9.0 Reproduction
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Transcript of 9.0 Reproduction
:
9.0 REPRODUCTION
AND
DEVELOPMENT
9.1 Asexual reproduction in plants and animals
9.2 Sexual reproduction in flowering plants
9.3 Human reproductive system
9.4 Fertilization and foetal development
9.5 Roles of hormones
9.0 REPRODUCTION AND DEVELOPMENT
9.5 Roles of hormones
a) Explain the role of hormones during pregnancy
i. progesterone
ii. estrogen
iii. human chorionic gonadotrophin (hCG)
b) Explain the role of hormones during parturition /
birth process
i. progesterone
ii. estrogen
iii. oxytocin
iv. prostaglandin
c) Explain the role of hormones during lactation
i. oxytocin
ii. prolactin
Learning outcomes :
(a) Explain the role of hormone during pregnancy
1st trimester
i. Progesterone
- initiates increased mucus in cervix (forming a protective plug)
- stimulates growth of the maternal portion of placenta
- maintains the thickness of endometrium
- prevents ovulation & menstrual cycle
- stimulates breasts enlargement
ii. Estrogen
• important for development of uterus, foetus & mammary glands
PREGNANCY & HORMONES INVOLVED
iii. hCG (human chorionic gonadotropin)
• The chorion secretes hCG
• Function: stimulate the corpus luteum to continue to secrete progesterone and estrogen
• hCG level is so high & some is excreted in urine
Learning outcomes :
(a) Explain the role of hormone during pregnancy
1st trimester
Learning outcomes :
(a) Explain the role of hormone during pregnancy
1st trimester
iv. hCS (human chorionic somatotropin )
• Starting at week 5, the placenta secretes hCS which stimulates:
– secretion of estrogens & progesterone by corpus luteum
– entry of amino acids into cells of embryo (for protein synthesis)
– development of mammary glands
– glucose & lipid metabolisms in the mother
Learning outcomes :
(a) Explain the role of hormone during pregnancy
2nd trimester
Learning outcomes :
(a) Explain the role of hormone during pregnancy
• hCG secrete by the placenta declines
• Corpus luteum degenerates, progesterone decrease
• Placenta takes over from corpus luteum by secreting progesterone & estrogen, (maintain pregnancy)
Learning outcomes :
(a) Explain the role of hormone during pregnancy
3rd trimester
• Level of estrogen & progesterone increase during pregnancy prevent from miscarriage
• And induce the birth
process
PARTURITION & HORMONES INVOLVED
During pregnancy, progesterone & estrogens are
secreted by placenta
i. Progesterone
High level of progesterone prevents contractions of
uterus (prevents birth of immature baby)
ii. Estrogen
- Estrogens reach highest level during last weeks
of pregnancy
- This triggers formation of oxytocin receptors on
uterus
Learning outcomes :
(b) Explain the role of hormone during parturition / birth process
PARTURITION & HORMONES INVOLVED
iii. Oxytocin
- secreted by foetus & mother’s posterior pituitary
- stimulates contractions of uterus
- stimulates placenta to secrete prostaglandins
iv. Prostaglandins
- Enhance contractions of uterus
- The contractions stimulate release of more oxytocin &
prostaglandins by positive feedback
- Contractions become stronger & more frequent
- that push the baby
Learning outcomes :
(b) Explain the role of hormone during parturition / birth process
• Parturition (birth process)
occurs as a result of the strong,
rhythmic contractions (labour)
• Induced and regulated by
estrogen, oxytocin, and
prostaglandins.
• 3 stages of parturition:
i. dilation of cervix
ii. delivery of baby
iii. delivery of placenta
PARTURITION
Learning outcomes :
(b) Explain the role of hormone during parturition / birth process
i. dilation of cervix
- opening up & thinning of
cervix
- ending with complete
dilation
- amnion ruptures releasing
amniotic fluid, which flows
out through the vagina.
- contractions get stronger
PARTURITION
Learning outcomes :
(b) Explain the role of hormone during parturition / birth process
ii. delivery of baby
- The expulsion of the fetus
- continuous strong
contractions force foetus
down and out of the uterus &
vagina
- aided by mother’s pushing
- the umbilical cord is then cut
and clamped
PARTURITION
Learning outcomes :
(b) Explain the role of hormone during parturition / birth process
iii. delivery of placenta
- The expulsion of the
placenta
- continuing contraction
expel the placenta &
associated membranes
(the afterbirth)
PARTURITION
Learning outcomes :
(b) Explain the role of hormone during parturition / birth process
LACTATION & HORMONES INVOLVED
• ‘Milk production that occurs in the mammary glands’
• An aspect of postnatal care
• The breasts contain mammary glands
• Alveoli of mammary glands will produce milk, that is secreted into mammary ducts which open at the nipple
Learning outcomes :
(c) Explain the role of hormone during lactation
LACTATION & HORMONES INVOLVED
• During pregnancy, progesterone stimulates development of mammary alveoli
• Estrogens stimulate development of mammary ducts
• When placenta is discharged after birth, levels of estrogens & progesterone decrease
• This allows mother’s anterior pituitary
to secrete prolactin
[no lactation during pregnancy since
prolactin secretion is inhibited]
Learning outcomes :
(c) Explain the role of hormone during lactation
LACTATION & HORMONES INVOLVED
• Prolactin stimulates mammary
alveoli to produce milk (~ 2
days after birth)
• Mammary secretion for first
few days is the colostrum
(thick, yellowish fluid with high
protein content & rich in
maternal antibodies)
• Oxytocin stimulates
contraction of smooth muscles
surrounding mammary glands,
thus controlling release of milk
Learning outcomes :
(c) Explain the role of hormone during lactation
• Nerve impulse will be sent
to the hypothalamus & sent
impulse to posterior
pituitary to release oxytocin
• Fx (oxytocin): Contraction
of the smooth muscle of
alveoli & force milk through
the duct & out of the nipple
• The anterior pituitary responds by releasing prolactin
• Fx (prolactin): Stimulate the production of milk
After birth, milk production is stimulated
by the sucking infant
Learning outcomes :
(c) Explain the role of hormone during lactation
9.1 Asexual reproduction in plants and animals
9.2 Sexual reproduction in flowering plants
9.3 Human reproductive system
9.4 Fertilization and foetal development
9.5 Roles of hormones
9.0 REPRODUCTION AND DEVELOPMENT
9.5 Roles of hormones
a) Explain the role of hormones during pregnancy
i. progesterone
ii. estrogen
iii. human chorionic gonadotrophin (hCG)
b) Explain the role of hormones during parturition /
birth process
i. progesterone
ii. estrogen
iii. oxytocin
iv. prostaglandin
c) Explain the role of hormones during lactation
i. oxytocin
ii. prolactin
Learning outcomes :
(a) Explain the role of hormone during pregnancy
1st trimester
i. Progesterone
- initiates increased mucus in cervix (forming a protective plug)
- stimulates growth of the maternal portion of placenta
- maintains the thickness of endometrium
- prevents ovulation & menstrual cycle
- stimulates breasts enlargement
ii. Estrogen
• important for development of uterus, foetus & mammary glands
PREGNANCY & HORMONES INVOLVED
iii. hCG (human chorionic gonadotropin)
• The chorion secretes hCG
• Function: stimulate the corpus luteum to continue to secrete progesterone and estrogen
• hCG level is so high & some is excreted in urine
Learning outcomes :
(a) Explain the role of hormone during pregnancy
1st trimester
Learning outcomes :
(a) Explain the role of hormone during pregnancy
1st trimester
iv. hCS (human chorionic somatotropin )
• Starting at week 5, the placenta secretes hCS which stimulates:
– secretion of estrogens & progesterone by corpus luteum
– entry of amino acids into cells of embryo (for protein synthesis)
– development of mammary glands
– glucose & lipid metabolisms in the mother
Learning outcomes :
(a) Explain the role of hormone during pregnancy
2nd trimester
Learning outcomes :
(a) Explain the role of hormone during pregnancy
• hCG secrete by the placenta declines
• Corpus luteum degenerates, progesterone decrease
• Placenta takes over from corpus luteum by secreting progesterone & estrogen, (maintain pregnancy)
Learning outcomes :
(a) Explain the role of hormone during pregnancy
3rd trimester
• Level of estrogen & progesterone increase during pregnancy prevent from miscarriage
• And induce the birth
process
PARTURITION & HORMONES INVOLVED
During pregnancy, progesterone & estrogens are
secreted by placenta
i. Progesterone
High level of progesterone prevents contractions of
uterus (prevents birth of immature baby)
ii. Estrogen
- Estrogens reach highest level during last weeks
of pregnancy
- This triggers formation of oxytocin receptors on
uterus
Learning outcomes :
(b) Explain the role of hormone during parturition / birth process
PARTURITION & HORMONES INVOLVED
iii. Oxytocin
- secreted by foetus & mother’s posterior pituitary
- stimulates contractions of uterus
- stimulates placenta to secrete prostaglandins
iv. Prostaglandins
- Enhance contractions of uterus
- The contractions stimulate release of more oxytocin &
prostaglandins by positive feedback
- Contractions become stronger & more frequent
- that push the baby
Learning outcomes :
(b) Explain the role of hormone during parturition / birth process
• Parturition (birth process)
occurs as a result of the strong,
rhythmic contractions (labour)
• Induced and regulated by
estrogen, oxytocin, and
prostaglandins.
• 3 stages of parturition:
i. dilation of cervix
ii. delivery of baby
iii. delivery of placenta
PARTURITION
Learning outcomes :
(b) Explain the role of hormone during parturition / birth process
i. dilation of cervix
- opening up & thinning of
cervix
- ending with complete
dilation
- amnion ruptures releasing
amniotic fluid, which flows
out through the vagina.
- contractions get stronger
PARTURITION
Learning outcomes :
(b) Explain the role of hormone during parturition / birth process
ii. delivery of baby
- The expulsion of the fetus
- continuous strong
contractions force foetus
down and out of the uterus &
vagina
- aided by mother’s pushing
- the umbilical cord is then cut
and clamped
PARTURITION
Learning outcomes :
(b) Explain the role of hormone during parturition / birth process
iii. delivery of placenta
- The expulsion of the
placenta
- continuing contraction
expel the placenta &
associated membranes
(the afterbirth)
PARTURITION
Learning outcomes :
(b) Explain the role of hormone during parturition / birth process
LACTATION & HORMONES INVOLVED
• ‘Milk production that occurs in the mammary glands’
• An aspect of postnatal care
• The breasts contain mammary glands
• Alveoli of mammary glands will produce milk, that is secreted into mammary ducts which open at the nipple
Learning outcomes :
(c) Explain the role of hormone during lactation
LACTATION & HORMONES INVOLVED
• During pregnancy, progesterone stimulates development of mammary alveoli
• Estrogens stimulate development of mammary ducts
• When placenta is discharged after birth, levels of estrogens & progesterone decrease
• This allows mother’s anterior pituitary
to secrete prolactin
[no lactation during pregnancy since
prolactin secretion is inhibited]
Learning outcomes :
(c) Explain the role of hormone during lactation
LACTATION & HORMONES INVOLVED
• Prolactin stimulates mammary
alveoli to produce milk (~ 2
days after birth)
• Mammary secretion for first
few days is the colostrum
(thick, yellowish fluid with high
protein content & rich in
maternal antibodies)
• Oxytocin stimulates
contraction of smooth muscles
surrounding mammary glands,
thus controlling release of milk
Learning outcomes :
(c) Explain the role of hormone during lactation
• Nerve impulse will be sent
to the hypothalamus & sent
impulse to posterior
pituitary to release oxytocin
• Fx (oxytocin): Contraction
of the smooth muscle of
alveoli & force milk through
the duct & out of the nipple
• The anterior pituitary responds by releasing prolactin
• Fx (prolactin): Stimulate the production of milk
After birth, milk production is stimulated
by the sucking infant
Learning outcomes :
(c) Explain the role of hormone during lactation