1/69
Vocabulary-style flashcards covering key terms and definitions from the urinary system lecture notes.
Name | Mastery | Learn | Test | Matching | Spaced |
---|
No study sessions yet.
Urinary system
The body system that filters blood, forms urine, and removes wastes.
Urinary tract
Organs involved in urine production and transport: kidneys, ureters, bladder, urethra (and in males, the prostate).
Kidney
Primary organ of the urinary system; filters blood and forms urine via nephrons.
Ureter
Tube that carries urine from the kidney to the bladder through peristaltic movement.
Urinary bladder
Elastic sac that stores urine before it is excreted.
Urethra
Duct through which urine exits the body; in males it also carries semen.
Prostate
Male gland near the urethra contributing to semen; part of the urinary tract in men.
Nephron
Functional unit of the kidney responsible for filtration and urine formation.
Glomerulus
Ball of capillaries where blood is filtered to form filtrate.
Bowman's capsule (Glomerular capsule)
Double-walled capsule surrounding the glomerulus that collects filtrate.
Renal corpuscle
The glomerulus plus Bowman's capsule—the filtration unit of the nephron.
Renal tubule
Tubular structure where filtrate is converted to urine via reabsorption and secretion.
Proximal convoluted tubule (PCT)
Long, highly coiled segment with microvilli; major site of reabsorption.
Loop of Henle
Nephron loop with descending and ascending limbs; creates medullary osmotic gradient.
Descening limb
Part of the loop of Henle that is permeable to water, promoting water reabsorption.
Thin ascending limb
Segment of loop of Henle; relatively impermeable to water; reabsorbs Na+, K+, Cl- via cotransporters.
Thick ascending limb
Section of loop of Henle that reabsorbs Na+, K+, Cl- but is impermeable to water.
Distal convoluted tubule (DCT)
Renal tubule segment after the loop; shorter and less coiled; hormonally regulated reabsorption.
Collecting duct
Receives filtrate from multiple nephrons; concentrates urine; site of ADH action.
Glomerular filtration rate (GFR)
Rate of filtrate formation in the renal corpuscles; ~125 mL/min in adults; tightly regulated.
Urine
Fluid expelled from the body containing waste products filtered from the blood.
Filtration
Movement of fluid from blood into the nephron lumen at Bowman's capsule.
Reabsorption
Movement of substances from the filtrate back into the blood.
Secretion
Removal of specific wastes from blood into the filtrate in the tubule.
Excretion
Elimination of waste products in urine.
Filtration barrier
Three-layer barrier (fenestrated endothelium, basement membrane, podocytes) that limits filtration by size and charge.
Fenestrated endothelium
Capillary lining with pores that restrict large molecules from filtration.
Glomerular basement membrane
Negatively charged, proteoglycan-rich layer that repels large anions and governs filtration.
Podocytes
Visceral layer of Bowman's capsule with filtration slits that restrict filtration to small molecules.
Filtration slit
Narrow gaps between podocyte foot processes through which filtrate passes.
Afferent arteriole
Blood vessel delivering unfiltered blood to the glomerulus; larger diameter.
Efferent arteriole
Blood vessel leaving the glomerulus; smaller diameter, maintains glomerular pressure.
Peritubular capillaries
Network surrounding the renal tubules; site of reabsorption and secretion.
Juxtamedullary nephron
Nephron with a long loop of Henle extending into the medulla; ~15% of nephrons.
Cortical nephron
Most nephrons with shorter loops; located mainly in the renal cortex.
Macula densa
Cells in the ascending limb sensing NaCl content to regulate GFR via juxtaglomerular cells.
Juxtaglomerular cells
Granular cells that secrete renin in response to signals from the macula densa or sympathetic input.
Renin-angiotensin-aldosterone system (RAAS)
Hormonal cascade regulating blood pressure and GFR; renin → angiotensin II → aldosterone; increases Na+ and water reabsorption.
Renin
Enzyme released by juxtaglomerular cells; converts angiotensinogen to angiotensin I.
Angiotensin II
Potent vasoconstrictor that raises blood pressure and preferentially constricts efferent arterioles; stimulates aldosterone, ADH, and thirst.
Aldosterone
Steroid hormone that increases Na+ and water reabsorption in the collecting ducts.
Antidiuretic hormone (ADH/vasopressin)
Hormone that increases water reabsorption in the collecting ducts via aquaporins.
ACE (angiotensin-converting enzyme)
Enzyme that converts angiotensin I to the active angiotensin II.
ANP (atrial natriuretic peptide)
Hormone from the heart that promotes Na+ and water excretion and reduces renin/aldosterone effects.
Osmolarity
Measure of solute concentration; expressed in mOsm/L; essential for urine concentration.
Medullary gradient
Osmotic gradient from cortex to medulla in the kidney, enabling urine concentration.
Vasa recta
Countercurrent exchange vessels that preserve the medullary osmotic gradient.
AQP (aquaporin)
Water channels in tubule membranes that facilitate water reabsorption.
ANP vs RAAS balance
ANP promotes excretion of Na+ and water; RAAS promotes reabsorption to raise BP and GFR.
PTH (parathyroid hormone)
Hormone that increases Ca2+ reabsorption and decreases phosphate reabsorption in the kidney.
Urea cycling
Reabsorption and secretion of urea between the loop of Henle and collecting duct to maintain medullary osmolarity.
Urea recycling
Process where about half of filtered urea is reabsorbed and re-secreted to help maintain gradient.
Loop of Henle gradient
Generation of a hyperosmotic medullary interstitium via countercurrent multiplication.
Diabetes insipidus
Condition with excessive urination due to ADH deficiency or renal insensitivity to ADH.
Diabetes mellitus type 1
Autoimmune destruction of pancreatic beta cells leading to insulin deficiency and hyperglycemia.
Diabetes mellitus type 2
Insulin resistance with relative insulin deficiency; common cause of hyperglycemia.
Gestational diabetes
Glucose intolerance first recognized during pregnancy.
Diabetes mellitus vs diabetes insipidus (DI)
Mellitus: high blood glucose; Insipidus: impaired urine concentration and polyuria not due to lipids or glucose.
BUN (Blood Urea Nitrogen)
Blood level of nitrogenous wastes; normal ~10–20 mg/dL; high levels indicate azotemia.
Uric acid
Nitrogenous waste from nucleic acid metabolism; largely reabsorbed with some secretion.
Creatinine
Waste from muscle creatine phosphate breakdown; used to estimate GFR.
Filtration fraction
Fraction of renal plasma flow that becomes filtrate, influenced by hydrostatic and oncotic pressures.
Tm (Transport Maximum)
Maximum rate at which a solute can be reabsorbed or secreted by a transporter.
Paracellular transport
Movement of substances between adjacent epithelial cells, driven by gradients.
Transcellular transport
Movement of substances across an epithelial cell, via channels, transporters, or pumps.
SGLT (Sodium-glucose transporter)
Sodium-glucose cotransporter that reabsorbs glucose from filtrate into tubule cells.
PAH (para-aminohippurate)
Substance used to measure renal plasma flow; freely secreted by tubules.
Protein reabsorption in PCT
Proteins are reabsorbed and hydrolyzed into amino acids rather than excreted.
Autoregulation
Intrinsic ability of kidneys to maintain GFR despite BP changes via tubuloglomerular feedback and myogenic mechanisms.
Myogenic mechanism
Vascular smooth muscle response to stretch: increases resistance when BP rises to maintain GFR.