Lecture #6

Question 1

Sympathetic input has what kind of effect?

Answer 1

Positive inotropic.

Question 2

When stimulated to contract, cardiac myocytes contract as a single unit due to the presence of gap junctions at the intercalated discs - What do we call this?

Answer 2

Functional Syncytium

Question 3

When do L-type calcium channels open?

Answer 3

When a cardiac action potential is propagated down a transverse tubule.

Question 4

What do we call the calcium influx during excitation, that will stimulate the sarcoplasmic reticulum to release more calcium?

Answer 4

Trigger calcium - Allows for calcium-induced calcium release.

Question 5

Calcium will be actively pumped back into the sarcoplasmic reticulum to achieve what?

Answer 5

Lusitropy - relaxation.

Question 6

Resting tension on a myocyte is influenced by:

Answer 6

1. End-diastolic volume.
2. Preload
   Preload = EDV

Question 7

Down stream pressure from the ventricles that we must overcome to begin ejection phase:

Answer 7

afterload.

Question 8

Positive inotropic will cause an __________ is how much the myocytes can shorten.

Answer 8

increase.

Question 9

How does sympathetic innervation have a positive lusitropic effect?

Answer 9

By increasing the relaxation, by phosphorylating phospholamban.

Question 10

How does sympathetic input shorten the absolute refractory period?

Answer 10

By increasing cell membrane permeability to potassium VIA the delayed rectifier channels.