Human reproduction

• Morphology and Physiology of the Male Reproductive System:

  • Male reproductive organs include the urethra, penis, testes, epididymis, vas deferens, and scrotum
  • The urethra carries semen and urine, the penis delivers sperm, the testes produce sperm and testosterone, the epididymis stores sperm, the vas deferens gets sperm from the epididymis, and the scrotum protects and ensures sperm survival by lowering its temperature
• Glands and Ducts in the Male Reproductive System:

  • Glands and ducts include the urethra, vas deferens, seminal vesicles, and ejaculatory duct
  • The urethra carries semen and urine, the vas deferens loops over the urinary bladder, seminal vesicles secrete a thick fluid to nourish sperm, and ejaculatory ducts contract to force semen out during ejaculation
• Morphology and Physiology of the Female Reproductive System:

  • Internal parts include the ovaries, fallopian/uterine tubes, uterus or womb, and cervix
  • External parts include the vulva with the mons veneris, labia minora, labia majora, clitoris, and vaginal orifice
• Role of Hormones in Reproductive Systems:

  • Hormones are body messengers released by glands like the thyroid, pancreas, ovaries, and testes
  • Hormones control growth, metabolism, and reproduction, and can be proteins, fats, or amino acids
• Menstrual Cycle:

  • The menstrual cycle is a natural process in the female reproductive system that prepares the body for pregnancy
  • It lasts roughly 28 days and has 4 main phases: menstrual, follicular, ovulation, and luteal phases
• Embryonic Animal Development:

  • Gametogenesis is the formation of gametes (sperm and egg) controlled by parental genes
  • Fertilization occurs when a sperm penetrates an egg, leading to the formation of a zygote
  • Cleavage and blastulation involve mitotic cell divisions forming an early embryo with a hollow cluster of cells called a blastula
• Cleavage and Blastulation:

  • Third stage after fertilization where the fertilized egg undergoes series of mitotic cell divisions
  • Forms a hollow cluster of cells called a blastula with a fluid-filled cavity called the blastocoel
  • Blastula precedes the formation of the Gastrula
• Gastrulation:

  • Stage after Blastulation to organize cell migration patterns in the embryo
  • Forms the three germ layers: Ectoderm (outer layer), Mesoderm (middle layer), and Endoderm (inner layer)
• Organogenesis:

  • Process of cell differentiation and formation of major organs once germ layers have formed
  • Ectoderm forms the nervous system, Mesoderm forms the circulatory system, and Endoderm forms the respiratory tract and gut lining
• Growth and Tissue Specialization:

  • Last stage where organs acquire unique structures and chemical properties
  • After the three layers develop separately, the embryo becomes a fetus
• Embryonic Human Development:

  • Fertilization is the union of a sperm cell and an egg cell, forming a zygote
  • Zygote becomes a Blastocyst, a hollow ball of cells with an inner cell mass (embryoblast) and a Trophoblast providing nutrients and forming the placenta
• Embryo:

  • Initial development stage after fertilization, enclosed in the amniotic sac
  • Placenta and umbilical cord support the growth of the fetus
• The Fetus:

  • At 2 months, the fetus is about 1.2 inches long and has a recognizable human form
  • By 9 months, all organs are developed and the baby is ready to be born
• In Human Reproductive System:

  • Vas Deferens are ejaculation ducts
  • Ovaries and Uterus are internal female reproductive organs
  • Hormones are also known as fats, amino acids, and proteins
• Menstrual Cycle:

  • Phases include menstrual, follicular, ovulation, and luteal phases
  • Luteal phase begins on the 15th day and lasts till the end of the cycle
• Summary:

  • Penis ejaculates in the vagina, sperm travels to egg for fertilization
  • If no baby, egg breaks down the uterine walls causing menstruation
• Reproductive System:

  • Male reproductive system includes the penis and vas deferens
  • Female reproductive system includes ovaries, uterus, fallopian tubes, cervix, hymen, and vaginal canal
• Roles of Hormones:

  • Hormones include sex hormones, adrenaline, and insulin
  • Insulin is a type of protein
• Development of Life:

  • Animals have a reproductive lifestyle similar to humans
• Illustrations:

  • Blastocyst is a hollow ball of cells with an embryoblast and trophoblast
  • Embryo is enclosed in the amniotic sac, supported by the placenta and umbilical cord
• Embryonic Development Timeline:

  • Cleavage and Blastulation -> Gastrulation -> Organogenesis -> Growth and Tissue Specialization
• Human Development Timeline:

  • Fertilization -> Blastocyst formation -> Embryo development -> Fetus growth
• Fertilization Process:

  • Sperm penetrates egg, nuclei fuse to form a zygote
  • Zygote develops into a Blastocyst, then an embryo enclosed in the amniotic sac
• The testes are located outside the body to maintain an optimal temperature for sperm production.
• Spermatogenesis is the process by which male gametes (sperm) develop from germ cells within the seminiferous tubules.
• During puberty, hormonal changes stimulate the development of secondary sex characteristics such as facial hair growth, deepening voice, and increased muscle mass.
• Testosterone stimulates the growth of secondary sex characteristics such as facial hair, deepening voice, and muscle mass.
• Ovaries produce eggs (ova) and secrete estrogen and progesterone hormones that regulate menstruation and pregnancy.
• Estrogen promotes the growth of female secondary sexual characteristics like breasts and hips.
• Meiosis occurs during spermatogenesis, resulting in haploid sperm cells.
• Testosterone plays a crucial role in regulating the reproductive system and maintaining sexual function throughout adulthood.
• During puberty, hormonal changes trigger the release of mature sperm cells through ejaculation.
• In females, estrogen levels increase during pregnancy, promoting fetal development and preparing the mother's body for childbirth.
• Ejaculation involves contractions of smooth muscles surrounding the urethra that propel semen out of the penis during sexual activity or masturbation.
• Progesterone helps prepare the uterine lining for implantation of a fertilized ovum and maintains the pregnancy until birth.
• Eggs mature inside follicles in the ovaries until they reach maturity and ovulation occurs.
• Male reproductive system includes the scrotum, testes, epididymis, vas deferens, prostate gland, bulbourethral glands, Cowper's glands, and penis.
• Progesterone prepares the uterus lining for implantation of a fertilized egg during ovulation.
• The ovarian cycle involves follicle maturation, ovulation, luteal phase, and menstruation.