Answer: The correct answer is option c.
Explanation:
Cardiac conduction system is formed by specialized cardiac muscle cells which enable the heart to contract in coordinated fashion.
The main component of this system are:
- Sinoatrial node
- Atrioventricular node
- Bundle of His
- Branched bundle
- Punkinje fibers
SA node consists of cells known as pacemaker cells. These cells spontaneously generate action potentials which lead to the contraction of atria.
These potentials are then passed to AV node which relay them to bundle of His. These bundles are branched into right and left bundle which ultimately transfer these potentials to Purkinje fibers.
The potentials from these fibers lead to the contraction of ventricles.
I would say the answer is C
Galaxy
- It is a collection of billions of stars.
- Resembling human beings or animals.
- There are billions of galaxies in the Universe.
- There are not many galaxies, which are visible to the naked eyes.
Constellation
- It is a collection of only a few stars.
- Stars in the constellation are arranged in patterns resembling human beings or some animals.
- There are only about 88 constellations.
- There are many constellations, which can be observed with the help of naked eyes.