Answer:
B. a decrease in the number of pathogens in the body
Explanation:
White blood cell includes immune cell like monocytes, macrophages, neutrophils, basophils, eosinophils, etc. These cells are responsible for fighting with the pathogens or foreign molecules and eliminate them from the body.
So when any pathogens get enter in the body these cell kills those pathogen and protect us from them. Therefore the decrease in the number of pathogens in the body is a direct indication that the white blood cells in the body are working. So the right answer is B.
High pressure to low pressre
The sequence of impulse through the cardiac conduction system starts from SA node passes to AV node to atrioventricular bundle fibers and finally to Purkinje fibers.
Heart is an organ that receives oxygenated blood form lungs and deoxygenated blood from different parts of body. Oxygenated blood is transported to different organs and deoxygenated blood is transported to lungs for oxygenation.
Now, to perform this transportation, the auricles and ventricles of heart contract and relax. In order to contract and relax, impulse generation is required, which begins at SA node or Sinoatrial node. It is also referred to as pacemaker of the heart. SA node contracts the atria and the impulse transfers to AV node or Atrioventricular node.
This is followed by transfer of impulse to atrioventricular bundle fibers which further passes it on to Purkinje fibres for ventricular contraction. Now the blood is sent to lungs and aorta as per it's oxygen status.
Learn more about cardiac conduction system -
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Carbon dioxide :)
hope it helps!
Breaking cells open to release the DNA.
Separating DNA from proteins and other cellular debris.
Precipitating the DNA with an alcohol.
Cleaning the DNA.
Confirming the presence and quality of the DNA.
