This is a series of questions covering the learning outcomes of the lecture. Best of luck!
Reviewed by Daniel Mercer on 24 June 2019
Tubular processing and electrolyte balance
Why does tubular secretion occur?
If there is too much solute being filtered, it is also secreted
If there are substances that cannot cross the filtration barrier
It does not
If there is too much substance being reabsorbed
A patient presents with glycosuria and proteinuria, which portion of the nephron is most likely to be affected?
Distal convoluted tubule
Proximal convoluted tubule
Loop of Henle
Why do people get glycosuria?
Glucose transporters on the proximal convoluted tubule have a maximum rate at which they can uptake glucose (transport maximum - tm), so when glucose concentration exceeds tm, glucose is lost in the urine.
Because they develop an acute episode of diabetes
Feedback from high levels of blood glucose decrease the number of glucose transporters on the PCT
The body already has more glucose than it needs, so it is then eliminated in urine
What is the body’s main way of eliminating excess sodium to maintain homeostasis?
By down-regulating sodium transporters in the nephron
By causing diuresis, as water normally follows sodium down its concentration gradient
By sequestering sodium in cells
By converting it into sodium bicarbonate
A patient presents with palpitations, fatigue and on routine ECG peaked T waves are observed. A medication is prescribed for the immediate decrement of serum potassium, that is normally given in the management of T2DM. Which of the following best fits this prescription?
Selective COX2 inhibitor
Conformational change to activate GLUT4
Blocks sodium voltage gated channels
Which of the following is not a way in which the body regulates potassium concentration?
Increasing tubular flow rate
Release of renin from the kidney
Your patient presents to you smelling of pear drop, has an increased rate of breathing and tachycardia. You take their bloods and find that they have hypokaleamia. How can this be explained?
Both protons and potassium ions are cations. The increased concentration of cations in the ECF prevents potassium from being uptaken by the cells.
The acidic environment increases cation concentration in the extracellular fluid, drawing potassium out of the cell by diffusion to correct the cell membrane potential
The patient is in an acidotic state. The protons in the filtrate of the kidney displace sodium at the sodium and potassium ATPase which increases its activity. This drives more potassium out of cells into the filtrate, decreasing its concentration in the ECF
The increased acidity of the blood denatures the potassium channels specifically (as these are more susceptible to denaturation) thus preventing the uptake of potassium into the cell.
Which of the following is not a cause of hypokalaemia?
Reduced potassium intake from diet
Increased salt intake
A patient presents to your GP practice complaining of muscle weakness and anxiety. You check their pulse and find that they have an arrhythmia. In which condition are these symptoms more likely to occur?
Both hyper and hypokalaemia