Reproductive System The circle of Life zygote embryo male embryo female embryo male fetus female fetus Immature female Immature male Mature male Mature female Mature sperm Mature ovum Birth ID: 919439
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Slide1
Making hormones, gametes and little babies
Reproductive System
Slide2The circle of Life
zygote
embryo
male embryo
female embryo
male fetus
female fetus
Immature female
Immature male
Mature male
Mature female
Mature sperm
Mature ovum
Birth
Gameteogenesis
Puberty
Conception
Gender
Slide3Male reproductive system
Reproductive system = gonads + tubes
Male gonad = testes
Testes make gametes (sperm)
Testes make hormones to regulate sperm productionTubes provide pathway for sperm to be excreted
Slide4Spermatogenesis
Male gametogenesis = process to produce sperm (male gametes)
Normal adult male =
400 million sperm/day
Sperm produced in seminiferous tubules in the testesTestosterone is made by interstitial cells in the testes
Slide5spermatogenesis
Spermatogenesis = meiosis
Process starts with
spermatogonium
in outside of tubule wall
Mitosis results in two spermatogonium, one remains in basement layer
Meiotic divisions occur as developing sperm moves to tubule lumenFinal result is 4 haploid spermatozoa
Slide6spermatogenesis
Male gamete = sperm
Sperm are specialized for mobility and among the smallest cells in the human body
Structure
Head
contains DNA (in form of 23 chromosomes) and enzymes for penetration of egg
Midpiece contains mitochondria to produce energy for movement (in the form of ATP)Tail
is a flagellum that propels the sperm through the liquid medium of the female reproductive tract
Slide7spermatogenesis
Rate of sperm production is controlled by hormones
Brain hormones = GnRH, LH, FSH
Gonad hormones = testosterone + inhibin
Negative feedback is primary control
Slide8Spermatogenesis + negative feedback
Negative Feedback in spermatogenesis
Brain hormones
stimulate
gonad hormonesGonad hormones inhibit brain hormones
brain hormones stimulate
gonad hormones
gonad hormones cause
brain hormones
brain hormones cause gonad hormones
gonad hormones cause brain hormones
Slide9Female reproductive system
Reproductive system = gonads + tubes
Female gonad = ovary
Ovaries make gametes (ova/egg)
Ovaries make hormones to regulate egg production and prepare the uterus for fertilization
Tubes provide pathway for sperm to get in and fetus to get out
Slide10Oogenesis
Female gametogenesis = process to produce female gametes (eggs/ova)
Females normally release 1 egg/28 days in ovary
Cells in developing follicle produce estrogen
Cells in post-ovulation follicle produce progesterone
Slide11oogenesis
Oogenesis = meiosis
Primary oocytes begin meiosis before birth
After puberty, one cell/month continues meiosis
One meiotic division occurs before ovulation, with unequal division of cytoplasm (one big cell/one small cell)
After fertilization, second meiotic division occurs
Final result = 1 viable haploid cell + 3 small polar bodies
Slide12Oogenesis
Egg develops as part of follicle
Follicle = ovum + hormone-producing cells + protective cells
Corpus luteum = follicle after ovum is released
Slide13oogenesis
Egg development and uterine development are regulated by hormones
Brain hormones = GnRH, LH, FSH
Ovarian hormones = estrogen + progesterone
Egg and uterine development regulated by negative feedback, ovulation is regulated by positive feedback
Slide14Oogenesis + negative feedback
Negative Feedback in oogenesis
FSH + LH stimulate
estrogen + progesteroneestrogen + progesterone inhibit
FSH + LHEstrogen – from follicle cells – stimulates egg development + development of uterine lining
Progesterone – from corpus luteum – maintains developed uterine lining
When progesterone decreases, uterine lining breaks down (menstruation)When fertilization occurs, corpus luteum is maintained, progesterone produced and uterine lining maintained
Slide15Oogenesis + oral contraceptives
Increasing levels of progesterone decreases production of LH (negative feedback)
Decreased LH prevents ovulation
Artificial increase in progesterone prior to ovulation will prevent ovulation by decreasing LH
Most oral contraceptives (birth control pills) use this strategy