Reproduction in Humans

male glands

produce liquid that is added to sperm to keep it alive

male urethra

tube which runs down the center of the penis and carries semen during ejaculation and urine out of the body

sperm duct

sperm passes through the sperm duct before being passed into the urethra

penis

deposits semen into vagina and expels urine from bladder

what must happen to the penis in order for it to deposit semen?

in must be erect, meaning it swells and fills with blood

testes

where sperm and testosterone is made

scrotum

the sac which supports the testes outside the body, holding them in place and ensures that sperm is kept at a slight lower temperature than the rest of the body

female oviduct

tube which connects the ovary to the uterus and carries away the egg from the ovary. fertilisation occurs here

ovary

produces ova (plural of ovum), progesterone and oestrogen

uterus

muscular sat where the zygote (fertilised egg) develops into a foetus

cervix

a ring of muscle at the lower end of the uterus that keeps the developing foetus in place

vagina

a muscle that opens to the outside of the body, receives the penis during sex and where sperm is deposited

endometrium

the inner most lining of the uterus which is full of blood vessels and supplies the growing foetus with oxygen and nutrients

the menstrual cycle is a

sequence of changes that occur in a women’s body around every 28 days. these changes are controlled by sex hormones such as progesterone and oestrogen

oestrogen and progesterone are involved in

maintaining the uterus lining

oestrogen is produced by the

ovaries

progesterone is produced by

an empty follicle in the corpus luteum

a period is also known as

menstruation

when an egg is released, it is known as

ovulation

menstruation is when

the uterus lining breaks down

ovulation occurs at

day 14

menstruation occurs

at the end of the cycle, day 28

menstruation lasts for

5-7 days

menstruation signals

the beginning of the next cycle

after menstruation, what does the uterus lining do?

begin to thicken again in preparation for a possible implantation in the next cycle

oestrogen causes the

uterus lining to build up and thicken, which has just broken down from the previous cycle’s menstruation, meanwhile stimulating LH and inhibiting the production of anymore FSH

oestrogen levels peak

just before day 14

oestrogen stimulates LH which causes

the release of an egg (ovulation)

FSH stimulates the development of

a follicle in the ovary

in the follicle, what is produced?

an ova and oestrogen

why does oestrogen inhibit the production of anymore FSH

so that only one egg can be released during ovulation

oestrogen can only stimulate LH when

levels are high enough

once ovulation occurs, the follice becomes

corpus luteum, which starts producing progesterone

what is corpus luteum?

the remains of the follicle after the ovum is released in ovulation

progesterone does what?

maintain the uterus lining for fertilisation

if the ovum is not fertilised, what happens?

the corpus luteum breaks down, progesterone levels decrease and menstruation occurs

the pill contains…

oestrogen, as it inhibits FSH, which stimulates the development of a follicle in the ovary and an ovum inside it. without FSH, an ovum cannot be released and so you cannot get pregnant

if the ovum is fertilised, what happens?

the corpus luteum continues producing progesterone, preventing the uterus lining from breaking down and aborting the baby

why must the corpus luteum continue producing progesterone?

to maintain the uterus lining and stop it from breaking down and aborting the baby

the corpus luteum continues producing progesterone until…

the placenta has developed, at which point it starts secreting progesterone instead of the corpus luteum and continues to do so throughout the pregnancy

in the placenta, the mother’s blood

comes into very close proximity with the foetus’ blood, but they never mix

the foetus’ blood connects

too and from the placenta by the umbilical cord

the movement of molecules through the placenta occurs by

diffusion

how is the placenta good for diffusion?

it has a large surface area and thin wall

the placenta also acts as a

barrier to prevent toxins and pathogens from getting into the foetus’ blood

the placenta is an

organ that allows materials to be exchanged between the mother and embryo’s blood

the mother’s blood absorbs what from the foetus’ blood?

urea, co2

what does the foetus absorb from the mother’s blood?

antibodies, hormones, nutrients

what nutrients does the foetus gain to grow and develop?

amino acids, fatty acids, glucose, mineral ions, oxygen, vitamins, water

role of amniotic fluid

held by the amniotic sac, protects the embryo developing by cushioning it from bumps

male and female secondary sexual characteristics develop during

puberty, and are controlled by the sex hormones oestrogen and testosterone

female secondary sexual characteristics…

breasts develop, body hair, menstrual cycle begins and hips widen

male secondary sexual characteristics include…

growth in penis and testes, facial and body hair, voice breaks, testes begin producing sperm