There are instances
that when we are exposed to virus or bacteria, the antigen A in our body try to
fight but still we get sick, take some medication and we are then healed. Then,
another exposure to a new virus or bacteria, the antigen B reacts weakly for
our immune system do not recognized the foreign pathogen that invade the body
resulting to slight sore throat after visiting your sister at school.
Answer:
Osteons are cylindrical structures that contain a mineral matrix and living osteocytes connected by canaliculi, which transport blood. They are aligned parallel to the long axis of the bone. Each osteon consists of lamellae, which are layers of the compact matrix that surround a central canal called the Haversian canal.
1 I think this is the right answer
