Answer:
QRS represents ventricular depolarization. This depolarization initiates ventricular contraction which closes the mitral and tricuspid valves. It is the closure that is heard as the first heart sound.
Explanation:
Answer: The answer is Erosion
Explanation: It is probable that the natural process of Erosion caused the exposed layers of rock in The Valley.
Answer:
Explanation:
Elderly people are particularly at risk of vitamin B12 deficiency because of the high prevalence of atrophic gastritis-associated food-cobalamin (vitamin B12) malabsorption, and the increasing prevalence of pernicious anaemia with advancing age.