Urinary System Glossary

A comprehensive set of vocabulary flashcards covering essential terms and definitions related to the urinary system, kidney anatomy, urine formation processes, and associated disorders.

Urinary System

The organ system responsible for filtering blood, excreting waste, and regulating various balances.

Excretion

The process of removing metabolic wastes and excess substances from the body.

Homeostasis

The maintenance of stable internal conditions in the body.

Kidneys

A pair of bean-shaped organs that filter blood and produce urine.

Retroperitoneal

Located behind the peritoneum; the position of the kidneys.

Hilum (Renal Hilum)

The medial indentation of the kidney where vessels enter and exit.

Renal Capsule

The tough outer layer that covers the kidney and provides protection.

Perirenal Fat

Layer of fatty tissue that cushions and protects the kidney.

Renal Fascia

The dense connective tissue layer that anchors the kidney to surrounding structures.

Renal Cortex

The outer region of the kidney containing nephrons.

Renal Medulla

The inner region of the kidney composed of renal pyramids.

Renal Pyramids

Cone-shaped structures in the renal medulla that contain collecting ducts.

Renal Papilla

The tip of a renal pyramid where urine is collected into a minor calyx.

Renal Columns

Extensions of cortical tissue that separate renal pyramids.

Minor Calyces

Cup-shaped structures that collect urine from renal papillae.

Major Calyx

A larger collecting chamber formed by merging several minor calyces.

Renal Pelvis

The funnel-shaped structure that collects urine before it moves to the ureter.

Renal Lobe

A functional unit of the kidney consisting of a renal pyramid, cortex, and adjacent columns.

Nephron

The functional unit of the kidney that filters blood and forms urine.

Renal Corpuscle

The blood-filtering component of the nephron.

Glomerulus

A tuft of capillaries in the renal corpuscle where blood filtration occurs.

Bowman's Capsule (Glomerular Capsule)

The structure surrounding the glomerulus that collects filtrate.

Bowman's Space (Capsular Space)

The space in Bowman's capsule where filtrate collects.

Visceral Layer of Bowman's Capsule

The inner layer of Bowman's capsule made of podocytes.

Parietal Layer of Bowman's Capsule

The outer layer of Bowman's capsule composed of simple squamous epithelium.

Podocytes

Specialized epithelial cells in Bowman's capsule that form part of the filtration barrier.

Pedicels

Foot-like processes from podocytes that form filtration slits.

Filtration Slits

Narrow gaps between podocytes that prevent large proteins from passing.

Renal Tubule

The tubular portion of the nephron that extends from Bowman's capsule to the collecting duct.

Proximal Convoluted Tubule (PCT)

The first segment of the renal tubule responsible for reabsorption.

Microvilli (Brush Border)

Tiny projections on proximal tubule cells that increase surface area.

Loop of Henle (Nephron Loop)

The U-shaped portion of the renal tubule involved in concentrating urine.

Descending Limb of Loop of Henle

Part of the loop permeable to water but impermeable to solutes.

Ascending Limb of Loop of Henle

Part of the loop impermeable to water, actively transports ions.

Thick Ascending Limb

The upper portion of the ascending limb with active ion transport.

Thin Ascending Limb

The lower part of the ascending limb that allows passive ion movement.

Distal Convoluted Tubule (DCT)

Part of the nephron where regulated reabsorption and secretion occurs.

Macula Densa

Specialized cells that monitor sodium concentration in the filtrate.

Collecting Duct

Tube that receives filtrate from nephrons and is involved in urine concentration.

Cortical Nephron

Nephron type primarily located in the outer cortex.

Juxtamedullary Nephron

Nephron type with a long loop of Henle important for concentrated urine production.

Renal Artery

The blood vessel that supplies blood to the kidneys.

Segmental Arteries

Branches of the renal artery that supply different kidney segments.

Interlobar Arteries

Arteries that run through the renal columns.

Arcuate Arteries

Arteries that arch over the bases of renal pyramids.

Cortical Radiate Arteries (Interlobular Arteries)

Small arteries that branch from arcuate arteries.

Afferent Arteriole

Arteriole supplying blood to the glomerulus.

Efferent Arteriole

Arteriole carrying blood away from the glomerulus.

Peritubular Capillaries

Capillaries surrounding renal tubules, involved in reabsorption.

Vasa Recta

Straight capillaries associated with juxtamedullary nephrons.

Renal Vein

Vein that drains blood from the kidneys.

Juxtaglomerular Apparatus (JGA)

Regulates blood pressure and glomerular filtration rate.

Juxtaglomerular Cells (Granular Cells)

Cells in afferent arterioles that secrete renin.

Mesangial Cells

Cells between glomerular capillaries that provide support and regulate flow.

Glomerular Filtration

The movement of water and solutes from blood into Bowman's capsule.

Filtrate

Fluid that collects in Bowman's capsule, similar to blood plasma.

Filtration Membrane (Filtration Barrier)

Structure that restricts passage based on size.

Fenestrations

Pores in capillary endothelial that allow small solute passage.

Basement Membrane (Basal Lamina)

Layer restricting large proteins from passing into Bowman's capsule.

Net Filtration Pressure (NFP)

The sum of pressures that drive or oppose glomerular filtration.

Glomerular Hydrostatic Pressure (GHP)

Pressure in glomerular capillaries that drives filtration.

Blood Colloid Osmotic Pressure (BCOP)

Osmotic pressure that opposes filtration due to plasma proteins.

Capsular Hydrostatic Pressure (CHP)

Pressure exerted by fluid in Bowman's capsule that opposes filtration.

Glomerular Filtration Rate (GFR)

The volume of filtrate formed by the kidneys per minute.

Tubular Reabsorption

The movement of substances from filtrate back into blood.

Tubular Secretion

The movement of substances from blood into the filtrate.

Obligatory Water Reabsorption

Automatic water reabsorption occurring with solute reabsorption.

Facultative Water Reabsorption

Water reabsorption regulated by hormones.

Active Transport

The movement of substances against a concentration gradient using energy.

Secondary Active Transport (Cotransport)

Movement utilizing energy stored in ion gradients for reabsorption.

Passive Transport

Movement of substances down their concentration gradient without energy.

Osmosis

The movement of water across a semipermeable membrane.

Aquaporins

Proteins that facilitate rapid water movement in cell membranes.

Transcellular Reabsorption

Movement through the cells of tubules.

Paracellular Reabsorption

Movement between tubule cells through tight junctions.

Transport Maximum (Tm)

The maximum rate at which a substance can be reabsorbed.

Renal Threshold

Plasma concentration at which a substance appears in urine.

Renal Clearance

Volume of plasma from which a substance is completely removed by the kidneys.

Clearance

Rate at which kidneys remove a substance from the blood.

Inulin Clearance

The gold standard for measuring GFR, as it is not reabsorbed.

Creatinine

A waste product used clinically to estimate GFR.

Blood Urea Nitrogen (BUN)

Nitrogen amount in blood in the form of urea; indicates kidney function.

Plasma Creatinine

Concentration of creatinine in blood plasma, indicating kidney health.

Countercurrent Multiplier

Mechanism creating an osmotic gradient in the renal medulla.

Countercurrent Exchanger

Mechanism preserving osmotic gradient while supplying medulla with blood.

Medullary Osmotic Gradient

Increasing solute concentration from cortex to medulla.

Osmolarity

Concentration of osmotically active particles in a solution.

Antidiuretic Hormone (ADH/Vasopressin)

A hormone that increases water reabsorption in the collecting ducts.

Aldosterone

Hormone that increases sodium reabsorption and potassium secretion.

Renin

An enzyme that begins the renin-angiotensin-aldosterone system.

Renin-Angiotensin-Aldosterone System (RAAS)

Hormonal cascade regulating blood pressure and fluid balance.

Angiotensin I

Inactive precursor converted to angiotensin II.

Angiotensin II

A potent vasoconstrictor that increases blood pressure.

Angiotensin-Converting Enzyme (ACE)

Enzyme that converts angiotensin I to angiotensin II.

Atrial Natriuretic Peptide (ANP)

Hormone promoting sodium and water excretion to reduce blood pressure.

Parathyroid Hormone (PTH)

Hormone that increases calcium reabsorption and phosphate excretion.

Acid-Base Balance

Regulation of blood pH by the kidneys.

Bicarbonate Reabsorption

Recovery of bicarbonate to maintain blood pH.

Hydrogen Ion Secretion

Active transport of hydrogen ions to regulate pH.

Buffering Systems

Chemical systems to resist pH changes in blood.