Block 11 Flashcards
Why does total blood volume increase in pregnancy?
due to activation of RAAS in response to decreased diastolic BP + peripheral vascular resistance mediated by increased progesterone lvls
Why might pregnant women become more frequently constipated?
increased progesterone — increases SM relaxation – decreases gut motility
Why does GFR increase by 50-60% during pregnancy?
increased CO – increases renal blood flow – more blood to kidneys — more filtration
Duchenne’s is caused by
frameshift/nonsense mutation in dystrophin gene -> no functional dystrophin made
Role of oestrogens in breast development
- stimulates ductal proliferation + differentiation
- ducts lengthen + branch out causing breasts to enlarge
Role of prolactin in breast development
stimulates nipple growth
Role of serum hPL (human placental lactogen) in breast development
stimulates areola growth
Role of progesterone in breast development
stimulate growth of the lobes, lobules + alveoli
What are milk streaks?
thickening of epithelial cells
Glandular secreting structures of mammary glands
= ALVEOLI
At which gestational age do the primary milk ducts arise?
~32 WEEKS
How do the breasts grow during childhood
ISOMETRICALLY - i.e in proportion to limbs
Breast growth during puberty is
ALLOMETRIC - each reproductive cycle causes proliferation + active growth → causes irreversible mammary development
Electrolyte abnormalities seen in hyperemesis gravida
- hyponatremia
- hypokalaemia
- hypochloraemia
- metabolic alkalosis - H+ ions from stomach lost, makes blood to alkaline as acid depleted
Most common breast lumps in women aged 15-25.
Fibroadenomas
How many ducts approximately in an adult mammary gland?
15-20 lactiferous ducts
LACTIFEROUS SINUS
terminal expansion of lactiferous duct for milk storage
Function of suspensory ligaments:
maintain stability and shape of breast
site of progesterone production in luteal phase
corpus luteum
How long does epithelialisation of the endometrium take after menstruation?
4-7 days
How long is an egg viable for after ovulation?
24hrs
Which enzyme do sperm release to digest the egg ECM?
hylauronidase
- once ECM digested, ZP exposed
What triggers the acrosome reaction?
interaction of sperm head with ZP2 + ZP3 glycoproteins of the zona pellucida
site of early embryo development
fallopian tube
At what cell stage does the embryo leave the fallopian tube and enter the uterus?
when the embryo is a blastocyst
Factors stimulating uterus to become receptive to blastocyst implantation
OESTROGEN
EGF
Describe the term apposition in relation to implantation
process by which blastocyst orientates itself so trophoectoderm cells are in direct contact with the endometrium
How is the dorsal-ventral axis of the embryo established during implantation?
when blastocyst orientates itself so the inner cell mass is adjacent to the endometrium lining
Which substances secreted during decidualisation promote invasion?
histamine AND prostaglandins
Most common site of implantation
posterior uterine wall
Amniotic cavity is the space between the
inner cell mass(specifically Epiblast) and the syncytiotrophoblasts (digestive trophoblasts that burrowed into endometrium)
Which embryonic cavity acts as a source of germ cells?
Blastocoel (yolk sac) lies between outer trophoectoderm + hypoblasts
Where does the primitive streak form?
dorsal surface of epiblast
Which cells form the chorionic membrane?
syncytiotrophoblast cells + outer TE(cytotrophoblasts) + extraembryonic mesoderm cells
Main contributor to increased cardiac output during pregnancy
increased STROKE VOL.
Why do you get increased tidal volume during pregnancy?
progesterone relaxes the intercostal muscles + diaphragm
Hormone used in superovulation
FSH - stimulate follicular growth
Role of GnRH agonist in IVF
DOWNREGULATION
- suppress body’s own natural hormone production of FSH + LH
- desensitises AP receptors in prep for FSH+LH admin later in IVF cycle
What hormone can be given to prevent premature LH surge and follicle rupture in IVF?
GnRH antagonist
Key features in superovulation?
- high levels of FSH given to stimulate growth of cohort follicles + allow them to reach preantral phase
How come the FSH administered in Superovulation doesn’t cause a negative feedback effect on the AP?
because FSH levels are so high they overcome this
What hormone is given when it is confirmed that follicles are mature in IVF?
hCG which induces the final stage of follicular development + ovulation
Ovarian hyperstimulation syndrome
- too many follicles matured -> lrg increase in plasma oestrogen lvls
Briefly explain the process of ICSI - intracytoplasmic sperm injection
tiny needle used to take single sperm and inject it into egg
v valuable in case of low sperm count
What proportion of infetility causes are due to the female?
1/3:
- ovulatory disorders
- endometriosis
- tubal disease
Most common reason for infertility
MALE INFERTILITY
Azoospermia
absence of sperm in ejaculate
Which 4 main drugs can have an affect on female fertility?
- NSAIDs long-term use
- Chemotherapy
- Antipsychotics => can caused missed periods + infertility
- Spironolactone, fertility recovers ~2months after you stop taking it
Low sperm count
oligozoospermia
Uterus position
anteverted AND anteflexed
Which muscle lies posterior to the sacral plexus?
piriformis
What structure determines the size and shape of the birth canal?
PELVIC INLET
Which type of pelvis do women have?
GYNAECOID PELVIS
How can the pelvic ligaments aid childbirth?
sacrotuberous + sacrospinous ligaments can stretch under the influence of progesterone to increase size of the pelvic outlet
The minimum antero-posterior distance of the pelvic inlet/Narrowest portion of the pelvis the foetus must navigate through
= diameter between the sacral promontory AND the public symphysis midpoint
Which ligaments divide the sciatic notch into the greater and less sciatic foramina?
Sacrotuberous ligament + Sacrospinous ligament
Which uterine ligament passes through the inguinal canal?
ROUND LIGAMENT
=> remnant of embryonic gubernaculum
Do the ovaries sit posteriorly or anteriorly in the pelvic cavity in the anatomical position?
POSTERIORLY
Most superior part of the broad ligament is formed from the
Suspensory ligament of the ovary
structures contained with the suspensory ligament of ovary
ovarian artery, ovarian vein, ovarian nerve plexus and lymphatic vessels
Where does the bulbospongious muscle lie in females?
within each of the LABIA MINORA
Which structures meet at the perineal body?
The posterior fibres of the bulbospongiosus muscle and the anterior fibres of the external anal sphincter
Which muscle runs parallel to the ischiopubic rami?
ISCHIOCAVERNOSUS MUSCLE
Which structure do the bulbospongious muscles surround in the female?
Bulb of the vestibule => erectile tissue
Which structures lie within the ischiocavernosus muscles in the female?
CRURA of the clitoris
Which structure lies directly behind the bulb of the vestibule?
The GREATER VESTIBULAR GLANDS => Bartholin’s glands; produces watery secretion tht lubricates vaginal opening
Flat sheet-like structure that bridges the gap between the ischiopubic rami
PERINEAL MEMBRANE
Role of the foramen ovale
shunt blood straight to the LA from the RA bypassing the RV, lungs
Embryologically what is the name given to the gaps that form the foramen ovale
septum secundum and ostium secundum
When is the embryonic period?
The first 8weeks after fetilisation
most accurate estimation of gestational age in early pregnancy
Crown rump length - little biological variability at this time increases from ~ 5cm at 9wks to ~36cm - 36wks
What can be measured btwn 7+13wks to date pregnancy and estimate the delivery date?
CROWN RUMP LENGTH => length of the embryo or fetus from the top of its head to bottom of torso
Explain why there is little weight gain in the foetus during the embryonic foetal period?
Because foetus is undergoing intense differentiation + morphogenesis but placental growth needs to be established to allow nutrient + oxygen supply for foetal growth
Dominant cellular growth mechanism in foetal growth
0-20 wks - hyperplasia
20-28wks - hyperplasia + hypertrophy
28wks - term - hypertrophy
How long does it take for a fully mature placenta to be established?
12 WEEKS
Nutrient dependent hormone needed for foetal growth that dominates in T2 + T3:
IGF-I
Nutrient INDEPENDENT hormone needed for foetal growth
IGF-II
Average birth weight of a term baby
3.5kg ~7.7 pounds
Birth weight > 4.5kg suggests
Macrosomia
Birth weight < 2.5kg
suggest foetal growth restriction
Approx what gestational age is the fundus of the uterus palpable at the umbilicus
22 WEEKS
Early signs of foetal hypoxia on a doppler ultrasound
raised umbilical artery pulsatility index AND absent end diastolic flow
Decidua
tissue that has changed in the presence of trophoblasts
TORCH
T - Toxoplasma gondii O - other agents R- rubella C - cytomegalovirus(CMV) H- herpes simplex virus (HSV)
Oligohydraminos
reduced amniotic fluid volume
Consequences of prematurity in foetus
- Breathing problemsdue to immature respiratory system - less type II pneumocytes → reduced surfactant → Respiratory distress syndrome
- Heart problems
- *Patent ductus arteriosus**
- ductus arteriosus doesn’t close
- no blood flow to lungs → no oxygenated blood circulating
- extra blood gets pumped from aorta to pulmonary arteries
- extra blood being pumped into the lung arteries makes the heart and lungs work harder and the lungs can become congested
- child may breathe faster and harder than normal
- high pressure in lung blood vessels as they receive more blood → might permanently damage them
Late changes in a previously normal structure:
DEFORMATION (mechanical effect)
secondary disturbance due to early influence of external factors
DISRUPTION
primary disturbance of embryogenesis
MALFORMATION
Agents that have capacity to disrupt normal development
TERATOGENS
function of relaxin
regulates adenylate cyclase
relaxes pelvic ligaments AND widens+softens the cervix
Forces of release overwhelm forces of retention in pregnancy: list some forces of release
FORCES of release
- prostaglandins - increase contractility
- cortisol produced by foetal adrenal gland inhibits progesterone
- oestrogen -> sensitises tissues to oxytocin
- oxytocin - main hormone tht induces uterine muscle contraction
- mechanical stretch on uterus -> increases excitability of muscle fibres
- vasopressin -> acts alongside vasopressin
Purpose of latent phase
short, irregular contractions to induce cervical ripening a few days before labour starts => enables cervix to offer less resistance to the presenting part
regular contractions, 3-4cm dilated, cervix fully effaced =
1st STAGE of labour
in what stage of labour is the amniotic sac oft. ruptured
FIRST stage
Stage of labour where cervix FULLY DILATED
SECOND STAGE
4 foetal factors tht affect the 2nd stage of labour
foetal size -> head size mainly
foetal lie -> axis of baby shld be longitudinal in relation to the mother
foetal presentation -> cephalic presentation(head first)
foetal attitude -> bby shld be fully flexed
which 2 hormones inhibit early pregnancy levels of oxytocin?
relaxin + progesterone
How does oestrogen sensitise the myometrium to oxytocin?
around 36wks gestation oestrogen will upregulate the no. of oxytocin receptors in myometrium
When the baby’s head reaches the pelvic floor its shoulders
INTERNALLY ROTATE => so widest part of shoulders are in line w widest part of pelvic inlet
Site of growth hormone production
anterior lobe of pituitary gland
Direct effects of growth hormone on fat metabolism
GH binds Rs on adipocytes:
- stimulates triglyceride breakdown
- suppresses adipocyte ability to accumulate + take up lipids
- stimulates protein anabolism
- suppresses insulin’s ability to stimulate glucose uptake in peripheral tissues
Indirect effects of growth hormone:
signals to liver to produce IGF-1 which:
- stimulates chondrocyte proliferation
- stimulates both the differentiation and proliferation of myoblasts
- stimulates amino acid uptake and protein synthesis in muscle and other tissues.
Effect of somatostatin on GH
inhibits GH release in resp to Growth hormone releasing hormone AND low glucose conc.
Effect of ghrelin on GH
binds somatotrophs and potently stimulates GH secretion
Relationship btwn. IGF-1 and GH
high lvls of IGF-1 directly inhibit GH
IGF-1 secretion is independent of GH before birth
BUT stimulated by GH after birth
5 key places insulin like growth factors are made
liver
kidneys
muscles
cartilage
bone
Role of T3 + T4 thyroid hormones in growth
- GENERALLY: normal differentiation + maturation of skeleton + nervous tissue
- protein synthesis in foetal brain + young children
- promote linear growth of bone til puberty
- promote ossification of bone + maturation of epiphyseal growth regions
Effect of XS cortisol on growth
INHIBITORY EFFECT
=> increases rate of skeletal maturation so reduces potential for further growth
Common form of dwarfism in humans
Achondroplasia
- autosomal dominant condition; mutation in Chr 4 - gain of function in FGF receptor 3:
decreased endochondral ossification
inhibits chondrocyte proliferation -> decreased cartilage matrix production
epiphyseal growth plates in long bones close early
inhibits cellular hypertrophy
**Other organs develop normally!!
Hypersecretion of GH
ACROMEGALY
usually caused by adenoma of pituitary somatoproph cells
