Human Anatomy and Physiology

 Skin is the largest organ in the human body.

Blood group B is the most prevalent among Asian populations, particularly in East Asia. Group A (A) is common in Europe, Group AB (C) is the rarest worldwide, and Group O (D) is universal but not the most common in Asia specifically. Distribution varies by ethnicity and geography.

The vestibule is the space between the teeth, lips, and cheeks, and the gums. Polar space (B) is not a dental term, dentures (C) are artificial teeth, and dentine (D) is the tissue beneath tooth enamel. The vestibular space is crucial for proper oral hygiene and orthodontic appliance placement.

The pituitary gland is called the 'master gland' because it controls other endocrine glands through hormone secretion. The thyroid (A) regulates metabolism, pineal (B) produces melatonin for sleep cycles, and adrenal (D) glands produce stress hormones like cortisol.

The maxilla forms the upper jaw and holds the upper teeth. The mandible (B) is the lower jawbone (the only movable skull bone), vault (C) refers to the cranial vault (skull cap), and sagittarius (D) is a zodiac sign, not an anatomical term.

Glaucoma is caused by increased intraocular pressure that damages the optic nerve. Cataract (A) is lens clouding, conjunctivitis (C) is eye membrane inflammation, and ophthalmic neonatorum (D) is infant eye infection. The pressure build-up in glaucoma can lead to vision loss if untreated.

Myology is the study of muscles. Mycology (A) is the study of fungi, philology (C) is the study of language and literature, and mnemonics (D) are memory aids. The Greek root 'myo' refers to muscle, as seen in terms like myocardium (heart muscle).

Antidiuretic hormone (ADH or vasopressin) controls water balance by reducing urine production and promoting water reabsorption in kidneys. Estrogen (A), progesterone (B), and testosterone (C) are sex hormones not primarily involved in water balance regulation.

The pancreas is a dual-function gland that secretes hormones like insulin and glucagon into the bloodstream (endocrine function) and digestive enzymes like amylase, lipase, and proteases into the small intestine (exocrine function). The adrenal gland secretes only hormones, the pituitary gland secretes only hormones, and the thyroid gland secretes only hormones.

Tonsils are lymphoid tissues located in the throat area that form part of Waldeyer's ring, acting as the first line of defense against pathogens entering through the mouth and nose. They trap bacteria and viruses, initiating immune responses. The gums, teeth, and tongue have structural and digestive functions, not immune defense.

Involution is the medical term for the process by which the uterus returns to its normal size and position after pregnancy. This process involves the contraction of uterine muscles and the breakdown of enlarged muscle cells. Enuresis means bedwetting, hibernation is a dormant state in animals, and convolution refers to coil-like structures.

Encephalitis is inflammation of the brain parenchyma, often caused by viral infections. The prefix 'encephalon' refers to the brain and '-itis' indicates inflammation. Peritonitis is abdominal lining inflammation, gastritis is stomach inflammation, and folliculitis is hair follicle inflammation.

The nephron is the microscopic functional unit of the kidney that filters blood and produces urine. Each kidney contains about 1 million nephrons, which consist of glomeruli and renal tubules. Electrons are subatomic particles, sclera is eye white tissue, and capillaries are small blood vessels but not kidney functional units.

The aorta is the largest artery in the human body, originating from the left ventricle and distributing oxygenated blood to all parts of the body. It has a diameter of about 2.5-3.5 cm. The superior vena cava is a large vein, pulmonary arteries carry deoxygenated blood, and coronary arteries supply the heart muscle itself.

The normal pH of human arterial blood is 7.35-7.45, with 7.40 being ideal. A pH of 7.45 is within normal range, though at the upper end. pH below 7.35 indicates acidosis, above 7.45 indicates alkalosis. The body tightly regulates blood pH through respiratory and renal mechanisms.

Peristalsis is the wave-like muscular contractions of the digestive tract (especially intestines) that propel food contents forward. This rhythmic contraction and relaxation of smooth muscle is essential for digestion and absorption. Metabolism is all chemical reactions, osmosis is water movement, and catabolism is breakdown of complex molecules.

Bile emulsifies fats, breaking large fat globules into smaller droplets to increase surface area for lipase enzymes to act upon. This emulsification is crucial for fat digestion and absorption. Bile does not act on proteins (broken down by proteases), carbohydrates (broken down by amylases), or esters.