How do hormones coordinate the body more slowly than nerves, and how is blood glucose controlled?
The endocrine system and the role of hormones, the control of blood glucose by insulin and glucagon, type 1 and type 2 diabetes, the reproductive hormones and the menstrual cycle, and a comparison of nervous and hormonal control.
A focused answer to the OCR Gateway GCSE Combined Science A topic B3 on hormonal coordination, covering the endocrine system, control of blood glucose by insulin and glucagon, type 1 and type 2 diabetes, reproductive hormones and the menstrual cycle, and how nervous and hormonal control compare.
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What this topic is asking
OCR wants you to describe the endocrine system, explain how blood glucose is controlled by insulin and glucagon, distinguish type 1 and type 2 diabetes, outline the reproductive hormones and the menstrual cycle, and compare nervous and hormonal control.
The endocrine system
Hormones act more slowly than nerves but their effects often last longer and can be more widespread, because the blood carries them all over the body. Key glands include the pancreas (controls blood glucose), the thyroid and adrenal glands, and the ovaries and testes (which make the sex hormones). The pituitary gland in the brain is a master gland that releases hormones to control other glands. Because the message is carried in the blood rather than along a fixed neurone, a single hormone can affect several target organs at once.
Controlling blood glucose
Blood glucose must be kept steady so cells always have a supply for respiration. This is controlled by negative feedback using two hormones from the pancreas:
- When blood glucose rises (for example after a meal), the pancreas releases insulin. Insulin makes body cells take up glucose, and makes the liver and muscles convert excess glucose into glycogen for storage, so the glucose level falls.
- When blood glucose falls (for example during exercise or fasting), the pancreas releases glucagon. Glucagon makes the liver convert stored glycogen back into glucose and release it into the blood, so the level rises.
Reproductive hormones and the menstrual cycle
At puberty, sex hormones cause the development of secondary sexual characteristics. Testosterone (from the testes) drives male development, and oestrogen (from the ovaries) drives female development. In women, the menstrual cycle is controlled by four hormones: FSH causes an egg to mature in an ovary, oestrogen causes the uterus lining to build up and triggers a surge in LH, LH causes the mature egg to be released (ovulation), and progesterone maintains the uterus lining ready for a possible pregnancy. If the egg is not fertilised, hormone levels fall and the lining is shed. OCR expects you to know which gland makes each hormone and its main role, and how this knowledge underlies hormonal contraception and fertility treatment.
Exam-style practice questions
Practice questions written in the style of OCR exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
OCR 20186 marksExplain how the body controls blood glucose concentration after a meal high in sugar, and how this changes if the person has type 1 diabetes.Show worked answer →
A Biology Paper 1 six-mark extended response, marked on levels. Reward: after a sugary meal the blood glucose concentration rises; this is detected by the pancreas, which releases the hormone insulin. Insulin makes body cells take up glucose from the blood and makes the liver and muscle cells convert glucose into glycogen for storage, so the blood glucose concentration falls back to normal. In type 1 diabetes the pancreas does not produce enough (or any) insulin, so blood glucose can rise dangerously high after a meal; it is controlled by injecting insulin, along with managing diet and exercise. Top answers name insulin, the pancreas and glycogen storage in the liver, link the response to a fall in glucose (negative feedback), and identify the missing insulin in type 1 diabetes.
OCR 20214 marksCompare nervous and hormonal coordination in terms of speed, how the message travels, and how long the effect lasts.Show worked answer →
A B3 structured comparison. Reward: nervous coordination uses electrical impulses carried along neurones, is very fast, acts on a precise target, and has a short-lived effect. Hormonal coordination uses chemical hormones carried in the blood, is slower to act, can affect many target organs at once, and tends to have a longer-lasting effect. Markers award the contrast on at least three of: speed (fast versus slow), transmission (electrical impulse along neurones versus chemical in the blood), target (precise versus widespread), and duration (short versus long).
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