Active Transport and the Sodium Pump Flashcards
How is the steady-state intracellular ionic concentrations maintained across the membrane?
1- Constant movement of ions
2- Passive diffusion and active transport
Describe the structure of the sodium-potassium pump.
1- Globular protein tetramer, two α proteins and two β proteins 2- α subunit 95000 MW 3- β subunit 40000 MW 4- Total weight 270000 MW 5- Two ATP binding sites 6- Two cardiac glycoside binding sites (inhibit) 7- 3 Na+ bind internally on α proteins 8- 2 K+ bind externally on α proteins
How can the sodium pump be inhibited?
Removing K+
How can the sodium pump be stimulated?
Increasing Na+
What are cardiac glycosides?
1- Steroid glycoside molecule attached to sugar and R group
2- Increase force/output of heart muscles
3- Decrease heart rate
In regards to cardiac glycosides and the sodium pump, what happens when the concentration of K+ is decreased?
Affinity between cardiac glycosides and sodium pump increases
How is therapeutic index calculated?
Dose producing toxicity in 50% of population/minimum effective dose for 50% of population
What is the use of remifentanil and what is its therapeutic index?
1- Synthetic opiod
2- Patient controlled analgesia during labour
3- 33000:1
What is the use of diazepam and what is its therapeutic index?
1- Sedative
2- 100:1
What is the use of ethanol (medicinally) and what is its therapeutic index?
1- Sedative
2- 10:1
What is the use of digoxin and what is its therapeutic index?
1- Congestive heart failure
2- 2:1
What happens when blood potassium concentration is too low?
1- Hypokaelaemia 2- Low if less than 3.5 mEq/L 3- Moderate if between 2.5-3.0 mEq/L 4- Severely low if less than 2.5 mEq/L 5- Abnormal heart rhythms 6- Rhabdomyolysis: muscle damage 7- Muscle weakness or spasms 8- Paralysis 9- Increased digoxin binding
What are the symptoms of hypokalaemia?
1- Abnormal heart rhythms
2- Rhabdomyolysis: muscle damage
3- Muscle weakness or spasms
4- Paralysis
What is the range for normokalaemia?
3.6-5.2 mEq/L
What happens when blood potassium concentration is too high?
1- Hyperkalaemia 2- High is more than 5.5 mEq/L 3- Moderate if between 6.1-6.9 mEq/L 4- Severely high if higher than 7.0 5- Nausea 6- Palpitations 7- Muscle weakness
What are the symptoms of hyperkalaemia?
1- Nausea
2- Palpitations
3- Muscle weakness
In regards to digoxin, what happens when the concentration of potassium is decreased?
Increased digoxin binding
What is the role of diuretics?
1- Increase urine output by the kidneys
2- Treatment for HBP and excessive fluid retention
What are the side effects of diuretics?
Increased urinary secretion of potassium
What may happen when patients are on both digoxin and diuretics?
1- May become hypokalaemic
2- Lower concentration of K+ leads to inceased digoxin binding to Na+ pump
3- May lead to digoxin toxicity
How is digoxin toxicity treated?
1- Digibind
2- Rapidly binds to digoxin, causing it to dissociate from sodium pump and reverses toxicity
What are the five types of glucose transporters?
1- GLUT1 2- GLUT2 3- GLUT3 4- GLUT4 5- GLUT5
Where is GLUT1 found?
1- Placenta
2- Brain
Where is GLUT2 found?
1- Liver
2- Pancreatic β cells
