Anatomy Final Study Cards

The alveoli are the actual sites of gas exchange within the lungs. These tiny air sacs are located at the end of the bronchioles and are surrounded by a dense network of capillaries. Oxygen from the inhaled air diffuses across the thin walls of the alveoli into the bloodstream, while carbon dioxide, a waste product, diffuses from the bloodstream into the alveoli to be exhaled. This exchange of gases is crucial for maintaining the body's oxygen and carbon dioxide levels and ensuring proper respiratory function.

Surfactant is a substance produced by the cells in the alveoli of the lungs. It reduces the surface tension of the fluid lining the alveoli, which helps to prevent them from collapsing. The alveoli are tiny air sacs where the exchange of oxygen and carbon dioxide takes place. Without surfactant, the surface tension would be high, causing the alveoli to collapse and making it difficult for oxygen to enter the bloodstream. Therefore, surfactant plays a crucial role in maintaining the structure and function of the alveoli, ensuring efficient gas exchange in the lungs.

The upper respiratory tract is responsible for filtering, warming, and humidifying the air that enters the body. It consists of the nasal cavity, pharynx, and larynx. The nasal cavity contains tiny hairs called cilia that help trap and filter out dust, pollen, and other particles from the air. As the air passes through the nasal cavity, it is also warmed and humidified, ensuring that it is at an optimal temperature and moisture level when it reaches the lungs. Therefore, the upper respiratory tract plays a crucial role in preparing the air for efficient gas exchange in the lungs.

The nose performs several functions, including filtering the air, warming the air, humidifying the air, and acting as a resonating chamber in speech. Filtering the air helps to remove particles and impurities before they enter the respiratory system. Warming the air helps to bring it to body temperature, making it more comfortable to breathe in. Humidifying the air adds moisture, preventing the respiratory system from drying out. Lastly, the nose acts as a resonating chamber in speech, helping to shape and amplify sound.

Air moves into the lungs because the gas pressure in the lungs is less than the outside pressure. According to Boyle's law, when the volume of a gas increases, the pressure decreases. During inhalation, the diaphragm and intercostal muscles contract, increasing the volume of the lungs. This decrease in lung volume results in a decrease in gas pressure, creating a pressure gradient between the lungs and the outside environment. As a result, air flows from an area of higher pressure (outside) to an area of lower pressure (lungs), allowing for the movement of air into the lungs.

During expiration, the muscles involved in respiration, such as the diaphragm and intercostal muscles, relax. This relaxation causes the volume of the lungs to decrease. As a result, the pressure inside the lungs increases, causing air to be forced out of the lungs and into the atmosphere. This process is essential for removing carbon dioxide, a waste product of cellular respiration, from the body.

The internal intercostals are responsible for producing expiratory movements. These muscles are located between the ribs and work by contracting to pull the ribs downward and inward, decreasing the volume of the thoracic cavity. This contraction increases the pressure in the lungs, causing air to be forced out during expiration.

When the diaphragm and external intercostal muscles contract, they cause the thoracic cavity to expand. This expansion leads to an increase in the volume of the thoracic cavity. As the volume of the thoracic cavity increases, the lungs are able to expand and fill with air, allowing for inhalation to occur. This is a crucial process in respiration, as it enables the exchange of oxygen and carbon dioxide in the lungs.

Pulmonary ventilation is the process of inhaling and exhaling air, which involves the movement of air into and out of the lungs. This process allows for the exchange of oxygen and carbon dioxide between the lungs and the bloodstream, ensuring that the body receives oxygen and gets rid of waste gases.

Oxygen is primarily transported in the blood by binding to hemoglobin, a protein found in red blood cells. Hemoglobin has a high affinity for oxygen, allowing it to easily bind to oxygen molecules in the lungs and release them to the body's tissues when needed. This binding and releasing of oxygen is crucial for efficient oxygen delivery to cells throughout the body. Therefore, the statement "bound to hemoglobin" accurately describes how most of the oxygen is transported in the blood.

Carbon dioxide is transported in the blood primarily as bicarbonate ions. When carbon dioxide enters the red blood cells, it combines with water to form carbonic acid. This carbonic acid then dissociates into bicarbonate ions and hydrogen ions. The majority of the bicarbonate ions are transported out of the red blood cells and into the plasma, where they are carried to the lungs. In the lungs, the bicarbonate ions are converted back into carbon dioxide, which is then exhaled. This bicarbonate ion transport mechanism allows for efficient removal of carbon dioxide from the body.

Carbon dioxide is the most important chemical regulator of respiration because it plays a crucial role in maintaining the pH balance in our body. When carbon dioxide levels increase in the blood, it combines with water to form carbonic acid, which lowers the pH. This decrease in pH is detected by chemoreceptors in the brain, which then stimulate an increase in respiratory rate and depth. This helps to remove excess carbon dioxide from the body and restore the pH balance. Therefore, carbon dioxide acts as a powerful regulator of respiration.

An increase in the level of carbon dioxide in the blood is detected by chemoreceptors in the brainstem, which then stimulate the respiratory centers to increase the rate of breathing. This is because carbon dioxide is a waste product of cellular respiration and needs to be eliminated from the body. By increasing the rate of breathing, more carbon dioxide can be exhaled, helping to maintain the balance of gases in the blood.

During quiet breathing, the process of inspiration requires the contraction of certain muscles, such as the diaphragm and intercostal muscles, to expand the chest cavity and allow air to enter the lungs. This muscular effort is necessary to create a pressure gradient that facilitates the flow of air into the lungs. On the other hand, expiration during quiet breathing is a passive process that does not require muscular contractions. It occurs as a result of the relaxation of the inspiratory muscles and the elastic recoil of the lungs, which causes the chest cavity to decrease in size and air to be expelled from the lungs.

Vital capacity refers to the maximum amount of air a person can exhale after taking the deepest possible breath. In this scenario, the student inhales deeply and then exhales until they cannot exhale any more, which indicates that they are expelling the maximum amount of air they can. Therefore, the amount of air expelled in this situation would be the student's vital capacity.

A decreased pH would increase the amount of oxygen discharged by hemoglobin to peripheral tissues because it indicates a lower pH level or higher acidity. This change in pH causes a shift in the oxygen-hemoglobin dissociation curve to the right, resulting in a greater release of oxygen from hemoglobin to the tissues. This allows for increased oxygen delivery to the peripheral tissues where it is needed.

When the diaphragm and external intercostal muscles contract, it causes the volume of the thoracic cavity to increase. This increase in volume leads to a decrease in intrapleural pressure, which is the pressure within the pleural cavity surrounding the lungs. This decrease in intrapleural pressure helps to expand the lungs, allowing for inhalation and the intake of air.

Damage to the surfactant cells of the lungs can lead to alveolar collapse. Surfactant is a substance produced by these cells that helps to reduce surface tension in the alveoli, the tiny air sacs in the lungs. This reduces the effort required for breathing and prevents the alveoli from collapsing. When the surfactant cells are damaged, the production of surfactant is reduced, leading to increased surface tension and potential collapse of the alveoli. This can impair the exchange of oxygen and carbon dioxide in the lungs, resulting in respiratory difficulties.

The correct answer is that Harry's breathing problem is likely caused by thick secretions that are too difficult for his respiratory tract to clear. This is a common issue for individuals with cystic fibrosis, as the disease causes a buildup of thick mucus in the lungs and airways. The excess mucus can block the airways and make it difficult for air to flow in and out, leading to breathing difficulties.

In emphysema, the breakdown and coalescence of alveoli into large air spaces result in increased dead air space. This means that the air inhaled does not reach the alveoli where gas exchange occurs, leading to a decrease in vital capacity. The loss of elasticity in the lungs also causes difficulty in exhaling fully, causing an increase in the anteroposterior diameter of the thorax. Additionally, the impaired gas exchange in the damaged alveoli leads to an elevation in PCO2 levels in the blood. Therefore, all of these symptoms are expected in a person suffering from emphysema.