Chapter 24 - Urinary System

term

definition

Kidneys

Retroperitoneal organs connected to the urinary bladder by the ureters

Fibrous capsule

Layer of collagen fibers covering the outer surface of the kidney

Perinephric fat

Thick layer of adipose tissue surrounding the kidney

Renal fascia

Dense, fibrous outer layer anchoring the kidney to surrounding structures

Renal cortex

Superficial region of the kidney

Renal medulla

Inner region of the kidney

Renal pyramid

Conical structure located within the renal medulla

Renal papilla

Lip or tip of each renal pyramid

Renal column

Area of cortex between adjacent pyramids

Hilum

Medial indentation; entry/exit point for renal artery, vein, nerves, and ureter

Kidney lobe

Contains pyramid, overlying cortex, and adjacent columns

Minor calyx

Collects urine from a single kidney lobe

Major calyx

Formed by fusion of 4

Renal pelvis

Funnel

Renal artery

Delivers blood to the kidney; branches into segmental arteries

Segmental arteries

Branch within renal sinus; form interlobar arteries

Interlobar arteries

Travel within renal columns; branch into arcuate arteries

Arcuate arteries

Curve along cortex

Cortical radiate arteries

Supply afferent arterioles leading to nephrons

Afferent arterioles

Supply each nephron’s glomerulus

Cortical radiate veins

Drain blood from nephron capillaries into arcuate veins

Arcuate veins

Drain into interlobar veins

Interlobar veins

Drain into renal vein

Renal vein

Exits kidney and drains into inferior vena cava

Nephrons

Microscopic functional units of the kidney

Cortical nephrons

85% of nephrons; located in the cortex

Juxtamedullary nephrons

15% of nephrons; long loops extend deep into medulla; produce concentrated urine

Filtration

Process where blood plasma leaves kidney capillaries into nephron

Reabsorption

Nutrients, water, and essential ions reclaimed into bloodstream

Secretion

Active removal of unwanted molecules from blood into tubules

Renal corpuscle

Made of glomerular capsule and glomerulus

Renal corpuscle function

Filtration of blood via pressure forcing water/solutes into capsule

Renal tubule

Long tubular pathway that modifies filtrate into urine

Parts of renal tubule

Proximal convoluted tubule, nephron loop, distal convoluted tubule

Proximal convoluted tubule (PCT)

Reabsorbs nutrients from filtrate (now called tubular fluid)

Nephron loop

Reabsorbs water; has thin and thick segments in each limb

Distal convoluted tubule (DCT)

Adjusts composition of tubular fluid via reabsorption/secretion

Collecting duct

Receives fluid from many nephrons; transports through medulla

Afferent arteriole

Delivers blood to the nephron’s glomerulus

Glomerulus

Capillary knot where filtration occurs

Efferent arteriole

Carries blood away from glomerulus to peritubular capillaries

Peritubular capillaries

Surround renal tubule; reclaim solutes and secrete others

Vasa recta

Specialized peritubular capillaries in juxtamedullary nephrons

Urinary tract

Composed of ureters, urinary bladder, and urethra; stores and eliminates urine

Ureters

Muscular tubes that conduct urine from kidneys to bladder

Ureter inner mucosa

Transitional epithelium and lamina propria

Ureter middle muscular layer

Smooth muscle bands generating peristaltic waves

Ureter outer connective tissue

Anchors ureter to surrounding structures

Urinary bladder

Hollow muscular organ that stores urine; can hold up to 1 liter

Ureteric orifices

Slit

Trigone

Triangular zone formed by ureteral openings and urethra entry

Rugae

Folds in bladder lining that flatten as bladder fills

Internal urethral sphincter

Involuntary smooth muscle around bladder neck

External urethral sphincter

Voluntary skeletal muscle at urogenital diaphragm; must relax to urinate

Bladder histology

Includes mucosa, submucosa, and muscularis layers

Bladder wall layers

Inner longitudinal layer, circular layer, and outer longitudinal layer

Detrusor muscle

Collective name for the three smooth muscle layers in bladder wall