1. Define the following:
(a) Exocrine gland
(b) Endocrine gland
(c) Hormone
Solution:
1. Exocrine gland – These glands liberate their secretions into ducts conveying either on the surface of the body or to particular organs of the body
2. Endocrine gland – These ductless glands liberate their secretions into the bloodstream, conveying it to target organs located at a distance
3. Hormone – It is a non-nutrient chemical which serves as an intercellular messenger and is secreted in trace amounts
2. Diagrammatically indicate the location of the various endocrine glands in our body.
Solution:
The diagram indicating the location of the various endocrine glands in our body is given below:
3. List the hormones secreted by the following:
(a) Hypothalamus
(b) Pituitary
(c) Thyroid
(d) Parathyroid
(e) Adrenal
(f) Pancreas
(g) Testis
(h) Ovary
(i) Thymus
(j) Atrium
(k) Kidney
(l) G-I Tract
Solution:
The hormones secreted by the following structures are as follows:
4. Fill in the blanks:
Hormones Target Gland
(a) Hypothalamic hormones ______________
(b) Thyrotrophin (TSH) __________________
(c) Corticotrophin (ACTH) ________________
(d) Gonadotrophins (LH, FSH) _____________
(e) Melanotrophin (MSH) ________________
Solution:
(a) Hypothalamic hormones – Pituitary gland
(b) Thyrotrophin (TSH) – Thyroid gland
(c) Corticotrophin (ACTH) – Adrenal cortex
(d) Gonadotrophins (LH, FSH) – Testis and ovaries
(e) Melanotrophin (MSH) – Pigment cells of the dermis of the skin
5. Write short notes on the functions of the following hormones:
(a) Parathyroid hormone (PTH)
(b) Thyroid hormones
(c) Thymosins
(d) Androgens
(e) Estrogens
(f) Insulin and Glucagon
Solution:
(a) Parathyroid hormone (PTH)
1. It is a peptide hormone which is secreted by the parathyroid gland
2. The circulating levels of calcium ions regulate its secretion
3. The levels of calcium ions in the blood are increased by PTH.
4. The bone resorption process is triggered by PTH.
5. The reabsorption of calcium ions by the renal tubules is triggered, which increases calcium ions absorption from the food that is digested
6. PTH is a hypercalcemic hormone which increases the blood Ca2+ levels
7. It has a critical role to play in balancing calcium in the body along with TCT, i.e., in calcium homeostasis.
(b) Thyroid hormones Thyroxine/Tetraiodothyronine(T4)
1. This hormone checks the basal metabolic rate (BMR) and body growth, such as mental development and ossification of bones
2. The body weight is controlled by it
3. It controls the tissue differentiation and metamorphosis of the tadpole larva into an adult frog
4. Formation of RBC is suppressed
5. Tri-iodothyronine(T3) – The energy consumption and the body’s oxygen are increased. It also increases heart rate and force of contraction, which in turn increases the cardiac output
(c) Thymosin
1. The differentiation of T-lymphocytes is triggered, which provides cell-mediated immunity
2. The antibody production is facilitated to provide humoral immunity
3. The rate of division of cells in children is triggered, thereby promoting growth
(d) Androgens
1. The interstitial cells located in the intertubular space generate a collection of hormones called androgens mainly testosterone
2. Checks the maturation, development and functions of the male accessory sex organs such as epididymis, vas deferens, urethra, seminal vesicles, prostate gland etc.
3. They trigger the growth of facial and axillary hair, muscles, aggressiveness, low pitch of voice etc.
4. In the phenomena of spermatogenesis, they play a critical stimulatory role
5. They act on the central neural system, which influences the male sexual behaviour
6. They generate anabolic effects on carbohydrate metabolism and protein
(e) Estrogen
1. It triggers the development of ovarian follicles and the growth & development of the female reproductive organs, namely the fallopian tube, uterus and vagina
2. It causes the LH secretion to increase and FSH secretion to decrease
3. The sensitivity of the uterus to the hormone – oxytocin is enhanced
4. The development of mammary gland is facilitated
5. Female sexual behaviour is regulated
(f) Insulin
1. Glucose homeostasis is regulated
2. It acts on hepatocytes and adipocytes
3. The transport of glucose to the muscles from blood is triggered
4. The oxidation of glucose is facilitated and brings about glycogenesis, i.e. the conversion of glucose to glycogen, causing hyperglycemia
Glucagon
1. It is critical in maintaining normal blood glucose levels
2. It acts on hepatocytes which trigger the conversion of glycogen to glucose
3. The gluconeogenesis phenomena is triggered, i.e. the conversion of non-carbohydrate particles, namely, proteins and fats, to glucose
6. Give example(s) of the following:
(a) Hyperglycemic hormone and hypoglycemic hormone
(b) Hypercalcemic hormone
(c) Gonadotrophic hormones
(d) Progestational hormone
(e) Blood pressure lowering hormone
(f) Androgens and estrogens
Solution:
(a) Hyperglycemic hormone and hypoglycemic hormone – Glucagon and Insulin, respectively
(b) Hypercalcemic hormone – Parathormone hormone (PTH)
(c) Gonadotrophic hormones – Follicle-stimulating hormone (FSH) and luteinising hormone (LH)
(d) Progestational hormone – Progesterone
(e) Blood pressure lowering hormone – Atrial natriuretic factor (ANF)
(f) Androgens and estrogens – Androgen – Testosterone and androsterone
Estrogen – β- oestradiol
7. Which hormonal deficiency is responsible for the following?
(a) Diabetes mellitus
(b) Goitre
(c) Cretinism
Solution:
The hormonal deficiency responsible for the above are as follows:
(a) Diabetes mellitus – Insulin (inadequate secretion) which is caused due to abnormally high glucose levels in the blood
(b) Goitre – Thyroxin (inadequate secretion)
(c) Cretinism – Thyroid (inadequate secretion)
8. Briefly explain the mechanism of action of FSH.
Solution:
Follicle-stimulating hormone (FSH) is a glycoprotein polypeptide hormone which is not soluble in lipids and, therefore, cannot enter the target cell. It binds to the surface of the cell, which activates the cellular systems to carry out its functionalities.
Mechanism of FSH
1. FSH molecule binds to the receptor protein, which is located on the surface of the cell, forming the hormone-receptor complex
2. The formation of the hormone causes the receptor complex to activate the adenyl cyclase enzyme
3. This enzyme converts ATP to cyclic AMP as a second messenger, which in turn activates the follicular cells of the membrane of granulose to produce estrogens.
9. Match the following:
Solution:
.jpeg)
0 Comments