Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
Hormones are chemical messengers produced by endocrine glands in trace amounts and are transported by the bloodstream to target organs to regulate physiological activities.
Classification based on chemical nature: (i) Steroids (e.g., estrogens, androgens, cortisol), (ii) Polypeptides (e.g., insulin, glucagon, oxytocin), (iii) Amino acid derivatives (e.g., epinephrine, norepinephrine).
Thyroxine () is an iodinated derivative of the amino acid tyrosine, secreted by the thyroid gland. Deficiency of iodine in the diet leads to Hypothyroidism and enlargement of the thyroid gland, known as Goitre.
Blood glucose levels are maintained by the antagonistic action of two hormones: Insulin (which lowers blood sugar by converting glucose to glycogen) and Glucagon (which raises blood sugar by mobilizing glucose from glycogen).
Epinephrine (Adrenaline) and Norepinephrine are 'fight or flight' hormones that prepare the body for emergency situations by increasing heart rate and blood pressure.
Sex hormones include Androgens (e.g., Testosterone) responsible for male secondary sexual characteristics, and Estrogens and Progesterone responsible for female secondary sexual characteristics and the menstrual cycle.
📐Formulae
💡Examples
Problem 1:
Identify the hormone that is responsible for maintaining the blood glucose level and specify the gland that secretes it.
Solution:
Insulin and Glucagon.
Explanation:
Insulin and Glucagon are secreted by the pancreas (specifically the Islets of Langerhans). Insulin converts glucose to glycogen when blood sugar is high (), whereas glucagon converts stored glycogen back to glucose when blood sugar is low.
Problem 2:
Why is the intake of iodized salt recommended for humans?
Solution:
To prevent Goitre and ensure the synthesis of Thyroxine ().
Explanation:
The thyroid gland requires iodine () to synthesize the hormone thyroxine. Thyroxine regulates the metabolism of carbohydrates, proteins, and fats. A deficiency of iodine leads to an enlargement of the thyroid gland, a condition called Goitre.
Problem 3:
Classify the following hormones into their chemical categories: Insulin, Testosterone, and Epinephrine.
Solution:
Insulin: Polypeptide; Testosterone: Steroid; Epinephrine: Amino acid derivative.
Explanation:
Insulin is a protein consisting of amino acids. Testosterone is derived from the cholesterol skeleton (steroid nucleus). Epinephrine is derived from the amino acid tyrosine.