Physiology of the Respiratory System

The volume of air in the conducting airways that doesn't participate in gas exchange.

The amount of air that reaches the alveoli each minute. It is calculated as: Respiratory rate x (Tidal volume - Anatomical dead space).

The ability of the lungs to expand and contract, influenced by factors such as surface tension and surfactant.

The resistance to airflow in the airways. It depends on factors like airway diameter, mucus presence, and muscle tension.

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

The maximum amount of air that can be forcefully exhaled after taking in a deep breath.

The volume of air exhaled in the first second of a forced expiration.

A measure of how effectively your lungs exchange oxygen and carbon dioxide.

A device used to measure the speed at which air can be exhaled.

A technique used to measure lung volumes and capacities.

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

The process of breathing, which includes inhalation and exhalation.

An attractive force between molecules at the surface of a liquid, minimizing surface area. Think of a stretched membrane.

The relationship between pressure, surface tension, and radius of a sphere. Higher surface tension means higher pressure needed to expand.

A substance that reduces surface tension, particularly in the alveoli, allowing them to remain inflated.

A condition in premature babies due to lack of surfactant, resulting in collapsed alveoli and difficulty breathing.

Increased airway resistance due to narrowing of airways, caused by factors like smoke or allergens.

Relaxation of airway muscles, leading to wider airways and easier breathing. Often triggered by sympathetic nerves or adrenaline.

The movement of a gas from an area of high concentration to an area of low concentration. In the context of blood gas transport, it's how oxygen moves from the alveoli to the blood and carbon dioxide moves from the blood to the alveoli.

The pressure exerted by a single gas in a mixture of gases. It's directly proportional to the percentage of that gas in the mixture.

The ability of a gas to dissolve in a liquid, like blood. Different gases have different solubilities.

The difference in partial pressures of a gas between two areas. This drives the diffusion of gases across membranes.

A protein found in red blood cells that binds to oxygen and transports it through the bloodstream. It's crucial for delivering oxygen to tissues.

Fetal hemoglobin has a higher affinity for oxygen compared to adult hemoglobin. This allows for efficient oxygen transfer from the mother to the fetus across the placenta.

Carbon dioxide, produced during metabolism, is transported in the blood in three main ways: 1) dissolved in plasma, 2) bound to hemoglobin forming carbaminohemoglobin, and 3) as bicarbonate ions.

The enzyme carbonic anhydrase helps convert CO2 and water into carbonic acid (H2CO3), which then dissociates into bicarbonate ions (HCO3-) and hydrogen ions (H+). This is the primary way CO2 is transported in the blood.

The chloride shift is a process that maintains the balance of ions during CO2 transport. Bicarbonate ions move out of red blood cells, while chloride ions move in. This ensures that the electrical neutrality of the cell is maintained.

Hemoglobin, a protein in red blood cells, acts as a buffer to minimize changes in blood pH caused by the production of hydrogen ions (H+) during CO2 transport.

Deoxygenated hemoglobin has a higher affinity for hydrogen ions (H+) compared to oxygenated hemoglobin. This plays a role in CO2 unloading from the lungs and CO2 uptake in the tissues.

The Haldane effect states that in the lungs, oxygenated hemoglobin releases H+ ions, promoting CO2 unloading. In the tissues, deoxygenated hemoglobin binds to H+ ions, facilitating CO2 uptake.

The Bohr effect describes the relationship between oxygen affinity and hemoglobin's sensitivity to pH changes. Lower pH (more acidic) results in decreased oxygen affinity, promoting oxygen release in tissues.

Carbon dioxide transport is crucial for removing waste products from the body and maintaining proper blood pH levels.

Understanding the mechanisms of CO2 transport is fundamental for understanding how the body regulates blood pH and gas exchange.

The amount of a specific gas dissolved in a liquid is proportional to its partial pressure in the air above the liquid. Think of a soda bottle. When you open it, the dissolved CO2 escapes because the pressure inside the bottle is higher than the atmospheric pressure.

The difference in partial pressures of gases across the respiratory membrane is significant. This drives the diffusion of gases between the alveoli and the blood. Imagine a hill with a steep incline. The steeper the incline, the greater the pressure difference.

At sea level, oxygen makes up approximately 20.9% of the atmosphere. This means that for every 760 mmHg of atmospheric pressure, 159 mmHg is due to oxygen. This is the partial pressure of oxygen at sea level.

Atmospheric pressure decreases as altitude increases. At 10,000 feet, atmospheric pressure is about 523mmHg, and the partial pressure of oxygen is about 109mmHg. This means that the amount of oxygen available for breathing is significantly less at higher altitudes. Think of breathing on a mountaintop, you might feel short of breath because there is less oxygen available.

A decrease in the partial pressure of oxygen (PO2) in the alveolar gas and arterial blood below 60mmHg, leading to a condition known as acute mountain sickness.

Specialized cells in the brain (medulla oblongata) and peripheral tissues (e.g., carotid and aortic bodies) that monitor the levels of carbon dioxide (CO2), hydrogen ions (H+), and oxygen (O2) in the blood and cerebrospinal fluid (CSF).

The brain's control center for breathing located in the pons and medulla, coordinating signals from chemoreceptors and other input to adjust the rate and depth of respiration.

The central chemoreceptors located in the medulla, sensitive to changes in the acidity (pH) of the cerebrospinal fluid (CSF).

The process by which carbon dioxide (CO2) crosses the blood-brain barrier into the cerebrospinal fluid (CSF), affecting its pH. This change triggers the central chemoreceptors to increase ventilation.

Specialized sensory cells located in the carotid body at the bifurcation of the carotid arteries and in the aortic bodies above and below the aortic arch. They detect changes in arterial blood oxygen levels (PO2), carbon dioxide levels (PCO2), and pH.

The rate at which peripheral chemoreceptors fire action potentials, increasing as PO2 decreases, PCO2 increases, or pH decreases. This signals the brain to increase breathing rate and depth to restore blood gas balance.

A condition characterized by a decrease in blood pH due to an increase in carbon dioxide levels. This can occur when gas exchange in the lungs is impaired.

The process of adjusting breathing rhythm to meet changing physiological demands, like metabolic, mechanical, and non-ventilatory needs.

The ability of active tissues to directly influence blood flow and oxygen delivery, ensuring efficient gas transport.

Specialized cells within the brain that monitor blood pH, carbon dioxide, and oxygen levels, triggering changes in breathing rate and depth.

Receptors within the lungs that respond to stretching and pressure changes during breathing, providing feedback to the brain about lung volume and airflow.

Regions in the brain stem, specifically the pons and medulla oblongata, that control the rhythm and depth of breathing.

The state of having a dangerously low oxygen level in the blood, which can stimulate breathing.

The condition of elevated carbon dioxide levels in the blood, which can trigger an increase in breathing rate.

A change in pH, typically a decrease (more acidic), can trigger a breathing response to eliminate excess CO2.

The coordinated action of multiple factors, including central and peripheral chemoreceptors, lung mechanoreceptors, and respiratory centers, working together to regulate breathing.

A condition affecting the airways, causing inflammation and narrowing, leading to difficulty breathing. Triggers include allergens, air pollution, exercise, and stress.

This medication relaxes the muscles in the airways of asthma sufferers, widening the passage and making breathing easier.

Long-term dust exposure can cause this condition, leading to lung tissue scarring and breathing difficulties.

This process involves mast cells releasing histamine and cytokines in response to triggers, leading to airway inflammation and narrowing in asthma.

A higher affinity for oxygen allows the fetus to efficiently get it from the mother's blood across the placenta.

A type of restrictive lung disease where scar tissue forms in the lungs, making it difficult to breathe. This is often caused by exposure to environmental pollutants, cigarette smoke, or autoimmune diseases.

A serious complication of pulmonary fibrosis where alveoli (tiny air sacs in the lungs) are replaced by scar tissue, reducing lung capacity and oxygen diffusion. This leads to shortness of breath and decreased gas exchange.

The ability of the lungs to transfer oxygen from the air to the bloodstream. This is reduced in pulmonary fibrosis due to the thickened alveolar walls.

A drug used in the treatment of rheumatoid arthritis. It can also be used to treat some forms of pulmonary fibrosis, but it's not a cure.

A group of lung diseases that make it difficult to breathe, including chronic bronchitis and emphysema.

Inflammation of the bronchi, characterized by excessive mucus production.

Destruction of the alveoli, leading to reduced lung elasticity and airflow.

A measure of how much air can be forcefully exhaled in one second, indicating airway resistance.

Conditions that prevent the lungs from expanding to their full capacity, affecting lung volume and vital capacity (VC).

A condition that causes the body to develop scar tissue in the lungs, leading to reduced lung compliance.

The ability of the lungs to expand and contract.

An inflammatory process in the respiratory system, often caused by infections.

Inflammation of the lungs, often caused by bacterial or viral infections.

A contagious disease caused by bacteria, affecting the lungs and causing coughing, fever, and weight loss.

A viral respiratory illness that can cause severe respiratory problems, including pneumonia.

The volume of air that remains in the lungs after a normal exhalation.

The volume of air that can be forcefully exhaled after a deep inhalation.

The ratio of FEV1 to FVC, indicating the effectiveness of air movement.

A condition that causes the narrowing of airways, leading to difficulty breathing.