Birth and first breath

Question 1

what does progesterone do in relation to labour?

Answer 1

inhibits uterine contraction

Question 2

what does oestrogen do in relation to labour?

Answer 2

promotes connexin insertion between myometrial cells
stimulates oxytocin receptor insertion into myometrium
allows unified strong contractions
PGE2 prostaglandin softens cervix

Question 3

corticotropin releasing hormone surge

Answer 3

causes corticotropin release and then cortisol which causes lung maturation

Question 4

relaxin

Answer 4

produced by placenta - peptide

increased in last trimester

Question 5

what does relaxin do?

Answer 5

relaxes/ softens pelvic ligaments

softens cervix for labour and delivery

Question 6

what triggers labour

Answer 6

unknown - variable and unpredictable

Question 7

how does labour start?

Answer 7

increase in CRH and drop in progesterone
causing membrane rupture - release of amniotic fluid
uterine contractions
which ever starts first triggers the other

Question 8

what is EDD

Answer 8

estimated date of delivery from first day of last menstrual period

Question 9

how many stages are there of labour?

Answer 9

3

stage 1-3

Question 10

1st stage of labour

Answer 10

cervix needs to fully dilate - 10cm

contractions are painful

Question 11

rate of cervix dilation

Answer 11

1cm/hour roughly

Question 12

what do uterine contractions do?

Answer 12

push fetal head down causing oxytocin to be released from posterior pituitary

Question 13

oxytocin role in labour

Answer 13

positive feedback
increases uterine contractions
forms more prostaglandins - PGF2

Question 14

prostaglandins

Answer 14

local hormones
from arachidonic acid
work quickly/ short lived

Question 15

what does PGF2 - alpha

Answer 15

increases contractions

Question 16

what can be used to measure contractions?

Answer 16

tokodynamometer

Question 17

fetal oxygenation in labour

Answer 17

uterine contractions produce extrinsic compression of uteroplacental blood vessels reducing flow and oxygen delivery to fetus

Question 18

what happens to uterine contractions over labour

Answer 18

get stronger and closer together

Question 19

stage 2 of labour

Answer 19

delivery of fetus
combination of uterine contraction and maternal effort
helped by oxytocin

Question 20

stage 3 of labour

Answer 20

delivery of placenta after shearing off
uterine contraction compresses vessels to produce haemostasis enhanced by oxytocin
spiral arteries of placenta are cut off

Question 21

fetal respiration

Answer 21

in utero the fetal lungs are filled with amniotic fluid, which must be eliminated and replaced with air by ventilation

Question 22

how is the first breath stimulated

Answer 22

mechanical stimulation and temperature change

Question 23

surfactant

Answer 23

thin layer of cells….

Question 24

fetal lung fluid

Answer 24

at the onset of labour hormones decrease fetal lung fluid production and initate active reabsorption
some lung fluid is forced out of trachea as fetus passes through birth canal

Question 25

complicance

Answer 25

the ease with which something can be stretched

Question 26

compliance of lungs

Answer 26

poorly compliant for initial inflation and so difficult to initially inflate and sustain it

Question 27

surface tension

Answer 27

surface tension in the fluid lining the alveoli reduces lung compliance and makes alveolar collapse more likely

Question 28

pulmonary surfactant

Answer 28

lipoprotein interspersed between water molecules lining the alveoli
reduces surface tension increases compliance and contributes to lung stability
reduces risk of pulmonary oedema

Question 29

surfactant production

Answer 29

secreted by type 2 alveolar cells
increases after 34 weeks
cortisol
thyroxine 
prolactin 
stimulate production

Question 30

what happens as alveoli get smaller

Answer 30

surfactant concentration increase, which lowers the surface tension more in small alveoli than in large ones
makes different sized alveoli equal and provides lungs stability

Question 31

infant respiratory distress syndrome

Answer 31

lack of surfactant

Question 32

how can you treat infant respiratory distress syndrome

Answer 32

oxygen
continuous positive airway pressure
artificial ventilation
instillation of artificial surfactant

Question 33

how to prevent infant respiratory distress syndrome

Answer 33

corticosteroid treatment to mother 24hrs before delivery

Question 34

what is a risk of ventilation

Answer 34

pneumothorax - hole in alveoli, air between wall and???

Question 35

treatment of pneumothorax

Answer 35

chest drain insertion

Question 36

what does PGE2 do?

Answer 36

relaxes cervix

Question 37

how to enhance labour

Answer 37

synthetic oxytocin is used to increase uterine contractility and augment labour

Question 38

how to treat post-partum bleeding?

Answer 38

synthetic PGF2-alpha/ oxytocin

to enhance uterine contraction and cut off the arteries of the placenta

Question 39

what does the first breath do?

Answer 39

causes secretion of surfactant to form a mononuclear layer and reduce surface tension and improve compliance

Question 40

what is surface tension?

Answer 40

tendency of liquid surface to pull together by molecular forces

Question 41

pressure in alveolus

Answer 41

inversely proportional to radius
P=T/R
T = surface tension
R= radius

Question 42

what happens if there is no surfactant

Answer 42

due to P=T/R
the pressure in small alveoli is higher than large one and so small alveoli empties in to large ones and causes collapse at low lung volumes

Question 43

what does lack of surfactant appear like on x-rays?

Answer 43

ground glass/ hazy appearance