Urinary (Renal) System – Anatomy & Physiology

Vocabulary-style flashcards covering essential terms and definitions from the lecture on urinary (renal) system anatomy, kidney structure, nephron components, and basic renal physiology.

Urinary (Renal) System

Body system responsible for maintaining blood homeostasis by filtering blood and producing urine; includes kidneys, ureters, bladder, and urethra.

Kidney

Primary organ of the urinary system where filtration, re-absorption, and secretion occur to form urine.

Ureter

Muscular tube that transports urine from each kidney to the urinary bladder.

Urinary Bladder

Hollow, muscular organ that temporarily stores urine before elimination.

Urethra

Tubular passageway that conveys urine from the bladder to the exterior of the body.

Renal Artery

Blood vessel that delivers oxygenated, unfiltered blood to a kidney.

Renal Vein

Blood vessel that drains filtered, de-oxygenated blood away from a kidney.

Adrenal Gland

Endocrine gland located atop each kidney; produces hormones such as cortisol and adrenaline.

Homeostasis (Blood)

Stable internal environment of blood volume, pressure, pH, and solute concentration maintained largely by the kidneys.

Urea

Nitrogenous waste product formed from amino acid catabolism, excreted in urine.

Uric Acid

Waste product of nucleic acid (RNA) catabolism, removed via urine.

Hilum (Renal Hilum)

Medial indentation of the kidney where ureter, blood vessels, and nerves enter/exit.

Retroperitoneal

Located behind the peritoneal lining of the abdominal cavity; describes kidney position.

Renal Capsule

Fibrous outer covering directly enveloping the kidney.

Adipose Capsule

Protective fat layer surrounding the renal capsule.

Renal Fascia

Connective tissue layer that anchors kidneys to surrounding structures.

Renal Cortex

Outer region of the kidney containing most nephrons.

Renal Medulla

Inner region of the kidney composed of renal pyramids.

Renal Pyramid

Cone-shaped tissue in the renal medulla that funnels urine toward the papilla.

Minor Calyx

Small cup-like structure that collects urine from a renal papilla.

Major Calyx

Convergence of several minor calyces; channels urine toward the renal pelvis.

Renal Pelvis

Central collecting region of the kidney that continues as the ureter.

Nephron

Microscopic functional unit of the kidney that produces urine.

Glomerulus

Tuft of fenestrated capillaries where blood filtration begins.

Bowman’s (Glomerular) Capsule

Cup-shaped nephron structure that surrounds the glomerulus and receives filtrate.

Renal Corpuscle

Combination of glomerulus and Bowman’s capsule; site of filtration.

Afferent Arteriole

Blood vessel bringing blood into a glomerulus; larger diameter promotes high glomerular pressure.

Efferent Arteriole

Blood vessel carrying blood away from a glomerulus; smaller diameter maintains filtration pressure.

Peritubular Capillaries

Network of capillaries surrounding cortical nephron tubules for re-absorption and secretion.

Vasa Recta

Long, straight capillaries paralleling juxtamedullary nephron loops, important in urine concentration.

Proximal Convoluted Tubule (PCT)

First nephron segment after Bowman’s capsule; major site of nutrient and ion re-absorption.

Nephron Loop (Loop of Henle)

U-shaped segment that creates osmotic gradient via descending water re-absorption and ascending salt transport.

Distal Convoluted Tubule (DCT)

Nephron segment distal to the loop; fine-tunes ion, acid-base balance, and participates in secretion.

Collecting Duct

Tubule receiving fluid from multiple nephrons; final site of water/ion adjustment before urine exits the kidney.

Cortical Nephron

Nephron located mostly within the renal cortex; majority type in humans.

Juxtamedullary Nephron

Nephron with long loop extending deep into medulla; crucial for producing concentrated urine.

Filtration (Renal)

Passive movement of water and small solutes from blood into Bowman’s capsule driven by blood pressure.

Re-absorption

Movement of water, ions, and nutrients from nephron tubules back into peritubular blood.

Secretion (Renal)

Active transfer of additional wastes, ions, or drugs from blood into nephron tubules.

Countercurrent Multiplication

Process in nephron loops where opposing fluid flows create medullary osmotic gradient to concentrate urine.

Renin-Angiotensin-Aldosterone (RAA) System

Kidney-initiated hormone cascade regulating blood pressure and volume.

Erythropoietin

Hormone produced by kidneys that stimulates red blood cell production in bone marrow.

Bilirubin

Pigment released from hemoglobin breakdown; excess causes jaundice and can be excreted by kidneys after phototherapy.

Jaundice

Yellow discoloration of skin/eyes due to elevated bilirubin levels.

Phototherapy (Neonatal)

Light treatment converting bilirubin to water-soluble form that kidneys can excrete in jaundiced infants.

Pelvic Kidney

Congenital condition in which a kidney remains in the pelvic cavity instead of ascending to normal position.

Horseshoe Kidney

Congenital fusion of lower poles of both kidneys into a U-shaped organ that usually functions normally.

Renal Pyramid Papilla

Tip of a renal pyramid where urine drains into a minor calyx.

Metabolic Waste

By-products of cellular metabolism (e.g., urea, creatinine, uric acid) eliminated via urine.

Creatinine

Waste from creatine phosphate breakdown in muscles, excreted by kidneys.

Renal Hilum Structures

Triad entering/exiting hilum: renal artery, renal vein, and ureter.