Homeostasis：練習問題

Why is it crucial for the human body to maintain a relatively constant internal temperature?

A person stays in a cold environment for a long period. Which of the following describes the correct coordination between the coordinating centre and the effector to maintain body temperature?

When a person experiences prolonged cold stress over several weeks, the body undergoes physiological acclimatization to maintain a stable core temperature. Which of the following best describes the integrated hormonal and metabolic coordination initiated by the hypothalamus in this specific long-term scenario?

I. The hypothalamus releases TRH, which eventually stimulates the thyroid gland to secrete thyroxine.
II. Increased thyroxine levels promote mitochondrial activity and protein synthesis to raise the basal metabolic rate (BMR).
III. The hypothalamus triggers sympathetic nerve impulses to cause the permanent constriction of shunt vessels in the skin.

Which of the following is a parameter of the internal environment that is strictly regulated by homeostatic mechanisms in humans to ensure the survival of body cells?

During vigorous exercise, the rate of aerobic respiration in muscle cells increases, leading to a rise in the concentration of carbon dioxide in the blood. Which of the following correctly describes the homeostatic response to return the gas content to its normal level?

In which part of the central nervous system is the respiratory center located, and what is its primary role in maintaining gas homeostasis?

Explain how sympathetic nerves act on the cardiac pacemaker to help maintain the homeostasis of blood gas levels during a sudden increase in physical exertion.

Following the consumption of a very salty meal, explain the negative feedback loop involving osmoreceptors and the pituitary gland, and describe the specific physiological change in the collecting duct of the nephron.

Homeostasis is the process by which a stable internal environment is maintained.
(a) Define the term homeostasis and state one reason why it is crucial for the survival of humans. (2 marks)
(b) Identify two different parameters of the internal environment that are strictly regulated by the body to maintain stability. (2 marks)

An athlete is competing in a challenging marathon. During the prolonged strenuous exercise, their body faces multiple homeostatic challenges, including maintaining a stable core body temperature, ensuring sufficient energy supply to muscles, and regulating blood gas levels.

(a) Explain the physiological mechanisms, including the role of specific structures and feedback pathways, by which the athlete's body regulates its core body temperature when overheating during the race. (4 marks)

(b) Describe how the nervous and endocrine systems interact to coordinate the maintenance of stable blood glucose levels and efficient gas exchange (oxygen uptake and carbon dioxide removal) in the athlete during strenuous exercise. (4 marks)