Actions that are reactions to a stimulus are called

The answer is reflex actions.

A reflex action is an involuntary and rapid reaction to a stimulus. So, when a receptor detects a stimulus, the information is sent to relay neuron through a sensory neuron. Relay neuron sends information to the effector through a motor neuron and effector produces a response.

the level of progesterone is low at the pre-ovulatory phase of the cycle but it gradually increases and the levels are high at the luteal phase. if pregnancy occurs, the level of progesterone will be high throughout the pregnancy.

if egg is fertilized and the mother gets pregnant, progesterone starts preparing the uterus for the implantation. it starts building up the lining of uterus and make it hostile of the period of pregnancy.