HUMB1000 Lecture Notes - Lecture 7: Cardiac Output, Body Fluid, Creatinine
21 Jun 2018
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C7 L1 – Anatomy of the Renal System:
Kidney Location:
- Lie behind the parietal peritoneum on the posterior abdominal wall
- Right kidney slightly lower (due to liver)
- Lumbar vertebrae and ribs partially protect kidneys
- Bean shaped, size of fist ~130g
- Renal capsule: fibrous connective tissue surrounding
- Adipose tissue: engulfs renal capsule, acts as cushioning and insulation
- Renal fascia: thin layer of loose connective tissue anchors kidneys to posterior abdominal
wall
External anatomy:
- Hilum: renal artery and nerves enter and the renal vein and ureter exit. Most medial
- Hilum opens into RENAL SINUS: cavity filled with loose connective tissue and fat
- Ureter: exits at the hilum, connects to urinary bladder
- Cortex: outer area
- Renal columns: part of cortical tissue that extends into medulla (between pyramids)
Internal anatomy:
- Medulla: inner, surrounds renal sinus
- Renal pyramids: cone shaped. Base is boundary between cortex and medulla
- Renal papilla: apex of pyramid, points towards sinus
- Minor calyces: funnel shaped chambers into which papillae extend
- Major calyces: converge to form the renal pelvis
- Pelvis: enlarged chamber formed by major calyces
The Nephron:
- Functional unit of the kidney
- Parts: renal corpuscle, proximal convoluted tubule, loop of Henle, distal convoluted tubule
- Blood enters the nephron for filtration, filtrate/urine produced
- Urine continues from nephron to papillary ducts, minor calyces, major calyces, renal pelvis
and ureter
- 1.3 million nephrons in each kidney, 50-55mm in length (large SA)
find more resources at oneclass.com
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- Juxtamedullary nephrons: renal corpuscle located near medulla (lower). Long loops of Henle
(15%)
- Cortical nephrons: renal corpuscle located nearer to the periphery. Loops of Henle not deep
(85%)
Renal corpuscle:
- Bowman’s capsule: double walled chamber filters blood/fluid that enters proximal
convoluted tubule
- Glomerulus: network/ball of capillaries
- Blood enters glomerulus through afferent arteriole, exits through efferent arteriole
- Afferent > efferent for pressure to force absorption into blood
- Peritubular capillaries: reabsorption and secretion happening. Surround tubules, merge to
renal veins
Bowman’s Capsule:
- Parietal layer: outer layer, simple squamous, becomes cuboidal in PCT
- Visceral layer: inner layer, specialised podocytes that wrap around glomerular capillaries
Filtration membrane:
- Fenestrae: window like openings in endothelial cells of glomerular capillaries
- Filtration slits: gaps between podocytes
- Basement membrane: between endothelial cells of glomerular capillaries and podocytes
Renal Tubules:
- Proximal convoluted tubule: filtrate drains from Bowman’s capsule into PCT
- Loop of Henle: each has a descending and ascending limb
- Distal convoluted tubule: shorter than PCT
- Collecting ducts: large diameter, extend through medulla towards renal papilla to ureter
Histology of the Nephron:
- Proximal tubule: simple cuboidal with microvilli. Active reabsorption of Na2+, K+ and Cl-
- Loop of Henle: thick parts simple cuboidal, thin parts simple squamous for osmosis/diffusion
- Distal tubule: simple cuboidal, few microvilli, numerous mitochondria
Urine movement:
- Pressure forces urine through nephron
- Smooth muscle in ureters, peristalsis moves urine from renal pelvis in kidneys through
ureters to the urinary bladder
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
C7 l1 anatomy of the renal system: Lie behind the parietal peritoneum on the posterior abdominal wall. Adipose tissue: engulfs renal capsule, acts as cushioning and insulation. Renal fascia: thin layer of loose connective tissue anchors kidneys to posterior abdominal wall. Hilum: renal artery and nerves enter and the renal vein and ureter exit. Hilum opens into renal sinus: cavity filled with loose connective tissue and fat. Ureter: exits at the hilum, connects to urinary bladder. Renal columns: part of cortical tissue that extends into medulla (between pyramids) Renal papilla: apex of pyramid, points towards sinus. Minor calyces: funnel shaped chambers into which papillae extend. Major calyces: converge to form the renal pelvis. Parts: renal corpuscle, proximal convoluted tubule, loop of henle, distal convoluted tubule. Blood enters the nephron for filtration, filtrate/urine produced. Urine continues from nephron to papillary ducts, minor calyces, major calyces, renal pelvis and ureter. 1. 3 million nephrons in each kidney, 50-55mm in length (large sa)
