Consider the following statements about the endocrine system: 1. The pituitary gland is the master gland. 2. Thyroxine regulates basal metabolic rate. 3. Adrenaline decreases heart rate during stress. Which of the above is/are correct? MCQ with Answer and Explanation

Explanation:
The Blood-Brain Barrier (BBB) is formed by tight junctions between endothelial cells in brain capillaries, making it highly selective. It allows the free diffusion of small, lipid-soluble molecules and essential gases. Therefore, oxygen, carbon dioxide, and lipid-soluble substances (like alcohol, nicotine, and some anesthetics) easily cross. Glucose, a water-soluble molecule essential for brain energy, crosses via specific carrier-mediated transport (GLUT1 transporters). Large proteins, peptides, most water-soluble drugs, and pathogens like bacteria and viruses are generally blocked from entering the brain parenchyma.

Explanation:
Glaucoma is a group of eye diseases that result in damage to the optic nerve, often associated with elevated intraocular pressure. It can lead to permanent vision loss if untreated. Cataract is lens clouding, conjunctivitis inflammation of the conjunctiva, retinal detachment is separation of the retina.

Explanation:
Hypothyroidism in adults causes myxedema, characterized by puffy face, edema, lethargy, weight gain, and mental dullness. Goiter is an enlarged thyroid due to iodine deficiency but thyroxine may be normal or low. Cretinism is congenital hypothyroidism causing stunted growth and mental retardation. Acromegaly is due to excess growth hormone in adults.