Additional causes of bleeding in early pregnancy include: 1  Cervical changes. During pregnancy, extra blood flows to the cervix. 2  Infection. Any infection of the cervix, vagina, or a sexually transmitted infection (such as chlamydia, gonorrhea, or herpes) can cause bleeding in the first trimester.
A: Afferent neurons are special nerve cells that are responsible for carrying nerve impulses from the receptors to the central nervous system. Efferent neurons carry nerve impulses from the central nervous system to the muscles and glands. Continue Reading.
Afferent nerves are responsible for relaying sensation from the body to the central nervous system (CNS); efferent nerves are responsible for sending out commands from the CNS to the body, stimulating muscle contraction; they include all the non-sensory neurons connected with skeletal muscles and skin.