Science Quiz: Physiology Of Gas Exchange

Oxygen is transported in the blood by binding to haemoglobin. Haemoglobin is a protein found in red blood cells that has a high affinity for oxygen. When oxygen enters the lungs, it binds to haemoglobin molecules in red blood cells, forming oxyhemoglobin. This oxyhemoglobin is then carried through the bloodstream to the body's tissues, where it releases oxygen for cellular respiration.

Remember that gaseous exchange results when there is a difference in partial pressure across a semi-permeable membrane - movement occurs across a pressure gradient

Oxygen makes up approximately 21% of the air. This is a well-known fact in atmospheric science. The other options provided, such as 31%, 40%, and 50%, do not accurately represent the percentage of oxygen in the air.

Remember that atmospheric pressure at sea level = 760mmHg

Air is composed of various components, including oxygen, carbon dioxide, nitrogen, and water vapor. Oxygen is essential for respiration and combustion, while carbon dioxide is a byproduct of respiration and combustion. Nitrogen is the most abundant component of air, making up about 78% of the atmosphere. It is an inert gas that plays a crucial role in maintaining atmospheric pressure. Water vapor is the gaseous state of water and is present in varying amounts depending on the humidity of the air. These four components make up the majority of the composition of air.

Internal respiration refers to the exchange of gases (O2 and CO2) between the cells and the surrounding tissues. It occurs at a cellular level, where oxygen is taken up by the cells for cellular respiration, and carbon dioxide is released as a waste product. This process is essential for providing oxygen to the cells and removing carbon dioxide, allowing for proper cellular function and metabolism. External respiration, on the other hand, refers to the exchange of gases between the lungs and the external environment. Gas transfer and gas transport are broader terms that encompass various processes involved in the movement of gases within the body.

Carbon dioxide is transported in the blood by combining with water in the plasma to produce bicarbonate. This process, known as carbonic anhydrase, occurs in red blood cells. Carbon dioxide diffuses from the tissues into the bloodstream and is converted into bicarbonate ions. These ions are then transported in the plasma to the lungs, where they are converted back into carbon dioxide and released from the body through exhalation. This bicarbonate buffering system helps maintain the pH balance in the blood and ensures efficient transport of carbon dioxide.

External respiration refers to the exchange of gases between the lungs and the external environment. It specifically occurs at the alveoli level within the lungs, where oxygen is taken in from the air and carbon dioxide is released. This process allows for the oxygenation of blood and the removal of waste gases, enabling the transportation of oxygen to cells and the removal of carbon dioxide from the body.

The left ventricle is responsible for pumping oxygen-rich blood out of the heart into the aorta. It receives oxygenated blood from the left atrium and contracts to push the blood into the largest artery of the body, the aorta. This oxygen-rich blood is then distributed to the rest of the body through the systemic circulation.

The left and right pulmonary arteries carry deoxygenated blood to the lungs. These arteries are responsible for transporting blood from the heart to the lungs, where it can be oxygenated. Once the blood reaches the lungs, it is able to release carbon dioxide and pick up oxygen, becoming oxygenated and ready to be returned to the heart.