Biology (9-1) - 0970 CIE

Hormones

Overview

Alongside the fast electrical signals of the nervous system, your body has a second messaging service: chemical messengers called hormones. They travel in the blood and switch on changes in distant organs, controlling everything from your heartbeat in a fright to your blood sugar after a meal.

In this lesson you will learn what a hormone is, name the main endocrine glands and the hormones they release, study adrenaline as the 'fight or flight' hormone, and compare nervous and hormonal control. These comparisons are classic exam questions.

Objectives

Describe a hormone as a chemical substance, produced by a gland and carried by the blood, which alters the activity of one or more specific target organs
Identify in diagrams and images specific endocrine glands and state the hormones they secrete, limited to: (a) adrenal glands and adrenaline (b) pancreas and insulin (c) testes and testosterone (d) ovaries and oestrogen
Describe adrenaline as the hormone secreted in ‘fight or flight’ situations and its effects, limited to: (a) increased breathing rate (b) increased heart rate (c) increased pupil diameter
Compare nervous and hormonal control, limited to speed of action and duration of effect
[Supplement] State that glucagon is secreted by the pancreas
[Supplement] Describe the role of adrenaline in the control of metabolic activity, limited to: (a) i ncreasing the blood glucose concentration (b) increasing heart rate

Lesson Note

Hormones coordinate slower, longer-lasting and more widespread changes than nerves can. They control growth, reproduction, blood sugar and the body's response to stress. Examiners reliably ask you to define a hormone, name glands and their hormones, and compare hormonal with nervous control.

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Lesson Evaluation

Congratulations on completing the lesson on Hormones. Now that youve explored the key concepts and ideas, its time to put your knowledge to the test. This section offers a variety of practice questions designed to reinforce your understanding and help you gauge your grasp of the material.

You will encounter a mix of question types, including multiple-choice questions, short answer questions, and essay questions. Each question is thoughtfully crafted to assess different aspects of your knowledge and critical thinking skills.

Use this evaluation section as an opportunity to reinforce your understanding of the topic and to identify any areas where you may need additional study. Don't be discouraged by any challenges you encounter; instead, view them as opportunities for growth and improvement.

A hormone is a chemical substance that is: A. produced by a nerve and carried by impulses B. produced by a gland and carried by the blood C. made in the stomach and carried by ducts D. produced by a muscle Answer: B
Which gland secretes adrenaline? A. pancreas B. ovary C. adrenal gland D. testis Answer: C
Insulin is secreted by the: A. liver B. pancreas C. adrenal gland D. kidney Answer: B
Which is an effect of adrenaline? A. decreased heart rate B. smaller pupils C. increased breathing rate D. slower breathing Answer: C
Compared with nervous control, hormonal control is: A. faster and shorter-lasting B. slower and longer-lasting C. faster and longer-lasting D. slower and shorter-lasting Answer: B