BiologyCBSE Class 11 · Chemical Coordination and Integration

Adrenal, Pancreas, Gonads, Other Hormones and Mechanism of Hormone Action

Updated 17 October 2026 · Fact-checked

The adrenal cortex secretes glucocorticoids and mineralocorticoids and the medulla secretes adrenaline and noradrenaline. The pancreatic islets secrete insulin (lowers glucose) and glucagon (raises glucose). Testes secrete androgens; ovaries secrete oestrogen and progesterone. Hormones act through membrane receptors with second messengers or intracellular receptors that alter gene expression.

Read the layers from outside in: glomerulosa (aldosterone), fasciculata (cortisol), reticularis (androgens), then the medulla (adrenaline).

Illustration drawn for QuestionBuddy.

Understand Adrenal, Pancreas, Gonads and Hormone Action

Thymus. Lobular gland behind the sternum; secretes thymosins that differentiate T-lymphocytes (cell-mediated immunity) and promote antibody production (humoral immunity). It degenerates with age, so immunity falls in the old.

Adrenal gland. One on the anterior part of each kidney.

Cortex (outer) in three layers: zona reticularis (inner; small amounts of androgenic steroids), zona fasciculata (middle; glucocorticoids, cortisol), zona glomerulosa (outer; mineralocorticoids, aldosterone). Glucocorticoids stimulate gluconeogenesis, lipolysis, proteolysis; cortisol maintains cardiovascular and kidney function, suppresses immune response (anti-inflammatory), and stimulates RBC production. Aldosterone regulates reabsorption of Na⁺ and water and excretion of K⁺ and phosphate; it maintains electrolytes, body fluid volume, osmotic pressure and blood pressure. Addison's disease is deficiency of cortical hormones.
Medulla (inner): adrenaline (epinephrine) and noradrenaline, called emergency hormones or hormones of fight or flight: increase alertness, pupillary dilation, piloerection, sweating, heart beat, strength of heart contraction and respiration rate; stimulate breakdown of glycogen (raising blood glucose) and lipids.

Pancreas (endocrine and exocrine). Islets of Langerhans (1-2 million): α-cells secrete glucagon (raises blood glucose by glycogenolysis and gluconeogenesis), β-cells secrete insulin (lowers blood glucose by enhancing glucose uptake and utilisation, glycogenesis). Diabetes mellitus: prolonged hyperglycaemia, loss of glucose in urine (glycosuria) and formation of harmful ketone bodies (ketonuria); treated with insulin therapy.

Gonads. Testis (Leydig cells in the interstitial spaces): androgens (testosterone) regulate development, maturation and functions of male accessory sex organs, muscular growth, facial hair, aggressiveness, low pitch of voice, spermatogenesis. Ovary: follicles secrete oestrogen (growth of follicles, female secondary sex characters, mammary gland development); the corpus luteum secretes progesterone (supports pregnancy, alveoli formation in mammary glands, milk secretion).

Hormones of heart, kidney and gut. Atrial wall: ANF (lowers blood pressure by dilating vessels). Kidney (juxtaglomerular cells): erythropoietin (stimulates RBC formation). Gastrointestinal tract: gastrin (gastric juice), secretin (pancreatic and bile secretion), CCK (pancreatic enzymes and gall bladder contraction), GIP (inhibits gastric secretion, stimulates insulin release). Growth factors are secreted by many tissues.

Mechanism of hormone action. Hormones act on target tissues having specific receptors; the hormone-receptor complex changes the metabolism. Receptors are on the membrane or inside the cell.

Membrane-bound receptors (peptide, polypeptide, protein hormones and catecholamines): the hormone does not enter; the complex generates second messengers such as cyclic AMP (cAMP), IP₃ and Ca²⁺, which regulate cellular metabolism (e.g. glucagon uses cAMP).
Intracellular receptors (steroid hormones, iodothyronines): the hormone enters the cell, binds a receptor in the cytoplasm or nucleus, and the complex interacts with the genome to regulate gene expression, altering the physiological and developmental processes.

Draw and label: flow chart of insulin and glucagon controlling blood glucose around the normal level.

Adrenal, Pancreas, Gonads and Hormone Action: key facts

Adrenal cortex: $A l d os t er o n e (N a +, w a t er) ∣ cor t i so l (g l u cose, imm u ni t y)$; Mineralo- and glucocorticoids
Adrenal medulla: $A d r e na l in e + n or a d r e na l in e$; Fight or flight
Pancreas: Alpha: glucagon (raises glucose) | Beta: insulin (lowers glucose); Islets of Langerhans
Action: Membrane receptor: second messenger (cAMP) | Intracellular receptor: gene expression; Peptide versus steroid

How to answer Adrenal, Pancreas, Gonads and Hormone Action questions

Questions give an effect and ask for the hormone, or ask to contrast mechanisms.

1Identify gland and cell type.
2Give the effect on blood glucose, ions or immunity.
3State deficiency and excess disorders.
4For mechanism, classify the hormone as peptide or steroid.
5Name the second messenger.

Adrenal, Pancreas, Gonads and Hormone Action in real life

The idea, met in an everyday situation. Answer the question in your own words, then compare with the model answer. The one-line hook is what to remember.

Sudden scare

Suppose a person is startled by a loud noise and the heart pounds, pupils widen and hands sweat.

Name the hormones and gland and why blood glucose rises.

Try it first, then show the solutionSolution

Adrenaline and noradrenaline from the adrenal medulla are released.
They raise heart rate, dilate pupils and increase sweating.
They also break down glycogen to raise blood glucose, giving energy.

Answer: Adrenal medulla hormones prepare for fight or flight.

Memory hook: Scare means adrenaline.

Tricks to remember Adrenal, Pancreas, Gonads and Hormone Action

Short memory aids. Say each one aloud once, then use it on a question the same day.

GFR from out to in
Zona Glomerulosa, Fasciculata, Reticularis: outer to inner = Salt, Sugar, Sex.
Use it when: Cortex layers
Alpha up, Beta down
Alpha cells: glucagon raises glucose; beta cells: insulin lowers it.
Use it when: Pancreas
Peptide outside, steroid inside
Peptide hormones use membrane receptors; steroids use intracellular receptors.
Use it when: Mechanism

Adrenal, Pancreas, Gonads and Hormone Action: solved examples

Ordered from board level to HOTS. Try each one before you open the solution.

Example 1: Blood glucose control · 3 marks · Short answerBoard level

Explain how insulin and glucagon regulate blood glucose.

Try it first, then show the solutionSolution

Rise in glucose stimulates beta cells to release insulin (1 mark).
Insulin increases cellular uptake and glycogenesis, lowering glucose (1 mark).
Fall in glucose stimulates alpha cells to release glucagon, raising glucose by glycogenolysis (1 mark).

Answer: Insulin lowers; glucagon raises.

Example 2: Adrenal layers · 3 marks · Short answerBoard level

Name the three layers of the adrenal cortex from outside to inside with their hormones.

Try it first, then show the solutionSolution

Zona glomerulosa: mineralocorticoids (aldosterone) (1 mark).
Zona fasciculata: glucocorticoids (cortisol) (1 mark).
Zona reticularis: small amounts of androgenic steroids (1 mark).

Answer: Glomerulosa, fasciculata, reticularis.

Example 3: Mechanism · 4 marks · Short answerHarder board level

Differentiate the mechanism of action of glucagon and of a steroid hormone.

Try it first, then show the solutionSolution

Glucagon binds a membrane receptor and does not enter the cell (1 mark).
It forms a second messenger such as cAMP (1 mark).
A steroid enters the cell and binds an intracellular receptor (1 mark).
The complex regulates gene expression (1 mark).

Answer: Membrane receptor with cAMP; intracellular receptor and genes.

Example 4: Diabetes mellitus · 3 marks · Short answerHarder board level

State two symptoms in urine of diabetes mellitus and the treatment, and how it differs from Addison's disease.

Try it first, then show the solutionSolution

Glucose in urine (glycosuria) and ketone bodies (ketonuria) (1 mark).
Treatment by insulin therapy (1 mark).
Addison's disease is deficiency of adrenal cortex hormones, not insulin (1 mark).

Answer: Glycosuria, ketonuria; insulin.

Example 5: Stress response · 5 marks · Long answerHOTS / competency

Suppose a person under long-term stress has high blood sugar and weak immune response. Link these to the adrenal cortex, explain the physiology, and compare with the short-term response of the adrenal medulla.

Try it first, then show the solutionSolution

Cortisol (glucocorticoid) is raised in prolonged stress (1 mark).
It stimulates gluconeogenesis and proteolysis, raising blood glucose (1 mark).
Cortisol suppresses the immune response (1 mark).
Short-term: adrenaline and noradrenaline raise heart rate and alertness (1 mark).
Medulla response is immediate neural; cortex response is slower and longer lasting (1 mark).

Answer: Cortisol: sugar up, immunity down; medulla fast.

Where students lose marks in Adrenal, Pancreas, Gonads and Hormone Action

The slips examiners see most often, and what to write instead.

Mistake: Glucagon lowers glucose
Role reversed.
Wrong working
Glucagon lowers glucose.
Right working
Glucagon raises glucose.
Do this: Insulin lowers.
Usually costs: 1 mark.
Mistake: Steroid uses cAMP
Mechanism mixed.
Wrong working
Steroids use cAMP.
Right working
Steroids use intracellular receptors; peptides use second messengers.
Do this: Gene expression.
Usually costs: 1 mark.
Mistake: Adrenaline from cortex
Region mixed.
Wrong working
Adrenaline is made by the cortex.
Right working
Medulla makes adrenaline.
Do this: Medulla.
Usually costs: 1 mark.

Exam tips

Memorise cortex layers and hormones.
Write antagonists: insulin and glucagon.
Mention second messengers cAMP, IP3, Ca2+.
Link disorders with hormone shortage or excess.

Practice questions on Adrenal, Pancreas, Gonads and Hormone Action

Write each answer on paper first. Open the hint only if you are stuck, and the answer only when you have finished.

Q1 · 1 mark · MCQBoard level
The hormone that increases Na+ reabsorption in the kidney is
(a) cortisol (b) aldosterone (c) glucagon (d) insulin
Hint
Mineralocorticoid.
Answer
(b).
Q2 · 1 mark · Assertion-reasonHarder board level
Assertion (A): Steroid hormones can regulate gene expression.
Reason (R): They enter cells and bind intracellular receptors.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.
Hint
Intracellular.
Answer
(a).
Q3 · 2 marks · Very short answerBoard level
Name the hormones of the heart and kidney and one function of each.
Hint
ANF; erythropoietin.
Answer
ANF from the atrial wall lowers blood pressure by dilating vessels; erythropoietin from juxtaglomerular cells of the kidney stimulates RBC formation.
Q4 · 4 marks · Case-basedHarder board level
Read and answer.
Suppose a patient has high blood sugar, glucose and ketones in urine.
(a) Name the condition. (1)
(b) Name the cells affected. (1)
(c) Name the treatment. (2)
Hint
Beta cells.
Answer
(a) Diabetes mellitus. (b) Beta cells of the islets of Langerhans (insulin shortage). (c) Insulin therapy.
Q5 · 3 marks · Short answerHOTS / competency
Suppose an animal lacks thymus hormone from birth. Predict the effect on immunity, naming the cells involved and why the effect weakens with age in humans.
Hint
T-cells.
Answer
Thymosins differentiate T-lymphocytes; without them cell-mediated immunity and antibody production would be impaired. In humans the thymus degenerates with age, so immunity declines in older people.

Test your recall

Answer in your head or on paper first, then open the card. Pulling an answer out of memory makes it stick far better than re-reading.

1.Emergency hormones?Show answer
Adrenaline and noradrenaline.
2.Insulin made by?Show answer
Beta cells.
3.Hormone of Leydig cells?Show answer
Testosterone.
4.Source of progesterone?Show answer
Corpus luteum.
5.What is ANF?Show answer
Hormone from the atria lowering BP.
6.Second messenger?Show answer
cAMP.

Adrenal, Pancreas, Gonads and Hormone Action: frequently asked questions

What is Addison's disease?

Deficiency of adrenal cortex hormones.

What does glucagon do?

Raises blood glucose.

What are thymosins?

Thymus hormones that make T-cells.

What is erythropoietin?

Kidney hormone for RBC formation.

How do steroid hormones work?

Through intracellular receptors altering genes.