Transcript Slide 1

Reproduction and Development
Reproductive Systems
Human Development
The Reproductive Systems
Male
Female
Sexually Transmitted Infections
Hormonal Regulation
The Male Reproductive System
• The functions of the male reproductive
system include:
1. To produce male gametes
(spermatogenesis)
2. To produce hormones (testosterone)
3. To maintain primary and secondary
male sexual characteristics
The Female Reproductive System
• The functions of the female reproductive
system include:
1. To produce female gametes (oogenesis)
2. To produce hormones (estrogen and
progesterone)
3. To maintain primary and secondary female
sexual characteristics
4. To maintain and deliver a developing fetus
Sexually Transmitted Infections
• An STI is an infection that is transmitted
only or mainly by sexual contact
• STI’s are caused by
1. Bacteria (gonorrhea, syphilis,
chlamydia)
2. Viruses (HIV/AIDS, hepatitis B, genital
herpes, HPV)
3. Parasites (pubic lice)
Hormonal Regulation
• The male reproductive system is influenced
by a negative feedback loop and involves the
following hormones:
1. GnRH: stimulates the release of FSH and
LH from the anterior pituitary gland
2. FSH: stimulates spermatogenesis by the
seminiferous tubules of the testes
3. LH: stimulates testosterone production by
the interstitial cells of the testes
Hormonal Regulation
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Inhibin: inhibits FSH production by the
anterior pituitary gland
Testosterone: stimulates the development
of the male reproductive system and
secondary sex characteristics
Hormonal Regulation
• The female reproductive system is influenced
by a negative feedback loop and involves the
following hormones:
1. GnRH: stimulates the release of FSH and
LH from the anterior pituitary gland
2. FSH: stimulates estrogen production and
oogenesis by the follicles of the ovaries
3. LH: stimulates ovulation and progesterone
production by the corpus luteum of the
ovaries
Hormonal Regulation
4.
5.
Estrogen: stimulates the development of
the female reproductive system and
secondary sex characteristics
Progesterone: Causes uterine thickening
and prevents uterine contractions
* Hormones of the female reproductive system
are secreted according to a 28 day cycle
from puberty to menopause
Human Development
Fertilization and Embryonic
Development
Fetal Development and Birth
Reproductive Technology
Fertilization and Embryonic Development
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The embryonic period of human
development takes place from fertilization
until 8 weeks
The fetal period of development is from 8
weeks until full term (40 weeks)
Fertilization is the joining of male and
female gametes to form a zygote
The gender of the zygote is determined by
the X and Y chromosomes of the egg and
sperm
Fertilization and Embryonic Development
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The first cell divisions of the zygote is called
cleavage
Cleavage results in the formation of the
blastocyst
The blastocyst implants in the endometrium
within 5 days of fertilization
The implanted blastocyst begins secreting
the hormone human chorionic
gonadotropin (hCG)
Fertilization and Embryonic Development
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The blastocyst undergoes gastrulation to
make three tissues (differentiation*)
Endoderm
Ectoderm
Mesoderm
The extra-embryonic membranes develop
The process of neurulation and
organogenesis occur
Fetal Development and Birth
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Fetal development and human pregnancy is
divided into three trimesters
First Trimester (1-12 weeks)
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Embryonic development completes
The embryo becomes a fetus
The placenta grows from the chorion
External reproductive organs are
distinguishable
Teratogens are most harmful
Fetal Development and Birth
2. Second Trimester (13-24 weeks)
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Fetal organs continue to grow and
develop
Fetal skeleton begins to form bones
Mother begins to feel movement
Fetus is covered in fine hair and mucus
If the fetus is born prematurely he/she is
unlikely to survive
Fetal Development and Birth
3. Third Trimester (25-38 weeks)
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Fetal organs continue to grow and
develop
Testes descend in the male fetus
Fat layer forms and hair is lost
Digestive and respiratory systems
complete development
Fetal Development and Birth
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The birthing process is called
parturition and occurs due to
hormonal changes
• The events of parturition are
commonly called labour
• Labour occurs in three stages
1. Dilation (2 -20 hours): Uterine
contractions cause the cervix to
dilate and the amnion ruptures
Fetal Development and Birth
2. Expulsion (30 min-2 hours): forceful
contractions push the baby through
the cervix and the birth canal (a Csection may be necessary)
3. Placental: the placenta and umbilical
cord are expelled about 30 minutes
after the birth of the baby
Fetal Development and Birth
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Lactation is the production of breast
milk by the mother
The hormone prolactin is secreted
from the anterior pituitary gland and
stimulates lactation
Expressing milk is due to the
hormone oxytocin
Reproductive Technology
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Categories of reproductive
technologies include:
1. Conception Control
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Preventing fertilization using physical
barriers, spermicidal chemicals,
surgery, NFP or hormones
2. Birth Control
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Preventing birth by inhibiting
implantation or clinical abortion
Reproductive Technology
3. Diagnostic
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Detecting fetal abnormalities before birth
using ultrasound, amniocentesis , chorionic
villus sampling and fetal surgery
4. Fertility
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Increasing the likelihood of ovulation,
fertilization or implantation using
techniques including artificial
insemination, invitro fertilization, and
fertility drugs