Answer:
a. QRS
Explanation:
In Human anatomy, cardiac cycle can be defined as a complete heartbeat of the human heart which comprises of sequential alternating contraction and relaxation of the atria and ventricles, therefore causing blood to flow unidirectionally (one direction) throughout the human body.
Generally, the cardiac cycle occurs in two (2) stages;
Diastole : in this stage, the ventricles is relaxed and would be filled with blood.
Systole: at this stage, the muscles contracts and thus, allow blood to be pushed through the atria.
The right atrioventricular valve (AV) comprises of three (3) leaflets (flaps) which opens and closes in order to allow for the flow of blood from the right atrium of the human heart to the right ventricle. Also, the right atrioventricular valve is saddled with the responsibility of preventing blood from flowing backward in the mammalian heart.
The QRS complex represents the time necessary for the impulse to travel through the bundle of His, the bundle branches, and the Purkinje fibers to complete ventricular activation or contraction, known as ventricular depolarization. QRS is simply a combination of the Q-wave, R-wave and the S-wave which represents electrical impulses.
Answer:
Regarding pathogens, the statement that is true is that viruses cannot reproduce on their own.
Explanation:
Viruses are pathogenic agents not considered as living beings, since they are only constituted by genetic material surrounded by a viral capsid, besides not fulfilling vital functions.
These agents are unable to reproduce on their own, so they need to place their genetic material —DNA or RNA— inside a host cell, to modify its nuclear DNA and be able to reproduce.
The other options are not correct because:
- <u><em>Influenza can cause an upset stomach</em></u><em>. Influenza primarily affects the respiratory system.</em>
- <u><em>Pathogens affect everyone equally.</em></u><em> Each individual's immune response is different when exposed to the same pathogen.
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- <u><em>Fungi are large, stoneflies organisms</em></u><em>. The pathogenic fungi, such as Candida albicans and Trichophyton, are different from the mushrooms and fungi that can be seen in soil or decomposed organic matter.</em>
true. Nicotine patches have been shown to improve patients states of depression, but only in short term.