Urinary System Flashcards
Urinary System Overview
Structures: - 2 Kidneys - 2 Ureters - 1 Urinary Bladder - 1 Urethra Functions: - Regulates: 1) Blood volume 2) Blood pressure 3) pH 4) Ion concentrations - Eliminates wastes E.g. urea, uric acid, hormones, drugs
Kidneys (External Anatomy)
- Retroperitoneal
- Right lower than left
- Supported + protected by 3 layers of CT:
1) Fibrous Capsule
2) Perirenal Fat Capsule
3) Renal Fascia
-Renal hills (Hilum)
~Medial indentation
~ Entry point of: renal artery (superior), renal vein (inferior), Ureter, Nerves
Kidney (Internal Anatomy)
- Renal cortex (Superficial)
- Renal medulla
Contains:
1) Renal Pyramids - Apex of pyramid = renal papilla
2) Renal Columns - Separate pyramids
- Contains blood vessels
Nephron
- Functional unit of kidney (microscopic)
- Composed of:
1) Renal Corpuscle
2) Renal Tubules
Renal Corpuscle (Nephron)
- In cortex (Always)
- Site of blood filtration (first step in urine formation)
- Parts:
1) Glomerulus
2) Bowman’s Capsule
3) Filtration Membrane
Glomerulus (Renal Corpuscle)
= Capillary Bed
Bowman’s Capsule (Renal Corpuscle)
- Surrounds glomerulus
- Collects filtrate from glomerulus
- 2 layers:
1) Outer = Simple squamous epithelium
2) Inner = podocytes - Wrapped around glomerular capillaries
Filtration Membrane (Renal Corpuscle)
- Consists of:
1) Glomerular endothelium (capillaries) - Simple squamous with pores (= fenestrations)
2) Basement Membranes
3) Podocytes (of Bowman’s capsule) - Simple epithelium
- Projections “cling” to glomerulus
Renal Tubules
- 4 part:
1) Proximal Convoluted Tubule (PCT) - in cortex
2) Loop of Henle - Descending + ascending limbs
- in medulla
3) Distal Convoluted Tubule (DCT) - in cortex
4) Collecting Ducts (not part of nephron) - In cortex and medulla
- Connect nephron to ureter (via calyces/renal pelvis)
Cortical (Type of Nephron)
- 85%
- Renal corpuscles near kidney surface in cortex
- Short loop of Henle in outer medulla
Juxamedullary (Type of Nephron)
- 15%
- Renal corpuscles in cortex ear medulla
- Long loops - penetrate deep into medulla - allow concentration of urine, depending on need
Kidney + Nephron Blood Supply Route
Aorta - Renal Arteries - Segmental Arteries - Interlobar Arteries (up columns) - Arcuate Arteries (medulla/cortex junction) - Cortical Radiate Arteries - Afferent Arteriole - Glomerulus - Efferent Arteriole -Peritubular Capillaries (in cortex) and Vasa Recta (capillaries in medulla) - Cortical Radiate Veins - Arcuate Veins - Interlobar Veins - Renal Vein - Inferior Vena Cava
Juxtaglomerular
- Regulates filtrate formation
- Point of contact between end of ascending limb, afferent and efferent arterioles at the renal corpuscle of the same nephron
- Parts:
1) Tubular Portion
2) Arteriolar Portion
Tubular Portion (Juxtaglomercular)
- Modified (tall and narrow) ascending limb cells = macula densa
Arteriolar Portion (Juxtaglomercular)
- Afferent + efferent arteriolar portion = granular (juxtaglomerular) cells
- Monitor blood pressure
- Modified smooth muscle cells - contain renin (enzyme + hormone)
