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pop urin Flashcards

1
Q

What type of hormone is aldosterone?

A

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

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2
Q

Why does CT cause vertebrae clear and tissues blurry

A

Patient motion during a CT scan can cause the images to be “blurry”.

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3
Q

What is renal clearance?

A
  • 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
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4
Q

b) What is clearance of sodium if plasma conc is 140mM, urine conc is 100mM and urine flow rate is 1.3ml/min?

A

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
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5
Q

c) How is this compared to Creatinine Clearance value? Why?

A
  • 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.
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6
Q

d) Why does high plasma creatinine indicate renal failure?

A

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.

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7
Q

e) 2 properties of something to measure GFR?

A
  • Non-toxic
  • Freely filtered and neither reabsorbed nor secreted
  • Measurable in urine and plasma
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8
Q

f) A property of a substance that can be used to measure Plasma Flow Rate

A
  • 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)

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9
Q

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?

A

v = 30/20
=1.5
C = 200*1.5 / 0.5
= 600ml/min

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10
Q

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:

A
  • Freely filtered at the glomerulus
  • Not reabsorbed
  • Not secreted
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11
Q

a) 2 energy source for transportation of substance in the tubules.

A
  • 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
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12
Q

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.

A

Proximal convoluted tubule has a larger diameter than distal convoluted tubule.

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13
Q

b) Give 1 example of a diuretic drug used in tubule 1 and another in tubule 2
PCT

A

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)

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14
Q

c) Pointed to a lining of tubule 1- asked to identify it and give its function.

A

Microvilli brush border

Increase the membrane surface area, means more interaction with tubular fluid, more passive reabsorption.

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15
Q

d) There are lots of ‘these’ in both tubules. What are they? Why they are there?

A

Mitochondria
Allows active reabsorption to occur. To generate ATP for Na+/K+ pump which creates a Na+ gradient for other cotransporters.

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16
Q

e) Pointed to some granules in tubule 1 and state what was inside these granules?

A

Vesicles which contain aquaporin proteins?

17
Q

a) State the pH range that is normal in humans (1)

A

7.35-7.45

18
Q

b) If someone has CO2 38mmHg and HCO3 11mEq/L what do they have? (2)

A

Metabolic Alkalosis
Co2 normal = 25-45mmHg
HCO3 normal = 21-28mEq/L

19
Q

d) Why do non-volatile acids not contribute to pH? (2)

A

These H+ ions are excreted by the kidneys.

Only 50-100mmol of non volatile acid produced per day.

20
Q

i) Define glomerular filtration rate and give units (1/2)

A

The amount of fluid filtered from the glomeruli capillaries into the Bowmans capsule per unit time (ml/min)

21
Q

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)

A

Same

22
Q

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

A

decrease

no change

increase

decrease

23
Q

i) Define renal clearance and give units (1/2)

A
  • 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
24
Q

i) Why is creatinine lower in the plasma than sodium? (3)

A

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+.

25
Q

i) How does a diuretic work? (1/2)

A

A diuretic is any substance that promotes the production of urine. Increase the excretion of water from bodies.

26
Q

i) Explain what’s causing the dizziness and arrhythmias? (2)

A

Low BP causing dizziness, less blood reaching brain
High K+.
Depolarising membranes causing action potentials causing heart arrythmias

27
Q

i) Explain the mechanism of Spironolactone and its action (3)

A
  • Spironolactone is a K+ sparing diuretic and is an aldosterone antagonist.
  • It works on the DCT.
  • This decreases the reabsorption of sodium and water, while limiting the excretion of potassium.
28
Q

i) What are the three causes of the patient’s hyperkalaemia? (3)

A

Bananas are a source of K+, eating too many.

Using K+ sparing diuretic, limits the excretion of K+ by inhibiting aldosterone.

29
Q

a) Table of Na+,K+ and Ca2+ and you had to circle which ones are high and low intracellularly and extracellularly (3)

A

High K+ intracellularly
Low Na+ intracellularly
Low Ca2+ intracellularly

30
Q

a) Give 3 types of gated channels (3)

A
  • Voltage gated
  • Ligand gated
  • Mechanically gated
31
Q

d) Give an example on how the sodium channel gradient is used in (do not repeat the same mechanism for any answer): (3)
heart
kidney
intestine

A

i) Heart – Influx of Na+ causes depolarisation which opens L-type Ca2+ channel
ii) Kidney – Reabsorption of Na+ from tubular fluid
iii) Intestine – Transport of Na+ from lumen into enterocyte, causes osmosis – reabsorption of water

32
Q

a) When blood volume decreases, the heart produces less of A. What hormone is A? (1)

A

Atrial Natriuretic Peptide (ANP), Brain Natriuretic Peptide (BNP)

33
Q

b) When volume decreases, the brain makes more B. What is B? (1)

A

Vasopressin

34
Q

c) C is a renal enzyme that turns Angiotensinogen into AT1. What is C? (1)

A

Renin

35
Q

d) What happens to the levels of the enzyme in part C when blood volume decreases? (2)

A

increase

36
Q

e) AT1 is converted to D. What is D? (1)

A

Angiotensin II

37
Q

e) What enzyme in the lung causes the step described above? (1)

A

Angiotensin Converting Enzyme

38
Q

f) When blood volume decreases, what happens to Aldosterone concentrations? (1)

A

Increase

39
Q

g) Explain the mechanisms for changes in concentrations of A, B and aldosterone on blood volume (2 marks)

A

ANP/BNP released in response to atrial stretch detected by baroreceptors (i.e. high BP)
Causes vasodilatation of renal blood vessels
Inhibition of Na reabsorption in proximal tubule and in the collecting ducts
Inhibits release of renin and aldosterone
Reduces BP

High BP atrial stretch ANP release inhibits aldosterone release lowers BP
Low BP signal through afferent fibres to brainstem sympathetic activity release vasopressin increases BP

Atrial stretch detected by baroreceptors

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