Dr. Zachow - Lecture 4

Question 1

SERCA

Answer 1

responsible for sequestering calcium back into the sarcoplasmic reticulum.

Question 2

NCX

Answer 2

Sodium-calcium-exchanger. Responsible for taking calcium from intracellular and putting it extracellularly.

Question 3

What two things are used clinically to assess the likelihood of an MI?

Answer 3

Troponins and Creatine Kinase

Question 4

Cardiac Output =

Answer 4

CO=SV x HR

Question 5

Stroke Volume =

Answer 5

SV = EDV - ESV

• This makes sense because stroke volume is everything that is shot out of the left ventricle.
• End diastolic volume is everything that was moved from the left atrium to the left ventricle. Not everything that was moved from atrium to ventricle actually gets shot out of the ventricle. Only about 55-75% of it does. This percentage is called the ejection fraction. The portion that does not get shot out but rather stays in the left ventricle is called the ESV.

Question 6

Type L channels

Answer 6

responsible for the increase in calcium levels in the cardiomyocytes that create the action potentials.

Question 7

Mean arterial pressure =

Answer 7

MAP = CO x TPR

• TPR = total peripheral resistance
• TPR is the total resistance that is seen throughout the vascular system.
• Mean arterial pressure is the average pressure throughout a cardiac cycle.

Question 8

Central venous pressure / right atrial pressure

Answer 8

venous pressure in the right atrium

Question 9

Ejection fraction

Answer 9

EF = SV/EDV

Question 10

How does PKA regulate cardiomyocyte contractility?

Answer 10

PKA is responsible for contraction and relaxation. It phosphorylates phospholamban, which is a mechanism to activate SERCA to lower calcium and facilitate relaxation. However, it also targets and activates (phosphorylates) the Type L calcium channels, which are responsible for the influx of calcium and facilitates contraction. It also phosphorylates and activates Troponin I, which causes an uncoupling of Ca2+ from troponin C, which facilitates relaxation. During the contraction phase, there is more filling of calcium relative to the sequestration and removal of that calcium. During relaxation, more calcium is pumped back out into the interstitium and back into the sarcoplasmic reticulum