Intro To Renal Function Flashcards
What are the functions of the kidneys?
Regulate water and ion balance
Regulate body fluid osmolality and volume
Excretion of metabolic waste (urea, uric acid, creatinine)
Excretion of foreign chemicals
Secretion of hormones (renin, EPO, 1, 25-dihydroxycholecalciferol)
Regulate blood bicarbonate levels
(Sorry for this card i just thought it would be good to see a few times)
What are the two sources of water input?
- Food/beverage
2. Oxidative
What are the 3 sources of water output (DOES NOT INCLUDE URINE)?
Fecal
Sweat
Insensible (breathing)
How do you calculate water balance?
Water input - water output= balance
Remember, urine does NOT go into this calculation for water output, we are trying to see what urine flow NEEDS to be
If urine output matches the “balance” what do we say the patient is?
Steady state
If urine output is less than the “balance” what do we say the patient is?
In a positive water balance
They’re not peeing enough, they have too much water overall!
If urine output is larger than the “balance” what do we say the patient is?
In a negative water balance
They are outputting MORE than they are taking in
What are some conditions that can cause a negative sodium and water balance?
Diarrhea
Diuretic medication
Insufficient aldosterone (adrenal dysfunction)
What are some conditions that can cause a positive sodium and water balance?
Excess steroids
Congestive heart failure
Salt-retaining disease (hyperaldosteronism)
Is the cortex granular or striated?
Granular
Is the medulla granulated or striated?
Striated
What is the basic unit of the kidney?
Nephron
Nephrons have a tubular component and a vascular component. What is the third component?
Combined component = juxtaglomerular apparatus
What are the 2 parts of the renal corpuscle?
Glomerulus
Bowman’s capsule
What happens to the filtrate in the proximal tubule?
2/3 of solute and water is reabsorbed (ISOSMOTIC)
Urine does not get concentrated here
What happens in the Loop of Henle?
Osmotic gradients are generated in the medulla that allow the kidney to concentrate urine
Where is the juxtaglomerular apparatus?
Where the thick ascending limb passes between the afferent and efferent arteroiles
What happens at the distal convoluted tubule?
Some ions are reabsorbed
Fluid may be iso or hyposmotic
What happens at the collecting duct?
The final concentration of the urine is adjusted
It is surrounded by a lot of salt to draw water out of the filtrate
Which hormone controls the water permeability of the collecting duct?
Vasopressin aka ADH
What are the 2 types of nephrons?
Cortical
Juxtaglomerular
Where are the cortical nephrons and is the LOH short or long?
In outer cortex
LOH short and doesnt extend into inner medulla
Where are the juxtamedullary nephrons and is the LOH long or short?
Near the corticomedullary border.
LOH is long and extends into the inner medulla
Does each nephron have its own collecting duct?
No, each collecting duct is shared by many nephrons
The ability to produce concentrated urine is though to be proportional to the number of ______________
Juxtamedullary nephrons
Within the renal corpuscle, what are the layers that separate the capillaries from the Bowman’s capsule?
Endothelium of the capillary
Glomerular basement membrane (aka basal lamina)
Visceral epithelial cells (aka podocytes, the little amoeba looking things)
What are pedicels?
Extensions of the podocytes
How does filtrate get from the capillary into the Bowman’s capsule?
Through ~slits~ between the podocytes
What are the 3 kinds of cells in the juxtaglomerular appartus
Macula densa (MD)
Extraglomerular cells
Granular cells (G cells/ juxtaglomerular cells)
What does the juxtaglomerular apparatus do?
The MD cells monitor flow and can change GFR and renin release
The Granular/G cells release renin
Where are the mesangial/M cells and what do they do?
They are between capillary loops in the glomerulus and they will contract in response to angiotensin II
What are the 2 capillary beds in the nephron?
Glomerulus
Peritubular
If you were a red blood cell traveling into the nephron, what would your path be starting at the renal artery?
Renal artery- afferent arteriole - glomerular capillary bed- efferent arteriole- peritubular capillaries- renal vein
(You hit TWO capillary beds before leaving the nephron)
Each nephron has 2 arterioles and 2 capillary beds. Are they in parallel or series?
Series
Do all nephrons have vasa recta?
No, only the juxtamedullary nephrons. Vasa recta are ONLY in the medulla
(Cortical nephrons don’t have)
Are the vasa recta important for recovering water?
Yes
Does the kidney receive SNS and PNS stimulation?
No, only SNS
What kind of receptors are on the renal arterioles?
Are they on both the afferent and efferent?
a1 (….they cause constriction)
They are on both, but PRIMARILY on the afferent arterioles
What effect will SNS stimulation have on renal blood flow and GFR?
It tends to reduce it, but the simultaneous release of prostaglandins (PGE2 and PGI2) oppose the effect.
Reductions in RBF and GFR are minimized.
(The kidney does not like its blood flow to be messed with)
What effect will SNS stimulation have on the juxtaglomerular apparatus?
Granular cells will release renin
What kind of receptors are on the juxtaglomerular apparatus?
B1
Is there protein in the filtrate?
No
