Introduction to the Endocrine System

Post-Test Quiz — 20 Questions with Answers & Explanations

3rd Year Electrical & Communication Engineering Masinde Muliro University of Science and Technology (MMUST) Bloom's Levels: Remember · Understand · Apply Total: 20 Marks

Instructions to Students

REMEMBER — recall facts & terminology UNDERSTAND — explain concepts & relationships APPLY — use knowledge in simple scenarios
Question 1REMEMBER

Which of the following organs is a major endocrine gland that secretes hormones directly into the bloodstream?

  1. Salivary gland
  2. Pituitary gland
  3. Sweat gland
  4. Lacrimal gland

Correct Answer: B — Pituitary gland

Explanation: The pituitary gland is a ductless (endocrine) gland that releases hormones such as growth hormone and TSH directly into the blood. Salivary, sweat, and lacrimal glands are exocrine glands — they secrete through ducts.

Question 2REMEMBER

Hormones are chemical messengers that are transported throughout the body primarily by the:

  1. Nervous system
  2. Lymphatic system
  3. Bloodstream
  4. Digestive tract

Correct Answer: C — Bloodstream

Explanation: Endocrine glands are ductless; once secreted, hormones enter capillaries and are distributed to target cells via the circulatory system.

Question 3REMEMBER

Which hormone is produced by the pancreas to lower blood glucose levels?

  1. Glucagon
  2. Insulin
  3. Adrenaline
  4. Thyroxine

Correct Answer: B — Insulin

Explanation: Insulin is secreted by the beta cells of the pancreatic islets and stimulates cells to take up glucose, thereby reducing blood sugar. Glucagon raises blood glucose.

Question 4REMEMBER

The endocrine gland located in the neck, just below the larynx, is the:

  1. Adrenal gland
  2. Pineal gland
  3. Thyroid gland
  4. Thymus gland

Correct Answer: C — Thyroid gland

Explanation: The thyroid sits in the anterior neck below the larynx ("Adam's apple") and produces thyroxine (T4) and triiodothyronine (T3), which regulate metabolism.

Question 5REMEMBER

Which gland is often called the "master gland" because it controls many other endocrine glands?

  1. Thyroid gland
  2. Pituitary gland
  3. Adrenal gland
  4. Pancreas

Correct Answer: B — Pituitary gland

Explanation: The anterior pituitary secretes tropic hormones (e.g., TSH, ACTH, FSH, LH) that regulate the thyroid, adrenal cortex, and gonads — hence the title "master gland."

Question 6REMEMBER

Adrenaline (epinephrine) is secreted by which part of the adrenal gland?

  1. Adrenal cortex
  2. Adrenal medulla
  3. Adrenal capsule
  4. Renal pelvis

Correct Answer: B — Adrenal medulla

Explanation: The inner medulla secretes adrenaline and noradrenaline in response to sympathetic stimulation (the "fight-or-flight" response), while the outer cortex produces steroid hormones such as cortisol and aldosterone.

Question 7UNDERSTAND

A hormone travels through the blood and affects only certain cells in the body. The reason it does not affect all cells is that:

  1. Hormones are destroyed before reaching most cells
  2. Only target cells have the specific receptors that bind the hormone
  3. Most cells actively pump the hormone out
  4. The hormone is too large to enter most cells

Correct Answer: B — Only target cells have the specific receptors that bind the hormone

Explanation: Hormone specificity comes from receptor–ligand binding, analogous to a radio receiver tuned to a specific frequency: only cells carrying the matching receptor respond, even though the hormone circulates everywhere. This is directly relevant to communication engineering principles of selective reception.

Question 8UNDERSTAND

Which statement best describes the difference between the nervous system and the endocrine system?

  1. The nervous system uses electrical impulses and acts rapidly on specific targets; the endocrine system uses hormones, acting more slowly but often more broadly and for longer durations
  2. The nervous system only controls voluntary actions; the endocrine system only controls reflexes
  3. The endocrine system transmits signals along neurons at very high speed
  4. There is no difference; they are two names for the same system

Correct Answer: A

Explanation: Neural signalling is fast, precise, and short-lived (millisecond-scale voltage pulses along axons), whereas hormonal signalling is slower to start, can reach many organs at once, and produces sustained effects — a useful contrast with wired vs. broadcast communication.

Question 9UNDERSTAND

Negative feedback in the endocrine system means that:

  1. A gland always inhibits the secretion of all other glands
  2. The output of a hormone reduces or switches off its own further production, maintaining homeostasis
  3. Hormones are fed back into the gland that produced them and destroyed
  4. The pituitary stops growing after puberty

Correct Answer: B

Explanation: Negative feedback keeps a variable near a set point. Example: high blood thyroxine feeds back to the pituitary and hypothalamus to reduce TSH and TRH secretion — the same closed-loop stabilisation principle used in control systems and automatic gain control.

Question 10UNDERSTAND

A person with an underactive thyroid gland (hypothyroidism) would most likely experience:

  1. Weight loss, rapid heartbeat, and anxiety
  2. Slowed metabolism, fatigue, weight gain, and feeling cold
  3. Excess insulin production and hypoglycaemia
  4. Overproduction of growth hormone in childhood

Correct Answer: B

Explanation: Thyroxine raises basal metabolic rate. When it is deficient, cellular energy use drops, producing fatigue, weight gain, cold intolerance, and sluggishness — the opposite of hyperthyroid symptoms in option A.

Question 11UNDERSTAND

Why does a single hormone such as adrenaline produce several different effects at once (increased heart rate, dilated pupils, release of glucose)?

  1. Because adrenaline is converted into different hormones inside each organ
  2. Because adrenaline is secreted in separate chemical forms for each organ
  3. Because adrenaline travels along separate nerves to each organ
  4. Because many different tissues carry adrenaline receptors, and each tissue responds according to its own cellular machinery

Correct Answer: D

Explanation: One broadcast signal, many receivers with different responses — the heart speeds up, the liver releases glucose, and the pupils dilate because each tissue expresses adrenaline receptors coupled to its own internal response pathways.

Question 12UNDERSTAND

The hypothalamus links the nervous system to the endocrine system mainly by:

  1. Generating electrical impulses that travel down the spinal cord
  2. Contracting and relaxing to pump hormones into the brain
  3. Producing releasing and inhibiting hormones that control the anterior pituitary
  4. Filtering hormones out of the blood like a kidney

Correct Answer: C

Explanation: The hypothalamus receives neural input (e.g., stress, temperature) and converts it into hormonal commands — TRH, GnRH, CRH, etc. — that regulate pituitary secretion. It is the interface where electrical events are "modulated" into chemical signals.

Question 13APPLY

A diabetic patient has a blood glucose reading of 18 mmol/L (well above normal) two hours after a meal. Which hormone should be administered, and what is its expected immediate effect?

  1. Glucagon — stimulates the liver to release stored glucose
  2. Insulin — stimulates cells to absorb glucose from the blood, lowering blood glucose
  3. Thyroxine — increases overall metabolic rate
  4. Cortisol — stimulates gluconeogenesis in the liver

Correct Answer: B — Insulin; it lowers blood glucose

Explanation: Hyperglycaemia is corrected by insulin, which promotes glucose uptake by muscle and fat cells and storage as glycogen. Options A and D would raise blood glucose further, worsening the condition.

Question 14APPLY

During a laboratory viva examination, a student suddenly faces intense stress. Which endocrine response is most likely occurring in their body at that moment, and why?

  1. Release of insulin, to supply energy to brain cells
  2. Release of melatonin, to induce calmness and sleep
  3. Release of adrenaline, to raise heart rate and blood flow to muscles in a "fight-or-flight" response
  4. Release of calcitonin, to strengthen the bones under pressure

Correct Answer: C — Adrenaline release; fight-or-flight response

Explanation: Acute stress activates the sympathetic nervous system, which stimulates the adrenal medulla to release adrenaline. This prepares the body for action by increasing heart rate, alertness, and glucose availability — explaining the racing heart a student feels before an exam.

Question 15APPLY

A blood test shows very low levels of thyroid-stimulating hormone (TSH) but high levels of thyroxine (T4). Based on negative feedback, the most likely interpretation is:

  1. The pituitary is overactive and producing excess TSH
  2. The thyroid is overactive; excess T4 is feeding back to suppress TSH secretion
  3. The patient has an iodine deficiency
  4. The hypothalamus is secreting excess TRH

Correct Answer: B — Thyroid overactivity (hyperthyroidism); negative feedback suppresses TSH

Explanation: High T4 inhibits both TRH and TSH release. Low TSH with high T4 therefore points to a primary thyroid problem (e.g., Graves' disease), not a pituitary or hypothalamic failure — applying the feedback loop logic to diagnose from measured "signal levels."

Question 16APPLY

A patient has been taking high doses of cortisol (a corticosteroid drug) for several months. Their doctor warns that their natural adrenal cortex may have "shrunk." Which endocrine principle explains this?

  1. Positive feedback multiplying cortisol receptors
  2. Exogenous cortisol suppresses ACTH via negative feedback, so the adrenal cortex loses its stimulation and atrophies
  3. Cortisol drugs physically dissolve adrenal tissue
  4. The pituitary converts cortisol into ACTH

Correct Answer: B

Explanation: The drug raises blood cortisol, and negative feedback reduces pituitary ACTH. Since ACTH is the trophic stimulus that keeps the adrenal cortex healthy, prolonged suppression causes cortical atrophy — a clinically important consequence of feedback loops.

Question 17APPLY

An athlete competing at high altitude notices their breathing and heart rate remain elevated for weeks. Which endocrine adaptation would best explain a sustained increase in red blood cell production over this period?

  1. A surge of insulin improving cellular glucose uptake
  2. Release of erythropoietin (EPO) from the kidneys in response to low oxygen
  3. Increased secretion of growth hormone by the pituitary
  4. Release of parathyroid hormone to adjust blood calcium

Correct Answer: B — Erythropoietin (EPO)

Explanation: Chronic hypoxia (low oxygen) stimulates the kidneys to secrete EPO, which acts on bone marrow to increase red blood cell production, improving oxygen-carrying capacity. This slow, sustained hormonal adaptation complements the fast neural responses to altitude.

Question 18APPLY

A biomedical instrumentation team is designing a sensor to detect minute hormone concentrations in blood. Which property of hormone action makes this task comparable to detecting a very weak radio signal?

  1. Hormones act only inside the gland that produces them
  2. Hormones are effective at extremely low concentrations because their receptors amplify the signal inside target cells
  3. Hormones are only detectable when the patient is asleep
  4. Hormones change into completely different chemicals once they reach the blood

Correct Answer: B

Explanation: Many hormones circulate at nanomolar or picomolar levels yet trigger large intracellular responses through second-messenger amplification (e.g., cAMP cascades). Detecting them resembles extracting a faint signal from noise — a challenge familiar in communication systems engineering.

Question 19APPLY

A 25-year-old patient presents with abnormally tall stature, enlarged hands and jaw, and the doctor suspects a hormone-secreting pituitary tumour. Excess secretion of which hormone in an adult best explains these symptoms?

  1. Thyroxine
  2. Insulin
  3. Adrenaline
  4. Growth hormone

Correct Answer: D — Growth hormone

Explanation: Excess growth hormone in adulthood causes acromegaly (enlargement of bones in hands, feet, and jaw). The same excess before growth plates close causes gigantism — matching the hormone to the pattern of symptoms.

Question 20APPLY

A doctor wants to confirm whether a patient's adrenal gland can still function normally. Instead of injecting cortisol, the doctor injects synthetic ACTH and then measures blood cortisol. An increase in cortisol after the injection would indicate that:

  1. The pituitary gland has failed completely
  2. The adrenal cortex is responsive and can still produce cortisol when stimulated
  3. The patient's thyroid is overactive
  4. The patient has too much insulin

Correct Answer: B — The adrenal cortex is functional

Explanation: This is the principle of a stimulation test: supplying the input signal (ACTH) and checking the output (cortisol). A normal response localises the fault upstream (pituitary or hypothalamus), while no response indicates adrenal failure — a classic systems-level diagnostic approach.