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Reproductive system
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Learning objectives Understand the general anatomy of male and female reproductive systems including where and how gametes are formed. Understand that gametes are haploid (1n) and normal cells are diploid (2n). What is the menstrual cycle? Understand the basics of fertilization. Only one sperm is allowed to fertilize the egg. Gastrulation organizes the body into 3 layers, and 3 types of cell. Apoptosis = programmed cell death – helps sculpt body
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Human Life Cycle Diploid Haploid
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The Reproductive System • General structure: - Pair of gonads
- Accessory organs, ducts, hormones, etc.
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Male Reproductive System • Testes (gonads) – produce sperm,
secrete hormones Descend into scrotum for temperature regulation (sperm need 95°F) •
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pelvic girdle urinary bladder scrotum
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Travel to epididymis to mature
• Sperm form in seminiferous tubules Travel to epididymis to mature Move through Vas Deferens Ejaculatory Duct Epididymis Urethra Testis Seminiferous Tubule • • vas deferens, through ejaculatory duct, into urethra
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Sperm (150-350 million) mixed with secretions from:
Seminal vesicle Protects sperm from female immune system fructose for energy Prostate buffer to neutralize acidity of vagina Bulbourethral glands mucous-rich fluid that neutralizes urine Mixture is called semen
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How do sperm form? mitosis meiosis I meiosis II wall of seminiferous
tubule spermatogonium (diploid) primary spermatocyte early spermatids immature sperm (haploid) secondary spermatocyte late spermatid
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• Human seminiferous tubule (in testicle) filled with sperm
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Mature Sperm • Head: Nucleus with DNA, covered with
enzyme-containing cap Midpiece: Mitochondria to supply energy • • Tail: Propels sperm forward Head Midpiece Tail
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Human sperm seen through a Transmission Electron Microscope (TEM)
• Human sperm seen through a Transmission Electron Microscope (TEM)
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Responsibility: Protect & nurture developing
Female Reproductive System Responsibility: Protect & nurture developing offspring from conception to birth • • Ovaries (gonads) produce eggs, release sex hormones
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moves to oviduct (fertilization occurs here)
• From ovary, egg moves to oviduct (fertilization occurs here) Then, egg travels to uterus which is lined with endometrium Lower uterus called cervix Vagina connects cervix to outside Ovary Oviduct Uterus Cervix Bladder Vagina • • •
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Menstrual Cycle
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• Newborn has ~2 million primary oocytes Oocyte + nourishing cells = follicle Immature eggs mature 1 at a time Only will mature Continues until menopause • • • •
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“The penis and vagina are mechanically
compatible for sexual intercourse, which may lead to pregnancy” Adzuki Bean Beetle Copulatory Organ
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Birds do it, bees do it… • = Coitus, copulation
Erection – penis stiffens and lengthens due to dilated blood vessels and pooling blood Ejaculation – forceful expulsion of semen •
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Sperm entering an oviduct
• Muscle contractions in uterus move sperm into oviduct If ovulation has • recently occurred occurs soon, egg may be fertilized or Sperm entering an oviduct (SEM x500)
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Fertilization • Sperm enters egg
Zygote is formed after a series of steps • haploid egg and sperm nuclei
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Early Human Development • Egg + sperm = zygote (1st cell) •
Zygote develops via cleavage into morula
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Growth of the Baby Morula becomes embryo Amnion surrounds
Placenta starts to form Called fetus at 9 weeks of the Baby • • it •
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• Gastrulation organizes cells into germ layers: ectoderm, mesoderm, & endoderm
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• Cells go through differentiation (get their jobs) Organs & tissues form by morphogenesis Cells grow and migrate • •
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• Organs grow in size Apoptosis helps to sculpt some body parts •
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