Answer:
B I think. let me know if I'm right because I might be wrong.
When a microbe that is not part of the normal biota enters the body, it is likely to first encounter first line of host defense.
The term "normal microbiota" describes the microorganisms that are present in every human's conjunctiva, oral mucosa, skin's surface and deeper layers, saliva, and gastrointestinal tracts. The host employs a number of defences to defend against infection.
Mucus, which has a variety of normal microbiota that compete with and may even destroy invasive bacteria and virae, is one of the body's first lines of defence.Once a virus or bacteria penetrates the skin and mucosa, the host may experience changes that lessen the invader's power. A fever is one instance of such a shift.
Therefore, When a microbe that is not part of the normal biota enters the body, it is likely to first encounter first line of host defense.
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Answer:
The first heart sound (S1) represents closure of the atrioventricular (mitral and tricuspid) valves as the ventricular pressures exceed atrial pressures at the beginning of systole (point a). S1 is normally a single sound because mitral and tricuspid valve closure occurs almost simultaneously.
Explanation:
