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.
Neurons that receive stimuli from the outside environment and transmit them toward the brain are called afferent or sensory neurons. Those that carry impulses in the opposite direction, away from the brain and other nerve centers to muscles, are called efferent neurons, motor neurons, or motoneurons.