Ch. 22 Human Reproduction

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Ch. 22 Human Reproduction
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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.

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Reproductive anatomy of the human male

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

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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.)

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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

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Reproductive anatomy of the human male
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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.

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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

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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

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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

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Reproductive hormones

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

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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
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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

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Egg maturation in ovary
releasesprogesterone
maintainsuteruslining
produces estrogen
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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.

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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

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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

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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
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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.

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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.

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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.

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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
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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

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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

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Ch. 22.2

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

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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)

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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

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Fertilization
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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.

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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

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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)
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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

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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
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Placenta

• Food gases diffuse across blood vessels

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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

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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
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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
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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
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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
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Human fetal development

• 30 weeks (7.5 months)

umbilical cord
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Getting crowded in there!!

• 32 weeks (8 months)

The fetus sleeps 90-95 of the day sometimes
experiences REM sleep, an indication of dreaming
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Human development from conception to birth is
divided into three trimesters

• Third trimester
• Growth and preparation for birth

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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.

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Birth
positive feedback
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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)

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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

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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

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The end of the journey!
And you think 9 months of Biology is hard!
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Growth and Aging

• Once a baby is born, growth continues and
  learning begins
• Human growth varies with age and is somewhat
  gender dependent.

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An adult ages

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