THORAX ABDOMEN AND PELVIS

Detailed explanation-1: -At the beginning of the follicular phase, the lining of the uterus (endometrium) is thick with fluids and nutrients designed to nourish an embryo. If no egg has been fertilized, estrogen and progesterone levels are low. As a result, the top layers of the endometrium are shed, and menstrual bleeding occurs.

Detailed explanation-2: -If fertilization does not occur, the endometrium, coupled with blood and mucus from the vagina and cervix (the lower, narrow part of the uterus located between the bladder and the rectum) make up the menstrual flow (also called menses) that leaves the body through the vagina.

Detailed explanation-3: -The menstrual cycle is complex and controlled by many different glands and the hormones that these glands produce. The four phases of the menstrual cycle are menstruation, the follicular phase, ovulation and the luteal phase. Common menstrual problems include heavy or painful periods and premenstrual syndrome (PMS).

Detailed explanation-4: -If the egg does not become fertilized, the lining of the uterus (endometrium) is shed during menstruation. The average menstrual cycle lasts 28 days. The cycle starts with the first day of one period and ends with the first day of the next period. The average woman ovulates on day 14.