Hormonal Coordination and Homeostasis
The endocrine system coordinates the body using hormones, chemical messengers secreted directly into the blood by glands and carried to target organs, where they produce an effect; unlike nervous responses, hormonal responses are slower to start but longer-lasting. The pituitary gland, often called the body's master gland, releases hormones that act on other glands, and the pancreas controls blood glucose concentration using insulin and glucagon in a negative-feedback loop.
Before you start
Make sure you're comfortable with these topics first:
Method
- Learn the key endocrine glands and their main hormones: the pituitary gland (releases hormones that act on other glands, including the thyroid, ovaries, testes and adrenal glands), the thyroid (thyroxine, which regulates metabolic rate), the adrenal glands (adrenaline, which prepares the body for a fight-or-flight response), and the pancreas (insulin and glucagon).
- Learn blood glucose regulation as a negative-feedback loop centred on the pancreas: a rise in blood glucose concentration is detected, insulin is secreted, and insulin causes cells, especially liver and muscle cells, to take up glucose and the liver to convert it to glycogen for storage, lowering blood glucose back to normal.
- Learn the reverse pathway for a fall in blood glucose: the pancreas secretes glucagon, which causes the liver to convert stored glycogen back into glucose and release it into the blood, raising blood glucose concentration back to normal.
- Distinguish the two types of diabetes precisely: type 1 is where the pancreas produces little or no insulin, usually starting in childhood, and is treated with insulin injections; type 2 is where the body's cells no longer respond properly to insulin, often linked to obesity, and is managed with a carbohydrate-controlled diet, exercise, and medication if needed.
- For thermoregulation questions, learn the paired opposite responses: too hot triggers vasodilation, widening the blood vessels supplying the skin so more heat is lost by radiation, and sweating, which loses heat as sweat evaporates; too cold triggers vasoconstriction, narrowing those blood vessels to reduce heat loss, and shivering, rapid muscle contraction that releases some heat during respiration.
- For questions comparing hormonal and nervous coordination, structure the answer around speed of response, how long the response lasts, and how widely or precisely it acts.
- For blood glucose calculation questions, check the units given, usually mmol/dm^3, and compare the value in the question against the other value it gives you, rather than trying to recall a fixed normal range from memory.
Worked example
A person's blood glucose concentration is 9.6 mmol/dm^3 one hour after a meal. After insulin is released, it falls to 5.2 mmol/dm^3 two hours later. Calculate the percentage decrease in blood glucose concentration, giving your answer to 3 significant figures.
- Calculate the decrease in concentration: 9.6 - 5.2 = 4.4 mmol/dm^3.
- Write the percentage change formula: percentage decrease = (decrease in value / original value) x 100.
- Substitute the values: percentage decrease = (4.4 / 9.6) x 100.
- Calculate: 4.4 / 9.6 = 0.4583..., so 0.4583... x 100 = 45.83...
- Final answer, to 3 significant figures: blood glucose concentration decreased by 45.8%.
Practice questions
Type your answer and press Check to be marked straight away, or reveal the answer and mark yourself.
Q1Name the gland often called the body's master gland.Show answer
Answer: The pituitary gland.
Q2Name the hormone released by the adrenal glands that prepares the body for fight or flight.Show answer
Answer: Adrenaline.
Q3State the type of diabetes in which the pancreas produces little or no insulin.Show answer
Answer: Type 1 diabetes.
Q4State one risk factor linked to type 2 diabetes.Show answer
Answer: Obesity (being overweight); poor diet and lack of exercise are also accepted.
Q5A person's blood glucose concentration is 4.8 mmol/dm^3 before breakfast and 7.2 mmol/dm^3 after breakfast. Calculate the increase in blood glucose concentration.Show answer
Answer: 2.4 mmol/dm^3 (7.2 - 4.8 = 2.4).
Q6Explain why sweating cools the body down.Show answer
Answer: Sweat is produced on the skin, and as it evaporates it transfers heat energy from the skin to the surroundings, cooling the body.
Q7Name the hormone that causes the liver to convert stored glycogen back into glucose.Show answer
Answer: Glucagon.
Q8Explain why type 1 diabetes is treated with insulin injections rather than tablets.Show answer
Answer: Insulin is a protein, so if it were taken as a tablet it would be digested and broken down by enzymes in the digestive system before it could take effect; it must be injected directly into the body instead.
Exam-style questions
Written in the style of a GCSE Science exam paper, with a full mark scheme.
State two ways that hormonal communication in the body differs from nervous communication.
Show mark scheme
Tick each line you got. Your score builds from the marks on the scheme.
Nothing ticked yet - 2 available
A student with type 2 diabetes has a fasting blood glucose concentration of 9.4 mmol/dm^3. After 6 months of dietary change and increased exercise, her fasting blood glucose concentration falls to 6.6 mmol/dm^3. (a) Calculate the percentage decrease in her fasting blood glucose concentration, to 3 significant figures. (b) Suggest why regular exercise can help lower blood glucose concentration in a person with type 2 diabetes.
Show mark scheme
Tick each line you got. Your score builds from the marks on the scheme.
Nothing ticked yet - 4 available
A person has just eaten a large, sugary meal. Explain how the body detects and responds to the resulting rise in blood glucose concentration, and explain what would happen instead if this person had untreated type 1 diabetes.
Show mark scheme
Tick each line you got. Your score builds from the marks on the scheme.
Nothing ticked yet - 6 available
See real GCSE Science past-paper questions, with official mark schemes →
Free printable worksheet
Want more practice on paper? Download the hormonal coordination and homeostasis worksheet pack - 22 pages of exam-style questions with a full mark scheme. One email opens every download in this browser for 14 days - no account, no card. Print it for personal and classroom use.
This topic is chapter 22 of GCSE Biology Workbook, the whole course as one free printable PDF.
Next topics
Not quite what you needed?
Tell us what is missing on hormonal coordination and homeostasis, or which topic to write up next. Every request is read, and we reply to every one.
Build a full practice pack.
This topic is one of hundreds in the library - pick the ones a student needs and generate a printable PDF in minutes.