Systemic Pathology and Human Disease

Vocabulary practice flashcards covering systemic pathology modules: haematology, vascular pathology, cardiology, respiratory disease, neuromuscular disorders, gastrointestinal and hepatobiliary systems, genitourinary tracts, neurology, nephrology, endocrinology, musculoskeletal pathology, and dermatology.

Haematocrit

The proportion of total blood volume made up of erythrocytes, normally representing approximately $40\text{--}50\%$ of total blood volume.

Reticulocyte

A newly formed, anuclear immature erythrocyte released from bone marrow into the peripheral blood that loses residual RNA over time to become a mature red blood cell.

Erythropoietin (EPO)

A glycoprotein hormone produced primarily ($90\%$) by the kidneys in response to reduced renal oxygen tension that stimulates erythropoiesis in the bone marrow.

Megaloblastic Anaemia

A macrocytic anaemia resulting from Vitamin B12 or folate deficiency, characterized morphologically on peripheral blood smear by oval macrocytes and hypersegmented neutrophils.

Hereditary Spherocytosis

An inherited defect in red blood cell membrane structural proteins (spectrin, actin, protein 4.1, and band 3) resulting in spherical erythrocytes, splenomegaly, and gallstones.

Chronic Myeloid Leukaemia (CML)

A myeloproliferative neoplasm characterized genetically by the $t(9;22)$ chromosomal translocation, producing the Philadelphia chromosome and an oncogenic $BCR\text{-}ABL1$ fusion tyrosine kinase.

Immune Thrombocytopaenic Purpura (ITP)

A bleeding disorder caused by autoantibodies directed against platelet membrane glycoproteins ($GPIIb\text{-}IIIa$ or $GPIb\text{-}IX\text{-}V$), leading to clearance of IgG-coated platelets by the splenic reticuloendothelial system.

Disseminated Intravascular Coagulation (DIC)

A complex thrombohemorrhagic disorder characterized by widespread systemic activation of coagulation, formation of microvascular thrombi, and subsequent consumption of platelets and clotting factors, especially fibrinogen.

Virchow’s Triad

The three primary pathogenic factors that contribute to thrombus formation: endothelial injury or dysfunction, abnormal blood flow (stasis or turbulence), and blood hypercoagulability.

Atheroma

A fibrofatty intimal plaque consisting of a necrotic core containing cell debris, cholesterol crystals, foam cells, and calcium, covered by a luminal fibrous cap of smooth muscle cells and collagen.

True Aneurysm

A localized abnormal dilation of a blood vessel that involves all three layers of the arterial wall (intima, media, and adventitia), categorized morphologically as saccular or fusiform.

Giant Cell Arteritis

A chronic granulomatous vasculitis predominantly affecting large to medium-sized arteries of the head (especially the temporal artery) in individuals aged $>50$, characterized by T cell-mediated inflammation and fragmentation of the internal elastic lamina.

Cardiac Troponin

The gold-standard intracellular muscular protein biomarker released into circulation from irreversibly damaged cardiomyocytes, used for the rapid clinical identification of acute coronary syndrome.

Cardiac Tamponade

A life-threatening complication of excessive pericardial fluid accumulation (pericardial effusion) that compresses cardiac chambers and prevents normal ventricular filling.

Stable Angina

Predictable, episodic chest discomfort caused by transient myocardial ischemia insufficient to cause necrosis, occurring typically upon exertion when a fixed coronary atherosclerotic lesion causes critical stenosis ($\ge 70\%$ luminal occlusion).

Dilated Cardiomyopathy

An intrinsic myocardial disorder characterized by progressive ventricular dilation and systolic contractile dysfunction, usually associated with concurrent hypertrophy.

Emphysema

A form of chronic obstructive pulmonary disease (COPD) defined anatomically by permanent, irreversible destruction of the alveolar septum and airspace enlargement distal to the terminal bronchiole without fibrosis.

Bronchiectasis

A respiratory disorder characterized by permanent abnormal dilation of major bronchi and bronchioles caused by recurrent cycles of chronic inflammation, infection, and destruction of bronchial wall architecture.

Idiopathic Pulmonary Fibrosis (IPF)

A progressive, lethal interstitial lung disease characterized histologically by distortion of gas exchange units, excessive collagen deposition, myofibroblast accumulation, and peripheral honeycomb architecture.

Small Cell Carcinoma of the Lung

A highly aggressive, rapidly proliferating neuroendocrine pulmonary malignancy virtually always associated with smoking, composed of small round-to-oval cells with dense-core neurosecretory granules capable of paraneoplastic hormone secretion.

Duchenne Muscular Dystrophy (DMD)

An X-linked recessive neuromuscular disease caused by deletions or mutations in the $DMD$ gene at $Xp21$, leading to absent dystrophin, muscle membrane fragility, calcium influx, and myofiber necrosis.

Excitation-Contraction Coupling (ECC)

The physiological cascade whereby an electrical action potential from a motor neuron is transduced into intracellular $Ca^{2+}$ release from the sarcoplasmic reticulum to trigger mechanical muscle contraction.

Barrett Metaplasia

A premalignant transformation of the distal oesophageal lining from normal stratified squamous epithelium to intestinal-type columnar epithelium with goblet cells, secondary to chronic acid reflux.

Intussusception

A form of mechanical intestinal obstruction caused by the telescoping of one bowel segment into an immediately adjacent distal segment.

Cirrhosis

The end-stage irreversible histological transformation of the liver characterized by diffuse bridging fibrosis and the architectural reorganization of parenchyma into structurally abnormal regenerative nodules.

Non-Alcoholic Fatty Liver Disease (NAFLD)

Hepatic steatosis characterized by triglyceride accumulation in hepatocytes in individuals who do not consume excessive alcohol, strongly associated with insulin resistance, obesity, and metabolic syndrome.

Cryptorchidism

Failure of one or both testes to completely descend from the abdomen into the scrotal sac during fetal development, associated with impaired spermatogenesis, infertility, and increased risk of testicular cancer.

Varicocele

An abnormal dilation and tortuosity of the pampiniform venous plexus in the scrotum caused by incompetent venous valves, causing stasis, testicular hypoxia, oxidative stress, and male infertility.

Benign Prostatic Hyperplasia (BPH)

Androgen-dependent proliferation of both glandular and stromal prostatic elements specifically localized to the periurethral transition zone, leading to urinary bladder outflow obstruction.

Polyendocrine Metabolic Ovarian Syndrome (PMOS)

A complex endocrine-metabolic disorder defined by hyperandrogenism, chronic ovulatory dysfunction, and polycystic ovarian morphology, featuring elevated $LH:FSH$ ratios and compensatory hyperinsulinaemia.

Endometriosis

The pathological presence of functioning endometrial glands and stroma in extrauterine locations (such as the ovaries, pouch of Douglas, and peritoneal surface) that undergoes cyclical hormone-driven proliferation and hemorrhage.

Spina Bifida Occulta

The mildest neural tube defect characterized by incomplete fusion of the posterior vertebral arches in the lumbosacral spine without protrusion of the meninges or spinal cord.

Hydrocephalus

An abnormal enlargement of the cerebral ventricular system caused by impaired drainage, reabsorption, or mechanical obstruction of cerebrospinal fluid (CSF) flow.

Prion

A proteinaceous infectious agent consisting of a misfolded conformational isoform ($PrP^{Sc}$ or $PrP^{CJD}$) that templates the conformational conversion of normal host cellular prion protein ($PrP^C$), causing transmissible neurodegenerative spongiform encephalopathies.

Neurofibrillary Tangles

Intracellular pathological bundles of paired helical filaments composed of hyperphosphorylated tau protein, leading to microtubule depolymerization, axonal transport failure, and neuronal death in Alzheimer's disease.

Multiple Sclerosis (MS)

An autoimmune inflammatory disease of the central nervous system characterized by T cell-mediated demyelination of axons, multifocal plaque formation, and astrocytic glial scarring.

Podocyte

A specialized visceral epithelial cell lining the urinary aspect of glomerular capillary basement membranes, whose interdigitating foot processes form filtration slits that restrict the passage of large proteins into primary urine.

Metabolic Acidosis

An acid-base disturbance characterized by plasma $pH < 7.4$ and a primary reduction in serum bicarbonate ($HCO_3^-$), resulting from excessive acid accumulation (e.g. ketoacidosis, lactic acidosis) or failure of renal bicarbonate reabsorption.

Prolactinoma

The most prevalent functioning anterior pituitary adenoma, which secretes prolactin to cause galactorrhoea, amenorrhoea, decreased libido, and infertility.

Graves Disease

An autoimmune hyperthyroid condition caused by autoantibodies directed against the thyroid-stimulating hormone ($TSH$) receptor that chronically stimulate follicular cells, causing thyrotoxicosis, diffuse goiter, and ophthalmopathy.

Hashimoto Thyroiditis

The most common cause of hypothyroidism in iodine-sufficient areas, characterized histologically by progressive autoimmune destruction of thyroid parenchyma accompanied by extensive lymphocytic infiltration and germinal center formation.

Lamellar Bone

Secondary, mature bone tissue created by the remodeling of woven bone, composed of parallel sheets of collagen fibers that confer high mechanical strength.

Osteoprotegerin (OPG)

A soluble decoy receptor synthesized and secreted by osteoblasts that competitively binds $RANKL$, blocking its interaction with $RANK$ on osteoclast precursors to inhibit osteoclastogenesis and bone resorption.

Paget’s Disease of Bone

A localized skeletal disorder characterized by disordered bone remodeling that progresses through osteolytic, mixed, and sclerotic phases, resulting in thickened, structurally weak bone with a pathognomonic mosaic histological pattern.

Osteoarthritis

A chronic degenerative joint disease characterized by progressive loss and erosion of articular cartilage, thickening of subchondral bone, and formation of osteophytes at joint margins.

Psoriasis

A chronic T cell-mediated autoimmune dermatosis characterized clinically by well-demarcated salmon-pink plaques with silvery-white scales, and histologically by epidermal acanthosis and parakeratosis.

Lichen Planus

A chronic inflammatory skin and mucosal disorder characterized by pruritic, purple, polygonal, flat-topped papules bearing Wickham striae and a dense band-like lymphocytic infiltrate along the dermoepidermal junction.