Human Reproduction Lecture Notes

Reproduction

• Asexual Reproduction

  • Offspring from a single parent, no gametes.

  • Offspring genetically identical (clone).

• Sexual Reproduction

  • Fusion of male and female gametes from separate parents.

  • Offspring not genetically identical.

Gametes and Fertilization

• Egg (Ovum): 23 Chromosomes

• Sperm: 23 Chromosomes

• Fertilization: Zygote with 46 Chromosomes (23 pairs)

• Embryo: 46 Chromosomes (23 pairs)

Meiosis

• Parent cell produces 4 gametes incapable of further division.

Egg (Ovum) Structure

• Corona radiata

• Zona pellucida

• Nucleus

• Cytoplasm

Sperm Cell Structure

• Head (Acrosome, Nucleus)

• Neck

• Middle piece (Mitochondrion)

• Tail

• Plasma membrane

Hormones and Secondary Sexual Characteristics

• Oestrogen

  • Widening of hip bone, increase storage of fat, development of mammary glands

• Progesterone

  • Increases the lining of the uterus, prevents menstruation, ensures pregnancy, Prevents ovulation

• Testosterone

  • Deeper voice, increased growth of hair, development of muscles, produce sperms cells

Female Reproductive Organ

• Ovary

• Fallopian tubes/oviducts

• Uterus (Endometrium)

• Cervix

• Vagina

Male Reproductive System

• Pubic bone

• Sperm duct

• Seminal vesicle

• Urinary bladder

• Prostate gland

• Epididymis

• Testis

• Scrotum

• Urethra

• Shaft

• Foreskin

• Glans

Copulation and Fertilization

• Insemination occurs.

• Sperm swarm around egg.

• New membrane forms to prevent further entry of sperm.

• Head of sperm enters egg.

Growth and Development

• Foetus develops in uterus.

• Placenta facilitates nutrient and waste exchange.

• Amnion and amniotic fluid protect the foetus.

• Umbilical cord connects foetus to placenta.

Diffusion in the Placenta

• Exchange of substances between mother's and foetus' blood via placental membrane.

Birth and Parental Care

• Gestation period: time for foetus to develop from fertilization to birth.

• Oxytocin: causes uterus and abdomen contractions.

• Amniotic fluid: lubricant during labor.

• Prolactin: causes mammary glands to produce milk.

• Milk production depends on prolactin levels and baby’s suckling.

Milk and Weaning

• Human milk is nutritious but low in iron.

• Babies accumulate iron in the liver during gestation.

• Cow’s milk is not equivalent to human milk.

• Powdered milk lacks antibodies found in human milk.

• Weaning: shifting from mother’s milk to solid food.

Menstrual Cycle and Hormones

• If fertilization occurs, corpus luteum secretes progesterone to maintain endometrium.

• FSH (Follicle Stimulating Hormone)

  • Produced by: Pituitary Gland

  • Acts on: Ovary

  • Major effects: Stimulates growth and maturation of follicle.

• LH (Luteinizing Hormone)

  • Produced by: Pituitary Gland

  • Acts on: Ovary

  • Major effects: Ovulation, Development of yellow body (corpus luteum)

• Oestrogen

  • Produced by: Developing follicle

  • Acts on: Pituitary gland, Uterus, General body

  • Major effects: Inhibits the secretion of FSH, Triggers the secretion of LH, Stimulates repair and thickening of lining. Development of female secondary sexual characteristics.

• Progesterone

  • Produced by: Yellow body / Corpus Luteum

  • Acts on: Uterus, Pituitary gland

  • Major effects: Maintains lining, Inhibits secretion of LH and FSH

• Testosterone

  • Produced by: Testes

  • Acts on: Testes, General body

  • Major effects: Sperm production, Development of male secondary sexual characteristics.