female Flashcards
describe the biochemical/endocrine changes in response to pregnancy
weight gain
protein synthesis
lipid synthesis
insulin resistance
state the hormones associated with pregnancy
human chorionic gonadotrophin oxytocin prolactin relaxin oestrogen progesterone prostaglandin
what is the role of the human chorionic gonadotrophin
pregnancy test hormone
diminishes once placenta matures and oestrogen and progesterone levels are high
role of oestrogen in pregnancy?
produced throughout pregnancy
prepares uterus for baby
prepares breasts for lactation
role of progesterone in pregnancy?
inhibits contractions
prevents miscarriage
builds endometrium
role of prolactin in pregnancy?
- secreted by pituitary gland
- increase milk producing cells
- after birth when oestrogen and progesterone levels fall prolactin is able to stimulate milk production
- prevents ovulation (unreliably)
role of relaxin?
it is high in early pregnancy
limits uterine ativity
softens the cervix
role of oxytocin?
triggers caring reproductive behaviour
uterine contractions
contractions felt during breast feeding
can be used as a synthetic drug to induce labour
what is the role of prostaglandin in pregnancy?
it is a tissue hormone
role in delivery initiation
used as a synthetic used to induce labout
what is maternal weight gain attributed to?
around 12 kg baby placenta blood fluid in tissue amniotic fluid fat uterus breast tissue
what physiological changes occur in terms of blood chemistry during pregnancy?
increased blood volume
inc blood cells
inc clotting factors and fibrinolytic activity
iron deficiency and anaemia
what physiological changes occur in terms of systemic circulation during pregnancy?
tachycardia increased blood volume so increased SV increased cardiac output decrease in blood pressure (CO x TPR) decreased TPR
what physiological changes occur in terms of respiratory systems during pregnancy?
inc alveolar ventilation - hyperventilation
diaphragm displaced superiorly
decreased functional reserve capacity
inc risk of apnea and dyspnea
what physiological changes occur in terms of Gastro systems during pregnancy?
acid reflux
nausea and vomiting
inc nutritional demands
what skin changes occur during pregnancy?
linea nigra
striae gravidarum
varicose veins
How do the breasts change during pregnancy?
change shape and size
nipples become more erect
areola becomes larger and more darkly pigmented
mongomery’s tubercles become more active and secrete nipple lubricating substance
What happens to the spine during pregnancy?
lumbar lordosis
inc curvature of lumbar spine
why is folic acid important in pregnancy?
decreases risk of neural tube defects
describe the pregnancy landmarks
conception = missed period
foetal heartbeat on ultrasound 5/6 week
‘quickening’ movement felt my mother
symphysio-fundal height (measuring the foetus height by meauring top of uterus to top of pubic symphysis)
head engagement
show
labour
what is parturition?
the birth process. successful transition from intra uterine to extra uterine life.
describe the composition of the cervix
mainly collagen and ground substance
glysoaminoglycans
which is the main prostaglandin type released in labour? which is mostpotent
PGE2 is 10x potent than PGF2 alpha
PGF2 alpha is mainly produced in labor
describe how labour is induced
ACTH produced by baby pituitary gland
stimulates baby adrenal gland to increase production of glucocorticoids and androgens
causes decrease in progesterone in placenta. decrease in progesterone means uterus becomes more sensitive to stretch. this helps stimulates contraction
adrenal gland also causes increase in oestrogen in placenta. This stimulates increased sensitivity of uterus to oxytocin, stimulates contraction and softening of the cervix. softening results in stretch of cervix and vagina.
oxytocin also stimulates contractions.
contractions induce labour.
how does oestrogen help to induce labour?
induced oxytocin receptors on uterus.
oxytocin from fetal and mothers posterior pituitary can then act on uterus.
causes contraction
causes placental prostaglandin production
prostaglandin stimulate vigorous contraction and more oxytocin release. .positive feedback
how is oxytocin stimulates
head of baby pushes against cervix
nerve impulses to the brain
brain stimulates post pituitary to release oxytocin
oxytocin reaches uterus
causes contraction
head of baby pushed more strongly against the cervix
what does the placenta provide?
nutrition
gas exchange
waste removal
endocrine and immune support
describe the menstrual cycle
hypothalamus secretes GNRH (gonadotropin releasing hormone) which stimulates FSH/LH production from anterior pituitary
LH causes the Theca cells to convert cholesterol to aldosterone. Aldosterone enters granulosa cells. Granulosa cells, with help of FSH transform into oestrogen.
as follicle grows, release of oestrogen increases and inhibin.
low level oestrogen inhibits the release of GNRH by hypothalamus therefore inhibits FSH and LH release.
as follicle matures, more oestrogen is released. High level oestrogen has positive feedback causing LH surge (and increase in FSH).
Ovulation occurs due to LH surge. egg completes meiosis 1 and cytoplasmic maturation.
follicle forms the corpus luteum. This secretes some oestrogen and progesterone.
progesterone inhibits FSH and LH by inhibiting GNRH release. Also does endometrial growth
if no fertilisation, Corpus luteum degenerates. FSH and LH no longer are inhibited
endometrium breaks down at day 28
what are the 2 divisions of the menstrual cycle
follicular phase
ovulation
luteal phase
describe the initiation of labour
foetal distress
release of ACTH (corticotropin) from foetal anterior pituitary.
acts on foetal adrenal glands releasing cortisol
acts on placenta resulting in decrease in progesterone and oestrogen. Increases the prostaglandin production.
prostaglandins facilitate contractions
uterine stretch activates sensory receptors located in the lining. Results in increase oxytocin production from the hypothalamus which is then stored in the posterior pituitary.
oxytocin released. causes contractions and upregulates prostaglandin production.
uterine stretch
describe follicle development and the follicular phase of the menstrual cycle
follicles begin as PRIMORDIAL FOLLICLE
consist of a primary oocyte surrounded by a single cell layer of granulosa cells. these granulosa cells secrete progesterone, oestrogen and inhibin.
primordial follicle develops to form a PRIMARY FOLLICLE.
here oocyte increases in size and separates from inner layer of granulosa cells by the zona pellucida.
next forms the PREANTRAL FOLLICLE
via mitosis of granulosa cells and THECA cell layers form.
next forms the EARLY ANTRAL FOLLICLE
primary oocyte reaches full size and fluid filled antrum forms between layers of granulsa cells.
at the start of the menstrual cycle 10-25 of these early antral and antral cells develop into LARGER ANTRAL FOLLICLES
DOMINANT FOLLICLE is the one which undergoes full development. non dominant follicles undergo ATRESIA (degradation).
immediately before ovulation, primary oocyte completes meiosis 1 to become a secondary oocyte.
ovulation
what secretes the zona pellucida
follicular cells
what is important about the zona pellucida?
it contains glycoproteins important for binding of sperm after ovulation
how can granulosa cells contact the oocyte with the zona pellucida between?
cytoplasmic processes that form gap junctions with the oocyte.
how does ovulation occur?
enzymatic digestion at the point where follicle membrane touches the ovary .
secondary oocyte released still with zona pellucida and granulosa cells. Carried by the antral fluid.
what is FSH important for?
follicle development beyond pre antral and early antral.
how are granulosa cells and sertoli cells similar?
Both help to control the microenvironment in which germ cell develops and matures. both stimulated by FSH and oestrogen (equivalent to testosterone)
why does atresia of non dominant follicles occur?
high level oestrogen inhibits FSH.
when do LH receptors appear on granulosa cells?
during maturation of the dominant follicle
induced by FSH
when does the LH surge occur?
18 hours before ovulation. FSH has facilitated formation of LH receptors on follicle.
how are theca cells like leydig cells?
proceeds mainly androgens
stimulated to do so by LH
when does inhibin concentration increase?
in the very late follicular phase
stays high during luteal phase
decreases as corpus luteum degenerates
what are the divisions of the uterine phases?
menstrual 0-5 shedding of endometrium
proliferative 5- 14 menstrual flow ceases. endometrium and myometrium thickens under oestrogen influence. oestrogen also induces synthesis of progesterone receptors in endometrial cells.
secretory 14-28
occurs soon after ovulation
endometrium secretes glycogen in the glandular epithelium followed by glycoproteins and mucopolysaccarides.
why is progesterone important in fertilised egg implantation?
inhibits action of oestrogen and PG’s in stimulating contraction.
how do progesterone and oestrogen affect mucus in the cervix?
under oestreogen production alone, mucous is abundant clear and watery. allows ovulation which allows sperm to travel easily.
progesterone after ovulation causes mucus to become thick and sticky forming a PLUG that prevents bacterial entry into the uterus from the vagina. protects the embryo if fertilization has occured
for fertilisation to occur, when must sperm be introduced?
between 5 days before and 1 day after ovulation
ovulated egg only remains viable for 24-48 hours
sperm 4-6 days
how is the ovulated egg transported to the uterus?
at ovulation the egg is extruded onto ovary surfac
smooth muscles of the fimbriae cause the egg to pass over the surface of the ovary. the cilia of the fimbriae beat in waves towards the interior of the fallopian tube.
inside the tube, egg moved by the fallopian tube cilia. very slow, takes 4 days for egg to reach the uterus.
how does the sperm reach the fallopian tube/ovary?
ejaculated into the vagina
fluid pressure of ejaculate helps sperm travel into the cervix (neck of uterus).
passage through the mucus is dependent on oestrogen causing it to be watery.
sperm travels to uterus and tubes using its flagellum.
what is capacitation?
the final maturation phase
once sperm have reached the fallopian tube they are unable to fertilise egg as they are not mature enough.
they must reside in female tract for several hours and be acted upon by secretions of the tract.
sperms plasma membrane alters.
wavelike beats of sperms tail replaced with more whiplike actions.
when and where does fertilisation occur?
24/48 hours after ovulation
at ampulla of fallopian tube
how does sperm bind to egg
receptors on the zona pellucida
what does sperm-egg binding induce?
acrosome reaction
plasma membrane of sperm altered so that underlying enzymes are exposed to zona pellucida. enzymes are able to digest a path through zona pellucida. first sperm to be able to penetrate entire zona pellucida and reach egg plasma membrane fuse.
head of sperm passes into egg cytosol.
zygote formed
how is polyspermy prevented?
after fusion egg membrane potential changes which prevents additional sperm binding
the CORTICAL reaction is initiated resulting in the exocytosis of secretory vesicles into the space between the zona pellucida and egg plasma membrane. contents are enzymes which inactivate sperm binding receptors and cause hardening of the zona pellucida preventing the binding of sperm which are advancing.
when does the fertilised egg complete meiosis 2?
4-7 hours after gamete fusion
what are the pronuclei? what happens to them?
the 2 sets of haploid chromosomes 23 from egg and 23 from sperm each surrounded by distinct membrane. migrate to cell centre. haploid chromosomes pair and DNA replication occurs in prep for mitosis 1.
pronuclei membranes break down and metaphase spindle forms.
what happens at day 2/3
cleavage
day 2/3
24 hours after fertlisation
these are a series of mitotic divisions but no cell growth occurs.
cell numbers increase essential to provide cells available for differentiation. these cells are totipotent
why does the zygote stay in the fallopian tube for 3/4 days?
because oestrogen maintains the contraction of smooth muscle near where the fallopian tube enters the uterus, holding the zygote in the fallopian tube. as progesterone levels increase smooth muscle relaxes and zygote allowed to pass.
how are identical twins formed
during the cleavage process, dividing cells become completely separated.
what happens on day 4?
cells flatten and maximie intracellular contacts resulting in the formation of tight junctions and polarisation of outer cells. this is important in order to differentiate quickly.
what happens on day 5?
cavitation and differentiation
fluid filled cavity expands to form a blastocyst
defined as having more than 80 cells. these cells are no longer totipotent and have begun to differentiate
blastocyst consists of an outer layer of cells known as a trophoblast, an inner cell mass and a central fluid filled cavity.
what happens next on day 5/6? (after cavitation and differentiation)
expansion
cavity expands
diameter of blastocyst expands
zona pellucida thickness decreases
what happens after expansion?
hatching
blastocyst expansion and enzymes result in hatching of embryo from zona pellucida. required for implantation.
when does the embryo reach the uterus?
day 5/6
describe the implantation phases
apposition - 9 days after fertilisation
the hatched blastocyst orientates via the embryonic pole and synchronises with receptive endometrium on day 19-22 of the menstrual cycle
attachment
endometrial epithelial cells and trophoblastic cells express INTEGRINS which connect with each other.
differentiation of trophoblast
forms the cytotrophoblast and the syncitiotrophoblast
invasion
enzymatic degradation of the basal lamina
decidual reaction
differentiation of stromal cells adjacent to the blastocyst
maternal recognition
secretion of interleukin 2 prevents antigenic rejection of the blastocyst.
implantation complete by day 11 and endometrial cells can provide neccesary nutrients
what is the placenta?
it is a combo of interlocking foetal and maternal tissues which serves as an exchange organ.
the simple nutritional system from the endometrial cells is only adequate for the first few weeks. Placenta takes over role. It begins to develop at blastocyst implantation.
describe the placenta development
begins at blastocyst implantation
the outermost layer of the trophoblast is the CHORION. this forms the embryonic portion of the placenta. maternal portion is supplied by the endometrium underlying the chorion. called the DECIDUA
CHORIONIC VILLI (finger like projections) extend into the endometrium. these villi contain rich vasculature. endometrium around the villi is altered by enzymes so that each villus is completely surrounded by a placental SINUS filled with maternal blood.
blood reaches sinus via uterine artery and exits via uterine vein. blood flows from the fetus into capillaries of the choroinic villi via the umbilical arteries and back to the fetus via the umbilical vein.
where is the amniotic cavity
between the chorion and the inner cell mass
amnion and chorion fuse
how can embryonic disorders be determined?
amniocentesis - sample of amniotic fluid at week 16
chorionic villus sampling - high risk
ultrasound
describe placental function
metabolism
synthesises glycogen, cholesterol and fatty acids
transport
gas, nutrition, water, glucose, vitamine, AA, hormones (NOT PROTEIN), electrolytes, maternal antibodies IgG NOT IgM
waste products , drugs, metabolites, infectious agents
endocrine function
ie. produces HCG, oestrogen, progesterone
describe the placental barriers to transport
maternal endothelial cells maternal connective tissue endometrial epithelial cells chorionic epithelial cells fetal connective tissue fetal endothelial cells
