Lecture 23

Question 1

What are the anatomical strains of pregnancy on the body?

Answer 1

• restriction of lung expansion
• compression of digestive organs
• weight is misaligned with body axis
• pressure on rectum compresses blood vessels
• bladder is compressed

Question 2

What are the physiological strains of pregnancy on the body?

Answer 2

• maternal respiratory rate and tidal volume increases
• blood volume increases
• nutrient requirements increase
• hypertrophy of uterine cells
• volume of urine increases
• glomerular filtration rate increases
• mammary glands develop

Question 3

How does the myometrial layer change in late stages of pregnancy?

Answer 3

• The smooth muscle cells switch to single-unit, gap-junction coupled organization, and express oxytocin receptors
• allows the whole myometrium to contract and relax in synchronized waves

Question 4

How does the myometrium produce labour contractions?

Answer 4

• the brain stimulates pituitary gland to secrete oxytocin, it travels to the uterus
• the whole myometrium contracts and relaxes in synchronized waves in response to oxytocin
• head of baby pushes on cervix, and sends the signal back to the brain (positive feedback loop)

Question 5

How are contractions produced? Placenta foetus, maternal

Answer 5

Placental: estrogens increase sensitivity of smooth muscle cells, relaxin is produced to dilate cervix and relax pelvic floor
Foetal: growth and increase in weight stretch the myometrium, fetal pituitary gland releases oxytocin in response to estrogens
Maternal: myometrium stretches and becomes more sensitive, prostoglandins are produced and stimulate contractions, oxytocin release caused by high estrogen, cervix softens and opens, uterine/pelvic floor contractions

Question 6

What are the three phases of a successful labour?

Answer 6

1. Dilation
2. Expulsion
3. Placental

Question 7

What medical interventions can be used to initiate labour? Circumvent it?

Answer 7

Initiate: artificial rupture of membranes, balloon catheter, prostaglandin gel, IV OXT

Question 8

What is the structure and function of colostrum?

Answer 8

• no nutrients, lots of antibodies

- yellow, secreted before breastmilk

Question 9

What is the function and composition of breastmilk?

Answer 9

• nutrient rich in fat and lactose, fewer immune molecules

- vitamnins and minerals, protein

Question 10

How does lactation happen neurohormonally?

Answer 10

Anterior pituitary: prolactin is released for milk production
Posterior pituitary: OXT must be released for myoepithelial contraction and milk ejection
Tactile reflex loop: mechanoreceptors in nipple, or sometimes just a baby crying

Question 11

What are the 6 main pregnancy related hormones?

Answer 11

HCG, P, E, relaxin, oxytocin, prolactin

Question 12

How does lactation happen?

Answer 12

Merocrine and apocrine secretion in mammary glands