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
Where is GLUT3 found?
Brain
Where is GLUT4 found?
Skeletal muscle
What is GLUT4 function dependent on?
Insulin
Where is GLUT5 found?
Small intestine
What does GLUT5 transport?
Fructose
What are two transporters of glucose which display secondary active transport, and where are they found?
1- SGLT1
2- SGLT2
3- Small intestine
What part of the Sodium potassium pump is the catalytic driver?
The 2 alpha units
