Explain the menstrual cycle in human females.

The menstrual cycle is the regular natural change that occurs in the female reproductive system. It makes pregnancy possible. The cycle is required for the production of ovum and the preparation of the uterus for pregnancy. This cycle completes in 28 days. The menstrual phase is divided into 4 phases: Menstruation (1-4 days): It lasts about four days. If fertilization does not occur in the secondary oocyte undergo autolysis and progesterone inhibits the release of LH from the pituitary gland. The reduction in the LH level causes the regression of Corpus luteum which leads to falling in the progesterone level in the blood. The uterine lining due to deficiency of progesterone dies off and blood vessels rupture which causes bleeding through the vaginal hole. Follicular phase (5-13 days): This phase occurs from 5 th to 14 th day. The anterior pituitary secretes follicle-stimulating hormone that helps in the growth of selected primary ovarian follicles and maturation of primary oocytes in this follicle. The graafian follicle is formed. The estrogen hormone is also secreted under the stimulation from the FSH hormone. Estradiol inhibits the secretion of FSH and stimulates the secretion of luteinizing hormone. Luteinizing hormone plays a role in ovulation. The egg is released into the fallopian tube. Estradiol also prepares the uterus for implantation. Ovulatory phase (14th day): There is no change in endometrium thickness. Luteal phase (15-28 days): It involves the formation of corpus luteum from empty graafian follicle cells. Corpus luteum is a yellow coloured body that secretes another ovarian hormone named progesterone. Progesterone and estradiol continue the hypertrophy of the endometrial lining in the uterus The progesterone hormone inhibits the secretion of hormones from the proliferative phase so, it may not develop additional follicles and eggs.

Draw a diagram of mature human sperm. Label any three parts and write their functions.

The sperm is divided into three parts Head, Middle piece, and Tail. The functions of different parts of the sperm are mentioned below: Head: The anterior part of the sperm is the head. It consists of an acrosome at its tip and a haploid nucleus is present behind it. Middle piece: The region below the head is the middle piece. This region is rich in mitochondria. Mitochondria provide the necessary energy in the form of ATP to the sperm for motility. Tail: This is the last part of the sperm. It is flagellar in nature, due to which it can propel and move forward in the female reproductive system.

Medically it is advised to all young mothers that breastfeeding is the best for their newborn babies. Do you agree? Give reasons in support of your answer.

During pregnancy, the maternal pituitary gland secretes prolactin that stimulates the growth and differentiation of mammary glands. A process called lactation occurs during pregnancy, which facilitates secretion of milk. The fluid secreted during the initial days after parturition is called colostrum. Breastfeeding is best for new-born babies because, breast milk has antibodies are required for the new-born baby to develop immunity and resistance against diseases. This provides passive immunity to the babies. Colostrum is thick, sticky and yellowish fluid rich in proteins and antibodies but contains no fat. Most importantly, colostrum contains IgA (secretory immunoglobulin) that protects the mucous membranes of the upper respiratory tract. Breastfeeding the new-born is recommended by doctors for bringing up a healthy child.