Ion Flux

Question 1

What is cystinuria?

Answer 1

Autosomal recessive disease caused by defect in the transport system responsible for the uptake of the dimeric amino acid Cystine and dibasic amino acids Arginine, Lysine, and ornithine

Question 2

What does cystinuria result in?

Answer 2

Results in the formation of Cystine crystals or stones in the kidney (renal calculi) which can be identified via a positive nitroprusside test

Patients present with renal cholic (abdominal pain that comes in waves and is linked to kidney stones)

Question 3

What is hartnup disease?

Answer 3

Autosomal recessive disorder caused by a defect in a transporter for non-polar or neutral amino acids
Tryptophan
Found primarily in the kidneys and intestine

Question 4

What are the symptoms of hartnup disease

Answer 4

manifest in infancy as failure to thrive, nystagmus (abnormally repetitive eye movement) intermittent ataxia, tremor, and photosensitivity

Question 5

What mediates the unidirectional movement of Na and glucose across the small intestine and renal tubules?

Answer 5

Sodium glucose transporter called SGLT1

Question 6

What is NCX?

Answer 6

Na-Ca exchanger: antiporter
Function is to maintain low levels of intracellular calcium in cells.
Imports 3Na down their concentration gradient and exports 1 Ca against its gradient
Uses the energy stored in the Na gradient

Question 7

How does D-glucose and D-galactose enter intestinal epithelial cells from the lumen?

Answer 7

Along with Na, monosaccharides transport via secondary active transort mediated by SGLT1 in apical suface

Question 8

How are glucose and galactose transported across the enterocyte into blood stream?

Answer 8

via facilitated diffusion using GLUT2

Question 9

How is fructose transported?

Answer 9

Facilitated diffusion down its concentration gradient using GLUT5 transporter on apical side and GLUT5 transporters on basal side of enterocyte

Question 10

What is the primary active transport that provides the energy for the secondary active transport SGLT1 in enterocytes?

Answer 10

Sodium potassium ATPase

Question 11

What drugs act as contraction inducing drugs?

Answer 11

Cardiotonic drugs: gardiac glycosides (ouabain) and lipophilic drug digoxin

Question 12

What do cardiotonic drugs do?

Answer 12

inhibit the Na/K -ATPase on cardiac myocytes. Leads to increase in intracellular Na and a secondary increase in Ca due to slowing of NCX

Increased sarcoplasmic Ca results in stronger excitation concentration of heart muscle with each action potential

Question 13

What is cystic fibrosis?

Answer 13

autosomal recessive disorder

Thick mucous secretion in lungs interfere with breathing and lead to secondary microbial infections

Question 14

What is Cystic fibrosis caused by?

Answer 14

mutation of CF transmembrane conductance regulator gene. Defective CFTR protein created

Question 15

What is CFTR?

Answer 15

Chloride channel that mediates the active transport of Cl from inside cells to the outside in airways and sweat ducts
Uses ATP hydrolysis

Question 16

How does a defective CFTR cause cystic fibrosis?

Answer 16

Buildup of Cl and salt inside the airway epithelial cells and in sweat. Decreased water content of the surface mucous layer surrounding the airway epithelial cells leads to thicker mucous and leaves the airways susceptible to bacterial infections

*my explanation: Brings the Na from the outside to fight the increase of Cl-. So salt increases, then water increases. So the outside of the cell has less water, the mucous secretion on the outside then becomes really thick and thus causes CF