3a - Reproduction in humans Flashcards
What are special sex organs called?
gonads
What is the male gamete?
sperm cell
Where are male gametes produced?
testes
Where are female gametes produced?
ovaries
What is the function of a sperm cell?
to carry the male genetic information and fertilise the female egg
How many sperm cells does one ejaculation contain?
339 million
Why do sperm cells have a flagellum?
helps the sperm cell swim
What does the tip of the head of sperm cells have?
contain enzymes to attack the coat of the egg and several mitochondria to provide energy to swim
Why do sperm cells contain cytoplasm?
to give it a streamlined shape
What is the function of an egg cell?
to carry the female genetic information and provide nutrients for the embryo following fertilisation
Why do egg cells contain cytoplasm?
contains a store of food energy
Why do egg cells have a jelly coat?
make sure that only one sperm cell can enter the egg cell
Which gamete is larger?
egg cell
How many egg cells are produced?
1 a month
How many sperm cells are produced?
millions
Are egg cells able to move?
no
Are sperm cells able to move?
yes
Do egg cells have a food source?
yes
Do sperm cells have a food source?
no
When do boys hit puberty?
13-16
When do girls hit puberty?
11-14
What is puberty controlled by in males?
testosterone
What is puberty controlled by in females?
oestrogen
What are some female body developments that hit them during puberty?
- breasts develop
- ovaries start to release eggs (period starts)
- increase in body mass (hips widen)
What are some male body developments that hit them during puberty?
- voice breaks (get deeper)
- testes and penis develop
- sperm is produced by testes
- hair grows on face and body
- increase in body mass (body becomes more muscular)
What are some female and male body developments that hit them during puberty?
- pubic hair grows
- underarm hair grows
- stronger body smell
What does the menstrual cycle consist of?
- involves an egg and making sure the uterus lining is in perfect condition for implantation
- if pregnancy does not occur the body will reset
The menstrual cycle is controlled by ________
hormones
How long does the menstrual cycle last?
28 days
What is Phase 1 of the menstrual cycle?
Menstruation - the uterus lining breaks down for 4 days
What is Phase 2 of the menstrual cycle?
the uterus lining builds up again for 10 days
What is Phase 3 of the menstrual cycle?
Ovulation - by this time a follicle has matured which releases an egg
What is Phase 4 of the menstrual cycle?
the wall is maintained for 14 days, if the egg is unfertilised then the lining breaks down and the cycle starts again
What does oestrogen cause in the menstrual cycle?
- causes the lining of the uterus to build up
- stimulates another hormone which leads to ovulation
What does progesterone cause in the menstrual cycle?
- maintains the lining of the uterus
- inhibits the release of further eggs by stopping other hormones being produced
What is the journey of the sperm?
- sperms are produced in the testes
- they mix with liquid from glands to form semen
- semen is ejaculated into vagina during sexual intercourse
- the sperm cells swim through the cervix and into the uterus
- they swim up the oviduct (fallopian tube)
What is fertilisation?
nuclei of the 2 haploid cells fuse to make a new diploid cell
What happens when the egg pushes itself through the cell membrane?
the sperm cell loses its tail
What is created from fertilisation?
zygote
What is the process called that the zygote undergoes to become an embryo?
mitosis
Where does the embryo implant itself?
in the endometrium (in the uterus)
What does the embryo develop in the uterus lining?
- placenta
- amniotic sac
When does the embryo become a foetus?
when the embryo becomes a recognisable human
What does the placenta provide the foetus with?
- oxygen
- nutrients to the growing embryo
- removes waste (urea, carbon dioxide)
- secretes female hormones that maintain pregnancy
How is the placenta joined to the foetus?
via the umbilical cord
Does the mother’s blood mix with the foetus’s blood?
no
What is the purpose of the amniotic sac?
- encloses the developing embryo
- secretes a fluid called amniotic fluid which protects the developing embryo
