Renal Overview - Lecture 1 Flashcards
What is the Juxtaglomerular apparatus composed of?
Composed of macula Densa of the thick ascending limb, extraglomerular, mesangial cells and renin-angiotensin II producing GRANULAR cells
What are the 8 main functions of the kidneys?
1) Excretion of metabolic waste and foreign substances;
2) Regulation of water and electrolyte balance;
3) Regulation of extracellular fluid volume;
4) Regulation of plasma osmolality;
5) Regulation of red blood cell production;
6) Regulation of vascular resistance;
7) Regulation of acid-base balance;
8) Regulation of vitamin D production.
What does the nephron consist of?
- Renal Corpuscle
- Proximal Tubule
- Loop of Henle
- Distal Tubule
- Collecting duct system
What is within the renal corpuscle? Where does this lie in (Cortex, outer medulla, inner medulla?)
- Glomerular Capillaries
- Bowman’s Capsule
CORTEX
What is the Loop of Henle composed of?
- Descending thin limb
- Descending thick limb?
- Ascending thin limb
- Thick ascending limb
What is the short segment of the THICK ascending limb called? What part of the kidney is it situation in? (cortex, outer medulla, inner medulla)
Macula Densa
- short segment of the thick ascending limb
- in the CORTEX
The distal tubule extends into the cortex to meet two or more nephrons forming the _____
Cortical Collecting Duct
What is the function of the glomerulus?
Ultra - filtration
Where is the brush border located?
in the Proximal Tubule
- functions to rabsorb substances
What are the two cells types that the Collecting Duct is composed of?
- Principal Cells
2. Intercalated Cells
All cells (except the intercalated cells) in the nephron have what?
Cilia that protrude into the tubule fluid
- mechanosensors and detect changes in the rate of flow of tubule fluid
- chemosensors and initiate Calcium dependent signaling pathways
The glomerular capillaries form the efferent arteriole which lead into what 2nd capillary network?
Peritubular capillaries
- supply blood to the nephron
What are the 2 renal blood flow routes?
Through glomerular capillaries and then either through:
- Peritubular Capillaries
- Vasa Recta
What does the following coloration of urine signify?
- Amber
- Dark Amber on standing
- Dark amber on collection
- Pale Amber on collection
- Urochrome
- Due to oxidation of urobilinogen
- Anti-Diuresis (V< 1 ml/min)
4 Water Diuresis (V > 1 ml/min)
How does the Kidney function as an endocrine gland? (4)
- Erythropotein production - RBC production
- Calcitriol or Vitamin D3 - bone resorption
- Renin - increased levels of Angiotensin
- Prostaglandins - renal vasodilation and regulation of RPF and GRF
How is the kidney a target for hormones? (4)
- ADH from posterior pituitary - water balance
- Aldosterone from adrenal cortex - POSITIVE sodium & water balance
- ANP from heart - negative sodium & water balance
- PTH - calcium absorption by renal tubules
Hypertension usually has how much renal involvement?
10%
What affect does CHF have on the kidney?
Decreased cardiac output means increased salt & water reabsorption
- vicious cycle involving the renin-angiotensin-aldosterone axis
What is the function of the Proximal Tubule?
High-volume, low gradient reabsorption
- contain the brush border
- highly invaginated
What is the function of the Loop of Henle?
- Forms HIGH INTERSTITIAL OSMOLALITY
- Descending & Ascending thin limbs have poorly developed apical and basolateral surfaces
- Few mitochondria
What is the function of the Distal Tubule?
- Low Volume, high gradient reabsorption
What is the function of the Macula Densa & JGA?
- . Sensor of tubular flow
- thick ascending limb & distal tubule have abundant mitochondria and extensive infolding of the basolateral membranes
What is the function of the collecting duct?
- Concentration/dilution of final urine
- composed of principal & intercalated cells
principle cells = few invaginations, little mitochondria
Intercalated cells = regulated acid-base balance - high density of mitochondria
What cells secrete H+ and HCO3-?
Intercalated cells
Where is RBC produced? What stimulates this production?
Bone Marrow
- Erythropotein (from the liver)
- drops in pO2 cause increased secretion of erythropotein
What are the cortex and medulla composed of?
Nephrons!
What does the medulla divide into? What lies within the minor calyces?
Renal Pyramids
Papillae! (minor calyces colect urine from each papillae)
The cortical collecting duct leads into what 2 structures simultaneously?
Outer Medullary Collecting Duct
Inner Medullary Collecting DUct
What cells make up the Juxtaglomerular Apparatus?
- Macula Densa
- Extra-glomerular Mesangial Cells
- Granular Cells (produce renin)
State the function of the following
- Glomerulus
- Proximal Tubule
- Loop of Henle
- Distal Tubule
- Macula Densa
- Collecting Duct
- Glomerulus - FILTRATION
- Proximal Tubule - REABSORPTION (high volume, low gradient)
- Loop of Henle - OSMOLARITY FORMATION
- Distal Tubule - REABSORPTION (low volume, high-gradient)
- Macula Densa / JGA - SENSOR OF TUBULAR FLOW
- extensive infolding of basolateral membrane - Collecting Duct - DILUTION/CONCENTRATION OF FINAL URINE
What are the normal values for RPF & RBF?
RPF = 660 mL/min
RBF = 1200 mL/min
What is the normal value of GFR? Filtration Rate?
125 mL/min
(GFR/RPF = 125/660) = 20%
What second capillary network do the glomerular capillaries that form the efferent arteriole lead into?
PERITUBULAR CAPILLARIES
90% RBF
What vessels are responsible for 90% of RBF? 20%?
Peritubular Capillaries
Vasa Recta Capillaries
