Questions: Chemical Coordination and Integration

Q1. Define hormone and distinguish endocrine from exocrine glands.

Answer (English): A hormone is a chemical messenger made by an endocrine cell, released into the blood, and carried to a target cell that carries the matching receptor. An endocrine gland is ductless and releases its hormone into the blood, while an exocrine gland releases its secretion through a duct onto a surface or into a cavity, as the salivary gland does.

Hinglish: Hormone ek chemical messenger hai jo endocrine cell banata hai, blood mein chhoda jata hai aur matching receptor wale target cell par kaam karta hai. Endocrine gland ductless hoti hai aur hormone blood mein deti hai, jabki exocrine gland duct ke through secretion deti hai.

Q2. Which hormones are released by the anterior pituitary and what does each do?

Answer (English): The anterior pituitary releases growth hormone, prolactin, thyroid stimulating hormone, adrenocorticotrophic hormone, luteinizing hormone and follicle stimulating hormone. Growth hormone promotes body growth; prolactin promotes milk formation; thyroid stimulating hormone stimulates the thyroid; adrenocorticotrophic hormone stimulates the adrenal cortex; and luteinizing hormone and follicle stimulating hormone act on the gonads.

Hinglish: Anterior pituitary GH, prolactin, TSH, ACTH, LH aur FSH deta hai. GH growth karta hai, prolactin milk banata hai, TSH thyroid ko, ACTH adrenal cortex ko aur LH/FSH gonads ko stimulate karte hain.

Q3. Why are oxytocin and vasopressin stored in the posterior pituitary?

Answer (English): Oxytocin and vasopressin are made in the neurons of the hypothalamus and travel down their axons to the posterior pituitary, where they are stored and then released into the blood. The posterior pituitary does not make them; it only stores and releases them when the hypothalamic neurons send the signal.

Hinglish: Oxytocin aur vasopressin hypothalamus ke neurons mein bante hain aur axons se posterior pituitary tak aate hain, jahan store hokar release hote hain; posterior pituitary inhe banata nahi, sirf store aur release karta hai.

Q4. What are the functions of thyroxine and thyrocalcitonin?

Answer (English): Thyroxine, along with triiodothyronine, controls the metabolism of carbohydrates, proteins and fats and so regulates the basal metabolic rate, and it also supports growth and the activity of the nervous system. Thyrocalcitonin lowers the level of calcium in the blood and therefore opposes parathyroid hormone.

Hinglish: Thyroxine (T4) aur T3 metabolism ko control karke basal metabolic rate regulate karte hain aur growth aur nervous system ko support karte hain; thyrocalcitonin blood calcium kam karta hai, isliye PTH ka opposite kaam karta hai.

Q5. Explain goitre and cretinism.

Answer (English): Iodine is needed to make thyroid hormones, so a deficiency of iodine reduces their synthesis. The thyroid gland then enlarges and produces the swelling called goitre. When the deficiency occurs during pregnancy and infancy, the baby's growth and mental development are stunted, and this condition is called cretinism.

Hinglish: Iodine thyroid hormones ke liye zaroori hai; kami hone par thyroid gland badh jati hai jise goitre kehte hain. Pregnancy aur infancy mein iodine ki kami se baby ki growth aur mental development ruk jati hai, jise cretinism kehte hain.

Q6. What are the two parts of the adrenal gland and what does each secrete?

Answer (English): The adrenal gland has an outer cortex and an inner medulla. The cortex secretes glucocorticoids such as cortisol, which act on carbohydrate metabolism and inflammation, and mineralocorticoids such as aldosterone, which control sodium and water balance. The medulla secretes adrenaline and noradrenaline, which produce the fight or flight response.

Hinglish: Adrenal gland ke cortex se cortisol (glucocorticoid) aur aldosterone (mineralocorticoid) nikalte hain jo metabolism aur Na+/water balance control karte hain, aur medulla se adrenaline aur noradrenaline nikalte hain jo fight or flight response dete hain.

Q7. How do insulin and glucagon control blood glucose?

Answer (English): Insulin is secreted by the beta cells of the islets of Langerhans and it lowers the blood glucose by increasing the uptake of glucose into the cells and by promoting the conversion of glucose into glycogen in the liver and the muscle. Glucagon is secreted by the alpha cells and it raises the blood glucose by promoting the breakdown of glycogen into glucose. The two hormones act in opposite directions and keep the blood glucose steady.

Hinglish: Insulin beta cells se nikalta hai aur glucose uptake aur glycogen formation badhakar blood glucose kam karta hai; glucagon alpha cells se nikalta hai aur glycogen todkar glucose badhata hai. Dono opposite kaam karke glucose balance banaye rakhte hain.

Q8. What are the hormones of the testis and the ovary?

Answer (English): The Leydig cells of the testis secrete androgens, mainly testosterone, which control the male reproductive organs and the male secondary sexual characters. The ovary secretes estrogens, which control the female reproductive organs and secondary sexual characters, and progesterone, which prepares the uterus for pregnancy and maintains pregnancy.

Hinglish: Testis ke Leydig cells androgens (testosterone) banate hain jo male reproductive organs aur secondary characters control karte hain; ovary estrogens aur progesterone banata hai jo female organs aur pregnancy ke liye zaroori hain.

Q9. Explain the mechanism of action of a protein hormone.

Answer (English): A protein hormone cannot cross the cell membrane, so it binds a receptor on the membrane. The activated receptor produces a second messenger such as cyclic AMP inside the cell, and cAMP activates enzymes that speed up or slow down specific reactions. The result is the physiological response. The response is quick but short lived because the second messenger is destroyed soon after the hormone is removed.

Hinglish: Protein hormone membrane cross nahi kar sakta, isliye membrane receptor se bind karta hai; receptor andar second messenger (cAMP) banata hai jo enzymes activate karke response deta hai. Response jaldi aata hai par der tak nahi rehta.

Q10. Explain the mechanism of action of a steroid hormone.

Answer (English): A steroid hormone is lipid soluble, so it enters the target cell and binds an intracellular receptor. The hormone-receptor complex enters the nucleus and binds to a specific region of the DNA, which switches on particular genes. The genes are copied into mRNA and the mRNA is translated into proteins, and the new proteins carry out the response. Because the response depends on making proteins, it develops slowly but lasts longer.

Hinglish: Steroid hormone cell mein ghuskar intracellular receptor se bind karta hai; complex nucleus mein jaakar DNA par bind hota hai aur genes on karta hai, jisse mRNA aur proteins bante hain aur response milta hai. Response dheere aata hai par lamba chalta hai.

Quiz pointer. A five question chapter quiz follows this page. Attempt it without looking back and read the explanation for every question you miss, because the quiz retests the glands, their hormones and the two mechanisms of action.