Human Reproduction 1
Contents
Introduction
The Male Reproductive System
The Female Reproductive System
The Menstrual Cycle
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Introduction
The human reproductive system is organised as
follows: • paired structures for gamete production i.e. in
the male – sperm and in the female – eggs (ova)
• a series of tubes for transporting various
substances
• glands for secretion of hormones that control the
entire process
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The Male Reproductive System
Contents
Diagram – front view
Diagram – front view
Uncircumcised &
circumcised penis
Parts and Functions
The male reproductive
organs – side view –
diagram
Sperm formation in
testes – slide
Sperm – diagram
Sperm – slide
Male reproductive
hormones
5
The male reproductive system
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The male reproductive system
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Uncircumcised and circumcised penis
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Parts and Functions
PART
(1/2)
FUNCTION
Testis
Produce sperm and hormone testosterone
Scrotum
Keeps testes at lower temperature for
successful production of sperm (35°C)
Seminiferous
tubules
Coiled tubes in testes – sperm made here by
meiosis – chromosome no. halved from 2n to n
Epididymis
Coiled tube – sperm stored and mature here
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Parts and Functions
Vas deferens
(2/2)
Transports sperm from epididymis to urethra
Seminal vesicles
Prostate gland
Make seminal fluid and provides nourishment
and medium for sperm to swim
Cowper’s gland
Penis
Organ of sperm release – top of penis
protected by foreskin
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The male reproductive organs
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Testes, mammalian, tubule showing
sperm formation
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Sperm
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Human sperm
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Male reproductive hormones
(1/2)
Follicle stimulating hormone (FSH): produced by
pituitary – stimulates certain cell of the testes to
produce sperm
Luteinising hormone (LH): produced by pituitary
– stimulates other cells in the testes to produce
testosterone
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Male reproductive hormones
(2/2)
Testosterone:
1. stimulates the development of, and maintains,
the secondary sexual characteristics e.g.
broadening of the shoulders, growth and
enlargement of penis, deepening of the voice,
body and facial hair, etc.
2. works with FSH in the production of sperm
3. produced throughout the life of the male
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The Female Reproductive System
Contents
Diagram – front view
Diagram – front view
Parts and Functions
The Ovaries
Mammalian ovary – slide
Mammalian ovary –
developing follicles –
slide
Mammalian ovary – follicle
containing egg - slide
T.S. of ovary – diagram
Egg cell – diagram
After ovulation
The cervix and vagina
The vulva – diagram
The female reproductive
organs – side view –
diagram
Female reproductive
hormones
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The female reproductive system
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The female reproductive system
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Parts and Functions
PART
Ovaries
FUNCTION
Oviducts
Produces eggs and hormones oestrogen and
progesterone
Transport eggs to the uterus
Uterus
Holds the developing baby during pregnancy
Cervix
Remains closed during pregnancy
Vagina
Holds the penis during intercourse and acts as
the birth canal
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The Ovaries
(1/2)
Girls are born with thousands of immature egg
cells in her ovaries = oocytes.
From puberty (10 to 12 yrs) to menopause (45 to
50 yrs) each month a number of oocytes begin
to grow.
A fluid-filled follicle forms around each one.
One follicle will develop faster than the rest and its
oocyte will divide by meiosis to form an egg cell.
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The Ovaries
(2/2)
Egg cell contains half the number of chromosomes
i.e. n instead of 2n.
Follicle moves to surface of ovary and releases the
egg.
This is ovulation.
An egg can live for 24 to 48 hours.
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Mammalian ovary
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Mammalian ovary – developing
follicles
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Mammalian ovary – follicle
containing egg
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T.S. of ovary
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Egg cell
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After ovulation
(1/2)
Egg enters the oviduct and is carried along by
means of cilia into the uterus.
One of two events may now happen:
1. egg does not meet a sperm – egg cell will die
within 48 hours and pass out of the body
through the vagina
2. egg meets a sperm and they fuse – fertilisation
occurs
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After ovulation
(2/2)
Fertilised egg = zygote, as it travels along the
oviduct, divides by mitosis to form the embryo
Embryo arrives in the uterus and becomes
implanted in the endometrium (womb wall) and
pregnancy begins.
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The cervix and vagina
Cervix = the base or neck of the womb (uterus) - ring
of muscle to retain developing embryo.
Vagina = muscular tube about 10 cm long – holds the
erect penis during intercourse – also birth canal.
Vulva = area surrounding and protecting the external
opening of the vagina.
Above the vaginal opening is the opening to the
urethra
and above this is a small sensitive organ the clitoris.
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The vulva
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The female reproductive organs
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Female reproductive hormones
(1/2)
Oestrogen: produced by the ovaries – stimulates
1. thickening of the endometrium in preparation
for implantation
2. development of secondary sexual
characteristics e.g. enlargement and growth of
the breasts, growth of body hair under arms
and pubic regions
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Female reproductive hormones
(2/2)
Progesterone: produced by the ovaries –
stimulates endometrium growth during
pregnancy.
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The Menstrual Cycle
Contents
The Menstrual Cycle
– definitions
The Menstrual Cycle
– diagram
Day 1
Day 5
Day 14
Days 15 – 21
Days 21 – 28 (no fertilisation)
Menstrual Disorders
Endometriosis
Fibroids
Hormonal control of Menstrual
Cycle
Hormonal control of Menstrual
Cycle – diagram / graph
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The Menstrual Cycle - definitions
menstrual cycle: is a series of changes undergone by
the uterus in preparation for receiving a fertilised
egg - takes about 28 days - controlled by hormones.
If the egg is not fertilised menstruation occurs.
menstruation: the discharge through the vagina over
a period of about five days of menstrual fluid
consisting of blood, lining of womb (endometrium)
and unfertilised egg, which occurs monthly from
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puberty to menopause.
The menstrual cycle
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Day 1
In the womb: Menstruation
begins.
In the ovary: a follicle
begins to develop and
produce an egg.
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Day 5
In the ovary: ripening
follicle releases
oestrogen.
In the womb: oestrogen
causes the repair of
the endometrium.
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Day 14
In the ovary: egg
released from ovary
into oviduct = ovulation.
In the womb:
proliferation of uterine
wall continues.
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Days 15 – 21
In the ovary: empty follicle
becomes the corpus luteum
(yellow body).
Corpus luteum produces
progesterone and oestrogen.
In the womb: progesterone
stimulates endometrium
growth.
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Days 21 – 28 (no fertilisation)
In the ovary: corpus luteum
degenerates.
progesterone and oestrogen
levels drop
In the womb: egg arrives not
fertilised – breaks down
endometrium begins to break
down – menstruation begins
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Menstrual Disorders
One of the following need to be known:
Endometriosis
or
Fibroids
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Endometriosis
(1/3)
What is it?
A condition where fragments of the uterus lining
migrate to other parts of the pelvic cavity, and
stick to the outside of various organs – ovaries,
bladder, uterus, vagina.
They continue to respond to the menstrual cycle
hormones and bleed each month.
They cause pain during menstruation and sexual
intercourse.
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Endometriosis
(2/3)
The blood cannot escape and causes painful cysts
to grow on the pelvic organs.
Caused by
Not fully understood.
May be due to a hormone imbalance or a
weakness in the immune system that allows the
fragments to become attached.
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Endometriosis
(3/3)
Symptoms
Very heavy painful periods and abdominal pain
Treatment
Painkillers – to ease discomfort
Drugs – to prevent menstruation
Surgery – to remove the cysts in severe cases.
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Possible sites of endometriosis
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Fibroids
(1/3)
What are they?
Benign (non-cancerous) growths in the uterine
wall.
They range in size from a pea to an orange.
Consist of muscle and connective (fibrous) tissue
and grow slowly in the uterine wall.
Mostly occurring in women over 30, often multiple
and cause discomfort.
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Fibroids
(2/3)
Caused by
Not fully understood but thought to be associated
with the levels of oestrogen.
Oral contraceptives containing oestrogen can
cause fibroids to enlarge.
Symptoms
Large fibroids may cause uterine lining to wear
away  heavy menstrual bleeding  loss of
iron  anaemia.
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Fibroids
(3/3)
Treatment
The large fibroids that are causing complications
are surgically removed.
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Location of fibroids
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Fibroids
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Hormonal control of Menstrual Cycle
(1/4)
Follicle Stimulating Hormone (FSH)
Secreted by
Pituitary
- stimulates - follicle development
- stimulates - follicle cells to produce oestrogen
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Hormonal control of Menstrual Cycle
(2/4)
Oestrogen
Secreted by
Ovaries
- stimulates - repair of endometrium
- inhibits - FSH production (Negative feedback)
- stimulates - LH production
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Hormonal control of Menstrual Cycle
(3/4)
Luteinising Hormone (LH)
Secreted by
Pituitary
- stimulates - ovulation on day 14
- stimulates - corpus luteum development and
production of progesterone
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Hormonal control of Menstrual Cycle
(4/4)
Progesterone
Secreted by
Corpus luteum
- stimulates - endometrium growth
- inhibits - FSH production
- inhibits - LH production (Negative feedback)
 corpus luteum degenerates
Progesterone levels fall – menstruation begins –
FSH produced – cycle begins again
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Hormonal control of the
menstrual cycle
END
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