Anatomy of Kidneys, Ureters & Suprarenal Glands

Vocabulary flashcards covering the essential anatomical structures, vascular supply, physiology, and relations of the kidneys, ureters, and suprarenal glands.

Kidney – primary functions

Excretes metabolic wastes, regulates water & electrolyte balance, and maintains blood acid–base balance.

Hilum of kidney

Vertical slit on the medial border transmitting (from anterior to posterior) renal vein, two renal artery branches, ureter, and a third renal artery branch.

Renal sinus

Large cavity extending from the hilum that contains the renal pelvis, calyces, vessels, nerves, and fat.

Fibrous (renal) capsule

Tough connective-tissue layer directly surrounding the kidney.

Perirenal (perinephric) fat

Adipose tissue surrounding the fibrous capsule of the kidney.

Renal fascia

Condensation of connective tissue enclosing kidneys & suprarenal glands; laterally continuous with the transversalis fascia.

Pararenal (paranephric) fat

Fat external to the renal fascia that forms part of the retroperitoneal fat.

Renal cortex

Dark-brown outer part of kidney extending into medulla as renal columns.

Renal medulla

Light-brown inner region composed of 8–12 renal pyramids.

Renal pyramid

Conical mass of medulla with base facing cortex and apex (renal papilla) projecting into a minor calyx.

Renal papilla

Apex of a renal pyramid that releases urine into a minor calyx.

Renal column

Cortical tissue extending between adjacent renal pyramids.

Medullary ray

Striation of tubules extending from pyramid base into the cortex.

Renal lobe

A pyramid plus its overlying cortical tissue.

Renal pelvis

Funnel-shaped expanded upper end of the ureter located in the renal sinus.

Major calyx

Branch of renal pelvis that receives two or three minor calyces.

Minor calyx

Small cup-like cavity that receives urine from one renal papilla.

Renal artery

Arises from abdominal aorta (L2 level) and supplies the kidney.

Segmental arteries

Five branches of the renal artery entering the hilum (four anterior, one posterior).

Lobar artery

Branch of a segmental artery that supplies a renal pyramid.

Interlobar arteries

Vessels running between pyramids toward cortex; give rise to arcuate arteries.

Arcuate arteries

Arteries arching over pyramid bases at cortico-medullary junction; give off interlobular arteries.

Interlobular arteries

Small cortical branches of arcuate arteries that give rise to afferent glomerular arterioles.

Afferent glomerular arteriole

Arteriole delivering blood into the glomerular capillary tuft.

Renal vein

Vessel emerging anterior to renal artery and draining into the IVC.

Left renal vein

Longer renal vein that passes anterior to the aorta beneath the SMA.

Nutcracker syndrome

Compression of the left renal vein between SMA and aorta causing hematuria, flank pain, etc.

Transpyloric plane & kidneys

Plane intersects left hilum; the right kidney lies ~2.5 cm lower due to liver.

Kidney movement in respiration

Both kidneys descend about 2.5 cm with diaphragmatic contraction.

Ureter

25-cm muscular tube conducting urine from renal pelvis to urinary bladder.

Ureter peristalsis

Rhythmic contractions propelling urine toward the bladder.

Ureter constrictions

Natural narrowings at ureteropelvic junction, pelvic brim crossing, and intramural bladder wall.

Ureteropelvic junction (UPJ)

Site where renal pelvis joins ureter; common stone impaction point.

Pelvic brim crossing (ureter)

Second ureteric constriction where ureter crosses common iliac artery bifurcation.

Intramural ureter

Segment passing obliquely through bladder wall, site of third constriction.

Blood supply – proximal ureter

Branches of the renal artery.

Blood supply – middle ureter

Gonadal (testicular or ovarian) arteries.

Blood supply – pelvic ureter

Superior vesical artery branches.

Ureteric pain referral

Referred to T11–L2 dermatomes: lower abdomen, groin, scrotum/labia, proximal thigh.

Renal sympathetic plexus

Autonomic plexus conveying sympathetic fibers from T10–T12 to kidney and ureter.

Suprarenal (adrenal) gland

Yellowish retroperitoneal endocrine organ atop kidney; cortex + medulla.

Adrenal cortex

Outer region producing mineralocorticoids, glucocorticoids, and sex hormones.

Adrenal medulla

Inner region secreting catecholamines (epinephrine & norepinephrine).

Right suprarenal gland

Pyramidal gland capping upper pole of right kidney and lying posterior to IVC.

Left suprarenal gland

Crescent-shaped gland along medial border of left kidney behind pancreas, stomach, lesser sac.

Superior suprarenal artery

Branch of the inferior phrenic artery supplying the adrenal gland.

Middle suprarenal artery

Direct branch of the abdominal aorta to adrenal gland.

Inferior suprarenal artery

Branch of the renal artery to adrenal gland.

Right suprarenal vein

Short vein draining directly into the IVC.

Left suprarenal vein

Vein draining into the left renal vein.

Fetal suprarenal size

Fetal glands are 10–20× larger (relative to body weight) due to massive fetal cortex.

Nephron

Functional unit of kidney consisting of renal corpuscle and renal tubule.

Renal corpuscle

Glomerulus plus Bowman’s (glomerular) capsule where filtration occurs.

Glomerulus

Fenestrated capillary tuft receiving blood from an afferent arteriole and drained by an efferent arteriole.

Bowman’s capsule

Double-layered capsule with parietal (simple squamous) and visceral (podocyte) layers.

Podocyte

Visceral epithelial cell with foot processes forming filtration slits.

Filtration membrane

Composed of fenestrated endothelium, fused basement membrane, and podocyte slit diaphragm.

Proximal convoluted tubule (PCT)

First, microvilli-rich segment reabsorbing most filtrate nutrients, water, ions.

Loop of Henle

U-shaped portion with descending thin limb and ascending thin/thick limbs; concentrates urine.

Distal convoluted tubule (DCT)

Tubular segment involved in selective secretion and reabsorption; part of JGA.

Collecting duct

Tubule that receives urine from DCTs and participates in water reabsorption; drains to renal papilla.

Cortical nephron

85 % of nephrons; short loops of Henle limited to cortex and outer medulla.

Juxtamedullary nephron

15 % of nephrons; long loops extending deep into medulla for urine concentration.

Peritubular capillaries

Low-pressure capillaries arising from efferent arterioles that absorb solutes from cortical nephron tubules.

Vasa recta

Thin-walled looping vessels paralleling juxtamedullary loops; key to countercurrent exchange.

Juxtaglomerular apparatus (JGA)

Specialized structure where DCT contacts afferent arteriole; regulates BP & GFR.

Macula densa

DCT epithelial cells sensing tubular Na⁺; signal afferent arteriole to adjust GFR.

Juxtaglomerular (granular) cells

Modified smooth muscle cells of afferent arteriole that secrete renin when BP falls.

Renin

Enzyme hormone initiating the renin-angiotensin-aldosterone system to raise blood pressure.

Extraglomerular mesangial (lacis) cells

Flat cells near JGA thought to mediate signaling between macula densa & juxtaglomerular cells.

Transitional epithelium

Ureter mucosal lining capable of stretching without tearing.

Ureter muscularis layers

Inner longitudinal and outer circular smooth-muscle layers producing peristalsis.

Adventitia of ureter

Outer connective-tissue layer anchoring ureter to surrounding structures.

Glomerular filtration

Process where blood plasma is forced through the filtration membrane into Bowman’s capsule.

Tubular reabsorption

Movement of valuable nutrients, water, ions from filtrate back into blood.

Tubular secretion

Active transfer of undesirable substances from blood into tubular fluid.

Afferent vs efferent arteriole

Afferent brings blood to glomerulus; efferent carries it away to peritubular capillaries or vasa recta.

Posterior relations – right kidney

Diaphragm, 12th rib, pleural recess, psoas major, quadratus lumborum, transversus abdominis, and T12–L1 nerves.

Posterior relations – left kidney

Similar to right but higher, reaching the 11th rib.

Anterior relations – right kidney

Suprarenal gland, liver, 2nd part duodenum, right colic flexure, small-intestinal coils.

Anterior relations – left kidney

Suprarenal gland, spleen, stomach, pancreas (body), left colic flexure, descending colon, jejunum.

Right ureter – anterior relations

Duodenum, terminal ileum, right colic & ileocolic vessels, gonadal vessels, mesentery root.

Left ureter – anterior relations

Sigmoid colon, sigmoid mesocolon, left colic vessels, gonadal vessels.

Kidney surgical approach

Usually through the posterior abdominal wall to avoid peritoneal cavity.