Title: Human Reproduction
1Human Reproduction
2Human Reproduction
3Human Reproduction
- Male Reproductive Anatomy
- Spermatogenesis and Male Hormones
- Male Reproductive Technologies and Birth Control
- Female Reproductive Anatomy
- Oogenesis and Female Hormones
- Uterine and Ovarian Cycles
- Development of the Fetus
- Parturition and Lactation
- Teratogens and Birth Defects
- Reproductive Technologies
4Human Reproduction
5Reproduction
- ensures the survival of a species
- Sexual reproduction produces offspring with new
and unique characteristics that may increase
their chance of survival.
6Reproduction
- 2 types of gametes (sex cells)
- Males 1 billion sperm each day from the ages
13-90 - Females born with 400, 000 eggs, 400 mature
from ages 12 to 50
7Reproduction
- The average gestational period for a human is 266
days.
8Male Reproductive System
- The male reproductive structures are responsible
for - producing sperm
- storing sperm
- delivering sperm
- to the female
9Male Reproductive System
10Male Reproductive System
- Scrotum
- holds the testes away from the body to keep them
cool. - Sperm production only occurs at temperatures
about 3 degrees below body temperature.
11 Male Reproductive System
- Testis
- descend about 2 months before birth
- spermatogenesis
- seminiferous tubule that produce sperm
12 Male Reproductive System
- Epididymis holds sperm for about 2-4 days while
they mature
13Male Reproductive System
- Vas Deferens
- conducts sperm during ejaculation
- vasectomy the vas deferens cut and tied off, to
prevent conduction of sperm.
14Male Reproductive System
- Ejaculatory Duct propels semen and sperm through
the urethra. - Urethra conduction of urine and semen out of the
penis. - a sphincter muscle closes off the bladder,
preventing urine from exiting the urethra.
15Male Reproductive System
- Penis
- male organ for copulation. Beneath the skin,
lies the urethra surrounded by spongy protective
tissue that expands to form the glans penis. - Prepuce (foreskin) is a loose sheath of skin
covering the glans penis of uncircumcised males.
The foreskin produces an oily secretion known as
smegma.
16Seminal Fluid
- Is produced by three different glands
- Seminal Vesicles
- fluid high in fructose that provides energy sperm
need to swim - Prostaglandins which cause contractions of
muscles in the female reproductive tract to help
move sperm in
17Seminal Fluid
- Prostate Gland
- milky white alkaline fluid that neutralizes the
acidity of the vagina - Cowpers Gland
- buffered fluid that cleanses and neutralizes the
acidity in the urethra
18Spermatogenesis
- Spermatozoa are the smallest cells in the body.
They have very little cytoplasm in the head, and
a large tail (flagellum).
19Spermatogenesis
- Spermatogonia undifferentiated germ cells that
have 46 chromosomes - Primary Spermatocytes larger cells that undergo
meiosis I
20- Secondary spermatocytes cells that undergo
meiosis II - Spermatids cells with 23 chromosomes, that are
ready to mature in the epididymis - Spermatozoa mature sperm cells
21- Sertoli Cells- nourish sperm cells
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23Terminology
- Erection
- parasympathetic nerve impulses dilate the
arteries of the penis, allowing blood to flow
rapidly into the highly vascular penile tissue - veins are compressed preventing blood from
leaving the penis. -
24Terminology
- Ejaculation occurs when sexual stimulation
forces semen to the urethra, where rhythmical
muscle contractions cause the semen to be
expelled from the penis. - Infertility the inability to produce viable
sperm. - Impotency the inability to achieve a sustained
erection.
25Regulation of the Male Reproductive Hormones
26Male Reproductive Hormones
- GnRH gonadotropic releasing hormone
- released from hypothalamus
- stimulates the anterior pituitary to release LH
and FSH - LH luteinizing hormone
- stimulates the interstitial cells (cells in
between seminiferous tubules) of the testes to
produce testosterone
27Male Reproductive Hormones
- Testosterone responsible for male secondary sex
characteristics, required for sperm production - FSH follicle stimulating hormone
- stimulates production of sperm in the
seminiferous tubules
28Male Reproductive Hormones
- Inhibin
- produced by Sertoli cells when sperm count is
high - Sends feedback to inhibit FSH and GnRH
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30Female Reproductive Structures
- The female reproductive structures are
responsible for - reception of sperm
- producing an egg
- nourishing and protecting the fetus
- delivering the baby
31Female Reproductive Structures
32Female External Structures (Vulva)
- Labia majora large, fatty, hair covered folds
that protect the genitals - Labia minora smaller folds of skin inside the
labia that are kept moist by secretions - Clitoris small shaft of erectile tissue
33Female Internal Structures
- Vagina
- intercourse accepts the penis
- birth canal during labor
- pH is generally acidic
34 Female Internal Structures
- Cervix
- Thick muscular tissue
- plugs closed with mucous during pregnancy
- prevents material from getting into the uterus,
and holds the baby in
35Female Internal Structures
- Uterus (womb)
- pear shaped muscular organ (5 cm wide)
- houses the developing fetus during pregnancy (30
cm wide) - strong contractions help push the baby out during
birth
36Female Internal Structures
- Ovaries
- produce the ovum from follicles found in the
outer cortex
37Female Internal Structures
- Oviducts /Fallopian tubes
- conduction of the ovum (egg) from the ovaries to
the uterus - where fertilization usually takes place
- If egg implants here ectopic pregnancy
- frequency
38Female Internal Structures
- Fimbriae
- small fingerlike projections at the ends of the
oviducts that sweep to draw the egg into the
fallopian tube
39Female Internal Structures
40Ovarian Structures
- Follicle
- cells that support and protect the ovum
- secrete estrogen to mature the ovum
- become a corpus luteum following ovulation.
- Ovum egg cell, viable for about 24 hours after
release.
41Ovarian Structures
- Corpus Luteum
- cells remaining after a follicle has ruptured
during ovulation - secretes progesterone and some estrogen for about
3 months if fertilization and pregnancy occurs - deteriorates after about 14 days if fertilization
does not occur.
42Oogenesis
43Regulation of the Female Reproductive Hormones
- GnRH stimulates the anterior pituitary to
produce FSH and LH - FSH stimulates development of the follicle and
the production of estrogen within the ovary
44Regulation of the Female Reproductive Hormones
- LH causes ovulation, development of the corpus
luteum which secretes progesterone
45Reproductive Hormones
- Estrogen
- secreted by the follicles in the ovaries
- causes maturation of the egg
- stimulates growth of the endometrium (uterus
lining) - Female secondary sex characteristics
- Inhibits FSH
46Reproductive Hormones
- Progesterone
- secreted by the corpus luteum
- continues preparation of endometrium
- inhibits both FSH and LH to prevent ovulation
- prevents uterine contractions
- firms the cervix
47P 525 Fig 6
48The Uterine and Ovarian Cycles
49- Day 1-5 Menstruation/Flow Phase
- Estrogen and progesterone levels are low
- endometrium is sloughed off and shed
- Day 1-13 Follicular Phase
- FSH secreted from ant. pit. promotes development
of the follicle - follicle releases estrogen, which promotes growth
of the endometrium.
50- Day 14 Ovulation
- An increase in LH causes the ovum to be released
- FSH is lowered
- Day 15 28 Luteal Phase
- LH promotes formation of the corpus luteum
- corpus luteum produces progesterone, inhibits
GnRH, LH and FSH, preventing subsequent
ovulation.
51- Many birth control pills are high in progesterone
which prevents ovulation - cancer
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53- No Fertilization ? corpus luteum degenerates,
estrogen and progesterone levels drop, and
menstruation occurs.
54The Uterine Cycle
55Fertilization
- Fertilization
- -union of sperm and secondary oocyte in the
fallopian tube - Only one spermatozoa will fertilize an egg
- Now called a zygote
- fertilization
56Early Embryonic Development
- Zygote fertilized egg, divides by cleavage,
mitosis with no increase in size - 36 hours 1st division (2 cells)
- 60hours 4 cells
- 72h 8 cells
- Morula solid ball of cells the same size as the
fertilized egg (day4-5)
57Early Embryonic Development
- Blastocyst
- hollow ball of cells filled with fluid,
- outer layer forms the chorion, inner layer forms
the embryo - Implants day 7-10
58Early Embryonic Development
59Implantation
- embryo embeds itself in the endometrium.
- produces HCG (human chorionic gonadotropic
hormone) maintains the corpus luteum for about
2-3 months. - Reminder corpus luteum produces progesterone and
estrogen to maintain the endometrium and prevent
ovulation)
60- HCG detected in blood or urine with a pregnancy
test - hCG Pregnancy Test ELISA
61Early Embryonic Development
- Gastrula
- the blastocyst pushes in (invaginates) and forms
the 3 primary germ layers - the hollow space forms a primitive gut
- 2nd week
62Gastrulation
63Germ Layers
- Ectoderm nervous system and epidermis of the
skin - (hair, nails,retina, lens, inner ear, lining of
the nose, mouth, anus and tooth enamel) - Neurula- notochord/neural tube forms from the
ectoderm layer (forms in 3rd to 4th week)
64Germ Layers
65Germ Layers
- Mesoderm skeleton, muscles, reproductive organs
- (connective tissue,cartilage, blood, blood
vessels, kidneys) - Endoderm lining of the digestive and respiratory
system, endocrine glands - (trachea, bronchi, lungs, gallbladder, urethra,
liver, pancreas, thyroid,bladder)
66- Gastrulation
- Embryonic development
67Embryo at 4 weeks
68Extra Embryonic Membranes
- Amnion inner membrane filled with fluid to
provide protection, maintain temperature,
swallowing - Chorion-outer membrane, contributes to placenta
- Extraembryonic coelom fluid filled space
between amnion and chorion
69 Extra Embryonic Membranes
- Allantois collects nitrogenous wastes and forms
the umbilical blood vessels - Yolk Sac surrounds embryo, first site of blood
cell formation, becomes part of the primitive gut
70Extra Embryonic Membranes
- Placenta
- forms around the fetus
- exchange of gases, delivery of nutrients and
removal of wastes for the fetus
71 Extra Embryonic Membranes
- no blood shared between the mother and the fetus
- Produces progesterone and estrogen at about 4
months
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73How Old Are You?
- Gestational age
- -calculated from the first day of the mothers
last menstrual period. - length of pregnancy is 40 weeks
74How Old Are You?
- Fertilization age actual age of the fetus
- - estimated to be about two weeks after the date
of the last menstrual period. - To calculate due date LMP 3 months 7 days
- calculator
75 76Trimesters
- 1rst until end of third month
- 2nd 4-6months
- 3rd 7-9 months
77Developmental Milestones
- 1 week fertilization, cleavage, blastocyst
- 2 weeks implantation, chorion secretes HCG, 3
germ layers form
78Developmental Milestones
- 3 weeks nervous system is evident, heart begins
to form (2 tubes), heart beats around day 22 - 4-5 weeks limb buds appear, eyes, ears and nose
develop, umbilical cord is attached to placenta
79Developmental Milestones
- 6-8 weeks fetus is recognizable as a human, all
organ system are developed, reflexes begin (size
1.5, 0.5 g) - 8th week fetus
80- 9-16 weeks heartbeat is audible with a
stethoscope, bone replaces cartilage, eyelashes
formed, fetus can suck and swallow (size 6,
0.5 lb)
81Developmental Milestones
- 17-28 weeks movement is felt by mother, eyelids
open (size 12, 3lb) - Week 25 premature baby has 50 chance of survival
82Developmental Milestones
- 32 weeks fetus moves to head down position and
lungs mature - (good survival rate if born)
83Developmental Milestones
- after about 32 weeks significant weight gain
- 40 weeks full term (size 21, 7.5 lbs)
- See summary chart on page 534
84Developmental Milestones
85Virtual Development
- Conception to Birth
- Visible Embryo
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87Teratogens
- Teratogens - chemical substances or infections
that cause specific birth defects
88Teratogens
-Thalidomide-prescribed for morning sickness in
the late 50s and early 60s -rubella during the
first 12 weeks of pregnancy eye problems,
hearing problems and heart damage.
89Parturition Birth
- Hormones
- -relaxin made by placenta, loosens pelvis
ligaments - -prostaglandins contractions
- -oxytocin from Post. Pit - contractions
90Parturition
- Stage 1 dilation and effacement(thinning) of
the cervix, mucous plug dislodges, uterine
contractions open the cervix - Stage 2 delivery of the baby, cervix is dilated
to about 10 cm, intense contractions every 1-2
min push the baby down the birth canal - Stage 3 delivery of the placenta
91Parturition
- The average labor lasts about 12 hours, but can
range from 1 hour to 36 hours. - caesarean section may be required.
- involves removing the baby from an incision in
the front of the abdomen.
92Lactation
- prolactin stimulates the glandular tissue in the
breasts to produce fluids, colostrum, and milk. - Colostrum is a rich fluid containing mostly sugar
and proteins. This first milk is believed to
play a role in early immunity.
93Lactation
- Regular suckling stimulates the pituitary gland
to release oxytocin - causes weak uterine contractions to return it to
its pre pregnancy shape - causes let down of milk
- 1.5 L of milk each day
94Reproductive Technologies and Health
- Pap Smear a sample of cervical cells are taken
and examined for abnormal growth (cancer) - Ultrasound uses sound waves to view the baby in
the womb - Ultrasound Scan Fetal Video Clips
95Reproductive Technologies and Health
- Amniocentesis sampling of the cells from the
amniotic fluid at about 16 weeks to check for
genetic abnormalities -
- Amniocentesis Flash Animation
96Reproductive Technologies and Health
- Chorionic Villus Sampling sampling of cells
from the chorion at about 5 weeks to check for
genetic abnormalities -
- http//www.pbs.org/wgbh/nova/miracle/windows.html
97Fertility Technologies
- IVF in vitro (in glass) fertilization
fertilizing the egg in a petri dish, and
implanting the embryo 2-4 days later - Life Changine Science - Program 3 IVF
- AID artificial insemination by donor, sperm is
artificially placed in the vagina.
98Fertility Technologies
- Egg Screening testing and selecting eggs to be
fertilized, fertility drugs produce eggs that are
collected using a needle biopsy - TSE testicular sperm extraction
- removal of sperm via biopsy (not ejaculation)
- ICSI intracytoplasmic sperm injection
- sperm head is injected directly into the egg
99Fertility Technologies
- GIFT gamete intra-fallopian transfer
- sperm and egg are transferred to the fallopian
tube for fertilization - AH assisted hatching
- a chemical solution is dripped over the egg to
allow the sperm to penetrate more easily
100Fertility Technologies
- Embryo Transfer implantation of an embryo (at
blastocyst stage) into the womb or fallopian
tube, may be frozen or unfrozen - Fertility Drugs induce ovulation, usually many
ova are produced at one time, often results in
multiples
101Fertility Technologies
102Human Reproduction