pop urin Flashcards
(39 cards)
What type of hormone is aldosterone?
Steroid, mineralocorticoid
Aldosterone: regulate blood pressure.
Adjusts Na+,K+, H+ and NH4+ (urea)
in response to Angiotensin II, decreased blood pressure (via baroreceptors) and decreased osmolarity of the ultra filtrate
Aldosterone stimulates the principal cells of the distal convoluted tubule/cortical collecting duct
o Increased sodium reabsorption (+ thus water reabsorption)
o Increased potassium secretion
o Increased hydrogen secretion
Why does CT cause vertebrae clear and tissues blurry
Patient motion during a CT scan can cause the images to be “blurry”.
What is renal clearance?
- As substances in the blood pass through the glomerulus, they are filtered to different degrees
- The extent to which substances are removed from the blood is called clearance
b) What is clearance of sodium if plasma conc is 140mM, urine conc is 100mM and urine flow rate is 1.3ml/min?
C=U*V/P (ml per min)
U = concentration of substance in urine
P = concentration of substance in plasma
V = rate of urine production
C = 100 * 1.3 / 140
= 0.928…
=0.93ml of plasma are cleared of Na per minute
- NB: clearance is affected by the processes following ultrafiltration, unlike GFR
- However, if a molecule is freely filtered (i.e. neither reabsorbed nor secreted following its ultrafiltration), clearance = GFR (i.e. amount excreted = amount filtered)
- Freely filtered = same concentration of solute in filtrate and plasma
c) How is this compared to Creatinine Clearance value? Why?
- Na clearance value is much lower than Creatinine clearance value.
- Creatinine is secreted by the proximal tubule as well as filtered by the glomerulus.
- Creatinine is a waste product from creatine in muscle metabolism.
d) Why does high plasma creatinine indicate renal failure?
It indicates that glomerular filtration rate has decreased, which led to the build up of creatinine in the plasma. This indicates that the kidneys are not working properly.
e) 2 properties of something to measure GFR?
- Non-toxic
- Freely filtered and neither reabsorbed nor secreted
- Measurable in urine and plasma
f) A property of a substance that can be used to measure Plasma Flow Rate
- Filtered and actively secreted in one pass of the kidney
* All of substance is removed from the plasma passing through the kidney (so its clearance equals the renal plasma flow)
g) Renal plasma flow can be measured using PAH - if conc in blood is 0.5μmol and the conc in urine is 200μmol and the urine output is 30ml in 20 minutes then what is the clearance?
v = 30/20
=1.5
C = 200*1.5 / 0.5
= 600ml/min
The renal clearance of a substance is equal to the glomerular filtration rate (GFR) provided that THREE essential conditions concerning its renal handling are satisfied. State these THREE conditions. The substance must be:
- Freely filtered at the glomerulus
- Not reabsorbed
- Not secreted
a) 2 energy source for transportation of substance in the tubules.
- Directly coupled to ATP hydrolysis, i.e. substance is moved into the cell using the energy from ATP hydrolysis (usually occurs at apical membrane)
- Indirectly coupled to ATP hydrolysis, i.e. the substance is moved out of the cell using the energy from ATP hydrolysis (at basal membrane), and this creates a concentration which causes passive movement of the substance into the cell at the apical membrane
a) Given an electron micrograph of the renal cortex with two tubules 1 and 2. You had to identify each tubule based on its appearance.
Proximal convoluted tubule has a larger diameter than distal convoluted tubule.
b) Give 1 example of a diuretic drug used in tubule 1 and another in tubule 2
PCT
PCT
Osmotic Diuretics – Mannitol (cannot be reabsorbed)
Carbonic anhydrase inhibitors (Na+ cannot be reabsorbed)
DCT
Thiazides (block Na/Cl co-transport)
K+ sparing diuretics – Amiloride (block Na channels), Spironolactone (aldosterone antagonist)
c) Pointed to a lining of tubule 1- asked to identify it and give its function.
Microvilli brush border
Increase the membrane surface area, means more interaction with tubular fluid, more passive reabsorption.
d) There are lots of ‘these’ in both tubules. What are they? Why they are there?
Mitochondria
Allows active reabsorption to occur. To generate ATP for Na+/K+ pump which creates a Na+ gradient for other cotransporters.
e) Pointed to some granules in tubule 1 and state what was inside these granules?
Vesicles which contain aquaporin proteins?
a) State the pH range that is normal in humans (1)
7.35-7.45
b) If someone has CO2 38mmHg and HCO3 11mEq/L what do they have? (2)
Metabolic Alkalosis
Co2 normal = 25-45mmHg
HCO3 normal = 21-28mEq/L
d) Why do non-volatile acids not contribute to pH? (2)
These H+ ions are excreted by the kidneys.
Only 50-100mmol of non volatile acid produced per day.
i) Define glomerular filtration rate and give units (1/2)
The amount of fluid filtered from the glomeruli capillaries into the Bowmans capsule per unit time (ml/min)
The concentration of Na+ in the plasma is 120mmol/l and the glomerular filtration rate is 120ml/min. Calculate the concentration of sodium in the ultrafiltrate (2)
Same
i) State how the GFR changes for the following situations (2):
a. Severe haemorrhage
b. Increase blood pressure during exercise
c. Decreased plasma osmolarity
d. Obstruction in nephron tubule
decrease
no change
increase
decrease
i) Define renal clearance and give units (1/2)
- As substances in the blood pass through the glomerulus, they are filtered to different degrees
- The extent to which substances are removed from the blood is called clearance
- ml/min
i) Why is creatinine lower in the plasma than sodium? (3)
Creatinine is not reabsorbed but it is secreted in the PCT.
Na+ is reabsorbed into the plasma.
Creatinine has a higher clearance value than Na+.
