Revision: Human Anatomy and Physiology >> The Reproductive System Biology (English Medium) ICSE Class 10 CISCE

Reproduction is the process of formation of new individuals by sexual or asexual means, which can repeat the process in their own turn.

or

Formation of new organism of same species by earlier existing organism is called as reproduction.

or

Reproduction is a biological process that results in the formation of new individuals of the same kind, though usually with slight genetic, structural and physiological variations.

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.

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.

The process of expulsion of semen from the urethra is called ejaculation.

Hernia is an abnormal condition that is caused when the intestine, due to the pressure in the abdomen, bulges into the scrotum through the inguinal canal.

Spermatogenesis is the process of formation and development of sperm cells (spermatozoa) in the testes from spermatogonial stem cells through mitosis and meiosis.

The secretion of glands with spermatozoa is a whitish viscous fluid known as seminal fluid or semen.

The opening of the vagina in young females is partially closed by a thin membrane called the hymen (or virgin knot).

Puberty is the period during which the immature reproductive system of boys and girls matures and becomes capable of reproducing. At age 10 in girls, the first sign is the enlargement of breasts. In boys at 11 years, the enlargement of testes is the first sign.

It is the stage when a girl menstruates for the first time.

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).

The release of the ovum from the ovary is called ovulation.

A disc-like structure attached to the uterine wall that supplies food and oxygen to the foetus and removes waste is called placenta.

or

The intimate connection established between the foetal membrane and the uterine wall is known as placenta.

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.

Fraternal twins biologically produced from two zygotes are called dizygotic twins.

Fraternal twins biologically produced from two ova are called diovular twins.

Twins produced from two separately fertilised eggs are called fraternal twins.

Identical twins biologically produced from one zygote are called monozygotic twins.

Twins produced from the splitting of a single fertilised egg are called identical twins.

Birth of three babies from a single pregnancy is called triplets because it involves the formation of three embryos either from separate eggs or by splitting of one or more zygotes.

• Meaning - Reproduction is the production of young ones similar to their parents. It is an essential biological process for the continuation of the species and continuity of life.
• Two Types - All methods of reproduction fall into two categories: Asexual Reproduction and Sexual Reproduction.
• Asexual Reproduction - New individuals are produced without the fusion of gametes. Offspring are genetically identical to the parent (clones).
• Sexual Reproduction - Involves the fusion of male and female gametes, resulting in offspring with genetic variation from both parents.

1. Human reproductive organs are divided into primary (gonads) and accessory parts.
2. Primary gonads: Testes in males produce sperms; ovaries in females produce eggs.
3. Accessory organs include ducts and glands that aid in fertilisation and embryo development.
4. Secondary sexual characters (e.g., beard, breasts) are not reproductive parts, as they do not directly participate in reproduction.

• The male reproductive system is located in the pelvic region and includes testes, accessory ducts, accessory glands, and external genitalia (penis and scrotum).
• Testes are the primary sex organs present in the scrotum; they contain seminiferous tubules where sperm are produced, while Leydig cells secrete testosterone, and Sertoli cells provide nourishment.
• Accessory ducts—rete testis → vasa efferentia → epididymis → vas deferens → ejaculatory duct → urethra—help in storage, maturation, and transport of sperm.
• Accessory glands—seminal vesicles, prostate gland, and bulbourethral glands—add secretions like fructose, enzymes, and mucus, which nourish sperms and aid in their movement.
• The penis acts as the external genital organ, containing the urethra, and helps in the transfer of sperm during ejaculation.

• Includes — Ovaries, Fallopian tubes, Uterus, Cervix, Vagina, External genitalia, Bartholin's glands, Mammary glands — all in the pelvic region.
• Ovaries — outer cortex (follicles) + inner medulla; produce ova and ovarian hormones; release one ovum monthly after puberty.
• Fallopian tube — 3 parts: Infundibulum (fimbriae collect ovum) → Ampulla (site of fertilisation) → Isthmus (connects to uterus); cilia push egg towards uterus.
• Uterus — 3 layers: Perimetrium (outer), Myometrium (muscular), Endometrium (inner, menstrual changes); opens into vagina via cervix (birth canal).
• Zygote implants in the endometrium; the placenta connects the embryo to the mother for nutrient and waste exchange till birth.
• External genitalia — Mons pubis, Labia majora, Labia minora, Hymen, Clitoris. Bartholin's glands provide lubrication.
• Mammary glands — produce milk for newborn. Puberty begins at 10–14 years in females.

1. Puberty begins around ages 10–14 in girls and 11–15 in boys, marking the maturation of the reproductive system.
2. In girls, ovaries start releasing ova and secrete oestrogens, which cause secondary sexual changes like breast development, widened hips, and pubic hair growth.
3. In boys, testes begin producing testosterone, leading to changes like voice deepening, growth of genital organs, and facial/body hair.
4. Progesterone, secreted by the corpus luteum, prepares the uterus for embryo implantation.

• The menstrual cycle is a series of monthly changes in females of reproductive age.
• The beginning of the cycle is called menarche, and its permanent stop is called menopause (around 45–50 years).
• It occurs mainly in primates, including humans, and involves changes in the ovaries and uterus.
• The cycle is controlled by hormones (gonadotropins and ovarian hormones) and repeats every ~28 days.
• In the middle of the cycle, ovulation occurs, where an egg is released from one of the ovaries.

• Meaning - Placenta is a temporary structural and functional connection between foetal and maternal circulation, formed by chorionic villi (finger-like projections of trophoblast) interdigitating with uterine tissue and maternal blood.
• Attachment - The placenta is attached to the wall of the uterus on one side and connected to the baby via the umbilical cord on the other side.
• Umbilical cord - Contains two small arteries (carry blood towards the placenta) and one large vein (returns blood to the foetus).
• Functions - Supplies oxygen and nutrients to the foetus; removes CO₂ and excretory wastes from foetal blood to maternal blood.
• Hormones produced - Placenta produces hCG (human Chorionic Gonadotropin), hPL (human Placental Lactogen), Oestrogen, and Progesterone. By the end of the 1st trimester, progesterone production shifts to the placenta.

• Parturition is the process of childbirth, i.e., the delivery of the foetus at the end of the gestation period.
• It is controlled by a neuro-endocrine mechanism involving signals from the fully developed foetus and placenta.
• Foetal signals trigger uterine contractions known as the foetal-ejection reflex (labour pain).
• Hormones like ACTH and corticosteroids from the foetus stimulate the release of oxytocin from the mother’s pituitary gland.
• Parturition occurs in three stages: dilation, expulsion of the baby, and after birth (placenta removal).