14.0 Lactation and Neonatal Physiology

Question 1

What are the respiratory changes that occur post-partum?

Answer 1

<b>1) Lung needs ability to inflate</b><br></br>- Drainage of lung fluid<br></br>- Surfactant production<br></br><br></br><b>2) Lung needs adequate ventilation and perfusion</b>

Question 2

What are the stimuli for post-partum respiratory changes?

Answer 2

1) Tying/cutting cord<br></br>2) Cold air<br></br>3) Sensory stimuli

Question 3

What are the circulatory changes that occur post-partum?

Answer 3

1) ↓ pulmonary vascular resistance<br></br>2) ↑ pulmonary blood flow<br></br>3) Closure of foramen ovale<br></br>4) Initiation of closure of ductus arteriosus<br></br>5) ↑ systemic vascular resistance

Question 4

What are the stimuli for post-partum circulatory changes?

Answer 4

1) pO₂<br></br>2) Pressure gradients<br></br>3) PGE<br></br>4) CT deposition

Question 5

What are the main neonatal fuel reserves?

Answer 5

1) Glycogen (muscle + liver)<br></br>2) Fat

Question 6

How long can fuel reserves maintain a neonate?

Answer 6

> 24hrs<br></br><br></br>(fat stores allow baby to last 3 days with minimal calorific intake)

Question 7

What percentage of neonatal glucose is endogenously produced?

Answer 7

50-80%

Question 8

What is immunity transferred to neonate?

Answer 8

Antenatally

Question 9

Where does non-shivering thermogenesis occur?

Answer 9

Brown adipose

Question 10

Why are premature babies less able to deal with post-partum stresses?

Answer 10

May not have had sufficient cortisol exposure to induce maturation of organs/physiology to deal with life

Question 11

What hormones promote breast development?

Answer 11

Begins at puberty due to:<br></br>1) Ovarian oestrogen<br></br>2) Adrenal steroids<br></br><br></br>Continues after menarche in response to cyclic changes in ovarian steroids

Question 12

What changes occur to breast tissue during pregnancy?

Answer 12

• Rapid growth + branching of terminal portions<br></br>- ↑ vascularity<br></br>- Formation of glandular acini

Question 13

When does breast alveolar secretion commence?

Answer 13

2nd trimester (fully activated after birth)

Question 14

What is required for the morphological and functional differentiation of breast tissue?

Answer 14

Range of hormones<br></br>Growth factors (IGF-1 + EGF)

Question 15

What is the main energy source in milk?

Answer 15

Fat

Question 16

What is colostrum?

Answer 16

Initial milk<br></br>Differs from mature milk:<br></br>- Less fat + lactose<br></br>- More proteins, Ig, and fat soluble vitamins (D,E,A,K)

Question 17

What cells produce milk?

Answer 17

Alveolar epithelial cells

Question 18

What are the 5 different pathways for milk secretion?

Answer 18

<b>1) Exocytosis</b><br></br>- Secretion of lactose and milk proteins (lactalbumin)<br></br><br></br><b>2) Lipid transfer</b><br></br>- For triglycerides<br></br><br></br><b>3) Apical transport</b><br></br>- For water, minerals and monosaccharides<br></br><br></br><b>4) Transcellular</b><br></br>- Immunoglobulins (IgG)<br></br><br></br><b>5) Paracellular</b><br></br>- Bulk flow down gradients<br></br>- WBCs

Question 19

Define lactogenesis:

Answer 19

Onset of lactation

Question 20

What hormone does lactogenesis depend on?

Answer 20

Prolactin<br></br><br></br>(also needs withdrawal of progesteron and oestrogen)<br></br><br></br>Prolactin gradually increases throughout pregnancy and stays high for 4-6weeks post partum

Question 21

How do progesterone and oestrogen inhibit lactogenesis?

Answer 21

Oestrogen inhibits prolactin<br></br><br></br>Progesterone inhibits lactose synthetase <br></br><br></br>(levels of these hormones decrease rapidly following delivery of placenta)

Question 22

Define galactopoiesis:

Answer 22

Maintenance of lactation

Question 23

What is the mechanism of galactopoiesis?

Answer 23

Suckling the nipple starts several reflexes (mediated in the hypothalamus)

Question 24

What are the consequences of the suckling induced reflexes in galactopoiesis?

Answer 24

<b>1) ↑ Prolactin</b> <br></br>- from ant. pituitary <br></br>- forms milk<br></br><br></br><b>2) ↑ oxytocin</b> -<br></br>- From post. pituitary<br></br>- causes contraction of myoepithelial cells around ducts → milk ejection<br></br><br></br><b>3) ↓ GnRH release</b><br></br>- Thus ↓ ovulation

Question 25

Human infants express milk from the nipple by stripping out milk stored in the lactiferous sinus using their tongues and hard palates.<br></br>The baby __________ have to generate a negative pressure to <b>breast</b> feed.<br></br>The baby __________ have to generate a negative pressure to <b>bottle</b> feed

Answer 25

Human infants express milk from the nipple by stripping out milk stored in the lactiferous sinus using their tongues and hard palates.<br></br>The baby DOES NOT have to generate a negative pressure to <b>breast</b> feed.<br></br>The baby DOES have to generate a negative pressure to <b>bottle</b> feed

Question 26

What is the percentage risk of transmitting HIV from mother to baby?<br></br><br></br>What is the additional risk from breast feeding?

Answer 26

20-25%<br></br><br></br><br></br>10-14% increase with breast feeding