Cervical effacement (also called cervical ripening) refers to a thinning of the cervix. It is a component of the Bishop score. It can be expressed as a percentage. Prior to effacement, the cervix is like a long bottleneck, usually about four centimeters in length. Throughout pregnancy, the cervix is tightly closed and protected by a plug of mucus. When the cervix effaces, the mucus plug is loosened and passes out of the vagina.
A reflex arc is a neural pathway that controls a reflex action. In higher animals, most sensory neurons do not pass directly into the brain, but synapse in the spinal cord.hen the patellar tendon is tapped just below the knee, the patellar reflex is initiated and the lower leg kicks forward (via contraction of the quadriceps). The tap initiates an action potential in a specialized structure known as a muscle spindle located within the quadriceps.
When the safety of an organism demands a very quick response, the signals may be passed directly from a sensory neuron, via a relay neurone, to a motor neurone motor: motor neurones carry messages out of the CNS to effector organs for instant, unthinking action. This is a reflex action.A reflex arc is the nerve pathway which makes such a fast, automatic response possible. It does not matter how brainy you are-you will always pull your hand away from a flame without thinking about it. It is in-built, or innate, behaviour, and we all behave in the same way.imple reflexes produce rapid involuntary responses to a stimulus. This ensures that an animal responds in the way most likely to result in its survival. Examples include: 1  moving towards and finding food.