1. Which of these answers are correct
The first heart sound, \"lubb,\" is caused by the________.
| closing of the atrioventricular valves |
| closing of the semilunar valves |
| regurgitation of the atrioventricularvalves |
| blood flowing into the ventricles |
2. Choose the right answer:
The plateau phase of the ventricular action potential iscaused by _______.
| slow K+ channels opening |
| fast Na+ channels opening |
| fast voltage-gated Ca2+ channelsopening |
| slow voltage-gated Ca2+ channelsopening |
3.. How is heart rate controlled?
| Parasympathetic and sympathetic divisions of the ANScontrol heart rate. |
| Heart rate is controlled through the cardiacplexus. |
| Dual innervation controls the heart rate. |
| All the listed answers are correct. |
