Untitled Flashcard Set

Urinary System

Maintains internal environment by filtering blood, removing wastes, regulating ions/fluids, acid–base balance, producing renin & erythropoietin, and activating vitamin D.

Renin

Enzyme produced by kidneys that helps regulate blood pressure.

Erythropoietin

Hormone produced by kidneys that stimulates red blood cell production.

Acid–Base Balance

Kidneys help control blood pH by regulating H⁺ and bicarbonate.

Vitamin D Activation

Kidneys convert vitamin D to its active form.

Kidneys

Organs that filter blood and make urine.

Ureters

Tubes that carry urine from kidneys to bladder by peristalsis.

Urinary Bladder

Stores urine prior to micturition.

Urethra

Carries urine to the body’s surface.

Retroperitoneal

Kidneys lie behind the peritoneum between the dorsal body wall and parietal peritoneum.

Renal Fascia

Outermost connective tissue layer anchoring kidney & adrenal gland.

Adipose Capsule

Fatty layer cushioning kidneys and holding them in place.

Renal (Fibrous) Capsule

Thin, protective CT layer preventing infection spread into kidneys.

Renal Cortex

Outer region of kidney where renal corpuscles are found.

Renal Medulla

Inner region containing pyramids.

Renal Pyramids

Cone-shaped medullary structures containing nephron loops and collecting ducts.

Renal Columns

Cortical tissue extensions between pyramids.

Renal Pelvis

Funnel-shaped tube collecting urine from calyces into ureter.

Major Calyces

Large branches collecting urine from minor calyces.

Minor Calyces

Small cup-shaped structures that collect urine from papillae.

Nephron

Functional unit of the kidney; filters blood and forms urine.

Renal Corpuscle

Includes glomerulus + glomerular capsule; site of filtration.

Glomerulus

Capillary tuft where filtration occurs.

Glomerular Capsule (Bowman’s Capsule)

Double-walled structure capturing filtrate.

PCT (Proximal Convoluted Tubule)

Reabsorbs most filtrate; has brush border.

Loop of Henle (Nephron Loop)

Creates osmotic gradients; contains descending and ascending limbs.

DCT (Distal Convoluted Tubule)

Adjusts ion levels; fewer microvilli.

Collecting Duct

Receives filtrate from many nephrons; final urine adjustments.

Cortical Nephrons

Short loops in cortex; main site of filtering/reabsorption.

Juxtamedullary Nephrons

Long loops deep into medulla; create concentrated urine.

Brush Border

Microvilli in PCT that increase reabsorption surface area.

Podocytes

Cells of visceral glomerular capsule forming filtration slits.

Filtration Slits

Openings between podocyte foot processes that regulate what enters filtrate.

Renal Artery

Supplies blood to kidneys.

Afferent Arteriole

Brings blood into glomerulus.

Efferent Arteriole

Carries blood away from glomerulus.

Peritubular Capillaries

Surround cortical nephrons; reabsorb and secrete materials.

Vasa Recta

Capillary loops around juxtamedullary nephrons; maintain medullary gradient.

Renal Plexus

Sympathetic nerve supply controlling vasomotor tone & renin release.

Transitional Epithelium

Stretchable epithelium lining ureters and bladder.

Detrusor Muscle

Smooth muscle of bladder wall responsible for contraction.

Trigone

Triangular area at bladder base defined by ureter & urethral openings.

Internal Urethral Sphincter

Smooth muscle; involuntary control.

External Urethral Sphincter

Skeletal muscle; voluntary control.

Glomerular Filtration

Movement of fluid/solutes from blood into glomerular capsule.

Tubular Reabsorption

Movement of substances from filtrate back into blood.

Tubular Secretion

Movement of substances from blood into filtrate.

Filtration Membrane

Made of glomerular endothelium, basement membrane, podocytes.

Glomerular Endothelium

Fenestrated capillary wall; blocks formed elements.

Basement Membrane

Negative charge blocks proteins and anions.

Podocyte Foot Processes

Create filtration slits restricting large molecules.

Filtrate

Plasma minus large proteins.

HPg (Glomerular Hydrostatic Pressure)

Blood pressure pushing fluid out of glomerulus.

OPg (Osmotic Pressure in Glomerulus)

Pull of plasma proteins drawing fluid in.

HPc (Capsular Hydrostatic Pressure)

Pressure from fluid in capsule resisting filtration.

Net Filtration Pressure (NFP)

HPg – (OPg + HPc); determines filtration rate.

Myogenic Mechanism

Afferent arteriole constricts/dilates in response to pressure changes.

Macula Densa

Cells sensing filtrate flow/osmolarity; adjust afferent arteriole.

Juxtaglomerular (JG) Cells

Release renin when BP is low.

Renin–Angiotensin Mechanism

Raises BP via vasoconstriction and aldosterone.

Aldosterone

Promotes Na⁺ and water retention → increases BP.