physiology Flashcards
where is GnRH secreted from
hypothalamus
what is the role of GnRH
stimulates the release of FSH and LH
where are LH and FSH secreted from
the anterior pituitary
what is the role of FSH
stimulates the growth and development of the follicle
what is the role of LH
stimulates theca cells to produce androgens
where is oestrogen mainly produced
granulosa cells of the follicles in the ovaries
where is progesterone produced
the corpus luteum after ovulation
what is the corpus luteum
temporary collection of cells left over from the follicle after the ovum has been released
what are the 2 main phases of the menstrual cycle
follicular phase and the luteal phase
when is the follicular phase of the menstrual cycle
from the start of menstruation until ovulation (first 14 days of 28 cycle)
when is the luteal phase of the menstrual cycle
from ovulation to the start of menstruation
what triggers ovulation
LH surge
what happens to the corpus luteum if fertilisation doesn’t occur
degenerates into the corpus albicans
what happens to the corpus luteum if fertilisation occurs
embryo secretes hCG (synctiotrophoblast cells) which maintains corpus luteum
means progesterone is still secreted and the pregnancy is maintained
what is a fertilised egg called
zygote
what are blastomeres
the individual cells resulting from cleavage of a zygote
what is a morula
solid ball of 16-32 blastomeres
what does the morula differentiate into (+ describe it)
blastocyst
inner cell mass (embryoblast) and outer layer that becomes the placenta (trophoblast)
hatches from the zona pellucida
describe what happens in the follicular phase
- menstruation
- GnRH secreted and triggers the secretion of LH and FSH
- these stimulate development of follicles
- as follicles mature they release oestrogen - downregulates the other hormones so focus is on developing one ovum (from the dominant follicle)
- LH surge triggers ovulation
describe what happens during the luteal phase
ruptured follicle becomes the corpus luteum which secretes progesterone
this prepares the endometrium for implantation
when and where does implantation usually occur
day 5-8
implants on the posterior uterine wall
what vessel carries oxygen saturated blood to the foetus
umbilical vein
what vessel carries deoxygenated blood back from the foetus into the maternal circulation
uterine veins
what is the role of human placental lactogen hormone
increases insulin resistance - makes more glucose available for foetus
promotes fat breakdown for maternal energy
prepares the breasts for lactation
what happens to blood volume during pregnancy
increases to support the growing foetus
how does cardiac output change in pregnancy
increases due to higher stroke volume and heart rate
why does BP decrease in early and middle pregnancy
due to decreased peripheral vascular resistance from vasodilation
what happens to respiration in pregnancy
tidal volume and respiratory rate increase
how does kidney function change in pregnancy
increased renal blood flow and GFR
what hormone increases salt and water retention in pregnancy
aldosterone
why does hydronephrosis occur in pregnancy and which side is it more commonly found on
dilatation of ureters and collecting system
the right side
why do pregnant women have higher iron, folate and B12 needs
increased red blood cell production
why does pregnancy cause physiological anaemia
plasma volume increases more than RBC volume, reducing haematocrit
why is pregnancy a hypercoagulable state
increased fibrinogen, factor 7,8 and 10
what role do prostaglandins play in labour
stimulate uterine contractions and ripen the cervix
which prostaglandin is used to induce labour
E2 (dinoprostone) given as a pessary
what are braxton hicks contractions
irregular and painless contractions that DO NOT lead to labour
what is the first stage of labour
onset of regular contractions until the cervix is fully dilated to 10cm
what happens to the cervix during the first stage of labour
dilatation and effacement (thins out)
what are the 3 stages of the first stage of labour
Latent phase: 0–3cm dilation, irregular contractions
Active phase: 3–7cm dilation, regular contractions
Transition phase: 7–10cm dilation, strong contractions
what is the second stage of labour
full cervical dilatation until delivery of the baby
what are the 3P’s that determine success in the second stage of labour
power
passenger
pasage
what are the 3 foetal lies
Longitudinal lie – Baby is straight up and down
Transverse lie – Baby is straight side to side
Oblique lie – Baby is at an angle
what are the 7 cardinal movements of labour
1️⃣ Engagement
2️⃣ Descent
3️⃣ Flexion
4️⃣ Internal rotation
5️⃣ Extension
6️⃣ Restitution & external rotation
7️⃣ Expulsion
what does the foetal head station describe
baby’s position in relation to the ischial spines
what is the third stage of labour
delivery of the baby to the delivery of the placenta
what is active management of the third stage of labour
oxytocin + cord traction to speed up placental delivery
what drug can be given to speed up the third stage of labour
oxytocin
what hormone stimulates milk production
prolactin
what hormone is involved with the milk let-down reflex
oxytocin
what is the structure and role of the umbilical cord
connects the foetus to the placenta
3 vessels: one vein carrying O2 blood to baby, 2 arteries carrying de-O2 blood back to the placenta
how many shunts are there in the foetal circulation and name them
3: ductus venosus, foramen ovale, ductus arteriosus
what is the foramen ovale and what is its role
located between the 2 atria - allows oxygen-rich blood to bypass the non-functioning foetal lungs
what is the ductus arteriosus
blood vessel that connects the pulmonary artery to the aorta - stops blood flowing to the lungs
what is the role of the ductus venosus
shunt that makes oxygenated blood bypass the liver so it can reach the brain
where is surfactant in the lungs produced
alveolar type 2 cells
how do the lungs change after birth
lung fluid is reabsorbed and air filled lung is established
name some factors that stimulate a baby to breathe
cord clamping, changes in pO2, reducing circulating prostaglandin
what happens in the circulatory transition following birth
pulmonary vascular resistance decreases, systemic vascular resistance increases
circulating prostaglandins drop
ductus arteriosus and foramen ovale close
what is the consequence of the ductus arteriosus closing
all blood leaving the right ventricle to travel to the lung via the pulmonary arteries
what is the consequence of the foramen ovale closing
isolation of oxygen and deoxygenated blood in the atria
what is persistent pulmonary hypertension of the newborn
pulmonary arteries remain constricted - leading to high pulmonary vascular resistance
causes right-to-left shunting
management of persistent pulmonary hypertension of the new born
ventilation, nitrous oxide, ECMO in severe cases
what is the most common cause of respiratory distress in term newborns and what causes it
transient tachypnoea
delayed reabsorption and clearance of foetal alveolar fluid
how do babies prepare for thermoregulation after birth in-utero
lay down brown fat in the 3rd trimester
what are the 3 main parts of birth that are important for establishing gut biome in a foetus
birth canal, skin to skin contact, feeding (especially breastmilk)
what causes physiological anaemia after birth
adult Hb is synthesised slower than foetal Hb is broken down
