When a person is suddenly frightened, the body prepares itself to react quickly to the possible danger. A student was working quietly when they were suddenl...
Question 1 Report
When a person is suddenly frightened, the body prepares itself to react quickly to the possible danger. A student was working quietly when they were suddenly startled by a loud noise. The flow diagram summarises the sequence of events that followed, beginning with the brain detecting the fright and ending with the release of a hormone from gland Q into the blood. The table shows three measurements that were taken from the student, once before the event and once during it, so that the effects of the hormone can be compared. Use the flow diagram and the table to answer the questions.
| Measurement | Before | During |
|---|---|---|
| Heart rate / beats per minute | 72 | 120 |
| Breathing rate / breaths per minute | 16 | 28 |
| Blood glucose / mmol per dm3 | 5.0 | 7.5 |
(a) Name gland Q, which produces the hormone shown in the flow diagram. [1]
(b) Using the table, calculate the increase in the student's heart rate during the event. [1]
(c) Describe the two other changes shown in the table when the hormone is released. [2]
(d) State two features of this hormone that show it is acting as a hormone and not as a nervous signal. [2]
Answer Details
This question tests the "fight or flight" response and how a hormone differs from a nervous signal.
(a) Gland Q. [1] The hormone released in fright is adrenaline, made by the adrenal gland [1].
(b) Increase in heart rate. [1] \(120-72=\mathbf{48}\) beats per minute [1].
(c) The two other changes in the table. [2] The breathing rate increases from 16 to 28 breaths per minute [1]; the blood glucose increases from 5.0 to 7.5 mmol per dm3 [1]. Both prepare the body to release more energy quickly.
(d) Two features showing it acts as a hormone, not a nervous signal. [2] It is a chemical messenger [1]; and it is made by an endocrine gland and carried in the blood to its target organs [1]. Exam tip: a nervous signal is an electrical impulse along a neurone acting almost instantly, whereas a hormone travels in the blood and its effects are slower but longer-lasting.
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