NCERT Solutions for Class 11 Science Biology Chapter 22 - Chemical Coordination And Integration

Answer:

Pineal gland secretes a hormone called melatonin which is involved in regulating biological rhythm of the body. Thyroid gland secretes a hormone called tetraiodothyronine which regulates metabolism of body. Ovary secretes estrogen which is responsible for growth and development of female sexual characteristics and reproductive organs. Adrenal medulla secretes hormone epinephrine which is released in response to any kind of fight or flight situation.

Hence, the correct answer is option D.

Answer:

Hormones which are secreted by the pars distalis region of the pituitary are growth hormone (GH, prolactin (PRL), thyroid stimulating hormone (TSH), adrenocorticotropic hormone (ACTH), luteinizing hormone (LH) and follicle stimulating hormone (FSH). Pars distalis is also called anterior pituitary.
Pars nervosa is also known as posterior pituitary that stores and releases two hormones called oxytocin and vasopressin. These hormones are actually synthesized by hypothalamus and are transported to pars nervosa. 

Hence, the correct answer is option C.

Answer:

When Mary was about to face an interview, she was experiencing sweating, increased heart rate and respiration because adrenal gland released emergency hormones of fight or flight, i.e. adrenaline and nor-adrenaline which stimulate the breakdown of glycogen resulting in increasing concentration of glucose in blood.

Hence, the correct answer is option C.

Answer:

The steroid hormone aldosterone acts on the nephron for stimulating the reabsorption of Na⁺, water and excretion of K⁺ ions. This hormone is responsible for maintaining the balance of water and electrolytes in our body. It also regulates fluid volume, osmotic pressure and blood pressure. Insulin is a peptide hormone that regulates blood sugar level in the body.Testosterone is the male sex hormone that regulate spermatogenesis. Melatonin regulates 24 hour diurnal rhythm of the body.

Hence, the correct answer is option D.

Answer:

Thymosin is responsible for differentiation of T-lymphocytes. It provides cell mediated immunity and promotes antibody production to provide humoral immunity.

Hence, the correct answer is option C.

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Insulin, T₃ and gastrin are the hormones secreted by pancreas, thyroid gland and stomach respectively. Thus, cyclic AMP is the correct option as it is one of the secondary messengers involved in the action of a protein hormone.

​Hence, the correct answer is option A. 

Answer:

Leydig cells or interstitial cells are present in the interstitial spaces of testis. These produce a group of hormones called androgens. Testosterone is the main androgen that stimulates the growth and development of male secondary sex organs and regulates spermatogenesis. Gonadotropins are secreted by pituitary gland that stimulate gonadal activity. Aldosterone maintain electrolyte balance and estrogen stimulate female sex organs to produce ovum.

Hence, the correct answer is option A. 

Answer:

Corpus luteum secretes a hormone called progesterone. It supports pregnancy and also stimulate the development of duct system in the mammary gland for the milk production in females.

Hence, the correct answer is option B.

Answer:

Cortisol is secreted from adrenal gland. The zona fasciculata region of adrenal cortex secretes hormone cortisol, corticosterone, cortisone. These hormones are involved in maintaining glucose homeostasis. Pancreas secretes insulin, thyroid gland secretes thyroxine and thymus gland secretes thymosin. 

Hence, the correct answer is option C.

Answer:

A hormone responsible for normal sleep-wake cycle is melatonin. Gastrin is secreted by the endocrine cells of stomach and help in secretion of HCl and pepsinogen. Epinephrine is secreted by adrenal gland which is a fight or flight hormone. Pancreas secretes hormone insulin that regulate blood glucose level.

Hence, the correct answer is option C.

Answer:

Hormones act on the specific target tissue which possess hormone receptors. Protein hormones are hydrophilic in nature and can not cross the cell membrane. Receptors of these hormones are present on the plasma membrane of the cell on which it acts.

Hence, the correct answer is option C.

Answer:

Epinephrine called stress hormone increases heartbeat. Testosterone helps in the growth of secondary sexual characters in men. For example muscle growth to make males muscular. Glucagon stimulates the breakdown of glycogen in liver. Atrial Natriuretic Factor (ANF) decreases blood pressure by vasodilation.
 
Hence, the correct answer is option B.

Answer:

Thymosin hormone is secreted by thymus gland that plays a vital role in differentiation of T-lymphocytes. Thus, it has no role in regulation of blood calcium levels. Other hormones in the given options play an important role in calcium homeostasis in the body.

Hence, the correct answer is option D.

Answer:

Liver is the largest gland of the body. It is the only organ that does not consist of a central 'medullary' region surrounded by a cortical region.
Other three options, i.e. ovary, kidney and adrenal gland have a prominent medullary and cortical region.

Hence, the correct answer is option C.

Answer:

Exophthalmia is a condition in which there is a bulging of the eye anteriorly out of the orbit. It is due to over secretion of thyroid hormone that result in the increase in the amount of lymphocytes in the eye and swelling due to excess amount of thyroid hormone. Cretinism, goitre and myxoedema are linked to thyroid deficiency.
 
Hence, the correct answer is option D.

Answer:

In males, a pair of testis is present in the scrotum. Testes is a primary sex organ and an endocrine gland that secretes the hormone testosterone. This gland is absent in females. In females, a pair of ovaries are present which is the primary sex organ and produces hormone estrogen and progesterone. These endocrine glands are absent in males.

Answer:

Zone glomerulosa is the outermost layer that envelops the other layer such as zona reticularis (inner layer) and zona fasciculata (middle layer).

Answer:

The process of formation of RBCs is called erythropoiesis. Erythropoietin hormone secreted from juxtaglomerular apparatus of kidneys stimulate erythropoiesis.

Answer:

Pars intermedia of the pituitary gland secretes only one hormone known as melanocyte stimulating hormone (MSH). This hormone is responsible for skin darkening or skin pigmentation.

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Calcitonin is a peptide hormone which is secreted by thyroid gland. It regulates or checks the calcium concentration in the blood by decreasing mobilisation from bones.

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Thymosin hormone plays an important role in cell-mediated immunity.

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Peptide hormones are the derivatives of amino acids, polypeptides or proteins and are insoluble in lipids thus cannot enter the target cell. Hence, these act at the surface of target cell as primary messengers and create second messengers like cAMP affecting the functioning of target cells.

Answer:

(a) True because gastrointestinal tract produces gastrin, secretin, cholecystokinin (CCK) and gastric inhibitory peptide (GIP). Kidney produces epinephrine, nor-epinephrine and corticoids. Heart produces ANF or atrial Natriuretic Factor.
(b) True because it produces gonadotropic hormone, adrenocorticotropic hormone, thyroid stimulating hormone, growth hormone, follicle stimulating hormone, prolactin etc.
(c) False because T-lymphocytes provide cell mediated immunity and B-lymphocytes provide humoral immunity.
(d) True because insulin is a hypoglycemic hormone that decreases blood sugar level.

Answer:

The doctor wants to measure the level of ADH (anti-diuretic hormone) or vasopressin as low levels ADH can cause excessive urination, constant thirst and low blood pressure.

Answer:

(a) Insulin is a  protein/peptide hormone.
(b) TSH is secreted from the anterior pituitary.
(c) Tetraiodothyronine is a maintenance hormone.
(d) The adrenal gland is located on the anterior part of the kidney.

Answer:

Answer:

In males, luteinizing hormone stimulates the synthesis and secretion of androgens from testes. This hormone stimulates the leydig cells present in the interstitial spaces of testes to produce testosterone. It is the hormone that is involved in growth and development of male accessory organs and spermatogenesis. In females, LH induces ovulation of fully mature follicles and release secondary oocyte under its influence. It also promotes the development of corpus luteum, formed from the remains of graafian follicles which secretes progesterone.

Answer:

Hormones such as protein hormones cannot enter the target cell and interact with specific receptors located on the surface of the cell membranes of the target cell and forms a hormone-receptor complex. Thus they generate second messengers such as cyclic AMP (cAMP) on the inner side of the plasma membrane. These second messengers further carries out all the functions of hormone.

Answer:

(a) People with swollen necks must be suffering from goitre which is the enlargement of thyroid gland. This condition occurs due to iodine deficiency in the body. 
(b) It is caused due to the deficiency of iodine in the diet. Iodine is very important for the production of thyroid hormones-T₃ and T₄. 
(c) Iodine deficiency results in under-secretion of thyroid hormone and result in hypothyroidism. During pregnancy it can cause defective development and abnormalities in the growing baby that may lead to stunted growth (cretinism), mental retardation, low IQ etc.

Answer:

Jet lag is a temporary sleep problem that occurs due to the disruption of the body clock and affect the ones who travels different time zones.
Melatonin hormone is responsible for maintaining the body rhythms of sleep-wake cycle. After the sunsets, eyes perceive darkness and alert the hypothalamus to release melatonin  that promotes sleep, and in sunlight, it tells the hypothalamus to hold the release of melatonin. Thus, hypothalamus can not re-adjust to its schedule instantly and cause jet lag which takes several days to overcome this problem.

Answer:

Inflammatory response can be controlled by a steroid hormone called cortisol which is mainly a glucocorticoid. It is secreted by the middle zone of adrenal cortex called zona fasciculata. Cortisol affects carbohydrate metabolism, and metabolism of proteins and fats. It also stimulates gluconeogenesis, lipolysis and proteolysis. It is also a stress hormone as it modulates many changes in the body at the time of stress.

Answer:

Thymus gland is an endocrine gland that secrets hormone thymosin which stimulates the development of immune system by differentiation of T-lymphocytes. In old people, thymus is degenerated, resulting in decreased production of thymosin. As a result, old people develops a weak immune system.

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If a pregnant women is suffering from hypothyroidism there are chances of defective development of the baby in the womb. The growing baby may not develop properly, show mental retardation, stunted growth, abnormal skin development, low intelligence, deaf mutism etc.

Answer:

Answer:

LH or luteinizing hormone (A) is secreted by the pituitary gland. A stimulates the ovaries (X) to produce E₂ . When the concentration of E₂ increases in the blood it creates a negative feedback loop and reduces the synthesis of A.

In the case of first old woman, she has high levels of LH in the blood which should stimulate gland X to secrete more E₂. Here she has low levels of E₂ in the blood which signifies LH is not able to stimulate the ovaries to produce E₂.

In the second case, she has high levels of LH in blood and also high level of E₂ in the blood. High E₂ should show negative feedback control decreasing the secretion of LH. The given situation signifies there is some defect in the negative feedback loop.

Answer:

Milk secretion in mammals is stimulated by the hormone oxytocin which is released from neurohypophysis. When the calf sucks the cow's udder, it triggers the nerve impulses. Neurons in the Hypothalamic nuclei start to synthesize oxytocin. The concentration of oxytocin is increased within 1-2 minutes of udder stimulation.
Smooth muscles around the alveoli in the udder gets contracted and milk is released.
Udder (sucking stimulus) → Brain (Hypothalamus) → Neurohypophysis → Blood (oxytocin) → Udder (Smooth muscles) → Milk flow.

Answer:

(a) An endocrine gland-pancreas and the hormone insulin secreted by it is related to this condition.
β-cells present in islets of langerhans in the pancreas secrete insulin. Insulin is a peptide hormone that plays a major role in regulating blood glucose level. When insulin is dysfunctional or not produced, then glucose uptake is hampered and thus glucose along with ketone bodies appear in urine and causes diabetes mellitus.

(b) Insulin hormone acts on the liver cells/hepatocytes and the adipocytes (cells of adipose tissues). Insulin increases the glucose uptake and utilization.

(c) The condition arises is prolonged hyperglycemia which leads to the disorder called diabetes mellitus. In the condition, glucose level in the blood rise and glucose is lost through urine. Diabetes can be treated or controlled by insulin therapy which lowers the blood glucose level.

Answer:

The movement of calcium ions between the body fluids and cells is known as calcium homeostasis. The endocrine glands responsible for this are thyroid and parathyroid glands that secrete calcitonin and parathyroid hormone (PTH) respectively.
(i) Parathyroid Glands - The chief cells of parathyroid glands secrete parathyroid hormone (PTH) which is involved in regulating calcium and phosphate balance between the blood and other tissues. It mobilises the release of calcium ions into the blood from bones. It also increase of calcium reabsorption by body organs like intestine and kidneys.
(ii) Thyroid Glands - It releases thyrocalcitonin hormone produced by parafollicular cells when the calcium levels in the blood are high. it suppreses the mobilisation of calcium ions from bones.

Answer:

Peptide Hormone Action	Steroid Hormone Action
(i) Peptide hormones interact with membrane bound receptors. (ii) They generates second messenger for further second action. (eg - cyclic AMP, IP3, Ca2+ etc.). (iii) The second messengers affect cellular metabolism. (iv) Example: insulin, glucagon, vasopressin etc. (v)	(i) Steroid hormones interact with intracellular receptors. (ii) They do not generates second messengers. (iii) They regulate gene expression or functions of chromosomes by the interaction of hormone receptor complex with the genome. (iv) Example: cortisol, testosterone, estrogen and progesterone. (v)

Answer:

Hypothalamus is a very small but important part of the brain that is involved in endocrine, autonomic and behavioural functions. It consists of some neurosecreting cells called nuclei that produces hormones.
It produces two types of hormones:
(1) Releasing hormones (that stimulate the secretion of pituitary hormones).
(2) Inhibiting hormones (that inhibit the secretion of pituitary hormones).
Hypothalamus release major hormones that control the pituitary hormones. These are as follows:
(i) Adrenocorticotropic releasing hormone (ARH)- Regulates the secretion of ACTH from anterior pituitary.
(ii) Thyrotropin releasing hormone (TRH)- Regulates the pituitary gland for the secretion of TSH.
(iii) Growth hormone releasing hormone- Regulates the pituitary gland for the secretion of growth hormone.
(iv) Gonadotropin releasing hormone- Regulates the pituitary gland for the secretion of gonadotrophins.
(v) Prolactin releasing hormone- Regualtes the release of prolactin from anterior pituitary.
(vi) MSH releasing hormone- Regulates pars intermedia for the secretion of MSH (melanocyte stimulating hormone).
Hypothalamus is called the super master endocrine gland because it regulates the syntheses and secretion of pituitary gland hormones. Pituitary gland is a master gland as it regulates the synthesis and secretion of other endocrine glands.