Ion Flux Through Membranes

Question 1

What are examples of secondary active transporters?

Answer 1

Na+/Glucose symporter
Na+/Ca2+ antiporter
Cl-/HCO3- antiporter

Question 2

What is an autosomal recessive defect in transport systems that causes kidney stones and is identified with a nitropruside test?

Answer 2

Cystinuria

Question 3

What is an autosomal recessive defect in transporters in the kidneys/intestines that manifests in failure to thrive, nystagmus, intermittent ataxia, tremor, and photosensitivity

Answer 3

Hartnup Disease

Question 4

GLUT2, GLUT5, SGLT1 (secondary), & Na+/K+ ATPase (primary) transporters take up what molecule?

Answer 4

Dietary monosaccharides

Question 5

What does cardiotonic mean?

Answer 5

Contraction-inducing

Question 6

How do cardiotonic drugs work?

Answer 6

Inhibit Na+/K+ ATPase –> + intracellular Na+ –> + intracellular Ca2+ –> + SR Ca2+ –> stronger contraction of the heart

Question 7

How does a defective Cl- transporter lead to cystic fibrosis?

Answer 7

CFTR gene mutation…CFTR mediates Cl- out of cell and into airway, uptake of Cl- in sweat ducts
Buildup of Cl- in airway and sweat
Na+ and H2O move into airway no b/c of - charge
Decreased H2O on surface mucous layer creates thick mucous

Question 8

Where are the main 4 GLUT transporters found and what is their km value?

Answer 8

GLUT1: RBCs, brain… km=1
GLUT2: Liver… km=10
GLUT3: Neurons… km=1
GLUT4: Skeletal muscle, heart, fat…km=5

Question 9

What are examples of primary active transporters?

Answer 9

Na+/K+ ATPase

Ca2+ ATPase