Advertisements
Advertisements
Question
Sino-atrial node is called the pacemaker of our heart. Why?
Advertisements
Solution
- The sino-atrial (SA) node is a specialised bundle of neurons located in the upper part of the right atrium of the heart. The cardiac impulse originating from the SA node triggers a sequence of electrical events in the heart, there by controlling the sequence of muscle contractions that pumps blood out of the heart.
- Since the SA node initiates and maintains the rhythmicity of the heart, it is known as the natural pacemaker of the human body.
- Its fibres have a resting potential of 55 to 60 millivolts, whereas in cardiac muscles it is 85 to 95 millivolts and in the specific conducting fibres spread in the heart it is 90 to 100 millivolts. The heart beat starts due to the leakage of sodium ions from the inferior vena cava (SAN).
APPEARS IN
RELATED QUESTIONS
Describe the evolutionary change in the pattern of heart among the vertebrates.
Conversion of ammonia into uric acid occurs through --------------
A patient’s chart reveals that he has a cardiac output of 7500 mL per minute and a stroke volume of 50 mL. What is his pulse rate (in beats/min)
At any given time there is more blood in the venous system than that of the arterial system. Which of the following features of the veins allows this?
Distinguish between mitral valve and semi lunar valve.
Right ventricular wall is thinner than the left ventricular wall. Why?
Select the correct biological term.
Destroyed in the liver and spleen after circulating in the blood for four months.
Define the following terms and give their location?
Purkinje fibre
Write the features that distinguish between the two.
Open and Closed circulatory system
Write the features that distinguish between the two.
Sino-atrial node and Atrio-ventricular node
Answer the following:
Which part of heart is responsible for initating and maintaining its rhythmic activity?
Answer the following:
What is specific in the heart of crocodiles among reptilians?
In the diagrammatic presentation of heart given below, mark and label, SAN, AVN, AV bundles, bundle of His and Purkinje fibres.
Cardiac activities of the heart are regulated by ______.
- Nodal tissue
- A special neural centre in the medulla oblongata
- Adrenal medullary hormones
- Adrenal cortical hormones
Choose the correct answer from the options given below:
Following are the stages of pathway for conduction of an action potential through the heart:
- AV bundle
- Purkinje fibres
- AV node
- Bundle branches
- SA node
Choose the correct sequence of pathway from the options given below:
