Lab 5 Discussion Questions

Question 1

What frog heart structure is analogous to the vena cava?

Answer 1

Sinus venosus

Question 2

What frog heart structure is analogous to the aorta?

Answer 2

Conus arteriosus

Question 3

What frog heart structures keeps oxygenated and deoxygenated blood separate?

Answer 3

• Trabeculae (spongy folds) w/in the ventricular wall

- Spiral valve w/in the conus arteriosus

Question 4

What frog heart structure directs blood flow to the systemic or pulmonary circulations?

Answer 4

Spiral valve

Question 5

What frog heart structure is analogous to the AV node?

Answer 5

AV myocardium

Question 6

What does the P wave represent?

Answer 6

Atrial depolarization

Question 7

What does the QRS complex represent?

Answer 7

Ventricular depolarization

Question 8

What does the T wave represent?

Answer 8

Ventricular repolarization

Question 9

Why is it difficult to stimulate early diastole?

Answer 9

Relative refractory period was just beginning

Question 10

Explain the all-or-none principle.

Answer 10

As long as voltage used is above threshold voltage, the heart will contract

Question 11

What is the Frank-Starling Law of the heart?

Answer 11

Increased diastolic filling produces greater stretch of the heart muscle, resulting in a larger SV

Question 12

During the relative refractory period, increasing stimulus size can elicit an AP due to what?

Answer 12

Some Na+ inactivation gates are closed

Question 13

What occurs on a cellular level during bradycardia?

Answer 13

Activation of muscarinic receptors leads to hyperpolarization by opened K+ channels