Human Anatomy & Physiology — Example Quiz

The anatomical position is the universal reference posture: standing erect, face forward, feet slightly apart and flat, arms at the sides with the palms facing anteriorly (supinated). All directional terms (anterior, posterior, medial, etc.) are defined relative to this position.

The sagittal plane runs vertically and divides the body into left and right portions; a midsagittal (median) plane does so into equal halves. The frontal (coronal) plane separates anterior from posterior, and the transverse plane separates superior from inferior.

Medial pairs with lateral, not ventral (ventral pairs with dorsal). Proximal/distal, superficial/deep, and superior/inferior are all valid opposing pairs.

The adult human skeleton contains 206 bones. Infants are born with roughly 270; many fuse during growth (for example, the frontal bone and the sacral vertebrae).

Compact bone is organised into osteons (Haversian systems) — concentric lamellae of bone matrix surrounding a central (Haversian) canal that carries blood vessels and nerves. Osteocytes sit in small cavities called lacunae between the lamellae.

Osteoclasts are large multinucleated cells that break down (resorb) bone matrix. Osteoblasts build new bone, osteocytes are mature bone cells maintaining the matrix, and chondrocytes are found in cartilage.

The rotator cuff comprises Supraspinatus, Infraspinatus, Teres minor, and Subscapularis (mnemonic "SITS"). Together they stabilise the glenohumeral joint. Teres major and deltoid are not part of the cuff.

During contraction the sarcomere shortens: the I band and H zone narrow and the Z discs move closer together. The A band (the length of the thick/myosin filaments) stays constant because the filaments slide rather than shorten.

Calcium released from the sarcoplasmic reticulum binds troponin, causing tropomyosin to shift and expose the myosin-binding sites on actin. This allows cross-bridges to form and the power stroke to occur.

Ectoderm gives rise to the nervous system and epidermis; endoderm forms the epithelial lining of the gut and respiratory tract; mesoderm forms muscle, bone, and connective tissue. Skeletal muscle is mesodermal, and the epidermis is ectodermal — so A and D are mismatched.

Multipolar neurons — one axon and multiple dendrites — are by far the most common neuron type in the central nervous system, including motor neurons and interneurons. Bipolar neurons are found in special senses (e.g., retina), and unipolar (pseudounipolar) neurons are typical sensory neurons.

Oligodendrocytes myelinate axons in the CNS (a single oligodendrocyte can myelinate several axons). In the PNS, Schwann cells perform this role. Astrocytes provide metabolic/structural support, and microglia are the resident immune cells.

The vagus nerve is cranial nerve X. It carries the majority of parasympathetic fibres to the heart, lungs, and much of the gastrointestinal tract, and has the widest distribution of any cranial nerve.

Sympathetic preganglionic neurons arise from the thoracic and lumbar spinal cord (T1–L2), giving the "thoracolumbar" designation. The parasympathetic division is "craniosacral" (cranial nerves III, VII, IX, X and sacral segments S2–S4).

The cerebellum fine-tunes motor activity, coordinates voluntary movement, and maintains balance and posture. The medulla controls autonomic reflexes (heart rate, breathing), the hypothalamus governs homeostasis, and the thalamus is a sensory relay station.

Deoxygenated blood enters the right atrium (via the venae cavae), passes through the tricuspid valve into the right ventricle, then through the pulmonary semilunar valve into the pulmonary arteries and on to the lungs for gas exchange.

The bicuspid (mitral) valve separates the left atrium and left ventricle. The tricuspid valve is the right atrioventricular valve; the semilunar valves guard the exits to the aorta and pulmonary trunk.

The impulse originates at the SA node (the pacemaker), spreads across the atria to the AV node, is delayed briefly, then travels down the Bundle of His and its branches to the Purkinje fibres, which distribute it through the ventricular myocardium.

Blood vessel walls have three tunics: tunica intima (inner endothelium), tunica media (smooth muscle and elastic tissue — thickest in arteries), and tunica externa/adventitia (outer connective tissue). Serosa and mucosa are layers of hollow organs like the gut, not blood vessels.

Gas exchange occurs across the walls of the alveoli, where the thin respiratory membrane (alveolar epithelium + capillary endothelium fused basement membranes) allows oxygen and carbon dioxide to diffuse between air and blood. The bronchi, bronchioles, and trachea are conducting passages only.

The phrenic nerve (arising from cervical roots C3–C5, "C3, 4, 5 keeps the diaphragm alive") supplies motor innervation to the diaphragm, the principal muscle of respiration.

After the mouth, food passes through the pharynx, down the oesophagus, into the stomach, and then into the small intestine (duodenum → jejunum → ileum) before reaching the large intestine. Note: option C (pharynx) precedes B (oesophagus).

The liver, pancreas, and gallbladder are accessory digestive organs — they secrete substances (bile, enzymes) into the tract but are not part of the alimentary canal itself. The ileum is the final segment of the small intestine, part of the tract proper.

Filtration begins at the glomerulus, a capillary tuft enclosed by the glomerular (Bowman's) capsule; together they form the renal corpuscle. Filtrate then moves through the proximal convoluted tubule, loop of Henle, distal convoluted tubule, and collecting duct, where reabsorption and secretion refine it.

Filtrate collects in the glomerular capsule, then flows through the proximal convoluted tubule, into the loop of Henle, and on to the distal convoluted tubule before draining into the collecting duct.

Beta cells secrete insulin, which lowers blood glucose. Alpha cells secrete glucagon (raises glucose), and delta cells secrete somatostatin. Cortisol is produced by the adrenal cortex, not the pancreas.

ADH (vasopressin) and oxytocin are synthesised by hypothalamic neurons and transported down their axons for storage and release from the posterior pituitary (neurohypophysis). The posterior pituitary is neural tissue and does not manufacture its own hormones.

It is the reverse: the right lung has three lobes (superior, middle, inferior), and the left lung has two (superior and inferior), with the cardiac notch and lingula accommodating the heart.

From deep to superficial, the epidermis of thick skin is: stratum basale, spinosum, granulosum, lucidum, and corneum (mnemonic: "Come, Let's Get Sun Burnt" read superficial-to-deep). The stratum lucidum is present only in thick, hairless skin such as the palms and soles.

The body's four primary tissue types are epithelial (covering/lining), connective (support and binding — including blood and bone), muscle (contraction), and nervous (communication). All organs are built from combinations of these four.