The body keeps its inside conditions steady. This is true even when the outside changes a lot. This steady state is called homeostasis. One key thing that i...
Question 1 Report
The body keeps its inside conditions steady. This is true even when the outside changes a lot. This steady state is called homeostasis. One key thing that is kept steady is the body temperature. It is held near 37 degrees. If the body is too hot or too cold, its enzymes may fail. So the body can gain and lose heat. Part of the brain checks the temperature of the blood. It controls these changes. A student came in from a hot day. They were sweating. Their face was red. They were asked to explain the changes in the skin.
(a) State what is meant by the term homeostasis. [1]
(b) Name the part of the brain that monitors the temperature of the blood. [1]
(c) Explain how sweating helps to cool the body down on a hot day. [3]
(d) Explain how a change in the flow of blood to the skin helps to cool the body. [3]
(e) Describe how the body responds to being too cold in order to raise its temperature. [3]
Answer Details
This question tests temperature homeostasis and how the skin responds to being too hot or too cold.
(a) Homeostasis is the maintenance of a constant internal environment (steady internal conditions) [1].
(b) The part of the brain that monitors the temperature of the blood is the hypothalamus [1].
(c) Sweating cools the body because sweat is released onto the surface of the skin [1]; the water in the sweat evaporates [1]; and evaporation takes heat energy from the body, so the body cools [1].
(d) Changing blood flow to the skin cools the body by vasodilation: the arterioles supplying the skin widen [1]; so more blood flows near the surface of the skin [1]; and more heat is lost by radiation to the surroundings [1]. (Note the vessels themselves move blood nearer the surface; the capillaries do not "move".)
(e) To raise its temperature when too cold, the body responds by shivering: muscles contract rapidly, releasing heat from respiration [1]; vasoconstriction: skin blood vessels narrow so less heat is lost from the surface [1]; and less sweat is produced [1].
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