Please confirm topic selection

Are you sure you want to trigger topic in your Anconeus AI algorithm?

Please confirm action

You are done for today with this topic.

Would you like to start learning session with this topic items scheduled for future?

Review Question - QID 214599

In scope icon M 1 A
QID 214599 (Type "214599" in App Search)
A physiologist is studying the properties of a novel drug by placing the drug in a culture of cardiomyocytes. His culture is set up as a 2 chamber system where the first chamber is directly stimulated with electrodes and the second is isolated from direct electrical connections. The two chambers are connected by a thin layer of cells along the bottom of the plate. During a baseline test of her experimental system, she finds that inducing an action potential in one chamber led to depolarization of both chambers. After adding the drug, the first chamber is still depolarized normally, but the second chamber is non-reactive. The drug being studied most likely affects which of the following types of proteins?

Claudins

4%

6/136

Connexins

60%

81/136

Desmogleins

14%

19/136

E-cadherins

8%

11/136

Integrins

4%

5/136

Select Answer to see Preferred Response

bookmode logo Review TC In New Tab

The system described relies upon porous gap junctions between cardiomyocytes to conduct electricity between cells and cause depolarization in the second chamber. The drug most likely inhibits this spread of depolarization by inhibiting connexin proteins.

Gap junctions are a form of connection between adjacent epithelial cells that allow for movement of small solutes and electrical charges between cells. Gap junctions are formed by connexins, which are transmembrane proteins with 4 membrane spanning domains. A hexameric array of connexins creates a hemichannel in one cell and then docks with a similar array in an adjacent cell to create a full channel. Together, the inner surfaces of these proteins serve as a hydrophilic channel that connects the cells. Physiological functions of gap junctions include solute transport between adjacent glial cells in the nervous system and electrical connection between adjacent cardiomyocytes in the heart.

Incorrect Answers:
Answer 1: Claudins form tight junctions that serve as a diffusion barrier between adjacent cells. These junctions prevent paracellular movement of solutes and allow for establishment of distinct apical and basolateral surfaces.

Answer 3: Desmogleins are a key component of the desmosomes that connect adjacent keratinocytes in the stratum spinosum of the skin. These intercellular junctions provide physical strength and are lost in pemphigus vulgaris. Patients with this disease present with blisters that easily separate with minimal pressure and involve the oral mucosa.

Answer 4: E-cadherins form adherens junctions that link adjacent cells and serve a signaling function with contact inhibition. Loss of these junctions promotes cancer cell metastasis.

Answer 5: Integrins are located between epithelial cells and basement membranes and form hemidesmosomes that are disrupted in the disease bullous pemphigoid. Patients with this disease will present with tense bullae that spare the oral mucosa.

Bullet Summary:
Connexins form gap junctions that allow for transport of solutes and electrical charge between adjacent cells.

Authors
Rating
Please Rate Question Quality

4.2

  • star icon star icon star icon
  • star icon star icon star icon
  • star icon star icon star icon
  • star icon star icon star icon
  • star icon star icon star icon

(5)

Attach Treatment Poll
Treatment poll is required to gain more useful feedback from members.
Please enter Question Text
Please enter at least 2 unique options
Please enter at least 2 unique options
Please enter at least 2 unique options