reproduction in humans Flashcards
how is a human formed
through sexual reproduction
male gamete fuses with the female gamete forming a zygote
what are the female gametes
egg
made in the 2 ovaries
ovaries
organs that produce female gametes (egg)
oviducts
tubes leading from the ovaries to the uterus; also known as fallopian tubes
uterus
the organ in which a fetus develops before birth; also known as the womb
has thick walls made of muscle
size of fist
can stretch when woman is pregnant
lining of uterus contains large spaces filled with the mothers blood
cervix
a narrow opening leading from the uterus to the vagina
guards the uterus narrow opening with muscles
vagina
opening from the uterus to the outside of the body
testes
sing. testis
organs in which the male gamete (sperm or spermatoza) are made
scrotum
the sac that contains the testes
2 sacs
sperm duct
a tube that transports sperm from the testis to the urethra
join up from the testes with the urethra just below the bladder
penis
organ containing the urethra, through which urine and sperm are carried
prostate gland
organ that produces a nutritious fluid in which sperm are transported
where sperm duct joins with urethra
makes a fluid called semen which the sperm can swim in
eggs in woman
eggs are being formed before she is born
at birth, she has thousands of partly developed eggs inside her
when a girl reaches puberty
some of these eggs begin to mature, usually one at a time
ovulation
the egg bursting from the ovary and into the funnel at the end of the oviduct
happens once a month in a woman’s reproductive life
epididymis
part of testis where sperm is stored
sperm
developed from the cells in the walls of the tubules
made continually through puberty and onwards
production is very sensitive to heat
if too hot the cells will not develop into sperm
thats why the testes are outside the body -> colder
can only swim at a rate of 4mm per min
what type of cells are eggs and sperm
haploid cells
a single set of 23 chromosomes in its nucleus
how are eggs and sperm cells made
when cells in the ovaries and testes divide by meiosis
flagellum
plural: flagella
a long whip-like tail structure found on sperm cells, used for swimming
acrosome
a structure containing digestive enzymes, in the head of a sperm cell
fertilisation
- after ovulation egg is caught in funnel of oviduct
- slowly, egg travels to the uterus
- cilia lining the oviduct help sweep it along.
- muscles of the wall of the oviduct also help it move, by gently ripling
- if egg is not fertilised by a sperm in 8-24 hours, it dies
- this means the sperm must reach the egg while it is still near the beginning of the oviduct for fertilisation to be successful.
- when sperm reaches jelly coat of egg, acrosome is activated
- acrosome released digestive enzymes that digest the jelly coat
- only the head of the sperm goes into the cytoplasm, flagellum is left
- as soon as the sperm enter the egg, the egg membrane and jelly coat become impenetrable , so that no sperm can get in
- nucleus of sperm fuses with the egg (fertilisation)
- unsuccessful sperm die