Human Reproduction And Genetics Flashcards
Ovulation
An egg is released from the
ovary an average of every 28 days
Menstruation/Period
The lining and a
small amount of blood pass out through
the vagina (day 1-5)
Fertile period
These are the days of the
menstrual cycle when the woman is most
likely to become pregnant
Menopause
Signals the end of a female’s
ability to reproduce and also the end of her
menstrual cycle. It happens at different
ages for different people, typically in the
late 40’s to early 50’s.
Testes
Produce sperm
Scrotum
where the testes are, it is located outside
the body to ensure the temperature is lower than body
temperature for healthy sperm
Epididymis
is a coiled tube on the outside of each
testis that stores sperm and allows them to mature fully.
Vas deferens
(sperm duct) brings the sperm from
the testes to the penis
Seminal vesicles, prostate gland and cowpers gland
produce seminal fluid which mixes with sperm to
form semen, it nourishes the sperm and allow them to
swim.
Penis
enters the female and ejaculates semen
Puberty
describes when the body starts
becoming sexually mature (reproductive
organs develop). It normally happens
between the ages of 10 and 16
Male puberty
In males, sex hormones
(testosterone) are released causing the
voice to deepen, hair grows around the
sex organs, face, chest and underarms,
the testes and penis grow bigger and start
to produce sperm.
Female puberty
In females when the sex
hormones (oestrogen and progesterone)
are released the breasts develop, hips
widen, and hair begins to grow on the
body
Fertilisation
During intercourse the man’s penis fills
with blood and becomes hard enough to
be placed inside the woman’s vagina
A mixture of sperm cells and seminal fluid
called semen is released into the vagina
The sperm swim up the uterus and into
the fallopian tubes
Fertilisation women
If an egg is present in the
fallopian tube, and a couple have sexual
intercourse, then one of the sperm cells
may fuse with it
• The nuclei of the sperm and egg fuse
together to form a fertilised egg
• The woman is now pregnant
Embryo
The fertilised egg then divides a number of
times and the tiny group of cells moves
down the fallopian tubes to the uterus
• This group of cells settles into the lining of
the uterus and continues to divide to form
an embryo
Zygote - embryo - foetus
• Egg and sperm fuse to form a single
• → Zygote
• Cell division occurs and growth
• → Embryo, which attaches to the lining of
the uterus (implantation) grows more, and
after 8 weeks looks like a human
• →Foetus
Pregnancy
• The average length of a human pregnancy
is 40 weeks
• As the embryo develops in the uterus it is
protected inside a bag of fluid called
amniotic fluid
• This fluid provides a cushion for the
embryo
Umbilical cord
• A tube called the umbilical cord joins the
embryo to the placenta
Placenta
• The placenta is rich in blood vessels
• It is here at the placenta that food and
oxygen from the mothers blood pass into
the baby’s blood
• Also wastes such as Carbon dioxide pass
from the baby’s blood into the mothers
Birth
The birth of a baby begins when the uterus
muscles start to contract
• This is called labour
• The bag of amniotic fluid bursts “waters
break” and further contractions push the
baby out usually head first, through the
vagina
• The umbilical cord is cut and the placenta
(afterbirth) comes out after
Lactation
• The mother may choose to breastfeed the
infant.
• The production of breast milk is called
lactation.
• The first three days of milk is called
colostrum– very nutritious, and helps
protect the baby from infection
Natural methods of contraception
aim to detect the day ovulation takes place and
avoid intercourse during the fertile period
Artificial methods of contraception
(prevent the sperm and egg meeting)
• An example of this is a condom which
prevents sperm entering the vagina
• Another example is the contraceptive pill
which prevents ovulation
• It is important to realise no method is
100% reliable
Genetics
is the study of the
inheritance of Characteristics
Inheritable characteristics
Many physical characteristics such as eye colour and shape of ears were inherited from
your parents
Chromosomes
The nucleus of each sex
cell (gamete) contains 23 thread like
structures called Chromosomes
Chromosomes are made of
protein +
DNA. These chromosomes carry genes
Genes
are chemicals found on
chromosomes that pass on information
from parents to children
DNA
Deoxyribonucleic acid
46 chromosomes
When an egg and
sperm cell fuse (each has 23
chromosomes) they give the individual
they are creating 46 chromosomes
• One set comes from the mother the other
from the father
Characteristics
• Each characteristic will be controlled by a
pair of genes
• If the gene from the sperm is brown eyes
and the gene from the egg is brown eyes
then the child will have brown eyes
• The child is said to be homozygous for
brown eyes, as she has only one type of
eye colour gene
Gene types
The stronger gene is called the dominant
gene
The weaker gene is called recessive
Dominant gene
The dominant gene is the one that
appears in the child when two different
genes are controlling a characteristic
Recessive gene
The recessive gene does not appear in the
child when two different genes are
controlling a characteristic
