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Human reproduction
 

Human reproduction

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    Human reproduction Human reproduction Presentation Transcript

    • Human Reproduction
    • ReviewBoth males and females produce specialized sex cells called “gametes.”Each gamete contains ½ of the genetic information to form a new individual.The role of the male reproductive system is to produce sperm and deliver them to the female gamete, the egg.
    • The Male Reproductive SystemA sexually mature human male, produces millions of sperm cells each day.Sperm are produced in the testes by meiosis (spermatogenesis).Review (meiosis)
    • Structure of Sperm Tail- used for locomotion. Midsection- contains mitochondria. Why? Head- holds chromosomes and digestive enzymes which allow sperm to penetrate into the egg.
    • Male Testicle- Produces fluid that nourishes sperm
    • The “Pathway” of Sperm Seminal Vesicle Prostate Gland Penis Urethra Testes Bulbourethral Vas Epididymis Gland Deferens
    • The “Pathway” of SpermIn order for fertilization to occur, sperm must be released (ejaculated) from the penis.During ejaculation: 1.) Muscles in vas deferens push sperm toward urethra. 2.) Tube to bladder is blocked off by a valve. 3.) Glands add fluid to sperm. - Seminal vesicles provide fluid that “nourishes” sperm. - Bulbourethral gland and prostate gland create a fluid that makes sperm resistant to acid. - Sperm + Glandular secretions = SEMEN.
    • HormonesChemical messengers sent from one area of the body to another.In males and females, different hormones help to control sperm production and the menstrual cycle.
    • Female AnatomyOvary UterusUrethra CervixClitoris
    • “The Menstrual Cycle”Eggs begin to mature in the ovaries before a female is born.Growth of the eggs stop before they are completely developed.All the eggs remain immature until puberty.After puberty, several eggs begin to mature each month.Each egg develops inside a “follicle.”
    • “The Menstrual Cycle”Usually only one egg makes it to maturity.This egg will burst out of the follicle (ovulation) and move down the oviduct.Fertilization may or may not occur.The uterus must be ready to accept a fertilized egg.
    • Female HormonesThe females reproductive role is to: 1.) Make and release eggs. 2.) Nourish the developing fetus.A mix of hormones controls these events during the “menstrual cycle.”
    • Female Hormones1.) FSH (Follicle stimulating hormone) - Causes follicles to mature. - As follicles grow they release estrogen.2.) Estrogen - As estrogen levels rise, another hormone (LH) begins to rise.3.) LH (Leutinizing hormone) - Around day 14, LH levels shoot up. This causes at least one follicle to burst open. - Once the egg is released it begins to produce progesterone.4.) Progesterone - If egg becomes fertilized, progesterone levels stay high. - If egg begins to disintegrate, progesterone levels fall. - Role of progesterone is to prepare the uterus for possible pregnancy.
    • Birth Control1.) Physical forms - Condoms and diaphragms block the sperm from getting to the egg.2.) Chemical forms - “The pill.” Works by preventing FSH and LH to be released. - Result = No ovulation. Normal menstrual cycle proceeds.
    • Fertilization and DevelopmentZygote- Newly fertilized egg.Once it begins to divide, it is called an embryo.Embryo continues to release progesterone. Why?Embryo must “implant” itself into the uterine wall.
    • The PlacentaTransports materials back and forth to the embryo.Oxygen – Carbon dioxideNutrients (carbo’s, protein, fat)Urea (liquid, cellular waste)AntibodiesTeratogens
    • Maternal HealthThe health of the baby depends on the health and activities of the mother.Smoking, drugs, alcohol, radiation, and pathogens can all harm the fetus.Pregnancy is divided into three month segments called “trimesters.”
    • First TrimesterImplantation of zygote.All vital organs are formedHeart is formed.Brain and spinal cord.Sex organs.Limbs.Eyes and ears.
    • Second TrimesterCirculatory system is functioning.Hair formation.Major body changes in the mother.
    • Third TrimesterEyes open.Fat begins to form under the skin.Fetus gains lots of weight.If fetus spends a full three trimesters inside the uterus, survival outside the mother is very likely.
    • BirthAt nine months, the baby will position itself with its head against the cervix.Oxotycin (hormone) causes uterine muscles to push baby outwards (labor).Cervix opens up and baby is forced into vagina.“Afterbirth” is expelled.
    • Stopping of the Menstrual CycleBetween ages 45 – 55 ovulation and menstruation stop.The shut down of ovarian and uterine cycles is known as menopause.