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NCERT · Class 11 · Biology

Chapter 19: Chemical Coordination and Integration

Practice each question, then open the answer or worked solution.

Textbook exercises

9 questions
Q1Written answer

Define the following:

(a) Exocrine Gland

(b) Endocrine Gland

(c) Hormone

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Ans: Exocrine glands, such as sebaceous glands, sweat glands, salivary glands, and intestinal glands, secrete their secretions on the surface or into a specific region via ducts in order to conduct a metabolic function. 


Ans: The endocrine gland is a unique gland (from the epithelium that forms it) that secretes informational molecules or hormones that are injected into the venous blood or lymph to reach the target organ because there is no duct connecting the gland to the target organ. As a result, endocrine glands, such as the thyroid gland, are sometimes known as ductless glands.


Ans: Hormone is a chemical produced by an endocrine gland or a specialized nerve cell and released in very minute amounts into the bloodstream to control the growth or function of a specific tissue organ in a distant area of the body, such as insulin.


Q2Written answer

Diagrammatically Indicates the Location of the Various Endocrine Glands in Our Body.

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Solution coming soon.

Q3Written answer

List the Hormones Secreted by the Following:

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Ans.


Gland

Hormones

Function

Hypothalamus

Releasing & Inhibiting Hormones

Regulate hormone secretion from the pituitary gland

Pituitary (Anterior Lobe)

FSH, LH, TSH, ACTH, GH, Prolactin

Regulate various functions including reproduction, metabolism, growth, and stress response

Pituitary (Posterior Lobe)

Oxytocin, Vasopressin

Regulate muscle contractions (uterus) and water balance

Thyroid

Thyroxine, Triiodothyronine, Calcitonin

Regulate metabolism, growth and development, and calcium levels

Parathyroid

Parathyroid Hormone (PTH)

Regulates calcium levels in the blood

Adrenal Cortex

Glucocorticoids (cortisol), Mineralocorticoids (aldosterone), Sex hormones

Regulate metabolism, blood pressure, and sexual development and function

Adrenal Medulla

Epinephrine (adrenaline), Norepinephrine (noradrenaline)

Help the body respond to stress (fight-or-flight response)

Pancreas

Insulin, Glucagon, Somatostatin

Regulate blood sugar levels

Testis

Androgens (testosterone)

Promote male sexual development and function

Ovary

Estrogens, Progesterone, Relaxin

Regulate female sexual development and function, and prepare the body for childbirth

Thymus

Thymosin

Plays a role in the development of the immune system

Atrium

Atrial Natriuretic Factor (ANF)

Helps regulate blood pressure

Kidney

Renin, Erythropoietin

Regulates blood pressure and red blood cell production

G-I Tract

Gastrin, Secretin, Cholecystokinin, Enterocrinin, Duocrinin, Villikinin

Regulate digestion and nutrient absorption


Q4Written answer

Fill in the Blanks:

Hormones                                                   Target Gland

  1. Hypothalamic hormones                   ........................

  2. Thyrotrophin (TSH)                             ........................

  3. Corticotropin (ACH)                          ........................

  4. Gonadotrophins (LH, FSH)                 ........................

  5. Melanotropin (MSH)                        ........................

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Ans:

  1. Pituitary

  2. Thyroid

  3. Adrenal cortex

  4. Gonads – Tests in male and ovaries in female

  5. Skin.


Q5Written answer

Write short notes on the functions of the following hormones:

Parathyroid Hormones (PTH)

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Ans: Parathyroid hormone raises calcium levels while lowering phosphate levels in the blood.

Thyroid Hormones

Ans: Thyroxine, triiodothyronine, and calcitonin are the three hormones secreted by the thyroid gland. Thyroxine and triiodothyronine regulate the body's overall metabolism, encourage tissue development, and induce tissue differentiation. Calcitonin is a hormone that controls calcium levels in the blood.


Thymosin

Ans: Thymosin is produced by the thymus gland. Cell division is accelerated, T-lymphocyte growth and differentiation are stimulated, and sexual maturity is accelerated.


Androgens

Ans: The testis secretes androgens. They influence male sexual behavior and sex drive by stimulating the development of the male reproductive system, the production of sperm, and the development of male accessory sex characteristics.


Estrogens

Ans: Estrogens are produced by the ovaries. They encourage the female reproductive system to mature and become fully functional, as well as the differentiation of ova and the development of accessory sex characteristics.


Insulin and Glucagon.

Ans: Insulin is produced in the pancreas by the -cells. It reduces blood glucose levels and stimulates protein and fat synthesis. The a-cells of the pancreas produce glucagon. It causes a rise in blood glucose levels.


Q6Written answer

Give an example(s) of

  1. Hyperglycemic Hormone and Hypoglycemic Hormone

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Worked solution

 Ans: Parathormone (PTH)


  1. Hypercalcemic Hormone

 Ans: Glucagon, Insulin


  1. Gonadotrophic Hormones

 Ans: Follicle-stimulating hormone (FSH) and Luteinizing hormone (LH)


  1. Progestational Hormone

 Ans: Progesterone


  1. Blood Pressure-Lowering Hormone

 Ans: Atrial natriuretic factor


  1. Androgens and Estrogens.

 Ans: Testosterone and Estradiol.


Q7Written answer

Which Hormonal Deficiency is Responsible for the Following?

  1. Diabetes Mellitus

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Ans: Diabetes mellitus is characterized by excessively high blood glucose levels caused by a lack of the hormone insulin.


  1. Goiter

 Ans: Goitre is a condition in which the thyroid gland enlarges abnormally owing to a lack of thyroxine hormone in the body.

  1. Cretinism.

  Ans: Cretinism is a condition in which a baby's development is slowed owing to a lack of thyroid hormone in the body.


Q8Written answer

Briefly Mention the Mechanism of Action of FSH.

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Ans: (Follicle-stimulating hormone) is a glycoprotein that is lipid insoluble and so cannot penetrate target cells. It forms a hormone-receptor complex by binding to particular receptor molecules on the cell membrane's surface. The enzyme adenylate cyclase is released from the receptor site as a result of this combination. From ATP, this enzyme produces cell cyclic adenosine monophosphate (cAMP). The cAMP stimulates the cell's existing enzyme system. The metabolic processes in the cell are accelerated as a result of this. The hormone is referred to as the first messenger, whereas cAMP is referred to as the second messenger. The hormone-receptor complex alters the permeability of the cell membrane to allow items to pass across it more easily. As the cell obtains the required ingredients, its actions grow.


Q9Written answer

Column I                      Column II

  1. T4                        (i) Hypothalamus

  2. PTH                     (ii) Thyroid

  3. GnRH                  (iii) Pituitary

  4. LH                        (iv) Parathyroid.


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Ans: 

Column I

Column II

T4

Thyroid

PTH

Parathyroid

GnRH

Pituitary

LH

Hypothalamus