2.3 Distinguish between systolic and diastolic blood pressure.
2.4 What is the physiological relationship between the lymphatic and circulatory systems?
(5)
lamellare
QUESTION 3 17]
3.1 How does the gills' countercurrent exchange system optimise oxygen uptake from water? (3)
3.2 Discuss the adaptations in bird lungs that make them highly efficient for gas exchange.
(4)
3.3 Outline the fundamental physiological principles that underlie ventilation in all air-breathing animals with lungs.
(5)
3.4 Compare and contrast the common respiratory pigments found in animals.
(5)
3.1 The gills' countercurrent exchange system optimizes oxygen uptake from water by maximizing the concentration gradient of oxygen. In this system, water flows over the gills in one direction, while blood flows over the gills in the opposite direction. This creates a concentration gradient of oxygen between the water and blood, allowing for efficient diffusion of oxygen from the water into the blood. The countercurrent system ensures that there is always a higher concentration of oxygen in the water than in the blood, allowing for continuous diffusion of oxygen across the gill surface.
3.2 Birds have highly efficient lungs adapted for gas exchange at high altitudes and during flight. They have a system of interconnected air sacs that allow for a continuous flow of fresh air through their lungs. This unidirectional airflow ensures that oxygen-rich air is constantly available for gas exchange.
Bird lungs also have a large number of small air sacs called parabronchi. These parabronchi are supported by a network of air capillaries, which have thin walls and a large surface area for gas exchange. This efficient structure allows for rapid and efficient diffusion of oxygen into the bloodstream.
Bird lungs also have a high metabolic rate, which increases the demand for oxygen. They have a more rigid lung structure compared to mammals, which helps maintain a constant flow of air through their lungs, even during the expansion and contraction of the body cavity during flight.
3.3 The fundamental physiological principles that underlie ventilation in all air-breathing animals with lungs include the processes of inspiration and expiration. During inspiration, the diaphragm and intercostal muscles contract, causing the volume of the thoracic cavity to increase. This decrease in pressure in the thoracic cavity creates a pressure gradient, causing air to flow into the lungs.
During expiration, the diaphragm and intercostal muscles relax, causing the volume of the thoracic cavity to decrease. This increase in pressure in the thoracic cavity creates a pressure gradient, causing air to flow out of the lungs.
In addition to the muscles involved in inspiration and expiration, the respiratory system also includes structures such as the trachea, bronchi, bronchioles, and alveoli which facilitate the movement of air into and out of the lungs.
Gas exchange occurs in the alveoli, which have thin walls and a large surface area for diffusion of oxygen and carbon dioxide. Oxygen diffuses from the alveoli into the bloodstream, while carbon dioxide diffuses from the bloodstream into the alveoli to be exhaled.
3.4 The common respiratory pigments found in animals include hemoglobin, myoglobin, chlorocruorin, and hemocyanin.
Hemoglobin is the most common respiratory pigment found in vertebrates. It is found in red blood cells and has a high affinity for oxygen. Hemoglobin binds to oxygen in the lungs and carries it to the tissues, where it releases the oxygen for cellular respiration.
Myoglobin is a respiratory pigment found in muscle tissue and has a higher affinity for oxygen than hemoglobin. It serves to store oxygen in the muscles and release it when needed during periods of increased activity.
Chlorocruorin is a respiratory pigment found in certain marine invertebrates, such as polychaetes. It contains iron and has a red-green color. Chlorocruorin is similar to hemoglobin in function, binding to oxygen in the gills and transporting it throughout the body.
Hemocyanin is a respiratory pigment found in certain mollusks and arthropods. It contains copper and has a blue color. Hemocyanin carries oxygen in the blood by binding to it and forming a complex. It is less efficient than hemoglobin in oxygen transport but is able to function in low oxygen environments.