This lecture relates to the learning outcomes covered in the lecture on regulation of urine volume and fluid balance. Good luck!

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Regulation of urine volume and fluid balance

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Question 1

1a. Which of the following is not a symptom of hypovoleamia?

A
Thirst
B
Dizziness on standing
C
Confusion
D
Goitre
Question 2

You are asked to see a patient that was discharged a week ago from your ward. During a quick end of bed inspection you notice that their JVP is raised, have effortful breathing, and appear to have enlarged calves. What do you suspect has occurred?

A
Due to a physiological abnormality, fluid from the blood vessels has moved into the interstitial fluid , creating an excess fluid in places where it is not normally present. In this case the patient has developed oedema in their calves and potentially in their lungs which can be leading to the shortness of breath.
B
The patient has a chest infection
C
The patient has gained weight, the excess fat is pushing on their chest, making is more difficult to breath
D
They are having a heart attack
Question 3

Describe the purpose of regulating blood fluid volume

A
The body needs to change cellular fluid composition regularly
B
So that cells can maintain and isotonic solution for optimal functioning
C
So humans don’t carry around excess weight
D
So that waste can be excreted
Question 3 Explanation: 
Fluid and electrolyte regulation occurs by moving ions and water through different compartments. This can result in fluctuating intracellular concentrations that can be detrimental if they are significant deviations from the norm ( example a hypotonic cell can result in cell lysis under extreme conditions)
Question 4

Upon examination of a patient with kidney failure, you notice that they appear “puffy”. What could explain this observation?

A
Due to kidney failure, the patient is unable to excrete excess fluid from the blood and the fluid has thus diffused into their extracellular, giving them a swollen appearance
B
Due to a system wide inflammatory process, their entire body has become swollen
C
They have gained weight due to their inability to excrete cholesterol
D
They have lost the ability to utilise fat, so it is being inappropriately stored
Question 5

What is the amount of waste solutes that must be excreted by the body daily?

A
400 mOsm/day
B
200 mOsm/day
C
600 mOsm/day
D
800 mOsm/day
Question 6

What is the maximum possible concentration of urine?

A
1000 mOsm/L
B
1100 mOsm/L
C
1200 mOsm/L
D
1300 mOsm/L
Question 7

What is the normal concentration of filtrate?

A
400 mOsm/day
B
200 mOsm/day
C
300 mOsm/day
D
800 mOsm/day
Question 8

Given the equation Osmoles excreted/day (osmoles) = urine osmolarity (Osm/L) x urine output (L/day). What is the minimal urine output of a human in a day?

A
500 ml/day
B
900 ml/day
C
1 L/day
D
2 L/day
Question 8 Explanation: 
600 mOsm/day /1200 mOsm/L = 0.5L/day
Question 9

Which of the following is not a cause of polyuria?

A
Excess salt intake
B
Diabetes insipidus
C
Excess water intake
D
Excess fat intake
Question 10

You are monitoring a patient’s urine output on the ward and notice that they have oliguria, what cannot explain this?

A
They are not drinking enough fluid
B
They have decreased renal perfusion
C
They are dehydrated
D
They have taken caffeine
Question 11

Where is most water absorbed in the nephron?

A
Proximal convoluted tubule
B
Descending loop of Henle
C
Distal convoluted tubule
D
Collecting duct
Question 11 Explanation: 
Proximal convoluted tubule 65%, descending loop of Henle 20%, Distal convoluted tubule under the control of ADH
Question 12

A patient that had previously been treated on the ward has made a GP appointment to investigate her unquenchable thirst and needing to use the toilet more than 10 times per day. What part of the uriniferous tubule  is most likely to be affected?

A
Proximal convoluted tubule
B
Thick ascending loop of Henle
C
Thick descending loop of Henle
D
Collecting duct
Question 12 Explanation: 
This patient is showing symptoms of Diabetes insipidus. This can occur during a traumatic brain injury if a patient sustains damage to their hypothalamus or pituitary gland. The paraventricular and supra optic nuclei of the hypothalamus are responsible for the production of ADH and the posterior pituitary gland is responsible for its secretion.
Question 13

What are the main contributors to the hyper osmotic interstitium in the kidney that maintains the concentration gradient higher than that of the filtrate, allowing osmosis to occur?

A
sodium, potassium, chlorine
B
Sodium, calcium, chlorine
C
Urea sodium, chlorine
D
glucose, sodium, potassium
Question 14

A patient is administered furosemide and you find that the osmolarity of their urine has increased. What are the consequences of this?

A
Furosemide breaks down into multiple ions in the kidney filtrate, rendering the filtrate more concentrated, thus less water will want to leave the filtrate
B
There are less ions that can now contribute to the counter current exchange system, leaving the interstitum more diluted.Now less water will thus flow out of the filtrate and diuresis occurs.
C
The patient will feel thirsty and want to drink more water in order to have enough fluid to excrete the right osmolarity of concentrated urine
D
Furosemide exerts its effect on the RAAS system and not on the kidney directly
Question 15

What hormone is used to control the excretion of water in proportion to intake or restriction?

A
Renin
B
ADH
C
Oxytocin
D
TSH
Question 15 Explanation: 
ADH controls whether high amounts of dilute or concentrated urine is formed. In the absence of ADH, urine is very dilute. In the presence of ADH, Urine is concentrated
Question 16

Your patient presents with polyuria and polydipsia. Which of the following is not a differential you would consider?

A
Diabetes insipidus
B
Diabetes mellitus
C
Hyperthyroidism
D
Hyper parathyroidism
Question 17

Where is ADH produced?

A
Paraventricular nucleus of the hypothalamus
B
Suprachiasmatic nucleus of the thalamus
C
Arcuate nucleus of the hypothalamus
D
Dosal nucleus of the hypothalamus
Question 18

You are reading the results of a genetic screening and find that your patient has a mutation that codes for aquaporin 1. Which part of the nephron will have reduced water reabsorption capabilities?

A
Proximal convoluted tubule
B
Loop of Henle
C
Early distal convoluted tubule
D
Collecting duct
Question 18 Explanation: 
The proximal convoluted tubule contains Aquaporin 1 channels. The collecting duct is not part of the nephron but it contains Aquaporin 2 channels on the apical membrane and Aquaporin 3 and 4 channels on the basolateral membrane.
Question 19

Which of the following is not a main stimulus for ADH release?

A
Increased plasma osmolarity
B
Hypovoleamia or decreased blood pressure
C
Nausea
D
Alcohol
Question 19 Explanation: 
Alcohol is an ADH inhibitor
Question 20

A patient presents to you in clinic with headaches, vomiting, confusion, mood swings, hallucinations. Blood results:  hyponatreamia and decreased blood plasma osmolarity. A year ago they underwent surgery to remove their pituitary adenoma. Urinalysis: increased urine sodium. How do you interpret these results?

A
A mutation in their sodium channels is causing an increased output of sodium
B
Inappropriate over secretion of ADH
C
A cranial infection such as Meningitis
D
A diuretic that is working above its therapeutic range
Question 21

How would you distinguish cranial vs nephrogenic diabetes insipidus during a fluid deprivation test?

A
They are indistinguishable
B
During a fluid deprivation test you would see an increased concentration of urine if it was cranial relative to nephrogenic
C
During a fluid deprivation test you would see a decreased concentration of urine if it was cranial relative to nephrogenic
D
During a fluid deprivation test, you would see oedema with nephrogenic diabetes insipidus
Question 22

What treatment is normally given for diabetes insipidus?

A
Insulin
B
Metformin
C
Synthetic ADH
D
IV fluids
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