The blood pressure is regulated partly by which measure blood pressure and are located in the aorta and carotid arteries.

The answer is Baroreceptors.

Explanation:

Blood pressure is regulated in part by baroreceptors, which are nerve endings sensitive to sudden changes in blood pressure, that is, they are pressure receptors. They are located in the walls of the internal common carotid artery (carotid sinus) and the Aorta (aortic arch).

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.