1. The concentration of oxygen in inhaled air is always higher than the concentration of oxygen in the alveolar capillaries. Explain why this is so and how this helps to maximise the efficiency of gas exchange at the respiratory surface.
2. The concentration of carbon dioxide in inhaled air is always lower than the concentration of carbon dioxide in the alveolar capillaries. Explain why this is so and how this helps to maximise the efficiency of gas exchange at the respiratory surface.
3.
Write an account to
explain
how the digestive, circulatory and respiratory systems work together to provide all the cells of the body with adequate supplies of glucose and oxygen to support normal daily activities. In your account, you must
explain
how glucose and oxygen are taken from the environment into the blood and how they are transported around the body to the cells that need them
4. Write an account to explain the concept of homeostasis. In your account, you should use the following terms:
Internal environment, blood plasma, tissue fluid, endocrine system, nervous system, hormone, negative feedback loop, set point, receptor, controller, effector.
5. Blood glucose regulation in humans and other animals is an example of endocrine homeostasis. The following graph shows the variation in blood glucose concentration of a healthy person over an 8 hour period. Study the graph and then answer the questions that follow:
1) From the graph, what is the approximate “set point range value” for human blood glucose concentration? Which three letters on the graph best represent this?
2) Using your knowledge of normal blood glucose regulation, explain how the blood glucose peak at point
[A]
is corrected until glucose concentration falls to point
[B]. In your answer, identify and explain the roles of the receptor, controller (hormone) and effectors that are involved in the mechanism.
3) Following reduction back to point
[B], blood glucose concentration is prevented from falling further and starts to rise again. If the lowering of blood glucose concentration was allowed to continue beyond point
[B], what physiological state would result and what symptoms would develop?
4) Using your knowledge of normal blood glucose regulation, explain how blood glucose reduction is reversed until point
[C]
is reached. In your answer, identify and explain the roles of the receptor, controller (hormone) and effectors that are involved in the mechanism.
5) Your answers to parts (i) –(vi) highlight the components of negative feedback control. Using the example of blood glucose regulation, briefly explain the principles of a negative feedback loop and highlight why the endocrine system is well-suited to orchestrating this type of control.