ultimate urinary

Retroperitoneal

Describing organs (like the kidneys) that are located behind the peritoneum, the lining of the abdominal cavity.

Renal pyramid

Cone-shaped tissue inside the renal medulla that contains the collecting ducts.

Renal column

Extensions of the renal cortex that project between the renal pyramids to provide a path for blood vessels.

Renal papilla

The blunt tip or apex of a renal pyramid that drains urine into a minor calyx.

Cortex

The outer layer of the kidney where filtration begins and most nephrons are located.

Medulla

The inner region of the kidney containing the renal pyramids and columns.

Renal Capsule

The tough, fibrous outer skin of the kidney that protects it from injury and infection.

Major calyx

A large canal formed by the merging of several minor calyces

Minor calyx

A small cup-like structure that collects urine directly from the renal papilla.

Renal pelvis

The large, funnel-shaped central cavity that collects urine from the major calyces and sends it to the ureter.

Hilum

The indented "entryway" on the medial side of the kidney where the renal artery, vein, and ureter attach.

Nephron loops

The U-shaped part of the renal tubule (Loop of Henle) responsible for concentrating urine.

Collecting ducts

Tubes that receive processed filtrate from many nephrons and deliver the final urine to the renal papillae.

Segmental artery

The first branches of the renal artery after it enters the hilum.

Interlobar arteries

Vessels that travel through the renal columns between the pyramids.

Arcuate arteries

Vessels that arch over the bases of the renal pyramids at the boundary between the cortex and medulla.

Cortical radiate arteries

Small vessels branching off the arcuate arteries that head outward into the renal cortex.

Interlobar vein

Veins that travel through the renal columns to return blood toward the renal vein.

Arcuate vein

Veins that follow the curve of the pyramids, collecting blood from the cortex.

Cortical radiate veins

Small veins in the cortex that drain into the arcuate veins.

Renal Corpuscles

The initial filtering component of a nephron, consisting of the glomerulus and Bowman's capsule.

Glomerulus

A high-pressure capillary tuft where blood plasma is filtered into the nephron.

Glomerular capsule

The double-walled cup (Bowman’s capsule) that surrounds the glomerulus and collects filtrate.

Efferent arteriole

The small artery that carries blood away from the glomerulus after filtration.

Peritubular capillaries

A network of low-pressure capillaries surrounding the PCT and DCT that reabsorb water and nutrients.

Vasa recta

Long, straight capillaries that parallel the nephron loops in the medulla, primarily in juxtamedullary nephrons.

Proximal convoluted tubule

The first section of the renal tubule where the majority of reabsorption occurs.

Distal convoluted tubule

The section of the renal tubule between the nephron loop and the collecting duct

Ureters

Muscular tubes that use peristalsis to transport urine from the kidneys to the urinary bladder.

Transitional epithelium

Specialized stretchy tissue lining the bladder and ureters that allows for expansion.

Urinary bladder

A hollow, muscular sac that stores urine until it is excreted.

Detrusor muscle

The smooth muscle layers of the bladder wall that contract to expel urine.

Rugae

Folds in the bladder lining that disappear as the bladder fills and stretches.

Trigone

The smooth triangular area at the base of the bladder marked by the openings of the two ureters and the urethra.

Urethra

The single tube that carries urine from the bladder to the outside of the body.

Internal urethral sphincter

An involuntary smooth muscle at the bladder-urethra junction that keeps the urethra closed.

External urethral sphincter

A voluntary skeletal muscle that surrounds the urethra as it passes through the pelvic floor.

Meatus

The external opening of the urethra where urine exits the body.

Renal Pelvis

Funnel-shaped cavity located in the central region of the kidney. It acts as a primary collection point for urine before it leaves the kidney to travel toward the bladder.

Internal urethral orifice

Opening located at the lowest point of the urinary bladder, marking the exact transition point where the bladder ends and the urethra begins.

Function of kidneys

Regulating water volume, blood pressure, pH, RBC production, and removing wastes

Glomerulus

A high-pressure capillary tuft within the renal corpuscle; the primary site of blood filtration.

Macula densa

Specialized chemoreceptor cells in the DCT that monitor NaCl concentration in the filtrate.

Juxtaglomerular complex

A structure (JG cells + Macula Densa) that regulates blood pressure and GFR by secreting renin.

Mesangial cells

Contractile cells that provide structural support and regulate glomerular capillary surface area.

Capsular space

The space between the visceral and parietal layers of Bowman’s capsule where filtrate collects.

Podocyte

Specialized epithelial cells forming the visceral layer of Bowman’s capsule that wrap around capillaries.

Pedicels

The "foot processes" of podocytes that create filtration slits to prevent large proteins from entering urine.

Calculi

Solid masses of mineral salts (kidney stones) that form in the urinary tract.

Renal colic

Severe, episodic pain caused by the spasm of a ureter as it tries to move a kidney stone.

Hematuria

The presence of intact red blood cells in the urine; indicates trauma, stones, or infection.

Hydronephrosis

Dilation of the kidney due to urine buildup, usually caused by a downstream obstruction.

Urinary tract infection

An infection in any part of the urinary system, characterized by frequency and dysuria.

Extracorporeal shock wave lithotripsy

A non-invasive procedure using sound waves to break calculi into smaller fragments.

Nephrolithiasis

The specific condition of having calculi formed within the kidney.

Ureterolithiasis

The presence of calculi within the ureter.

Cystolithiasis

The presence of calculi within the urinary bladder.

Diabetes insipidus

A disorder of water metabolism caused by ADH deficiency or kidney insensitivity to ADH.

Pyelonephritis

Inflammation or infection of the renal pelvis and kidney tissue.

Urinalysis

The biochemical and microscopic examination of urine to detect metabolic or renal disorders.

Filtration

The passive process of forcing water and solutes through the glomerular membrane via hydrostatic pressure.

Reabsorption

The process of reclaiming water and useful solutes from the filtrate back into the blood.

Secretion

The active transport of wastes (H+, K+, drugs) from the blood into the tubular fluid for excretion.

pH range of urine

Typically 4.5 to 8.0; the average is 6.0 depending on diet and metabolism.

Specific gravity range of urine

A measure of concentration; normal range is 1.003 to 1.030.

Refractometer

An optical instrument used to measure the specific gravity of urine via light refraction.

Glycosuria

Glucose in the urine; occurs when blood glucose exceeds the renal threshold (~180 mg/dL).

Ketonuria

Ketones in the urine; indicates the body is using fat for fuel instead of glucose.

Albuminuria

Presence of albumin in the urine; indicates damage to the glomerular filtration membrane.

Hemoglobinuria

Free hemoglobin in the urine; results from the lysis of RBCs within the circulatory system.

Hemolytic anemia

A condition where RBCs are destroyed faster than they are made, causing hemoglobinuria.

Bilirubinuria

Appearance of conjugated bilirubin in urine; an early sign of liver disease or bile duct obstruction.

Hepatitis

Inflammation of the liver; a common cause of bilirubinuria.

Cirrhosis

Chronic liver scarring that disrupts normal bilirubin metabolism and clearance.

Crystals

Microscopic mineral deposits in urine that help identify the composition of kidney stones.

Pyuria

The presence of white blood cells (pus) in the urine; a sign of infection.

Urinary casts

Cylindrical structures formed by solidified proteins in the renal tubules; indicates renal disease.