The 'Hormone Leptin' is primarily secreted by adipose (fat) tissue and acts on the hypothalamus to: MCQ with Answer and Explanation

Explanation:
Simple (endemic) goiter is caused by iodine deficiency, leading to low production of thyroid hormones. The pituitary secretes excess TSH, stimulating the thyroid to enlarge in an attempt to produce more hormones. Cretinism is congenital hypothyroidism, Graves' disease is autoimmune hyperthyroidism, Hashimoto's is autoimmune hypothyroidism. Iodized salt prevents goiter.

Explanation:
Insulin is a peptide hormone produced by the beta cells of the Islets of Langerhans in the pancreas. It is initially synthesized as a single, inactive polypeptide precursor called proinsulin. During processing, a connecting peptide (C-peptide) is removed, leaving two polypeptide chains: the A chain (21 amino acids) and the B chain (30 amino acids). These two chains are held together by two interchain disulfide bridges (covalent bonds between sulfur atoms of cysteine residues), and there is also one intrachain disulfide bridge within the A chain.

Explanation:
Angiotensin II is a powerful octapeptide hormone formed in the blood by the action of angiotensin-converting enzyme (ACE). It has multiple effects to increase blood pressure and volume. It is a potent vasoconstrictor, increasing systemic vascular resistance. Crucially, it also acts on the zona glomerulosa of the adrenal cortex to stimulate the secretion of the mineralocorticoid hormone aldosterone. Aldosterone then acts on the kidneys to increase sodium and water reabsorption, further increasing blood volume and pressure.