BIOL 213 Anatomy and Physiology I COMPLETED EXAM 2026 (16pages)

1. What is the definition of homeostasis and why is it important for the human body? (2 marks) Homeostasis is the ability of the body to maintain a stable internal environment despite changes in external conditions. It is important for the human body because it ensures that vital functions such as metabolism, temperature, pH, blood pressure, fluid balance, and oxygen levels are kept within optimal ranges for survival and health. (2 marks) 2. What are the three components of a homeostatic control system and what are their roles? (3 marks) The three components of a homeostatic control system are: - The receptor, which detects changes in a variable that is being regulated, such as temperature or blood glucose. (1 mark) - The control center, which receives information from the receptor and determines the appropriate response to restore the variable to its set point. The control center may be a part of the brain, such as the hypothalamus, or an endocrine gland, such as the pancreas. (1 mark) - The effector, which carries out the response directed by the control center, such as a muscle, a gland, or an organ. The effector may increase or decrease its activity to bring the variable back to its normal range. (1 mark) 3. What are the two types of feedback mechanisms that regulate homeostasis and how do they differ? (3 marks) The two types of feedback mechanisms that regulate homeostasis are: - Negative feedback, which is the most common type of feedback mechanism. It involves a response that counteracts or opposes the initial change in a variable, thus restoring it to its set point. For example, when the body temperature rises above normal, negative feedback triggers sweating and vasodilation to lower the temperature. (2 marks) - Positive feedback, which is a less common type of feedback mechanism. It involves a response that amplifies or reinforces the initial change in a variable, thus moving it further away from its set point. Positive feedback usually occurs in situations that require a rapid or decisive action, such as blood clotting or childbirth. For example, when a blood vessel is damaged, positive feedback triggers the release of clotting factors that accelerate the formation of a clot until the bleeding stops. (2 marks)