Reproduction in Humans
Male Reproductive System
Objectives:
*Identify on diagrams the male reproductive
system and state their function
**Compare male and female gametes
scrotum
Organ
Testes
Functions
Function
Scrotum
Produce spermatozoa and make male hormone
testosterone which stimulates changes during puberty
Sac covering testes which hangs outside the body to keep
it cool as sperm can’t develop or be stored at 37 0C or
above
Sperm duct
Small tubules outside the testes store sperms for
maturation. Sperm duct connect these tubules to urethra
urethra
Urethra carries urine and sperm but not at the same time.
A ring of muscle around the urethra contracts to prevent
urine loss during sexual intercourse
Prostate and other glands Secrete fluid for sperm cell to swim. Prostate secrete
mucus and other secrete sugar for respiration of sperm
cells. Sperm cell + fluid = semen
Penis
Urethra runs down the centre of penis. Its main function
is to deliver sperm to the vagina for fertilization
Gametes (sex cells)
Acrosome (contain enzymes to break the
jelly coat
Cell membrane
nucleus
Head
Middle piece (Has mitochondria to
power swimming by the tail)
Jelly coat
Egg cell
cytoplasm
Drives sperm
forward
Sperms and eggs are specialised. Which statements belong to a
sperm and which to eggs?
Compare
Feature
Sperm cell
Egg cell
Much larger
size
small
movement
Swim using tail that lashes
from side to side
Does not move itself .
Moved along oviduct by
cilia and peristalsis
food store
Has very little – uses sugar
in seminal fluid for
respiration
Protein and fat in
cytoplasm- enough to last
till implantation in uterus
no. of chromosomes
23 (haploid)
23 (haploid)
number produced
Millions produced
constantly after puberty
often throughout life
One a month after puberty
until menopause except
when pregnant or taking
contraceptive pills
Female Reproductive System
Objectives:
* Identify on diagrams the female reproductive
system and state their function
**Describe sexual intercourse in humans
Functions
Organ
Function
Ovaries(attached to
inside of abdomen just
below the kidneys
releasing 1 ova /28days
alternately
Produce ova and make female hormones progesterone
and oestrogen which stimulates changes during puberty.
Oestrogen- development of sex organs and sec. sexual
characteristics progesterone prepares uterus for receiving
the embryo in case of pregnancy
oviduct
The egg passes out to the funnel shaped opening of the
oviduct in a process called ovulation which then either
gets fertilised by a sperm or die after passing into the
uterus
Foetus develops here. It develops a spongy wall for
implantation of the embryo in case of pregnancy
A ring of muscles at the lower end of the uterus leading to
vagina
A muscular tube opening outside the body
Uterus
cervix
Vagina
urethra
A separate opening above the vaginal opening for urination
clitoris
Above urethra a very sensitive area (lot of nerves)
vulva
Outer opening of vagina
Word Check
Describe sexual intercourse in bullet points (remember do not
have to mention movement of sperms through cervix as this
happens after )
•
•
•
•
•
•
Male, female stimulate each other
Blood pumped to spongy tissues of penis
Causes erection of penis
Penis enters vagina
Fluid made by vagina lubricates movement of penis in the vagina
This leads to contraction o f sperm duct to move sperms from the tubules
to the penis
• Secretions from glands are added for easy movement of sperm
• Urethra contracts to move seminal fluid through penis to vagina. This is
ejaculation which causes men to feel orgasm( a sense of pleasure)
• Repeated movement of penis against clitoris or vaginal walls may produce
orgasm in women
Each ejaculation contains 2-5cm3 of semen with up to 500million sperm cells
Fertilisation and Implantation
Objectives:
*Describe fertilisation in humans
**Describe early development of the zygote to
form a ball of cells for implantation into the
uterus wall
Why so many sperm cells?
What is the role of the acrosome?
What fuse first ?
What is the number of chromosomes after fertilisation?
Why do the other sperms not enter?
Fertilisation & Implantation
Villi or finger like projection of the
embryo to penetrate endometrium.
They are surrounded by blood vessels
which supply nutrients and oxygen
Add timeline
Division and Growth
Once the egg has been fertilised, we call it a ZYGOTE.
Zygote - 1 cell
2 cells
64 64
cells
cells
4 cells
32 cells
Ante-natal care and Birth
Objectives:
*Describe the ante-natal care of pregnant
women
**Describe the processes involved in labour and
birth
***Describe the advantages and disadvantages
of breast milk and formula milk
Why is it important that the mother has a balanced diet?
Which food groups are particularly important?
Bones of foetus can grow
Calcium :
To make extra red blood cells to carry oxygen to the foetus and so that
Iron:
both mother and baby can make extra haemoglobin
Carbohydrate:
So the mother has enough energy to move her heavy body around
Protein:
To provide amino acids for both to make tissues. The mother makes muscle
tissues in the uterus to prepare for birth and the fetus for growing and
developing its organs
The things a mother should not take
Alcohol: can cause birth defects and mental retardation
Drugs: like heroin can give baby an addiction
Cigarettes: nicotine and CO result in premature and underweight babies
Causes of premature birth:
Smoking Early breaking of the amnion (most common)
Birth:
A few weeks before birth a fetus turns over inside the uterus with the head towards
the cervix. Hormones released by the fetus and the increase in pressure in the uterus
stimulate hormonal changes in the mother. A hormone oxytocin is released from her
pituitary gland which stimulates uterine muscle to contract. The mother feels the
contraction and this is the beginning of labour.
When contractions become stronger and more frequent the opening of the cervix
stretches and the amnion breaks to release the amniotic fluid.
The contraction is even stronger now pushing the baby towards the cervix. The cervix
widens pushing the baby’s head through the vagina. The baby starts breathing for the
first time when born. The airways need clearing of mucus to help the baby breath.
The umbilical cord is cut and tied just above the point where it attaches to the baby.
The rest heals to form the naval. After a few minutes the placenta comes away from
the uterus wall. It is pushed out of the vagina as afterbirth
It is a painful experience but gentle exercise, special breathing technique, painkillers
in form of epidural (catheter between spine and spinal cord) to stop transmission of
impulses from pain receptors to the brain.
Breast feeding
Formula Milk
Contains antibodies which gives baby
passive immunity. The antibodies remain
there after a while after breast feeding is
stopped.
More convenient
Chance of getting infection
Expensive
Creates bonding
Research shows less likely to develop
childhood cancer, and diabetes. Mothers
less likely to develop breast uterine and
ovarian cancer
The Menstrual Cycle
Objectives:
*Describe the menstrual cycle in terms of
changes in the uterus and the ovaries
**Explain the roles of hormones in controlling
the menstrual cycle
Girls are born with potential egg cells.
Each potential egg is surrounded by small group of cells and together they
form a follicle.
At puberty some follicle develop and egg divide by meiosis
Cytoplasm fills with stored food
Each month one or a few follicle will develop
At the beginning of the cycle at the end of menstruation one follicle will
develop.
Follicle enlarges and fills with fluid move towards the edge of the ovary
After 2 weeks follicle bursts releasing egg and some fluid into the oviduct
This is
The follicle cells left behind make the yellow body which remains for next 2
weeks in case of pregnancy they are active otherwise they decrease in size
The uterus lining thickens during egg development
If not fertlised the egg passes to the vagina and the yellow body breakdown
in the ovary
Yellow body is stimulated in pregnancy by a hormone released by the embryo
which in turn stimulates the lining of the uterus to continue to thicken
Menopause is when menstrual cycle stops
The menstrual cycle lasts about 28 days. During this time the lining
of the uterus thickens and an egg is released.
If, once the egg has reached the uterus it still hasn’t been fertilised
by any sperm it will die and the lining of the uterus will start to
break up.
Within about 2 weeks, the woman has her period – blood and
dead cells pass out through the vagina. This is called menstruation.
A woman’s period can last between 3 and 8 days. Girls normally
start their periods between the ages of 11 and 14 (but it may be a
little earlier or later for some people).
The 4 stages of the menstrual cycle:
These are controlled by hormones
Day 1: Bleeding starts when the lining of the uterus breaks down
and passes out the vagina – “Having a period”
Day 6: The lining starts to build up again and thickens into a spongy
layer of blood cells
Day 14 (approx): An egg is released and lasts for around 3 days
Day 16-21: The lining stays thick awaiting the arrival of a fertilised
egg. If one doesn’t come then the lining breaks down again in next 6
days
Hormones
• Many processes within the body are coordinated by chemical substances
called hormones.
• Hormones are secreted by glands and are transported to their target
organs by the bloodstream.
• Hormones regulate the functions of many organs and cells.
Hormones in the menstrual cycle
FSH – follicle stimulating hormone
• Secreted from:
pituitary gland
• Effects:
egg matures in ovary(stimulates follicle to develop)
•
Release of oestrogen from ovary
Oestrogen
• Secreted from:
ovaries( cells in the ovary stimulate it)
• Effects:
inhibits release of FSH(stimulates thickening of the lining)
Causes release of LH
LH – luteinising hormone
• Secreted from:
pituitary gland travels to ovary
• Effects:
stimulates release of egg from ovary
Progesterone
• Secreted from: made by yellow body( corpus
luteum)
• Effects: Thickens and maintains uterus lining
for implantation
If pregnancy occurs both ovarian hormones
continue to be produced to prevent menstrual
cycle starting again
Sex Hormones
Objectives:
*Describe the role of testosterone and oestrogen in developing secondary
sexual characteristics at puberty
**Describe artificial insemination and the use of fertility drugs and discuss
their social implications
Starter:
What is secondary sexual characteristics?
Do both sexes develop at the same time? What causes
development?
Do all young people grow at a definite age ? What is this time
called?
What does the word adolescent mean? When adolescence
stops?
h/w complete worksheet and hand in on 20/9
Puberty
Hormones
Male
Brain/Hypothalamus
Female
Hormone
Brain/Pituitary Gland
Pituitary hormones
FSH, Pituitary Hormones
Testes
Ovaries
Testosterone
Oestrogen,
Testosterone
Secondary sexual characteristics
Progesterone,
Menstruation
Puberty
The statements below describe changes which happen to girls, boys or both during
puberty. Copy the table below into your book and list the statements under the
correct headings.
Changes to females during
puberty
Changes which happen in
both males and females
Changes to males during
puberty
• Production of oestrogen and progesterone by the ovaries
• Production of testosterone by the testes
• Growth hormones released causing growth of body (height and weight
increase) and reproductive organs
• Muscles develop and shoulders widen
• Ovaries begin to release ova (singular: Ovum)
• Voice becomes deeper
• Hips widen (often but not always) and breasts develop
• Menstrual cycle starts
• Growth of pubic hair
• Testes begin to produce sperm cells
• Increased body odour from sweat glands (many found in armpits) and
genitals
• Increase in erections
• Increased interest in the opposite sex
• Growth of facial hair
• Growth of hair under arms and in pubic region
Fertility Drugs and Treatment
What is infertility?
In woman
Causes of infertility
treatment
Ovaries do not release egg
Due to lack of FSH
production
Regular injections of a fertility drug
containing FSH or using tablets which
make pituitary gland insensitive to
oestrogen. It may cause multiple
fertilisation.
Semen collected from men and placed
in the uterus via a plastic tube. This is
called artificial insemination (AI) in the
later case or use sperms from a donor
who remains unknown. It is also
possible to take the nucleus from a
defective sperm and inject it into an
egg. The zygote is cultured for several
days to grow into embryo which is then
inserted in the uterus so that
implantation can take place.
In man
Do not produce enough
sperm or problems with
ejaculation
Methods of Birth Control
Objectives:
*Describe the methods of birth control by:
natural, chemical, mechanical and surgical
means
Starter:
What is birth control?
• Stop the sperm from reaching the egg
• Stop the eggs from being made
• Stop the fertilised egg from implanting and developing in the uterus
Mechanical methods:
IUD – A small plastic device wrapped in copper or contains
hormones(progesterone). Fitted in uterus prevents either sperm entering
uterus or embryo implanting. Progesterone makes mucus in cervix sticky.
Cap or diaphragm – A rubber dome used with sperm killing cream or foam
placed over cervix before intercourse prevents sperm from entering uterus
Condom/ femidom – Most common, rubber tube rolled over penis or
inserted in vagina stops sperm entering the vagina and stops STDs
Chemical methods:
The pill – different types available. Contains oestrogen and progesterone in
varying concentrations. Inhibits FSH thus no egg matures. Failure to take it
regularly may cause pregnancy. Side effects are weight gain, sore breast,
painful period depression and heart and circulation problems
Spermicides – Foam, cream or jelly to kill sperms. Not very effective on its
own.
Natural methods:
Abstinence / rhythm method– during the most likely time of fertilisation.
Determine ovulation date by keeping a record of period cycle and abstain 2
days before and after that date. It is unreliable
Sometimes checking symptoms of ovulation like increase in body
temperature, change in cervical mucus( less sticky) .Easy for people without
access to other methods.
Surgical method:
Vasectomy – Operate to cut and tie sperm duct. Irreversible. Ejaculation
happens but no sperm released
Sterilisation – Minor operation on women. Oviducts are cut and blocked.
Irreversible.
Sexually transmitted diseases
Objectives:
*Describe the methods of transmission of HIV
and the ways in which HIV/AIDS can be
prevented from spreading
**Describe the symptoms, signs, effects and
treatment of gonorrhoea
***Describe how HIV affects the immune
system
H/W Revise for test on 26/9
HIV(human immunodeficiency virus) identified in 1980s leads to AIDS
( acquired immunodeficiency virus syndrome).
It is a collection of diseases due to weak immune system and that is why
called a syndrome.
HIV positive- HIV attacks an important type of lymphocytes (T). Tlymphocytes stimulate other lymphocytes to produce antibodies. During HIV
infection the number of T lymphocytes decreases and so fewer antibodies
are produced every time there is an infection. Therefore diseases as well as
cancers , that form can’t be destroyed by the immune system because they
fail to recognise them.
Early symptoms of AIDS are very much like flu with swollen glands and high
temperature. Later symptoms include weight loss, various types of cancer
and decrease in brain function. Some HIV + people do not develop any
symptoms.
Transmission:
• In blood ( not by blood sucking insects)
• In semen
• Unprotected sex ( not by touch)
• Hypodermic needles contaminated with infected blood ( not by sharing
glasses or cups)
• Blood transfusion
• Across placenta
• At birth when two bloodstreams come in close contact
• Breast milk
Prevention:
• Antiviral drugs ( prevent virus from multiplying)
• Use of condoms
• Free needle exchange schemes to reduce the use of shared needles
among drug users
• Careful screening of donated blood for transfusion
Gonorrhoea only transmitted by sexual intercourse. Cause by spherical
bacteria Neisseria gonoerrhoea. It can only survive in the moist lining of the
male and female reproductive tract. If the bacteria is present in vagina or
urethra in female and male respectively it can be transmitted by sexual
intercourse.Symptoms after 2-7 days of infection.
In male bacteria multiply within urethra producing an unpleasant discharge
and pain when urinating. Sores develop on the penis. If not treated can cause
long term damage to both urinary and reproductive system( sterility).
In female bacteria multiply in cervix producing a discharge which is not
noticeable and painful but will lead to same kind of damage if not treated.
Prevention:
• Have only one partner who is disease free
• Use condom
Treatments:
• Antibiotics