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.
The efferent neurons are also known as motor neurons: they bring the responses from the brain to the muscles and the glands. An analogy for afferent and efferent neurons is that they are like one-way streets: on a given neuron the traffic can only travel in one direction: to or from the CNS.