(3.9-3.13) Hormones, menstruation, developing embryo

How long is the menstrual cycle?

around 28 days

Detail the process of the menstruation cycle.

(if there is no implantation)

1-6 menstruation

7-14 building lining

14 ovulation

15-28 maintaining lining

then menstruation

Which hormones are produced in the ovaries?

oestrogen and progesterone

What does oestrogen do?

stimulates thickening of uterus lining

inhibits FSH and LH production after ovulation

What does progesterone do?

maintains uterus lining

inhibits FSH + LH after ovulation (preventing another egg)

produces thick mucus

Which hormones controlling menstruation are produced in the pituitary gland?

Follicular Stimulating Hormone

Luteinizing Hormone

What does FSH do?

causes egg to start maturing → develops ovarian follicle

stimulates ovaries to start releasing oestrogen

What does LH do?

released at peak of oestrogen levels

stimulates release of egg

stimulates progesterone production

Describe the journey of the hormones through the cycle.

FSH released → develops ovarian follicle

• follicle = egg + O

O stimulates growth of lining + inhibits FSH

high O trigger LH , causing ovulation

follicle becomes corpus luteum → P

P maintains uterus lining

corpus luteum breaks down, P drops → period

What are some links we can make between the 4?

as O rises, FSH drops

O peaks just before LH

LH will peak on day 14

LH stimulate P so after LH rises, P does

P rises when lining stays, drops when it goes

What is the placenta?

a structure that forms at the implantation site that lets the blood of the mother and foetus come into close proximity

What does the umbilical cord do?

connects the foetus’s blood supply to the placenta, allowing for transport of substances

What functions does the placenta perform?

Respiratory

Excretion

Nutrition

Immunity

Endocrine

How does the placenta perform respiratory functions?

oxygen from maternal haemoglobin transfers to fetal haemoglobin

carbon dioxide form foetus diffuses across placental membrane

How does the placenta perform excretion?

waste diffuses across placental membrane to mother

• carbon dioxide

• urea

How does the placenta carry out nutrition?

mother digests food and nutrients diffuse across membrane to foetus

• glucose

• amino acids

• mineral ions

How does the placenta aid immunity?

Mother’s antibodies diffuse across membrane to foetus.

How does the placenta perform an endocrine function?

placental tissue releases hormones:

• HCG maintain corpus luteum

• progesterone to maintain pregnancy + relax uterus

• oestrogen to soften tissues for safe delivery

Why is the placenta efficient for diffusion?

large surface area- fetal villi

thin wall for short diffusion distance

constant blood supply → speed conc. grad.

What is amniotic fluid?

a substance made from mother’s blood plasma that surrounds the developing embryo

within the amniotic membrane/sac

What does amniotic fluid do?

cushions the embryo as it develops, protecting it

What is afterbirth?

the placenta, after detaching from the uterus wall, being pushed out after the baby

What are secondary sex characteristics?

changes that occur during puberty

Which hormones trigger secondary sex characteristics?

oestrogen + testosterone

What are female secondary sex characteristics?

breast development

body hair growth

hips widen

menstrual cycle begins

What are male secondary sex characteristics?

facial + body hair growth

muscles develop

voice breaks

testes begin to produce sperm

growth of penis and testes