Q.State whether true or false: a. Gastrointestinal tract, kidney and heart also produce hormones. b. Pars distalis produces six trophic hormones. c. B-lymphocytes provide cell-mediated immunity. d. Insulin resistance results in a disease called diabetes mellitus.
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🔒 Start your 14-day free trial to unlock the full solution →Concept understanding — Endocrine Glands And Hormones
Endocrine Glands and Hormones: The Body's Chemical Messengers
Think about how your body coordinates everything that happens inside it. When you run, your heart beats faster, your breathing quickens, and your muscles get more blood. When you're scared, your pupils dilate and your palms sweat. When you eat, your digestive system kicks into gear. How does your body know to do all these things at the right time?
You already know about the nervous system — it works like a telephone network, sending electrical signals along wires (nerves) to specific destinations. But there's another system that works differently. It's like sending a letter through the postal service instead of making a phone call. This is the endocrine system.
The Intuition: Ductless Glands and Chemical Messengers
Most glands in your body have ducts — little tubes that carry their secretions to where they're needed. Sweat glands have ducts that carry sweat to your skin. Salivary glands have ducts that carry saliva into your mouth.
But some glands have no ducts. They release their secretions directly into the bloodstream. These are endocrine glands (from Greek endon = within, krinein = to separate). Their secretions are called hormones (from Greek hormao = to set in motion, to excite).
Here's the key idea: a hormone is a chemical messenger. It's released by one part of the body, travels through the blood, and affects another part of the body that is far away. The hormone doesn't affect every cell it passes — only cells that have the right receptor for it, like a lock that only opens with a specific key.
The word "endocrine" contrasts with "exocrine" — exocrine glands (like sweat glands, salivary glands, digestive glands) have ducts and release their secretions to a surface or cavity. Endocrine glands have no ducts and release hormones into the blood.
The Precise Statement
Endocrine glands are ductless glands that secrete hormones directly into the bloodstream. Hormones are chemical substances that act as messengers, traveling through the blood to target organs or tissues, where they bind to specific receptors and trigger a response. This system provides chemical coordination — a slower but longer-lasting form of control compared to the nervous system.
Endocrine Gland (no duct) → secretes Hormone into blood → hormone travels to Target Organ → binds to Receptor → Response
How It Works: A Concrete Example
Consider the hormone insulin, secreted by the pancreas (an endocrine gland). When you eat a meal rich in carbohydrates, your blood sugar rises. The pancreas detects this rise and releases insulin into the blood. Insulin travels everywhere in your bloodstream, but it only affects cells that have insulin receptors — mainly liver, muscle, and fat cells. These cells respond by taking up glucose from the blood, bringing your blood sugar back down to normal.
Notice the sequence: stimulus (high blood sugar) → gland (pancreas) → hormone (insulin) → target cells (liver, muscle, fat) → response (glucose uptake, lower blood sugar).
Key Properties of Hormones
- Released in tiny amounts — hormones are incredibly potent. A few molecules can trigger a large response.
- Travel via blood — this means they reach every part of the body, but only targets with receptors respond.
- Slow but sustained — nervous system responses happen in milliseconds but fade quickly. Hormonal responses take seconds to minutes but can last for hours or days.
- Specificity — a hormone only affects cells that have the matching receptor. This is why the same hormone can have different effects on different tissues.
A common mistake is to think hormones affect all cells equally. They don't. A hormone is like a radio broadcast — it reaches everyone, but only those tuned to the right frequency (having the right receptor) can hear it.
Why This Matters for Coordination
Your body needs two systems for coordination because they complement each other:
| Nervous System | Endocrine System |
|---|---|
| Electrical signals along nerves | Chemical signals in blood |
| Fast (milliseconds) | Slow (seconds to minutes) |
| Short-lived effect | Long-lasting effect |
| Precise, point-to-point | Broadcast, widespread |
| For immediate actions | For sustained changes |
a. True — the gastrointestinal tract, kidney and heart all produce hormones, alongside the organised endocrine glands.
b. True — the pars distalis of the anterior pituitary produces six trophic hormones (GH, prolactin, TSH, ACTH, LH and FSH).
c. False — it is T-lymphocytes, not B-lymphocytes, that provide cell-mediated immunity. …
Statements (a), (b) and (d) are true, but statement (c) is false because cell-mediated immunity is a T-lymphocyte function, not a B-lymphocyte one.
Going through each statement in turn:
- (a) True. Hormones are not confined to the organised endocrine glands. The gastrointestinal tract, the liver, the kidney and the heart also release hormones from diffuse tissue, and this is explicitly part of the endocrine system.
- (b) True. The pars distalis, or anterior pituitary, produces exactly six hormones: growth hormone, prolactin, thyroid stimulating hormone, adrenocorticotrophic hormone, luteinizing hormone and follicle stimulating hormone. …
- TG EAPCET 2025Set ap-2025-04-30-FN1 markMCQQ.Match the following Hormone Function A. Melatonin I. Basal metabolic rate B. Thyroxine II. Hyperglycemia C. Aldosterone III. Sleep-wake cycle D. Glucagon IV. Water-electrolyte balance V. Somatotropin (A) A – III, B – I, C – IV, D – II (B) A – I, B – III, C – IV, D – V (C) A – II, B – IV, C – I, D – III (D) A – III, B – I, C – V, D – IV
›Reveal solutionSolution
Match each hormone to its primary physiological function by recalling their target tissues and metabolic roles. The correct pairing is A – III, B – I, C – IV, D – II.
This question tests your understanding of endocrine physiology—specifically, which hormone does what in the body. The key is to connect each hormone to its principal site of action and the metabolic or regulatory process it controls.
Let's work through each hormone systematically:
Matching Each Hormone to Its Function
A. Melatonin → III. Sleep-wake cycle
Melatonin is secreted by the pineal gland in response to darkness. Its primary role is regulating circadian rhythms—the body's internal 24-hour clock. When light decreases in the evening, melatonin levels rise, promoting sleepiness and helping synchronize the sleep-wake cycle. This is why melatonin supplements are often used for jet lag or shift-work sleep disorders.
B. Thyroxine → I. Basal metabolic rate
Thyroxine (T₄) and its active form triiodothyronine (T₃) are thyroid hormones that regulate metabolism in nearly every cell. They increase oxygen consumption, heat production, and the rate at which cells burn fuel—collectively termed the basal metabolic rate (BMR). Hypothyroidism (low thyroxine) slows metabolism and causes weight gain and lethargy; hyperthyroidism speeds it up, causing weight loss and heat intolerance.
C. Aldosterone → IV. Water-electrolyte balance
Aldosterone is a mineralocorticoid secreted by the adrenal cortex. It acts on the distal tubules and collecting ducts of the kidney to promote sodium reabsorption and potassium excretion. Because water follows sodium osmotically, aldosterone indirectly regulates blood volume and blood pressure—hence its central role in water-electrolyte balance. It is part of the renin-angiotensin-aldosterone system (RAAS).
D. Glucagon → II. Hyperglycemia …
- TG EAPCET 2022Set ap-2022-07-30-FN1 markMCQQ.Match the following: Gland A) Thyroid gland B) Hypothalamus C) Pituitary gland D) Epiphysis cerebri Hormone I) Prolactin II) Melatonin III) Calcitonin IV) Thymosin V) Somatocrinin The correct match is (A) A B C D IV V I II (B) A B C D III V II I (C) A B C D II I V IV (D) A B C D III V I II
›Reveal solutionSolution
This question tests your knowledge of endocrine glands and the specific hormones they produce. We will match each gland to its characteristic hormone, finding that the Thyroid gland produces Calcitonin, the Hypothalamus produces Somatocrinin, the Pituitary gland produces Prolactin, and the Epiphysis cerebri (Pineal gland) produces Melatonin. The correct match is (D).
The human body's endocrine system relies on glands to produce and secrete hormones, which act as chemical messengers regulating various physiological processes. Each gland typically specializes in producing a particular set of hormones, and understanding these specific relationships is key to comprehending how the body maintains homeostasis.
Here's how we can match each gland to its primary hormone from the given list:
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Analyze Gland A: Thyroid gland
The thyroid gland, located in the neck, is primarily known for producing thyroid hormones (thyroxine and triiodothyronine) which regulate metabolism. However, it also produces another crucial hormone:
- Calcitonin (III): This hormone plays a vital role in calcium homeostasis by lowering blood calcium levels. It does this by inhibiting osteoclast activity (bone breakdown) and stimulating calcium excretion by the kidneys. Therefore, the Thyroid gland matches with Calcitonin (III).
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Analyze Gland B: Hypothalamus
The hypothalamus is a part of the brain that serves as the main link between the nervous and endocrine systems. It produces neurohormones that control the pituitary gland. These include releasing hormones and inhibiting hormones.
- Somatocrinin (V): Also known as Growth Hormone-Releasing Hormone (GHRH), somatocrinin is produced by the hypothalamus. Its function is to stimulate the anterior pituitary gland to release Growth Hormone (GH). Therefore, the Hypothalamus matches with Somatocrinin (V).
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Analyze Gland C: Pituitary gland
Often called the "master gland," the pituitary gland is located at the base of the brain and is regulated by the hypothalamus. It produces a wide array of hormones that control other endocrine glands and various bodily functions.
- Prolactin (I): This hormone is secreted by the anterior pituitary gland. Its primary function is to stimulate milk production in the mammary glands after childbirth. Therefore, the Pituitary gland matches with Prolactin (I).
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Analyze Gland D: Epiphysis cerebri (Pineal gland) …
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- TG EAPCET 2022Set ap-2022-07-31-FN1 markMCQQ.Match the following : List-I A) Prolactin B) Oxytocin C) Parathormone D) Thymosin List-II I) Levels of Ca++ in circulating fluids II) Enlargement of mammary glands III) Stimulation of gluconeogenesis IV) Contraction of smooth muscles V) Differentiation of lymphocytes The correct match is (A) A B C D V I IV II (B) A B C D II IV I V (C) A B C D II IV III V (D) A B C D III I II V
›Reveal solutionSolution
This is a hormone-function matching problem. The correct pairing is Prolactin → mammary gland enlargement, Oxytocin → smooth muscle contraction, Parathormone → blood Ca²⁺ regulation, Thymosin → lymphocyte differentiation. The answer is option (B).
The question tests your knowledge of the primary physiological roles of four key hormones. Instead of memorising blindly, think about what each hormone's name hints at or what its most famous action is. Prolactin is about "lactation" — milk production requires mammary gland development. Oxytocin is the "love hormone" or "birth hormone" — it causes uterine contractions during labour and milk ejection. Parathormone (PTH) is all about calcium — it raises blood calcium levels. Thymosin comes from the thymus gland, which is where T-lymphocytes mature.
Let's match them step by step.
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Prolactin (A) — Secreted by the anterior pituitary. Its primary target is the mammary glands, where it stimulates milk synthesis and also promotes the enlargement (development) of mammary tissue during pregnancy. So A matches with II (Enlargement of mammary glands).
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Oxytocin (B) — Released from the posterior pituitary. It acts on smooth muscles — most famously, it causes uterine contractions during childbirth and myoepithelial cell contraction in the breast for milk ejection. So B matches with IV (Contraction of smooth muscles).
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Parathormone (C) — Secreted by the parathyroid glands. Its main job is to increase blood calcium levels by acting on bones (releasing Ca²⁺), kidneys (reducing Ca²⁺ excretion), and indirectly the gut. So C matches with I (Levels of Ca²⁺ in circulating fluids). …
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- TG EAPCET 2021Set ap-2021-08-09-AN1 markMCQQ.Study the following and pick up the correct combinations S.No Ductless Gland Hormone Function I) Thyroid Thyroxine Regulation of basal metabolic rate II) Parathyroid Calcitonin Lowers calcium in blood III) Pineal ADH Darkening of skin IV) Pituitary Prolactin Enlargement of mammary glands (A) I, II (B) II, III (C) I, IV (D) III, IV
›Reveal solutionSolution
The question tests your knowledge of endocrine glands, their hormones, and functions. Only combinations I and IV are correct, so the answer is option (C).
The key here is to recall the specific hormone secreted by each ductless gland and its primary function. Many students mix up parathyroid and thyroid hormones, or confuse the pineal gland's melatonin with ADH from the pituitary. Let's check each row carefully.
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Row I – Thyroid and Thyroxine: The thyroid gland secretes thyroxine (T4) and triiodothyronine (T3). Their main role is to regulate the basal metabolic rate (BMR), influencing how the body uses energy. This is correct.
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Row II – Parathyroid and Calcitonin: The parathyroid glands secrete parathyroid hormone (PTH), which raises blood calcium levels by stimulating bone resorption and kidney reabsorption. Calcitonin is actually secreted by the thyroid gland (parafollicular cells) and lowers blood calcium. So this pairing is wrong — the gland and hormone don't match. …
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- TG EAPCET 2021Set ap-2021-08-09-FN1 markMCQQ.Study the following table and pick up the correct combinations. S.No Hormone Chemical nature Function I) Melatonin Amine hormone Regulation of circadian rhythms of the body II) Oxytocin Peptide hormone Stimulate powerful contractions of uterus during child birth III) Insulin Proteinous hormone Increases the uptake and utilisation of glucose by body cells IV) Testosterone Steroid hormone Development and maturation of male sex organs (A) I only (B) I and II only (C) I, II, and III only (D) I, II, III and IV
›Reveal solutionSolution
The table lists four hormones with their chemical nature and functions. All four entries are factually correct, so the correct combination is I, II, III and IV — option (D).
The question tests your knowledge of hormones — their chemical classification and physiological roles. In biology, a hormone’s chemical nature (amine, peptide, protein, steroid) directly relates to how it is synthesised, stored, and acts on target cells. The function given for each must match what is established in human physiology.
Let’s check each entry one by one.
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Melatonin (I) — It is secreted by the pineal gland. Chemically, it is derived from the amino acid tryptophan, making it an amine hormone. Its primary role is to regulate the sleep-wake cycle, i.e., circadian rhythms. This entry is correct.
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Oxytocin (II) — This is a peptide hormone (a short chain of amino acids) produced in the hypothalamus and released from the posterior pituitary. It triggers powerful uterine contractions during childbirth and also aids milk ejection. The entry is correct.
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Insulin (III) — Insulin is a protein hormone (a polypeptide with two chains). It is secreted by the beta cells of the pancreas and acts to lower blood glucose by increasing glucose uptake and utilisation by body cells. This entry is correct. …
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