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Chemical Coordination and Integration

CBSE notes, revision, important questions, MCQs, mock tests & result analytics

Chemical Coordination and Integration

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CBSE Learning Objectives – Key Concepts & Skills You Must Know

Learning Objectives

  • Define exocrine and endocrine glands.
  • Explain the role of hormones in chemical coordination and integration.
  • Identify the major endocrine glands in the human body.
  • Describe the functions of hormones secreted by the hypothalamus, pituitary, thyroid, parathyroid, adrenal glands, pancreas, testis, ovary, thymus, atrium, kidney, and gastrointestinal tract.
  • Discuss the mechanism of action of hormones, including the role of hormone-receptor complexes.
  • Differentiate between peptide, steroid, iodothyronine, and amino-acid derivative hormones.
  • Analyze the physiological effects of major hormones on target tissues.

CBSE Revision Notes & Quick Summary for Last-Minute Study

Chapter 19: Chemical Coordination and Integration

19.1 Endocrine Glands and Hormones

  • Definition of Hormones: Non-nutrient chemicals acting as intercellular messengers, produced in trace amounts by endocrine glands.
  • Types of Hormones:
    • Peptide, polypeptide, protein hormones (e.g., insulin, glucagon)
    • Steroids (e.g., cortisol, testosterone)
    • Iodothyronines (thyroid hormones)
    • Amino-acid derivatives (e.g., epinephrine)

19.2 Human Endocrine System

  • Major Endocrine Glands:
    • Hypothalamus
    • Pituitary
    • Pineal
    • Thyroid
    • Parathyroid
    • Adrenal
    • Pancreas
    • Thymus
    • Gonads (Testis and Ovary)

19.2.1 The Hypothalamus

  • Function: Regulates body functions through releasing and inhibiting hormones.
  • Example: Gonadotrophin releasing hormone (GnRH) stimulates pituitary hormone release.

19.2.2 The Pituitary Gland

  • Structure: Divided into adenohypophysis (anterior) and neurohypophysis (posterior).
  • Hormones Produced:
    • Anterior Pituitary: Growth hormone (GH), Prolactin (PRL), Thyroid stimulating hormone (TSH), Adrenocorticotrophic hormone (ACTH), Luteinizing hormone (LH), Follicle stimulating hormone (FSH).
    • Posterior Pituitary: Oxytocin, Vasopressin.

19.3 Hormones of Heart, Kidney, and Gastrointestinal Tract

  • Atrial Natriuretic Factor (ANF): Secreted by the heart, decreases blood pressure.
  • Erythropoietin: Produced by kidneys, stimulates red blood cell formation.
  • Gastrointestinal Hormones:
    • Gastrin: Stimulates gastric acid secretion.
    • Secretin: Stimulates pancreatic secretion of bicarbonate.
    • Cholecystokinin (CCK): Stimulates pancreatic enzyme and bile secretion.
    • Gastric Inhibitory Peptide (GIP): Inhibits gastric secretion and motility.

19.4 Mechanism of Hormone Action

  • Hormone-Receptor Interaction: Hormones bind to specific receptors on target tissues, leading to biochemical changes.
  • Types of Receptors:
    • Membrane-bound receptors (for protein hormones)
    • Intracellular receptors (for steroid hormones)

Exercises

  1. Define the following:
    • Exocrine gland
    • Endocrine gland
    • Hormone
  2. Diagrammatically indicate the location of the various endocrine glands in our body.
  3. List the hormones secreted by the following:
    • Hypothalamus
    • Pituitary
    • Thyroid
    • Parathyroid
    • Adrenal
    • Pancreas
    • Testis
    • Ovary
    • Thymus
    • Atrium
    • Kidney
    • G-I Tract
  4. Fill in the blanks for hormones and their target glands.
  5. Write short notes on the functions of:
    • Parathyroid hormone (PTH)
    • Thyroid hormones
    • Thymosins
    • Androgens
    • Estrogens
    • Insulin and Glucagon
  6. Give examples of:
    • Hyperglycemic and hypoglycemic hormones
    • Hypercalcemic hormone
    • Gonadotrophic hormones
    • Progestational hormone
    • Blood pressure lowering hormone
    • Androgens and estrogens
  7. Identify hormonal deficiencies responsible for:
    • Diabetes mellitus
    • Goitre
    • Cretinism
  8. Briefly mention the mechanism of action of FSH.
  9. Match the hormones with their respective glands.

CBSE Exam Tips, Important Questions & Common Mistakes to Avoid

Common Mistakes and Exam Tips

Common Pitfalls

  • Misunderstanding Hormone Functions: Students often confuse the functions of different hormones, such as insulin and glucagon, leading to incorrect answers regarding blood glucose regulation.
  • Ignoring Hormone Sources: Failing to identify the correct endocrine glands that secrete specific hormones can result in errors in matching exercises.
  • Overlooking Mechanisms of Action: Not understanding the difference between how protein hormones and steroid hormones act can lead to mistakes in explaining hormone action.

Tips for Success

  • Memorize Key Hormones and Their Glands: Create flashcards for hormones and their corresponding glands to reinforce memory.
  • Understand Hormonal Interactions: Focus on how hormones interact with their target cells and the physiological responses that follow.
  • Practice Diagram Labeling: Familiarize yourself with diagrams of the endocrine system and hormone action mechanisms to improve your ability to visualize and recall information during exams.
  • Review Common Disorders: Study the hormonal deficiencies and excesses that lead to conditions like diabetes mellitus and hyperthyroidism, as these are frequently tested topics.

CBSE Quiz & Practice Test – MCQs, True/False Questions with Solutions

Multiple Choice Questions

A.

Glucagon

B.

Insulin

C.

Somatostatin

D.

Adrenaline
Correct Answer: B

Solution:

Insulin is a peptide hormone secreted by the ß-cells of the pancreas that lowers blood glucose levels by promoting glucose uptake in cells.

A.

Erythropoietin

B.

Atrial Natriuretic Factor (ANF)

C.

Vasopressin

D.

Aldosterone
Correct Answer: B

Solution:

Atrial Natriuretic Factor (ANF) is a peptide hormone secreted by the heart that decreases blood pressure by causing vasodilation.

A.

Thyrocalcitonin

B.

Parathyroid hormone

C.

Insulin

D.

Glucagon
Correct Answer: B

Solution:

Parathyroid hormone (PTH) increases blood calcium levels by stimulating bone resorption and increasing calcium reabsorption in the kidneys.

A.

Secretin

B.

Gastrin

C.

Cholecystokinin (CCK)

D.

Gastric inhibitory peptide (GIP)
Correct Answer: B

Solution:

Gastrin acts on the gastric glands and stimulates the secretion of hydrochloric acid and pepsinogen.

A.

Erythropoietin

B.

Insulin

C.

Thyroxine

D.

Cortisol
Correct Answer: A

Solution:

Erythropoietin is a peptide hormone produced by the juxtaglomerular cells of the kidney, which stimulates erythropoiesis (formation of red blood cells).

A.

Aldosterone

B.

Adrenaline

C.

Insulin

D.

Thyroxine
Correct Answer: A

Solution:

Aldosterone is a mineralocorticoid secreted by the adrenal cortex that helps in maintaining blood pressure by regulating sodium and water balance.

A.

Prolactin

B.

Oxytocin

C.

Vasopressin

D.

Luteinizing Hormone (LH)
Correct Answer: B

Solution:

Oxytocin, released from the posterior pituitary, stimulates milk ejection from the mammary glands during lactation.

A.

Erythropoietin

B.

Insulin

C.

Glucagon

D.

Thyroxine
Correct Answer: A

Solution:

Erythropoietin, produced by the juxtaglomerular cells of the kidney, stimulates erythropoiesis (formation of red blood cells).

A.

Glucagon

B.

Insulin

C.

Cortisol

D.

Epinephrine
Correct Answer: B

Solution:

Insulin is a peptide hormone secreted by the ß-cells of the pancreas, which enhances cellular glucose uptake and utilisation, thereby reducing blood glucose levels.

A.

Stimulates milk ejection and uterine contractions

B.

Regulates blood sugar levels

C.

Increases heart rate

D.

Promotes growth of bones
Correct Answer: A

Solution:

Oxytocin acts on the smooth muscles of the body, stimulating uterine contractions during childbirth and milk ejection from the mammary glands.

A.

Follicle-stimulating hormone (FSH)

B.

Luteinizing hormone (LH)

C.

Prolactin

D.

Thyroid-stimulating hormone (TSH)
Correct Answer: B

Solution:

Luteinizing hormone (LH) stimulates the synthesis and secretion of androgens, such as testosterone, from the testis.

A.

Thyroxine

B.

Parathyroid hormone (PTH)

C.

Insulin

D.

Cortisol
Correct Answer: B

Solution:

Parathyroid hormone (PTH) increases the Ca²⁺ levels in the blood by acting on bones, renal tubules, and the digestive system.

A.

Cortisol

B.

Aldosterone

C.

Adrenaline

D.

Noradrenaline
Correct Answer: B

Solution:

Aldosterone is the main mineralocorticoid in our body and it helps in the maintenance of electrolytes, body fluid volume, osmotic pressure, and blood pressure.

A.

Oxytocin

B.

Vasopressin

C.

Glucagon

D.

Thyroid-stimulating hormone (TSH)
Correct Answer: B

Solution:

Vasopressin, also known as anti-diuretic hormone (ADH), stimulates water reabsorption in the kidneys, reducing urine output.

A.

Oxytocin

B.

Prolactin

C.

Vasopressin

D.

Estrogen
Correct Answer: A

Solution:

Oxytocin acts on the smooth muscles of the body and stimulates their contraction, particularly during childbirth.

A.

Cortisol

B.

Aldosterone

C.

Adrenaline

D.

Insulin
Correct Answer: B

Solution:

Aldosterone, a mineralocorticoid secreted by the adrenal cortex, regulates sodium and water balance by acting on the renal tubules.

A.

Regulation of blood glucose levels

B.

Stimulation of T-lymphocyte differentiation

C.

Increase in calcium absorption

D.

Regulation of sleep-wake cycles
Correct Answer: B

Solution:

Thymosins are crucial for the differentiation of T-lymphocytes, which are essential for cell-mediated immunity.

A.

Thyroxine (T₄)

B.

Parathyroid Hormone (PTH)

C.

Calcitonin

D.

Insulin
Correct Answer: B

Solution:

Parathyroid Hormone (PTH) increases blood calcium levels by stimulating bone resorption, reabsorption of calcium in the kidneys, and absorption of calcium in the intestines.

A.

Atrial natriuretic factor (ANF)

B.

Vasopressin

C.

Glucagon

D.

Thyroxine
Correct Answer: A

Solution:

Atrial natriuretic factor (ANF) is a peptide hormone secreted by the atrial wall of the heart, which decreases blood pressure by causing dilation of blood vessels.

A.

Insulin

B.

Cortisol

C.

Aldosterone

D.

Thyroxine
Correct Answer: C

Solution:

Aldosterone, a mineralocorticoid secreted by the adrenal cortex, regulates water and electrolyte balance.

A.

Insulin binding to its receptor

B.

Epinephrine binding to its receptor

C.

Estrogen binding to its receptor

D.

Glucagon binding to its receptor
Correct Answer: C

Solution:

Estrogen, a steroid hormone, binds to intracellular receptors that directly interact with the genome to regulate gene expression. This contrasts with peptide hormones like insulin and glucagon, which typically act through membrane-bound receptors and second messengers.

A.

Increase blood glucose levels

B.

Decrease blood glucose levels

C.

Stimulate protein synthesis

D.

Regulate blood pressure
Correct Answer: B

Solution:

Insulin decreases blood glucose levels by enhancing cellular glucose uptake and utilization.

A.

Melatonin

B.

Cortisol

C.

Aldosterone

D.

Epinephrine
Correct Answer: A

Solution:

Melatonin is secreted by the pineal gland and plays a crucial role in regulating the sleep-wake cycle.

A.

Insulin

B.

Glucagon

C.

Cortisol

D.

Aldosterone
Correct Answer: A

Solution:

Insulin is a peptide hormone that enhances cellular glucose uptake and utilization, thus playing a major role in glucose homeostasis.

A.

Insulin

B.

Cortisol

C.

Thyroxine

D.

Aldosterone
Correct Answer: B

Solution:

Cortisol is a glucocorticoid hormone that stimulates gluconeogenesis, the process of synthesizing glucose from non-carbohydrate sources, in the liver.

A.

Insulin

B.

Glucagon

C.

Cortisol

D.

Aldosterone
Correct Answer: C

Solution:

Cortisol, a glucocorticoid hormone secreted by the adrenal cortex, stimulates gluconeogenesis and lipolysis, leading to an increase in blood glucose levels.

A.

Estrogen

B.

Progesterone

C.

Testosterone

D.

Thyroxine
Correct Answer: C

Solution:

Testosterone, an androgen produced by the testis, regulates the development, maturation, and functions of male secondary sexual characteristics.

A.

Aldosterone

B.

Cortisol

C.

Insulin

D.

Glucagon
Correct Answer: A

Solution:

Aldosterone, a mineralocorticoid secreted by the adrenal cortex, acts on the renal tubules to stimulate the reabsorption of sodium ions and water, while promoting the excretion of potassium ions. This action is essential for maintaining electrolyte balance and blood pressure.

A.

Aldosterone

B.

Cortisol

C.

Epinephrine

D.

Insulin
Correct Answer: B

Solution:

Cortisol is a glucocorticoid secreted by the adrenal cortex that stimulates gluconeogenesis, lipolysis, and proteolysis, thus playing a significant role in carbohydrate metabolism.

A.

Regulate blood glucose levels

B.

Increase blood calcium levels

C.

Stimulate milk production

D.

Regulate sleep-wake cycle
Correct Answer: B

Solution:

Parathyroid hormone (PTH) increases the Ca²⁺ levels in the blood by acting on bones and stimulating bone resorption.

A.

Erythropoietin

B.

Atrial Natriuretic Factor (ANF)

C.

Thyroxine

D.

Adrenaline
Correct Answer: B

Solution:

Atrial Natriuretic Factor (ANF) is a peptide hormone secreted by the atrial walls of the heart. It lowers blood pressure by causing vasodilation and reducing blood volume.

A.

Insulin

B.

Parathyroid hormone (PTH)

C.

Thyroxine

D.

Melatonin
Correct Answer: B

Solution:

Parathyroid hormone (PTH) increases blood calcium levels by stimulating bone resorption, reabsorption of calcium in kidneys, and absorption from the digestive tract.

A.

Cortisol

B.

Aldosterone

C.

Insulin

D.

Glucagon
Correct Answer: B

Solution:

Aldosterone, a mineralocorticoid secreted by the adrenal cortex, acts mainly at the renal tubules to stimulate the reabsorption of sodium and water, thereby helping in the maintenance of blood pressure.

A.

Decreases blood glucose levels

B.

Increases blood glucose levels

C.

Regulates calcium levels

D.

Stimulates milk production
Correct Answer: B

Solution:

Glucagon is a peptide hormone that increases blood glucose levels by stimulating glycogenolysis and gluconeogenesis.

A.

Aldosterone

B.

Cortisol

C.

Insulin

D.

Glucagon
Correct Answer: B

Solution:

Cortisol is a glucocorticoid secreted by the adrenal cortex and is involved in carbohydrate metabolism.

A.

Thyroid gland

B.

Thymus gland

C.

Pituitary gland

D.

Adrenal gland
Correct Answer: B

Solution:

The thymus gland secretes thymosins, which are essential for the differentiation of T-lymphocytes, thereby playing a critical role in cell-mediated immunity.

A.

Erythropoietin

B.

Insulin

C.

Glucagon

D.

Thyroxine
Correct Answer: A

Solution:

Erythropoietin is a peptide hormone secreted by the kidneys that stimulates the production of red blood cells.

A.

Atrial natriuretic factor (ANF)

B.

Erythropoietin

C.

Thymosin

D.

Gastrin
Correct Answer: A

Solution:

Atrial natriuretic factor (ANF) is a peptide hormone secreted by the atrial wall of the heart. It causes dilation of blood vessels, thereby reducing blood pressure.

A.

Stimulates milk production

B.

Regulates blood calcium levels

C.

Stimulates resorption of water in kidneys

D.

Increases blood glucose levels
Correct Answer: C

Solution:

Vasopressin acts mainly at the kidney and stimulates resorption of water and electrolytes by the distal tubules, reducing water loss through urine.

A.

Lowering blood glucose levels

B.

Increasing blood glucose levels

C.

Stimulating milk production

D.

Regulating water balance
Correct Answer: B

Solution:

Glucagon is a hyperglycemic hormone that increases blood glucose levels by stimulating glycogenolysis and gluconeogenesis.

A.

Insulin

B.

Glucagon

C.

Thyroxine

D.

Melatonin
Correct Answer: B

Solution:

Glucagon stimulates gluconeogenesis, which is the production of glucose from non-carbohydrate sources, thereby increasing blood glucose levels.

A.

Adrenocorticotrophic hormone (ACTH)

B.

Thyroid-stimulating hormone (TSH)

C.

Luteinizing hormone (LH)

D.

Follicle-stimulating hormone (FSH)
Correct Answer: A

Solution:

Adrenocorticotrophic hormone (ACTH) is secreted by the anterior pituitary gland and stimulates the adrenal cortex to produce glucocorticoids, which are involved in carbohydrate metabolism and stress response.

A.

Peptide hormone

B.

Steroid hormone

C.

Amino-acid derivative

D.

Protein hormone
Correct Answer: B

Solution:

Steroid hormones, such as cortisol and testosterone, bind to intracellular receptors and influence gene expression by forming a hormone-receptor complex that interacts with the genome.

A.

Glucagon

B.

Insulin

C.

Aldosterone

D.

Thyroxine
Correct Answer: A

Solution:

Glucagon is a hyperglycemic hormone secreted by the α-cells of the pancreas. It increases blood glucose levels by stimulating glycogenolysis and gluconeogenesis. A deficiency in glucagon would lead to hypoglycemia.

A.

Peptide hormones

B.

Steroid hormones

C.

Amino-acid derivatives

D.

Protein hormones
Correct Answer: B

Solution:

Steroid hormones interact with intracellular receptors, forming a hormone-receptor complex that influences gene expression by interacting with the genome.

A.

Aldosterone

B.

Vasopressin

C.

Insulin

D.

Thyroxine
Correct Answer: B

Solution:

Vasopressin acts mainly at the kidney and stimulates resorption of water and electrolytes by the distal tubules, hence it is called anti-diuretic hormone (ADH).

A.

Oxytocin

B.

Prolactin

C.

Estrogen

D.

Progesterone
Correct Answer: B

Solution:

Prolactin regulates the growth of the mammary glands and formation of milk in them.

A.

Steroid hormones

B.

Peptide hormones

C.

Thyroid hormones

D.

Amino-acid derivatives
Correct Answer: B

Solution:

Peptide hormones interact with membrane-bound receptors and generate second messengers like cyclic AMP to exert their effects.

A.

Melatonin

B.

Thyroxine

C.

Insulin

D.

Glucagon
Correct Answer: A

Solution:

Melatonin, secreted by the pineal gland, regulates the sleep-wake cycle.

A.

Parathyroid hormone (PTH)

B.

Thyrocalcitonin (TCT)

C.

Insulin

D.

Cortisol
Correct Answer: A

Solution:

Parathyroid hormone (PTH) is a hypercalcemic hormone that increases blood calcium levels by stimulating bone resorption, reabsorption of calcium in the kidneys, and absorption of calcium from the intestine.

A.

Melatonin

B.

Serotonin

C.

Dopamine

D.

Cortisol
Correct Answer: A

Solution:

Melatonin, secreted by the pineal gland, plays a crucial role in regulating the sleep-wake cycle and other circadian rhythms.

A.

Luteinizing hormone (LH)

B.

Follicle stimulating hormone (FSH)

C.

Prolactin

D.

Oxytocin
Correct Answer: B

Solution:

Follicle stimulating hormone (FSH) stimulates the growth and development of ovarian follicles in females.

A.

Calcitonin

B.

Parathyroid Hormone (PTH)

C.

Thyroxine

D.

Insulin
Correct Answer: B

Solution:

Parathyroid Hormone (PTH) increases blood calcium levels by stimulating bone resorption, increasing renal reabsorption of calcium, and enhancing intestinal absorption of calcium.

A.

Hypothyroidism

B.

Diabetes Mellitus

C.

Hyperthyroidism

D.

Diabetes Insipidus
Correct Answer: C

Solution:

The symptoms described are characteristic of hyperthyroidism, specifically a condition known as Graves' disease, which is marked by the overproduction of thyroid hormones.

A.

Calcitonin

B.

Parathyroid hormone (PTH)

C.

Thyroxine

D.

Insulin
Correct Answer: B

Solution:

Parathyroid hormone (PTH) increases blood calcium levels by stimulating bone resorption, increasing renal reabsorption of calcium, and enhancing intestinal calcium absorption.

A.

Thyroxine (T₄)

B.

Parathyroid hormone (PTH)

C.

Insulin

D.

Vasopressin
Correct Answer: A

Solution:

The symptoms described are characteristic of hyperthyroidism, specifically Graves' disease, where there is an overproduction of thyroid hormones such as thyroxine (T₄).

A.

Testosterone

B.

Progesterone

C.

Estrogen

D.

Thyroxine
Correct Answer: C

Solution:

Estrogens produce wide-ranging actions such as stimulation of growth and activities of female secondary sex organs and the appearance of female secondary sex characters.

True or False

Correct Answer: True

Solution:

The adrenal cortex secretes glucocorticoids, which are involved in carbohydrate metabolism, and mineralocorticoids, which regulate electrolyte balance.

Correct Answer: True

Solution:

The adrenal cortex secretes glucocorticoids, such as cortisol, which are involved in carbohydrate metabolism.

Correct Answer: False

Solution:

Hormones from the hypothalamus reach the pituitary gland through a portal circulatory system and regulate the functions of the anterior pituitary.

Correct Answer: False

Solution:

The neural system provides rapid, short-lived coordination among organs, while the endocrine system provides longer-lasting regulation through hormones.

Correct Answer: True

Solution:

The pituitary gland is attached to the hypothalamus by a stalk, which allows it to receive regulatory signals.

Correct Answer: False

Solution:

The neural coordination is fast but short-lived.

Correct Answer: False

Solution:

Steroid hormones interact with intracellular receptors and regulate gene expression.

Correct Answer: True

Solution:

Endocrine glands are known as ductless glands because they release hormones directly into the bloodstream, unlike exocrine glands which have ducts.

Correct Answer: True

Solution:

Thyroid hormones play a crucial role in regulating the basal metabolic rate and influence the metabolism of carbohydrates, proteins, and fats.

Correct Answer: False

Solution:

Insulin and glucagon are secreted by the pancreas, not the adrenal cortex.

Correct Answer: True

Solution:

The endocrine system, along with the neural system, coordinates and regulates physiological functions in the body by releasing hormones, which act as intercellular messengers.

Correct Answer: True

Solution:

The adrenal cortex secretes mineralocorticoids, such as aldosterone, which regulate the balance of water and electrolytes.

Correct Answer: True

Solution:

The pituitary gland is anatomically divided into an adenohypophysis and a neurohypophysis.

Correct Answer: False

Solution:

Steroid hormones interact with intracellular receptors, not membrane-bound receptors, to regulate gene expression or chromosome function.

Correct Answer: True

Solution:

The adrenal cortex secretes mineralocorticoids, such as aldosterone, which regulate water and electrolyte balance.

Correct Answer: False

Solution:

Insulin decreases blood glucose levels by promoting the uptake of glucose into cells and its conversion to glycogen.

Correct Answer: False

Solution:

Insulin is a peptide hormone, not a steroid hormone, and it regulates blood glucose levels by promoting glucose uptake.

Correct Answer: True

Solution:

The neural system provides rapid but short-lived coordination, while the endocrine system provides long-term regulation through hormones. Together, they coordinate and regulate physiological functions.

Correct Answer: True

Solution:

The pituitary gland is attached to the hypothalamus by a stalk and is involved in the synthesis and release of various hormones that regulate bodily functions.

Correct Answer: False

Solution:

Insulin decreases blood glucose levels by promoting the uptake and storage of glucose in cells.

Correct Answer: True

Solution:

The pituitary gland is anatomically divided into pars distalis, pars intermedia, and pars nervosa.

Correct Answer: False

Solution:

Insulin is a peptide hormone, not a steroid hormone.

Correct Answer: True

Solution:

The pituitary gland is indeed located in a bony cavity called the sella tursica and is attached to the hypothalamus by a stalk.

Correct Answer: True

Solution:

The hypothalamus regulates the pituitary gland through both hormonal and neural connections. The posterior pituitary is under direct neural regulation from the hypothalamus.

Correct Answer: True

Solution:

Hormones are defined as non-nutrient chemicals which act as intercellular messengers and are produced in trace amounts.

Correct Answer: True

Solution:

Hormones are indeed non-nutrient chemicals that serve as intercellular messengers and are produced in trace amounts, as per the current scientific definition.

Correct Answer: True

Solution:

The adrenal cortex secretes glucocorticoids, which are involved in carbohydrate metabolism, and mineralocorticoids, which regulate electrolyte balance.

Correct Answer: False

Solution:

The pancreas is a composite gland that functions both as an exocrine and an endocrine gland.

Correct Answer: False

Solution:

The thyroid gland secretes two hormones: thyroxine (T₄) and triiodothyronine (T₃).

Correct Answer: True

Solution:

Melatonin is involved in the regulation of the 24-hour diurnal rhythm of our body, including the sleep-wake cycle.

Correct Answer: False

Solution:

Endocrine glands are ductless glands. They release hormones directly into the bloodstream.

Correct Answer: True

Solution:

The thyroid gland secretes thyrocalcitonin (TCT), a hormone that helps regulate blood calcium levels.

Correct Answer: True

Solution:

The endocrine system is composed of several glands including the hypothalamus, pituitary, thyroid, adrenal, pancreas, parathyroid, thymus, and gonads.

Correct Answer: True

Solution:

The hypothalamus produces releasing and inhibiting hormones that control the pituitary gland's hormone production.

Correct Answer: True

Solution:

Melatonin, secreted by the pineal gland, plays a role in maintaining the normal rhythms of the sleep-wake cycle.

Correct Answer: False

Solution:

Parathyroid hormone (PTH) increases calcium levels in the blood by stimulating bone resorption, renal reabsorption of calcium, and absorption from the digestive tract.

Correct Answer: False

Solution:

Melatonin is secreted by the pineal gland, not the thyroid gland.

Correct Answer: True

Solution:

The pancreas is a composite gland functioning as both an exocrine and endocrine gland.

Correct Answer: True

Solution:

The hypothalamus produces releasing and inhibiting hormones that regulate the synthesis and secretion of pituitary hormones.

Correct Answer: True

Solution:

Endocrine glands lack ducts and are hence, called ductless glands. Their secretions are called hormones.

Correct Answer: False

Solution:

Glucagon is secreted by the alpha cells of the pancreas, not the beta cells.

Correct Answer: True

Solution:

Thyroid hormones play a crucial role in regulating the basal metabolic rate, as well as other metabolic processes.

Correct Answer: False

Solution:

Hormones that interact with membrane-bound receptors do not enter the target cell. Instead, they generate second messengers like cyclic AMP which regulate cellular metabolism.

Correct Answer: False

Solution:

Atrial natriuretic factor (ANF) is a hormone secreted by the heart that decreases blood pressure by causing dilation of blood vessels.