CBSE Class 11-science - Circulatory Pathways: Human Circulatory System, Cardiac Cycle, ECG Videos

• What is likely to  happen if artery of heart gets constricted due to the accumulation of plaque on its inner wall
• question no. 19
  
• What is open vascular system  
• A: elevated levels of sodium Ion increase the heart rate and contact ility R: elevated sodium Ion level increase excitability of s a node
• A: The resting heart rate about 75 per minutes usually is lower than the autorhythmic rate of SA node (90 to 100 beats per minute) R: at resting condition the parasympathetic effects dominates
• Why do cardiac muscles never get tired?
• the right answer in option A but here it is showing option C
  
• what will happen if pacemaker is non functional  a. only cardiac muscle will contract rhytically b. the cardiac muscle will not contract in a cordinated manner rhythmically c. cardiac muscle will contract rhythmically in a cordinated manner
• Name the two phyla which exhibit the open circulatory system.
• Name the germinal layer from which the heart is derived in humans.

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