7b Sex And Science Flashcards
Male and female sex cells are called
Sperm and egg
During fertilisation
The sperm and egg cell fuse so does their nuclei which produces a fertilised egg cell .
External fertilisation is where
Happens outside of the bodies and usually happens in water
Oviduct is lined with
Cilia to sweep the egg cell toward the uterus
Baby develops
In the uterus
What and where is the cervix
Is a ring of muscle in the lower and of the uterus which will hold the baby in place during the pregnancy . It opens into the vagina
Sperm cells are made where and why is their location important
In the testes . The testes are held in a bag of skin outside the body called the scrotum . It is important it is outside because only then the stem cell will be at the right temperature to develop properly
How is an egg cell adapted to its function
It has a jelly coating which make sure only one sperm cell enters . Cytoplasm has a store of food to provide energy for the fertilised egg cell .
Sperm cells travel up
Sperm ducts where fluid is added from glands to give sperm cell energy . Together the sperm cells and fluid are called semen . It leaves through the urethra .
Urethra also carries what
Urine from the bladder but never at the same time .
Adaptations of the sperm cell are
Streamlined shape to swim faster . Flagellum to help it swim faster . Tip of the head has chemicals that attack the outside of the egg to let the sorry cell burrow inside .
When does a man and when does a woman stop producing sperm and egg cells
A man doesn’t
A woman stops at around 45-50 however the age is decreasing now . It is known as menopause
As they prepare to have sex
She becomes moist and his penis becomes erected (filled with blood ) . After ejaculation the semen is sucked up through the cervix and small movements of the uterus wall carry it up to the oviducts . Here they swim along and then fertilisation occurs .
What happens and fertilisation
It divides,in two . It keeps on dividing and form a ball of cells as they travel toward the uterus . Here the embryo sinks into the soft lining . This is called implantation .
identical twins are caused because
Fertilised egg divides in two and this grows into two embryos. Produce identical twins either two girls or two boys .
Non identical twins are caused when
A woman releases two eggs at a time . If both are fertilised the twins will not be identical
Having more than one baby is called
Multiple birth
The menstrual cycle takes about
28-30 days
Menstrual cycle is controlled by
Chemicals in the brain called sex hormones
Menstrual cycle
The soft lining of the uterus breaks apart . It passes out of the vagina with blood
Immediately an egg cell begins to mature in one of the ovaries . Whilst this is happening the soft lining starts to build up again . Aftaer 14 days the egg cell is released . This is called ovulation
If egg has not been fertilised the soft lining breaks again and the cycle repeats it self
What is the embryo surrounded by
A watery amino tic fluid contains within a bag called the amnion
Placenta facts
Small plate shaped organ grows .Attached to the uterus lining provided the developing foetus with things it needs . Oxygen , water and food go from the mothers blood to the baby . Waste material like carbon dioxide go form the foetus blood to the mothers
Why does the mother blood not mix with the foetus ?
Because the mothers blood is pumped around her body under a lot of pressure which the foetus would not be able to handle .
Pregnant woman must take care not to
Do drugs Smoke - smokers carry less oxygen in the blood then they’re supposed too . If the baby gets less oxygen it is likely to be premature Drink Must work out get sick
What is gestation
the time of fertilisation until birth . In humans about 9 months (49 weeks )
Labour
At the start of labour Uterus begins to contract . Contractions become mor powerful as they go on . Next the muscle of the cervix slowly relax. At som
E stage the amnion breaks and the fluid flows out of the vagina . Once the cervix is about 10cm wide the string contractions will push the baby out usually head first . Umbilical cord is tied and cut . Within half an hour the placenta breaks away from the uterus lining and passes out through the vagina . Called afterbirth and marks the end of labour .
The breast contain
Mammary glands that produce milk which contains nutrients and antibodies that the baby needs .
Puberty changes in females
Underamprm hair grows
Pubic hair grows
Hips get wider
Breasts develop
Puberty changes in males
Voice deepens Shoulders get wider Hair grows under arms , on face and chest Pubic hair grows Penis grows bigger so do testes
