Answer:
There are 2 Valve Systems
Explanation:
The mitral valve and tricuspid valve are located between the atria (upper heart chambers) and the ventricles (lower heart chambers).
Answer: Possibly, a pulmonary exercise stress test.
Explanation:
Answer:
the external appearance of a plant community, which changes throughout the year in accordance with the succession of the phases of development of plants. As a rule, aspect is repeated year in and year out in almost identical sequence.
Answer:
antibodies
Explanation:
The third line of defense is specific resistance. This system relies on antigens, which are specific substances found in foreign microbes. Most antigens are proteins that serve as the stimulus to produce an immune response. The term "antigen" comes from ANTI-body GENerating substances.
