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Ch. 22 Human Reproduction

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Ch. 22 Human Reproduction * * * * * * * * * * * * Placenta Food & gases diffuse across blood vessels Fetal Development Gestation is pregnancy It begins at conception ... – PowerPoint PPT presentation

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Title: Ch. 22 Human Reproduction


1
Ch. 22 Human Reproduction
2
22.1 Section Objectives
  • Identify the structures and functions of the male
    and female reproductive systems.
  • Summarize the internal feedback control of
    reproductive hormones
  • Sequence the stages of the menstrual cycle.

3
Reproductive anatomy of the human male
  • main functions
  • 1. the production of spermthe male sex cells
  • 2. their delivery to the female.

4
Reproductive anatomy of the human male
  • Semen
  • Sperm, which are expelled through the ducts
    during ejaculation
  • Glandular secretions that carry, nourish, and
    protect the sperm
  • Testes
  • Produce sperm
  • Located outside abdominal cavity within the
    scrotum (saclike pouch 1-3C below normal body
    temperature- sperm can only form at this lower
    temp.)

5
How sperm leave the testes
  • . Seminiferous tubules carries/stores sperm in
    testes
  • 2.Epididymis a series of coiled ducts for
    maturation temporary storage organ for sperm
  • 3. Vas deferens tube which carries sperm past
    lubricating glands
  • 4. ( a.)Seminal vesicles secrete fluid that
    protects nourishes sperm
  • (b.) Prostrate gland produces an
    alkaline fluid that neutralizes urine in the
    urethra
  • (c.) Bulbourethral glands secrete
    fluid that may help lubricate the urethra
  • 5. Urethra tube in the penis that
    transports sperm out of the males body, also
    transports urine from the urinary bladder.
  • 6. Penis copulatory organ, releases semen
  • 7. Ejaculation the release of semen

6
Reproductive anatomy of the human male
7
Reproductive anatomy of the human female
  • main functions of the female reproductive system
  • 1. to produce eggs, the (female sex cells),
  • 2.to receive sperm,
  • 3. to provide an environment in which a
    fertilized egg can develop.

8
Reproductive anatomy of the human female
  • Ovaries
  • Contain follicles that nurture eggs (ova)
  • Produce sex hormones
  • Functional from puberty to menopause
  • Oviducts (Fallopian Tubes)
  • Convey eggs to the uterus
  • Muscular contractions cilia draw ovum (egg) into
    oviduct
  • Fertilization occurs

9
Reproductive anatomy of the human female
  • Uterus (womb)
  • Development of fertilized egg
  • Opens into the vagina
  • Vagina
  • Receives penis during intercourse
  • Forms the birth canal

10
Puberty
  • Puberty when secondary characteristics develop
    and the potential for sexual reproduction is
    reached(sperm production or ovulation)
  • Changes are controlled by hormones
  • secondary sex characteristics
  • Males hormone testosterone, characteristics
    body hair, muscle development, deep voice
  • Females Hormone estrogen. Characteristics
    breasts, broadened pelvis, distribution of body
    fat

11
Reproductive hormones
  • Testosterone
  • from testes
  • sperm production secondary sexual
    characteristics
  • Estrogen
  • from ovaries
  • egg production, preparing uterus for fertilized
    egg secondary sexual characteristics

12
Hormonal control of the testes
Stimuli from otherareas in the brain
  • Androgens (testosterone most important) stimulate
    sperm production
  • They also maintain homeostasis by a negative
    feedback mechanism that inhibits the secretion of
    FSH (follicle-stimulating hormone) and LH
    (luteinizing hormone)

Hypothalamus
Releasinghormone
Anteriorpituitary
Negative feedback
FSH
LH
Androgenproduction
Testis
Spermproduction
13
Oogenesis Production of eggs
  • Most of the process occurs within the ovaries
  • Lifetime supply of primary oocytes is present at
    birth
  • One primary oocyte matures each month to form a
    secondary oocyte
  • If the secondary oocyte is fertilized, it
    completes meiosis and becomes a haploid ovum

14
Egg maturation in ovary
releasesprogesterone
maintainsuteruslining
produces estrogen
15
Menstrual Cycle
  • The series of changes in the female reproductive
    system that includes producing an egg and
    preparing the uterus for receiving it.
  • Once an egg has been released during ovulation,
    the part of the follicle that remains in the
    ovary develops into a structure called the corpus
    luteum.
  • The menstrual cycle begins during puberty and
    continues for 30 to 40 years, until menopause.
  • At menopause, the female stops releasing eggs and
    the secretion of female hormones decreases.

16
The Reproductive Cycle of the Human Female
  • A cyclic pattern of hormone secretion and
    reproductive events.
  • Humans and many other primates have menstrual
    cycles.
  • If pregnancy does not occur the endometrium
    (lining of uterus) is shed through the cervix and
    vagina menstruation

17
The Menstrual Cycle
  • divided into three phases the flow phase, the
    follicular phase, and the luteal phase.
  • The timing of each phase of the menstrual cycle
    correlates with hormone output from the pituitary
    gland, changes in the ovary, and changes in the
    uterus

18
Menstrual cycle
LH
  • Controlled by interaction of 4 hormones
  • FSH LH
  • estrogen
  • progesterone

FSH
ovulation egg release
egg development
corpus luteum
estrogen
progesterone
lining of uterus
0
7
14
21
28
days
19
Flow Phase
  • Day 1 of the menstrual cycle is the day menstrual
    flow begins
  • the shedding of blood, tissue fluid, mucus, and
    epithelial cells that made up the lining of the
    uterus, the endometrium.
  • Contractions of the uterine muscle help expel the
    uterine lining and can cause discomfort in some
    females.
  • the level of FSH in the blood begins to rise, and
    a follicle in one of the ovaries begins to mature
    as meiosis of the prophase I cell proceeds.

20
Follicular Phase second phase of the menstrual
cycle
  • lasts from about day 6 to day 14.
  • As the follicle containing a primary oocyte
    continues to develop, it secretes estrogen, which
    stimulates the repair of the endometrial lining
    of the uterus.
  • Day 14 ovulation occurs follicle enlarges and
    ruptures ovary wall. Egg is released to oviduct.

21
Luteal Phase
  • Progesterone increases the blood supply of the
    endometrium
  • These changes correspond to the arrival of a
    fertilized egg.
  • If the egg is not fertilized, the rising levels
    of progesterone and estrogen from the corpus
    luteum cause the hypothalamus to inhibit the
    release of FSH and LH.
  • The corpus luteum degenerates and stops secreting
    progesterone or estrogen.
  • As hormone levels drop, the thick lining of the
    uterus begins to shed.
  • If fertilization occurs the endometrium begins
    secreting a fluid rich in nutrients for the
    embryo.

22
Female reproductive cycle
Feedback
eggmatures is released(ovulation)
builds up uterus lining
estrogen
progesterone
FSH LH
fertilized egg(zygote)
maintainsuterus lining
HCG
pituitarygland
pregnancy
progesterone
GnRH
corpus luteum breaks down progesterone
drops menstruation
maintainsuterus lining
hypothalamus
23
Female hormones
  • FSH LH
  • released from pituitary
  • stimulates egg development hormone release
  • peak release release of egg (ovulation)
  • Estrogen
  • released from ovary cells around developing egg
  • stimulates growth of lining of uterus
  • decreasing levels causes menstruation
  • Progesterone
  • released from corpus luteum in ovaries
  • cells that used to take care of developing egg
  • stimulates blood supply to lining of uterus
  • decreasing levels causes menstruation

24
Hormonal coordination of the menstrual and
ovarian cycles .
  • FSH (follicle stimulating hormone) produced by
    pituitary stimulates development of follicle
  • LH (luteinizing hormone) stimulates the
    development of the corpus luteum, stimulates
    ovulation
  • Estrogen secreted by ovaries, stimulates
    development of uterine lining
  • Progesterone secreted by corpus luteum,
    maintains uterine lining

25
Ch. 22.2
  • Section Objectives
  • Describe the processes of fertilization and
    implantation.
  • Summarize the events during each trimester of
    pregnancy.

26
Fertilization results in a zygote and triggers
embryonic development
  • Fertilization is the union of a sperm and an egg
    to form a diploid zygote
  • (PATH) Millions of sperm -gtvagina -gt cervix -gt
    uterus -gt oviduct (site of fertilization)
  • sperm egg -gt zygote
  • 23(n) 23(n) -gt 46(2n)

27
Fertilization
  • Only one of these sperm will penetrate this human
    egg cell to initiate fertilization
  • The shape of a human sperm cell is adapted to its
    function

28
Fertilization
29
Implantation
  • Implantation fertilized egg implants in
    thickened uterine lining
  • the embryo starts to secrete the hormone
    human chorionic gonadotropin (HCG)
  • (hormone for pregnancy tests)
  • This hormone keeps the corpus luteum alive so
    that it continues to secrete progesterone
  • By the third or fourth month, the placenta takes
    over for the corpus luteum, secreting enough
    estrogen and progesterone to maintain the
    pregnancy.

30
Embryonic Development
  • Development series of orderly, precise steps
    that transform a zygote into a multicellular
    embryo early stage of development of
    multicellular organism
  • Includes
  • 1. cell division
  • 2. cell growth
  • 3. cell differentiation
  • changing of unspecialized embryonic cells into
    specialized cells, tissues, organs

31
Early Embryonic Development
  • Cleavage is the first major phase of embryonic
    development
  • It is the rapid succession of cell divisions
    (Mitotic)
  • It creates a multicellular embryo from the zygote
  • NO growth
  • Stages
  • 1. Morulasolid ball of cells
  • 2.Blastula single layer of cells surrounding a
    fluid-filled cavity called the blastocoel

ZYGOTE
Blastocoel
Cross sectionof blastula
BLASTULA(hollow ball)
32
Embryonic Development
  • Gastrulation is the second major phase of
    embryonic development
  • The cells at one end of the blastula move inward
  • Organs start to form after gastrulation
  • Embryonic tissue layers begin to differentiate
    into specific tissues and organ systems

33
Embryonic Membranes and the Placenta
  • Amnionfluid filled sac for protection
  • Chorion will form the embryos part of the
    placenta
  • Yolk sac produces first blood cells germ
    cells
  • Allantois will form the umbilical cord
    (ropelike structure that attaches embryo to
    uterus)
  • PlacentaA growing fetus exchanges nutrients,
    oxygen, and wastes with the mother through the
    placenta.

Chorion
Amnion
Allantois
Yolk sac
34
Placenta
  • Food gases diffuse across blood vessels

35
Fetal Development
  • Gestation is pregnancy
  • It begins at conception and continues until birth
  • Pregnancy in humans usually lasts about 280 days,
    calculated from the first day of the mothers
    last menstrual period.
  • Embryonic development of essential organs occur
    in early pregnancy
  • The embryo may encounter risks from faults in its
    genes from mothers exposure to environmental
    factors

36
Human development from conception to birth is
divided into three trimesters
  • First trimester
  • First three months
  • The most rapid changes occur during the first
    trimester 10 weeks
  • 10 weeks10 weeks
  • 10 weeks

10 weeks
4 weeks
7 weeks
37
Human development from conception to birth is
divided into three trimesters
  • Second trimester
  • Increase in size of fetus
  • General refinement of human features

12 weeks
38
Human fetal development
  • The fetus just spends much of the 2nd 3rd
    trimesters just growing
  • and doing various flip-turns kicks inside
    amniotic fluid

Week 20
39
Human fetal development
  • 24 weeks (6 months 2nd trimester)

fetus is covered with fine, downy hair called
lanugo. Its skin is protected by a waxy material
called vernix
40
Human fetal development
  • 30 weeks (7.5 months)

umbilical cord
41
Getting crowded in there!!
  • 32 weeks (8 months)

The fetus sleeps 90-95 of the day sometimes
experiences REM sleep, an indication of dreaming
42
Human development from conception to birth is
divided into three trimesters
  • Third trimester
  • Growth and preparation for birth

43
22.3
  • Section Objective
  • Describe the three stages of birth.
  • physiological and physical changes a female goes
    through to give birth are called labor.
  • Labor begins with a series of contractions of
    the uterine muscles.
  • These contractions are stimulated by oxytocin, a
    hormone released by the pituitary.

44
Birth
positive feedback
45
Three stages of labor
  • .Dilation of the cervix is the first stage
  • -Cervix reaches full dilation at 10cm
  • Longest stage of labor (6-12 hours or longer)

46
Three stages of labor
  • Expulsion is the second stage
  • Period from full dilation of the cervix to
    delivery of the infant
  • Uterine contractions occur every 2-3 minutes
  • Mother feels urge to push down with her abdominal
    muscles
  • Infant is forced down and out of uterus and
    vagina within a period of 20 minutes

47
Three stages of labor
  • The delivery of the placenta is the final stage
    of labor
  • Usually occurs within 15 minutes after the birth
    of the baby

48
The end of the journey!
And you think 9 months of Biology is hard!
49
Growth and Aging
  • Once a baby is born, growth continues and
    learning begins
  • Human growth varies with age and is somewhat
    gender dependent.

50
An adult ages
  • As an adult ages, his or her body undergoes many
    distinct changes.
  • Slower metabolism
  • White hair
  • Thinner bones
  • Vision hearing dimminish
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