungs. Key expiratory muscles include the abdominal muscles and internal intercostals.

Ventilation is essential for gas exchange. It brings oxygen into the lungs and removes carbon dioxide from the body.

The pressure of a gas is inversely proportional to its volume. This means if volume decreases, pressure increases.

The solubility of a gas in a liquid is directly proportional to the partial pressure of the gas.

The pressure of a gas is directly proportional to its temperature (in Kelvin).

In a mixture of gases, each gas exerts a pressure as if it were the only gas present.

The process of gas movement from an area of high pressure to an area of low pressure. Important in respiration.

The system responsible for taking in oxygen and releasing carbon dioxide from the body.

During exercise, muscle cells produce lactic acid, which promotes the release of oxygen (O₂) from hemoglobin in the blood.

Higher temperatures increase the release of O₂ from hemoglobin. Active tissues produce heat, boosting local temperatures and promoting oxygen delivery.

Carbon dioxide is transported in the blood in three ways: dissolved in plasma (7-10%), bound to hemoglobin (20% as carbaminohemoglobin), and as bicarbonate ions in plasma (70%).

In red blood cells, carbon dioxide (CO₂) reacts with water (H₂O) to form carbonic acid (H₂CO₃) which then dissociates into hydrogen ions (H⁺) and bicarbonate ions (HCO₃⁻).

This enzyme in red blood cells speeds up the reversible conversion of carbon dioxide (CO₂) and water (H₂O) to carbonic acid (H₂CO₃).

In the tissues, bicarbonate ions (HCO₃⁻) move out of red blood cells into the plasma. To maintain electrical balance, chloride ions (Cl⁻) move from plasma into the red blood cells.

At the lungs, bicarbonate ions move back into red blood cells, combining with hydrogen ions to form carbonic acid. Carbonic anhydrase splits carbonic acid into CO₂ and H₂O, allowing CO₂ to be exhaled.

This area in the brainstem controls the basic patterns of breathing for inspiration and expiration.

The inspiratory center is a cluster of neurons in the medulla oblongata responsible for initiating and regulating inhalation.

The inspiratory center sends signals via the phrenic nerve to the diaphragm, causing it to contract and flatten, increasing the volume of the chest cavity and drawing air into the lungs.

The external intercostal muscles help expand the chest cavity during inspiration by pulling the ribs upwards and outwards, further assisting in drawing air into the lungs.

The expiratory center, also in the medulla oblongata, primarily regulates exhalation. It is less active during quiet breathing, becoming more active during forced exhalation.

During forced expiration, the expiratory center stimulates the internal intercostal muscles and abdominal muscles to contract, pushing air out of the lungs more forcefully.

The medullary rhythmicity area is the primary control center for breathing, located in the medulla oblongata. It houses the inspiratory and expiratory neurons.

The pneumotaxic area, found in the pons, limits the duration of inhalation, preventing overly deep breaths.

The apneustic area, also in the pons, prolongs inspiration, increasing the depth and duration of each breath.

Lung stretch receptors respond to lung inflation, sending signals to the medullary inspiratory center to stop inhalation and allow exhalation, preventing over-inflation.

The respiratory areas are clusters of neurons in the brainstem responsible for controlling breathing rate, depth, and rhythm. These areas include the medullary respiratory group and the pontine respiratory group.

The DRG is the 'pacemaker' of breathing, located in the medulla. It primarily controls the rate and depth of quiet breathing (eupnea).

The VRG, also in the medulla, is responsible for forced inspiration and expiration, taking over when more forceful breathing is needed.

The PRG, located in the pons, continuously inhibits the inspiratory center, helping to smoothly transition between inspiration and expiration.

Respiratory rhythm is a result of the interplay between interconnected neuronal networks in the medulla, specifically the inspiratory and expiratory neurons.

The depth of breathing is determined by the level of activity in the respiratory center, particularly the inspiratory neurons. More active neurons lead to deeper breaths.