Physiology of Pregnancy and Lactation

Question 1

At what stage does the embryo implant into the uterus

Answer 1

Blastocyst- inner cells become embryo. Outer cell burrow into uterine wall and become placenta

Question 2

What is the stage before blastocyst

Answer 2

Morula

Question 3

When does the blastocyst attach to the lining of the uterus

Answer 3

Day 5-8

Question 4

What are the surface layer cells of the blastocyst called

Answer 4

trophoblast

Question 5

By what day does the blastocyst become buried in the uterine lining

Answer 5

day 12

Question 6

What is the placenta made from

Answer 6

Trophoblast and decidual tissue

Question 7

When is the placenta and foetal heart functional

Answer 7

by week 5 of the pregnancy

Question 8

How is the placental developed

Answer 8

Invasion of trophoblastic cells into the decidua
HCG is secreated which signals to the corpus luteum to continue to secret progesterone - this stimulate decidual cells to concentrated glycogenm proteins and lipids to help placental development

Question 9

How does fetal, oxygenated blood return to the fetus

Answer 9

via the umbilical vein

Question 10

how does maternal, now oxygen poor blood flow from the intervillous space back to the maternal circulation

Answer 10

via the uterine arteries

Question 11

What is different about fetal Hb

Answer 11

increased ability to carry oxygen
higher Hb conc in fetal blood
Fetal Hb can carry more oxygen in low PCO2 than high pCO2

Question 12

What is the function of HCG

Answer 12

prevents involution of the corpus luteum (progesterone production maintained)
effect on testes of mall fetus - helps develop sex organs

Question 13

What is human chorionic somatomammotropin (HCS)

Answer 13

Growth hormone like effects - protein tissue formation
Decreases insulin sensitivity in the mother - more glucose available for the fetus
Involved in breast development and possibly lactation (?)

Question 14

When is HCS produced

Answer 14

from week 5

Question 15

what is the function of progesterone

Answer 15

development of decidual cels
decreases uterus contractility
preparation for lactation

Question 16

What is the purpose of oestrogens

Answer 16

enlargement of uterus
breast development
relaxation of ligaments

Question 17

what does the estriol level indicate

Answer 17

the vitality of the fetus

Question 18

What conditions can result as a consequence of hormonal changes in pregnancy

Answer 18

Hypertension
Diabetes
Hyperthyroidism
Hyperparathyroidism

Question 19

Why can hypertension and diabetes occur

Answer 19

CRH is increased – ACTH increases – aldosterone increases = HYPERTENSION
Increased ACTH – increased cortisol – insulin resistance and oedema = gestational diabetes.

Question 20

Why can hyperthyroidism occyr

Answer 20

HCG can causes increase thyroxin

Question 21

Why can hyperparathyroidism occur

Answer 21

increased calcium demands

Question 22

how much does the cardiac output increase in pregnancy

Answer 22

30-50 percent beginning week 6 and peaking at wk 24

Question 23

Why is the CO increased in pregnancy

Answer 23

demands of uteroplacental circulation
increases metabolism
renal circulation
thermoregulation

Question 24

when does the CO decrease in pregnancy and why is this

Answer 24

the last 8 weeks - the uterus compresses vena cava

but increases again in labour

Question 25

How are the heart rate and BP affected by pregnancy

Answer 25

Hr- increased up to 90/min | BP- drops during second trimester

Question 26

What are the haematological changes in pregnancy

Answer 26

Plasma volume increases Erythropoeiss increased by 1/4 Hv is decreased by dilutsion and this decreases blood viscosity Iron requirements increase to 6-7mg/day in 2nd half

Question 27

Why do lung changes occur

Answer 27

Progesterone increase - progesterone signals the brain to lower CO2 levels enlarging uterus interferes with lung function O2 consumption increases

Question 28

How are CO2 levels lowered

Answer 28

increased resp rate tidal and minute volume increases PCO2 decreases no change on PO2 or vital capacity

Question 29

What changes occur in the urinary system

Answer 29

glomerular filtration rate and renal plasma flow increase up to 30-50 percent increased reabsorption of ions and water slight increase in urine formation

Question 30

why is there more reabsorption of ions and water

Answer 30

because of increased aldosterone | and increased placental steroids

Question 31

how do postural changes affect renal function

Answer 31

upright position - decreased supine- increased lateral position during sleep - very increased

Question 32

How much weight does a mother typicaly gain

Answer 32

11kgs 5- fetus 6- mother

Question 33

how many extra calories should be ingested a day in pregnancy

Answer 33

250-300 | 30g extra protein

Question 34

When does the fetus have high metabolic demands

Answer 34

wks 21-40

Question 35

What special nutritional needs are there in pregnancy

Answer 35

``` high protein diet iron supplements 300mg B vitamins for erythropoesis folic acid vit D3 and calcium supplements vitamin K before parturition ```

Question 36

What happens to the oestrogen:progesterone ratio in parturition

Answer 36

Oestrogen increases as it increases contractility while progesterone inhibits it

Question 37

What other factors increase contractility

Answer 37

Maternal and fetal oxytocin mechanical stretch of uterine muscle fibres stretch of the cervix

Question 38

what does prostaglandidn fo

Answer 38

control timing of labour

Question 39

What effect does oestrogen and progesterone do in terms of lactation

Answer 39

Oestrogen - growth of ductile system Progesterone- development of lobule alveolar system Both inhibit milk production so their levels drop suddenly at birth

Question 40

What does prolactin do

Answer 40

stimulates milk production | stimulates colostrum

Question 41

describe the milk let down reflex

Answer 41

receptors in nipples stimulated- impulses propagates to spinal cord- stimulation of hypothalamic nuclei- oxytocin released- contraction- milk ejected

Question 42

where is oxytocin released from

Answer 42

the posterior pituitary gland

Question 43

describe the mothers nutritional status throughout pregnancy

Answer 43

wks 1-20 = anabolic | wks 21-40= catabolic ie fetus has high demands, mother experiences accelerated starvation

Question 44

what happens in the anabolic phase

Answer 44

normal or increases insulin sensitivity lower plasmatic glucose level lipogeneis, glycogen stores growth of breasts, uterus, weight gain

Question 45

what causes insulin resistance in pregnancy

Answer 45

HCS cortisol growth hormone