Download The Reproductive System - Coral Gables Senior High

The Reproductive System
Chapter 34.3 & 34.4
The Reproductive System
• At first male and female human embryos are
nearly identical in appearance
The Reproductive System
• During the 7th week male pattern
development is triggered by the production of
testosterone in the gonads of the embryo
• Female development is triggered by the
production of estrogen in the gonads
The Reproductive System
Estrogen and Testosterone are steroid
hormones
• Both act on cells and tissues to produce
physical characteristics of males and females
The Reproductive System
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Female Characteristics Produced by Sex
Hormones:
Breast Development
Widening Hips
Male Characteristics Produced by Sex
Hormones:
Facial Hair
Increase muscle development
Deepening of the voice
The Reproductive System
Puberty – a period of rapid growth and sexual
maturation during which the
reproduction system becomes fully
functional
• Occurs between the ages 9 and 15
• One year earlier for females
• Begins in the brain
• Hypothalamus signals the pituitary to produce two
hormones that affect the gonads
The Male Reproductive System
• When puberty is complete, the reproductive
system is fully functional meaning that the
male can produce and release active sperm
Testes – primary male reproductive organ
• Scrotum – external sac
The Male Reproductive System
Sperm Development
Seminiferous Tubules – tiny tubes inside testes where
sperm develop
Epididymis – area where sperm mature and are stored
Vas Deferens – some sperm are moved into this tube
The Male Reproductive System
Vas Deferens
• Extends upward from the scrotum into the abdominal
cavity
• The Vas Deferens merges with the Urethra
• This tube leads to the outside of the body
Seminal Vesicles
• The Prostate Gland
• The Bulbourethral Gland
• Produce a nutrient rich fluid called Seminal Fluid
Semen – the combination of sperm and seminal
fluid
The Male Reproductive System
Sperm Structure
The Female Reproductive System
Ovaries – primary reproductive organ of females
The main function of the female reproductive
system is to produce egg cells
• Ova (ovum) singular – egg cell
The Female Reproductive System
• At puberty each ovary contains as many as
400,000 primary follicles
• Cluster of cells surrounding a single egg
• Follicles help egg mature
• Females release only about 400 mature eggs
in a lifetime
The Menstrual Cycle
• A regular sequence of events involving the ovaries,
the lining of the uterus, and the endocrine system
• One ovary usually produces and releases one mature
ovum every 28 days or so……
• Regulated by hormones made by the hypothalamus,
pituitary, and ovaries
• During the Menstrual Cycle
• An egg develops within a follicle
• Then its released from an ovary
• Uterus is prepared to receive a fertilized egg
The Menstrual Cycle
• If the egg is not fertilized it is discharged
• Along with the uterus lining
• If the egg is fertilized, embryonic development
begins and menstrual cycle stops
The Menstrual Cycle
The menstrual Cycle includes:
Follicular Phase – hormones cause follicles to
mature
• Usually more than one but can be more
• Ovulation – the release of an egg from the ovary
into one of the Fallopian Tubes.
• follicle grows more estrogen is released
The Menstrual Cycle
The menstrual Cycle includes:
Luteal Phase – immediately after ovulation
• Progesterone (a hormone) is released
• Stimulates the growth and development of
blood supply
The Menstrual Cycle
The menstrual Cycle includes:
Menstruation – At the start of the new follicular phase,
low estrogen levels cause lining of
uterus to detach
• Uterus lining, blood, and unfertilized egg are
discharges through the vagina
• A new cycle begins on the first day of menstruation
Pregnancy
• Menstrual cycle ceases if pregnant
• First two days of the Luteal Phase is the
greatest time where fertilizing an egg is
greatest.
Pregnancy
• If sperm fertilizes an egg; the egg completes meiosis
and immediately undergoes mitosis
• After several divisions, a ball of cells form and
implant itself in the lining of the uterus.
• Uterus and embryo release hormones that keep
the corpus luteum functioning for several weeks
• This helps nourish and protect the developing
embryo
Fertilization & Development
Gametes – sperm and egg
Fertilization – the fusion of a sperm and egg cell
Fertilization
• Hundreds of millions of sperm are released
during ejaculation
• If egg is in one of the Fallopian Tubes the
chances of fertilization are high
Fertilization
• Egg is surrounded by a protective layer that
has binding sites
• Sperm releases enzymes that break down
eggs protective layer
Fertilization
• Once the 2 haploid (haploid =1/2 #
chromosomes) sperm and egg come together
a nucleus is formed
Zygote – the fertilized egg
• AKA - embryo
Fertilization
• When sperm enters the egg; the egg releases
granules to the outside of the cell
• This forms a barrier that prevents other sperm
from entering the egg.
Multiple Embryos
• If two eggs are released during the same
menstrual cycle and each is fertilized
• Result Fraternal Twins
• If a single zygote splits apart and produces
two genetically identical embryos
• Result Identical Twins
Implantation
Blastocyst – name of embryo after going
through the process of mitosis
• A hollow ball of cells are formed
Implantation
Implantation – 6 – 7 days after fertilization,
Blastocyst attaches to the wall of
the uterus
• At this point blastocyst begin to specialize
• This process is called Differentiation
Gastrulation
• The formation of three cell layers called:
• Ectoderm
• Mesoderm
• Endoderm
Neurulation
• The first step in the development of the nervous
system
• Shortly after gastrulation, a block of mesodermal
tissue begins to differentiate into the notochord
• Ectoderm near the notochord thickens and
forms the neural plate
• The raised edges of the neural plate from the
neural folds and the neural crest.
• The neural folds move together and form the
neural tube which form the spinal cord and brain
• Neural crest cells migrate and become nerve cells,
skin pigment cells, and other structures
Neurulation
Neurulation
Spina Bifida – neural tube not closing completely
• Some studies show that the vitamin supplement
folic acid can prevent
The Placenta
• Specialized membranes that protect and
nourish the embryo
• The embryo is surrounded by the Amnion
• A sac filled with Amniotic Fluid
• Cushions and protect the embryo
The Placenta
Chorion – (another sac) makes direct contact
with the tissues of the uterus
Chorionic Villi – finger-like projections that form
during the 3rd week on the outer
surface of the chorion and
extend into the uterine lining
The Placenta
Placenta – a vital organ formed by chorionic villi
and uterine lining
• This is the connection between the mother
and embryo
• This is the embryo’s organ of respiration,
nourishment, and excretion
• Blood barrier between mother and embryo
diffuse across the membrane
• Blood does not mix
The Placenta
Fetus – 8 weeks of development
• Most major organs and tissues are formed
• Begins to move
• 8 cm and 28 grams
Later Development
Second Trimester (month 4-6)
• Fetal heart becomes large enough to be heard with a
stethoscope
• Bone replace cartilage
• Hair grows over skin of fetus
• Increases in size
• Mother’s abdomen grows and
she begins to feel it
Later Development
Third Trimester (month 7-9)
• Organ systems mature
• Fetus grows
• Doubles in mass
• Lungs and other organs
change and prepare for
life outside
• Fetus able to regulate
body temperature
Later Development
• 9 months is average length of time for a fetus
to develop
Premature Babies – born before 8th month
Childbirth
Oxytocin – hormone released by posterior pituitary
gland; affects a group of muscles in the
uterine wall
Labor – a series of rhythmic contractions caused by the
muscles in the uterine wall
• Contractions become more frequent and more
powerful
• The opening of the cervix expands
• Amniotic sac breaks – fluid rushes out of the vagina
• Contractions force the baby out; usually head first
Childbirth
• Once the baby is born he or she will cough or cry to
clear the lungs of fluid
• Blood supply to placenta dries up
• Umbilical cord is clamped and cut
• Small piece stays on the baby
• It dries and falls off
• Navel – scar left from
umbilical cord
–AKA belly button
Childbirth
• More contractions expel the placenta and
amniotic sac
• Afterbirth
• Hormone prolactine (released by pituitary
gland) stimulates the production of breast
milk