- The female reproductive system includes ovaries, oviducts (fallopian tubes), uterus, cervix, vagina, external genitalia and mammary glands, all located in the pelvic region.
- Ovaries produce female gametes (ova) and ovarian hormones; each ovary has an outer cortex and inner medulla.
- The fallopian tubes collect the ovum through fimbriae, and fertilisation usually occurs in the ampulla region.
- The uterus (womb) is a pear-shaped organ with three layers—perimetrium, myometrium and endometrium—and supports pregnancy and childbirth.
- Mammary glands produce milk for nourishment of the newborn, and external genitalia play roles in protection and sexual functions.
Definitions [14]
Definition: Reproduction
Reproduction is a process that results in the formation of new individuals of the same kind, though usually with slight genetic, structural and physiological variations.
Define the term puberty.
Puberty is the process of physical and hormonal changes by which a child’s body matures into an adult body capable of sexual reproduction to enable fertilization.
Definition: Gametogenesis
Gametogenesis is the process by which male and female primary sex organs produce gametes (sperms and ova).
Definition: Oogenesis
The formation of ova in the ovary from primordial germinal cells is said to be oogenesis.
Definition: Menstrual Cycle
The rhythmic series of changes in the sex organs throughout the reproductive life of a female primate (e.g., monkeys, apes, and human beings) from puberty to menopause is called the menstrual cycle (L. mensis = month, lunar month).
Define ovulation.
The release of the ovum from the ovary is called ovulation.
Define: Menarche
It is the stage when a girl menstruates for the first time.
Define.
Fertilization
The formation of a zygote by the union of male and female gametes is known as fertilization.
Definition: Fertilization in Human
The fusion of the male gamete (sperm) and female gamete (ovum) to form a zygote is called fertilisation.
or
Formation of zygote by union of sperm and ovum is called as fertilization.
Definition: Implantation
The process of the blastocyst embedding itself into the endometrial lining of the uterus about 5–7 days after ovulation is called implantation.
or
The process of fixing of the blastocyst to the wall of the uterus/endometrium is termed implantation.
Definition: Gastrulation
Gastrulation is the early developmental process in which the embryo changes from a single-layered blastula into a three-layered structure called the gastrula.
Definition: Placenta
Placenta is a temporary organ formed during pregnancy that connects the foetus to the uterine wall and allows exchange of nutrients, gases and wastes between the mother and the foetus.
Definition: Parturition
After nine months of pregnancy, the fully developed foetus is ready for delivery. The process of childbirth is called parturition.
or
Parturition is the act of expelling the full term foetus from the mother's uterus at the end of gestation.
Definition: Lactation
The term lactation refers to the secretion and ejection of milk by the mammary glands.
Key Points
Key Points: Human Reproduction
- Human reproductive organs are divided into primary (gonads) and accessory parts.
- Primary gonads: Testes in males produce sperms; ovaries in females produce eggs.
- Accessory organs include ducts and glands that aid in fertilisation and embryo development.
- Secondary sexual characters (e.g., beard, breasts) are not reproductive parts, as they do not directly participate in reproduction.
Key Points: Male Reproductive System
- The male reproductive system consists of a pair of testes, accessory ducts, accessory glands and external genitalia.
- Testes are located in the scrotum, which maintains a lower temperature required for spermatogenesis.
- Seminiferous tubules in the testes produce sperms; Sertoli cells provide nourishment, and Leydig cells secrete androgens.
- Accessory ducts (rete testis, vasa efferentia, epididymis and vas deferens) transport and store sperms before ejaculation.
- Accessory glands add secretions to form seminal plasma, and the penis acts as the organ for copulation and insemination.
Key Points: Female Reproductive System
Key Points: Structure of Sperms
| Part of Sperm | Structure | Major Components | Function |
|---|---|---|---|
| Head | Conical | Haploid nucleus, acrosome | Carries genetic material; enzymes help in fertilization |
| Neck | Short region | Proximal and distal centrioles | Connects head to tail; initiates zygote division |
| Middle piece | Cylindrical | Axial filament, mitochondrial sheath | Supplies energy for movement |
| Tail | Long flagellum | Axial filament, plasma membrane | Locomotion of sperm |
Key Points: Major Events of Menstrual Cycle
| Phase of Menstrual Cycle | Duration (Days) | Hormonal Changes | Major Events |
|---|---|---|---|
| Menstrual phase (Bleeding phase) | 1–5 | Decrease in estrogen and progesterone due to degeneration of corpus luteum | Shedding of endometrium with blood, mucus and unfertilized ovum |
| Proliferative phase (Follicular phase) | 6–13 | Gradual increase in FSH, LH and estrogen | Growth of Graafian follicle; regeneration and thickening of endometrium |
| Ovulatory phase | 14 | LH surge (peak of LH and FSH) | Rupture of Graafian follicle and release of ovum (ovulation) |
| Secretory phase (Luteal phase) | 15–28 | Increased progesterone from corpus luteum | Endometrium becomes vascular and glandular; prepares for implantation; corpus luteum degenerates if no fertilization |
Key Points: Fertilization in Human
- Fertilisation is the union of sperm and ovum to form a zygote and is internal in humans.
- During copulation, millions of sperms are ejaculated into the vagina, but only one sperm fertilises the ovum in the oviduct.
- The acrosome of the sperm releases enzymes that help it penetrate the egg membrane; chemical changes then prevent entry of other sperms.
- Fusion of sperm nucleus and egg nucleus restores the diploid chromosome number (46) in the zygote.
- From puberty to menopause (45–50 years), only about 400 ova are released; ageing oocytes may lead to chromosomal abnormalities if fertilised.
- Gametes are formed by meiosis: sperms are of two types (22+X or 22+Y), while ova are of one type (22+X); meiosis in ova completes during fertilisation.
Key Points: Pregnancy and Embryonic Development
- Placenta is formed after implantation and helps in exchange of nutrients, oxygen and wastes between mother and foetus.
- Three germ layers (ectoderm, mesoderm and endoderm) are formed, which develop into all body organs.
- Hormones like hCG, progesterone and estrogen increase to support pregnancy and foetal growth.
- Foetal development occurs gradually, and by nine months the foetus is fully developed and ready for birth.
Important Questions [26]
- How Can the Scientific Understanding of the Menstrual Cycle of Human Females Help as a Contraceptive Measure?
- Explain the Changes that Occur in the Ovary and Uterus During Menstrual Cycle in Human Females. Mention the Influence of Pituitary and Ovarian Hormones in Bringing These Changes.
- Explain the menstruation phases in the menstrual cycle of a human female.
- ‘A proper understanding of the menstrual cycle can help immensely in family planning.’ Do you agree with the statement? Provide reasons for your answer.
- Explain the ovarian and uterine events that occur during a menstrual cycle in a human female under the influence of pituitary and ovarian hormones respectively.
- Name and Explain the Role of the Inner and Middle Walls of the Human Uterus.
- The graph given below shows the number of primordial follicles per ovary in women at different ages. Study the graph and answer the questions that follow.
- Describe the changes that occur in ovaries and uterus in human female during the reproductive cycle.
- Explain the Menstrual Phase in a Human Female. State the Levels of Ovarian and Pituitary Hormones During this Phase.
- Describe the Role of Pituitary and Ovarian Hormones During the Menstrual Cycle in a Human Female.
- Why is Follicular Phase in the Menstrual Cycle Also Referred as Proliferative Phase? Explain.
- Explain the Events that Occur in a Graafian Follicle at the Time of Ovulation and Thereafter.
- Draw a graafian follicle and label antrum and secondary oocyte.
- Explain the Role of Pituitary and the Ovarian Hormones in Menstrual Cycle in Human Females
- Describe the Roles of Pituitary and Ovarian Hormones During the Menstrual Cycle in a Human Female.
- Explain Menstrual Cycle in Human Females.
- Describe the process of fertilization.
- Draw a diagram showing human foetus within the uterus and label any four, parts in it.
- When and Where Do Chorionic Villi Appear in Humans?
- Comment on the Role of Placenta as an Endocrine Gland.
- During the Reproductive Cycle of a Human Female, When, Where and How Does a Placenta Develop? What is the Function of Placenta During Pregnancy and Embryo Development?
- Arrange the following hormones in sequence of their secretion in a pregnant woman. Mention their source and the function they perform: hcG, LH, FSH, Relaxin
- State the Function of Chorionic Villi
- Medically it is advised to all young mothers that breast-feeding is the best for their newborn babies. Do you agree? Give reasons in support of your answer.
- Assertion: Functional ADA cDNA genes must be inserted in the lymphocytes at the early embryonic stage. Reason: Cells in the embryonic stage are mortal, differentiated and easy to manipulate.
- Explain the formation of placenta after the implantation in a human female.
Concepts [14]
- Human Reproduction
- Overview of The Male Reproductive System
- Overview of The Female Reproductive System
- Overview of Gametogenesis
- Structure of Sperms
- Oogenesis
- Menstrual Cycle (Ovarian Cycle)
- Major Events of Menstrual Cycle
- Menstrual Hygiene
- Fertilization in Human
- Implantation in Human
- Pregnancy and Embryonic Development
- Parturition (Birth) in Human
- Lactation in Human
