week 2 preclass activity quizz

 

Question 2

0 / 1 pts

When I teach this in person, I like to make an analogy between pacemaker cells, contractile cells, and the autonomic nervous system (ANS). Remember that the ANS is divided into sympathetic (speeds up heart rate) and parasympathetic (slows down heart rate).

 

Consider how lights can be turned on/off and that some have a dimmer switch:

 

I would argue that each component: pacemaker, contractile cells and autonomic nervous system match the way this lighting system works. Check your understanding by matching the terms below.

Correct!

Pacemakers are autorhythmic and determine when contractile cells will depolarize.

 

               Light switch on/off             

Correct!

ANS can determine how fast or slow pacemaker and contractile cells depolarize and therefore speed up/slow down heart rate.

 

               Dimmer switch (controls how bright/dim lights are)             

Correct!

Contractile cells are THE cardiac muscle cells that generate contractions (pumping/beating) of the heart. They follow the pace set by pacemakers & ANS.

 

               The actual light (how bright or on/off)             

How are contractile and pacemaker cells connected? Select all

Correct!

  

They have continuous channels and share ions, forming a network of cells called a syncytium.

 

  

There are two syncytia: atrial and ventricular. This explains why the atria contract at once and the ventricles contract second.

 

You Answered

  

If connections between pacemaker & contractile cells are most similar to a chemical synapse.

 

Correct Answer

  

If connections between pacemaker & contractile cells are most similar to an electrical synapse.

 

How does the heart pump? How does it know when to beat?

  

Contractile cells set the pace/rhythm of beats. Autorhythmic cells cause cardiac muscle contractions

 

Correct!

  

Autorhythmic cells set the pace/rhythm of beats. Contractile cells cause cardiac muscle contractions