Transcript The Reproductive System

The Reproductive
System
Advanced Human Anatomy
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Schedule!
Wednesday (5/6) – Reproductive System Notes
Friday (5/8) – Study Guide for Final (Digestive, Urinary, Reproductive – 85 Qs)
Tuesday (5/12) – Finish Reproductive System; Cat Pre-Lab
Thursday (5/14) – Cat Dissection
Monday (5/18) – Cat Dissection
your anatomy books
Thursday (5/21) – Cat Dissection
Please, start bringing
back ASAP!
FRIDAY
May 22nd A-day
TUESDAY
May 26th B-day
WEDNESDAY
May 27th A-day
THURSDAY
May 28th B-day
8:25 – 9:27
A1 class
A2 class
B2 class
9:32 – 11:32
A2 FINAL
A1 FINAL
B1 FINAL
11:37 – 1:40
A3 class
B1 class
B2
FINAL
B3 class
A4 class
B4 class
1:45 – 3:45
A4 FINAL
B4 FINAL
A3 FINAL
B3 FINAL
Sexual Development
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In humans, the reproductive
system produces, stores, and
releases specialized sex cells
known as gametes.
◦ Haploid cells (23 chromosomes)
◦ Sperm – male // Egg – female
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These cells are released to create
the fusion of sperm and egg to
form a zygote, the single cell
from which all cells of the
human body develop.
Human male and female
embryos are identical until they
begin to differentiate at about 7
weeks of development.
Key Hormones
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FSH: follicle stimulating hormone;
promotes the formation of ovaries and
sperm.
LH: luteinizing hormone; stimulates
testosterone production in males and
female production of estrogen
Testosterone: main male sex hormone;
secretion by the fetal testis cells is
responsible for the development of
certain parts of the male genitals;
increased in puberty
Estrogen: primary female sex hormone;
plays a role in menstruation
Progesterone: female hormone
important for the regulation of
ovulation and menstruation
Sexual Development ~
Puberty
 Puberty is a period of rapid growth and sexual
maturation during which the reproductive
system becomes fully functional.
 When puberty ends, reproductive organs are fully
developed.
 Puberty usually begins between the ages of 9 and
15, and usually starts one year earlier in females
than in males.
Male
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Induced by
testosterone
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Deeper voice
Chest, pubic, facial hair
Lengthen bones
Increased size of testes
for sperm production
Female
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Induced by increased
LH, FSH, estrogen,
and progesterone
hormone levels
◦ Pubic hair
◦ Widen pelvis
◦ Enlarge mammary tissue
(breasts)
◦ Begin menstrual cycles
Secondary Sexual
Male Reproductive System
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The main function of the male
reproductive system is to produce and
deliver sperm.
 Release of FSH and LH stimulates cells in the
testes to produce testosterone.
 FSH and testosterone stimulate the development
of sperm.
Primary male reproductive organs are the
testes
 Accessory organs = penis, scrotum
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Sperm Cells
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A sperm cell consists
of:
Head
Nucleus
◦ Head, which contains
the nucleus
◦ Midpiece, which
contains energyreleasing mitochondria
◦ Tail, which propels the
cell forward
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Sperm are motile,
produced in large
numbers, and smaller
than most cells
Midpiece
Mitochondria
Tail
The Male Reproductive
System
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Male Reproductive System
Urinary bladder
Vas deferens
Pubic bone
Seminal vesicle
Urethra
Rectum
Penis
Prostate gland
Epididymis
Testis
Scrotum
Bulbourethral
gland
The Male Reproductive
System
The testes are located in an external sac
called the scrotum.
 The scrotum is located outside the body
cavity, where it is between 1 and 3
degrees cooler than normal body
temperature. The lower temperature
helps sperm development.
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The Male Reproductive
System
 Within each testis are
clusters of hundreds of
tiny tubules called
seminiferous tubules.
◦ The seminiferous tubules
are tightly coiled and
twisted together.
◦ Sperm are produced in the
seminiferous tubules.
◦ Sperm produced in the
seminiferous tubules move
into the epididymis, where
they mature and are stored.
The Male Reproductive
System
 From there, sperm
move into a tube
called the vas deferens, which extends
up from the scrotum into the abdominal
cavity.
 This merges with the urethra, the tube
that leads to the outside of the body
through the penis.
The Male Reproductive
 Glands lining theSystem
reproductive tract produce
seminal fluid.
◦ The Cowper’s glands (or bulbourethral glands) are a
pair of exocrine glands in the male reproductive
system
 Produce pre-ejaculate which neutralizes acidic urine that
may still be present in the urethra; lubricates the urethra
and external urethral orifice to protect sperm from
mechanical damage during ejaculation
◦ Prostate gland produces seminal fluid nourishes
sperm and protects them from the acidity of the
female reproductive tract.
◦ The combination of sperm and seminal fluid is called
semen.
 1 drop = approximately 3-5 million sperm cells
 Ejaculation = 300 – 600 million sperm cells
The Female
Reproductive
System
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main function of the female
reproductive system is to produce eggs.
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In addition, the female reproductive system prepares the
female's body to nourish a developing embryo.
The primary reproductive organs in the
female are the
ovaries.
◦ The ovaries are
located in the abdominal
cavity.
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Accessory organs:
uterus, fallopian tube, breasts,
and vagina
The Female
Reproductive System
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Female Reproductive System
Fallopian tube
Ovary
Uterus
Urinary bladder
Pubic bone
Cervix
Rectum
Vagina
Urethra
Egg Development
Each ovary contains about 500,000 primary
follicles, which are clusters of cells surrounding a
single egg (only about 400 are active)
 The follicle helps an egg mature for release into
the reproductive tract, where it can be fertilized.
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◦ Eggs develop within their follicles.
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Unlike men, who produce new sperm daily throughout
most of their lifetime, women are born with all
their eggs.
◦ To be more precise, a woman is born with about one to
two million immature eggs, or follicles, in her ovaries
◦ This number has decreased to about 400,000 eggs stored
in her ovaries.
◦ From puberty to the menopause only about 400-500
eggs will reach maturity, be released from the ovary, and
be capable of being fertilized
Egg Release ~
Ovulation
 When a follicle has matured,
its egg
is released in a process called
ovulation.
 The follicle breaks open, and the
egg is swept from the ovary into
one of the two Fallopian tubes.
 While in the Fallopian tube, an egg
can be fertilized.
 After a few days, the egg passes
from the Fallopian tube into the
uterus.
 hollow muscular organ of the female
reproductive system that is responsible
for the development of the embryo and
fetus during pregnancy
 If the egg is not fertilized it passes
through the cervix, and finally out
of the vagina.
 The vagina leads to the outside of
the body.
The Reproductive
System
Day 2 Notes
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The Menstrual
The menstrual Cycle
cycle is controlled by
internal negative feedback mechanisms
between the reproductive system and the
endocrine system.
◦ Negative feedback mechanisms reduce the
variable back to its original state or “ideal value”.
◦ The cycle takes an average of 28 days.
The Menstrual Cycle
During the menstrual cycle, an egg
develops and is released from an ovary.
 The uterus is prepared to receive a
fertilized egg.
 If the egg is fertilized, it is implanted in
the uterus and embryonic development
begins.
 If the egg is not fertilized, it is
discharged.
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The Menstrual Cycle
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The menstrual cycle has four phases:
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Follicular phase
Ovulation
Luteal phase
Menstruation
During these phases, hormone levels vary
◦ FSH, LH
◦ Progesterone
◦ Estrogen
The Menstrual Cycle
Follicular Phase
The anterior pituitary secretes FSH and LH, which cause a
follicle to develop to maturity
As the follicle develops, cells surrounding the egg enlarge and
produce more estrogen.
Estrogen causes the lining of the uterus to thicken.
Ovulation
This phase occurs midway through the cycle and lasts 3–4
days.
The pituitary gland produces more FSH and LH.
The release of these hormones causes the follicle to rupture,
and a mature egg is released into one of the Fallopian tubes.
The Menstrual Cycle
Luteal Phase
• The luteal phase begins after the egg is released.
• As the egg moves in the Fallopian tube, the follicle turns
yellow and is called the corpus luteum.
• The corpus luteum continues to release estrogen but also
begins to release progesterone.
Menstruation
If fertilization does not occur, the corpus luteum will
begin to disintegrate.
The follicle breaks down and releases less hormones,
which makes the uterine lining detach.
This tissue, blood, and the unfertilized egg are discharged
through the vagina.
This phase is menstruation, and it lasts 3–7 days
If fertilization does occur… whole different ballgame….
The Menstrual Cycle
Ovulation
Fertilization
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in upper 1/3 of Fallopian tube
 Only 1 sperm can fertilize an egg
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Fertilized egg = zygote
 Progesterone stimulates growth and development of
the blood supply and surrounding tissue.
 Within a few days of implantation, the uterus and the
growing embryo will release hormones that keep the
corpus luteum functioning for several weeks.
• This allows the lining of the uterus to nourish and
protect the developing embryo
Implantation
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Fertilized eggs are implanted into thick walls
of uterus
Chorion membranes dig into uterus to form
placenta
Zygote grows into an embryo
Embryo gets air and nutrients through the
umbilical cord
Once pregnant, progesterone levels stay high in
mom
Mom’s uterus grows with the baby
Duration of Pregnancy
First Trimester – 1st 12 Weeks
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Heart develops first
Neural tube develops
All body systems appear by Week 8 – Now a Fetus
Second Trimester – 13-27 Weeks
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Most growth
Looks more like a baby
Some premature births can survive at this stage
Third Trimester – 28-40 Weeks
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More growth
Kicking, rolling, stretching
Eyes open – Week 32
Lungs mature
Rotates to head-down position, unless baby is breech
Birth
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Labor
◦ Uterine contractions begin
◦ Cervix dilates to 10 cm.
Birth
◦ Uterus pushes baby through vaginal canal
◦ Placenta delivered after baby
◦ Cesarean Section (c-section) is a surgery that cuts
through the uterus to deliver the baby if it cannot be
born vaginally