Anatomy of the Breast and Physiology of Lactation

Question 1

The breasts lie over which muscle?

Answer 1

The pectoralis major

Question 2

What extends from the upper outer corner of the breast up into the axilla?

Answer 2

The axillary tail of Spence

Question 3

Why do breasts vary in size?

Answer 3

Due to differing amounts of adipose tissue.

Question 4

What are nipples composed of?

Answer 4

Connective tissue.

Question 5

Describe the surface of the nipple.

Answer 5

Nipples are covered in pigmented stratified squamous epithelium, which contain papillae. Papillae allow bundles of unmyelinated nerve endings to lie close to the skin.

Question 6

What are Montgomery’s tubercles and where can they be found?

Answer 6

Montgomery’s tubercles are sebaceous glands that produce sebum to lubricate the nipple. They are found in the areola.

Question 7

What is the functional substance of the breast, the glandular tissue, also known as?

Answer 7

Parenchyma

Question 8

How is parenchyma arranged?

Answer 8

Glandular tissue is arranged in lobes that radiate out from nipple. Each lobe is divided into smaller lobules.

Question 9

What two things are contained in lobules?

Answer 9

Alveoli and ductules.

Question 10

Where can acini cells (or lactocytes) be found?

Answer 10

In each alveolus.

Question 11

Describe the arrangement of cells in the alveoli.

Answer 11

Cells are arranged in a single layer. They rest on the basal lamina and myoepithelial cells.

Question 12

What is the basal lamina?

Answer 12

The basal lamina is the basement membrane dividing the epithelial and stromal parts of breast tissue.

Question 13

Ducts consist of an inner lining of ____ cells and an outer lining of ____ cells.

Answer 13

epithelial

myoepithelial

Question 14

How many groups of alveoli drain into a small duct?

Answer 14

10-100.

Question 15

Ducts from lobules unit to form what?

Answer 15

The main lactiferous duct for each lobe.

Question 16

What is the stroma?

Answer 16

The stroma refers to everything in the breast that is not the functional glandular tissue: connective tissue, adipose tissue, blood and lymph vessels, nerve tissues and surrounding skin.

Question 17

What holds breasts in position?

Answer 17

Suspensory ligaments of Astley-Cooper.

Question 18

What is the average amount of ducts exiting the nipple?

Answer 18

9

Question 19

What is the ratio of glandular to fatty tissue?

Answer 19

2:1

Question 20

65% of parenchyma is within how many millimetres of the nipple?

Answer 20

30mm

Question 21

List the five developmental stages of breast function.

Answer 21

1. Embryogenesis
2. Mammogenesis
3. Lactogenesis
4. Lactation
5. Involution

Question 22

Breasts start to develop on the ventral surface of the body from what week of gestation?

Answer 22

4th week

Question 23

Mammogenesis occurs in two phases, when do these occur?

Answer 23

Puberty and pregnancy.

Question 24

Mammogenesis is not complete until after parturition: true or false?

Answer 24

True.

Question 25

The ovulatory cycle enhances breast growth up until what age?

Answer 25

30

Question 26

Which hormones stimulate the growth of mammary ducts during puberty

Answer 26

Oestrogen and growth hormone.

Question 27

When do the lactiferous ducts and alveoli develop during mammogenesis?

Answer 27

In the second half of the menstrual cycle.

Question 28

What hormone stimulates development of the lactiferous ducts and alveoli in mammogenesis?

Answer 28

Progesterone

Question 29

What are the three stages of lactogenesis?

Answer 29

Priming, initiation and maintenance.

Question 30

When does stage 1 (priming) of lactogenesis occur?

Answer 30

During pregnancy.

Question 31

At how many weeks' gestation is the breast capable of synthesising milk components?

Answer 31

16 weeks

Question 32

Which hormones contribute to accelerated breast growth in pregnancy?

Answer 32

Human placental lactogen, prolactin, human chorionic gonadotrophin, oestrogen and progesterone.

Question 33

During stage 1 of lactogenesis, which hormone contributes to the development of differentiated secretory alveolar cells?

Answer 33

Prolactin

Question 34

During stage 1 of lactogenesis, which hormone contributes to ductal growth?

Answer 34

Oestrogen

Question 35

During stage 1 of lactogenesis, which hormone contributes to lobular formation and alveolar growth?

Answer 35

Progesterone

Question 36

During stage 1 of lactogenesis, what two things are responsible for suppressing secretory activity?

Answer 36

Progesterone and prolactin-inhibiting factor.

Question 37

Lactogenesis 1 can be considered the transitional milk stage: true or false?

Answer 37

False. Walker (2015) defines Lactogenesis 1 as the colostrum stage.

Question 38

How many millilitres of colostrum is available to the infant on day 0 postpartum?

Answer 38

100ml

Question 39

In the first trimester, what is the percentage increase in blood flow to the breasts?

Answer 39

50%.

Question 40

Stage 2 of lactogenesis involves which two maternal reflexes?

Answer 40

The milk production reflex and the milk ejection reflex.

Question 41

Stage 2 of lactogenesis is dependent on which three neonatal reflexes?

Answer 41

The rooting reflex, the sucking reflex and the swallowing reflex.

Question 42

What three hormones are necessary for initiation of lactation?

Answer 42

Prolactin, insulin and hydrocortisone.

Question 43

Why is the anterior pituitary gland no longer inhibited after the birth of the placenta?

Answer 43

Because there is an abrupt drop in progesterone, oestrogen and human placental lactogen.

Question 44

Nipple stimulation causes the hypothalamus to inhibit the release of what?

Answer 44

Dopamine

Question 45

Why are lower levels of dopamine necessary for stage 2 of lactogenesis?

Answer 45

Lower levels of dopamine stimulate the release of prolactin from the anterior pituitary gland.

Question 46

How many hours after birth does the composition of milk rapidly change from colostrum to transitional milk?

Answer 46

30-72 hours.

Question 47

When does stage 3 of lactogenesis occur?

Answer 47

Approximately 10 days after birth.

Question 48

When is a mature milk supply established?

Answer 48

Approximately 10 days after birth.

Question 49

When is lactation the earliest lactation is said to be established?

Answer 49

4 weeks after birth.

Question 50

Stage 3 of lactogenesis is reliant on an intact hypothalamic-pituitary axis regulating what?

Answer 50

Oxytocin and prolactin

Question 51

Stage 3 of lactogenesis is dependent on what neonatal behaviours?

Answer 51

Frequent suckling and removal of milk.

Question 52

Lactation involves two concepts: milk ____ and milk _____.

Answer 52

synthesis production

Question 53

What is milk synthesis?

Answer 53

The accumulation of milk within the breast.

Question 54

What is milk production?

Answer 54

The volume of milk removed from the breast.

Question 55

When is there an increased synthesis of milk?

Answer 55

In the morning, peaking between 8am and midday.

Question 56

Approximately how much milk can an infant remove from the breast?

Answer 56

76%

Question 57

List four factors influencing milk synthesis.

Answer 57

Frequency of feeds, the time of day, the amount of milk removed, and the storage capacity of each breast.

Question 58

How long is the average period of involution?

Answer 58

3 months.

Question 59

Is re-establishment of full lactation possible during involution?

Answer 59

Yes.

Question 60

During involution, accumulation of milk in the alveoli and ducts causes what to happen to the epithelial cells?

Answer 60

Distension and mechanical atrophy.

Question 61

During involution, accumulation of milk in the alveoli eventually causes what to happen to the alveoli?

Answer 61

The alveolar walls rupture.

Question 62

During involution, what happens to the waste cells and glandular debris?

Answer 62

Phagocytosis

Question 63

During involution, what happens to the alveolar lining?

Answer 63

Alveolar lining changes from a single secretory, to double non-secretory layer.

Question 64

Breasts often remain larger after lactation due to deposition of fat and connective tissue: true or false?

Answer 64

True.

Question 65

Describe the changes in milk composition whilst weaning.

Answer 65

There are higher levels of fat, sodium and immunoglobulins. There are lower levels of lactose.

Question 66

Why are the breasts vulnerable to infection with abrupt weaning?

Answer 66

Because it takes 2 days for immunoglobulin and lactoferrin levels to rise.

Question 67

Feedback Inhibitor of Lactation is found in which component of milk?

Answer 67

Whey.

Question 68

Where is Feedback Inhibitor of Lactation produced?

Answer 68

It is secreted by the alveolar cells.

Question 69

It is thought that the Feedback Inhibitor of Lactation inhibits secretion of lactose by blocking what?

Answer 69

Prolactin

Question 70

If milk accumulates in the breast, the concentration of Feedback Inhibitor of Lactation increases. What effect does this have?

Answer 70

It inhibits lactation by reducing the rate of milk synthesis.

Question 71

Where is prolactin produced?

Answer 71

In the anterior pituitary gland.

Question 72

Secretion of prolactin is modified by which hormones?

Answer 72

Oestrogen and Thyroid Stimulating Hormone

Question 73

What are the prolactin levels at term?

Answer 73

150-400ng/ml

Question 74

Prolactin levels are not reliant on infant suckling until when?

Answer 74

Approximately day 3 after birth.

Question 75

Describe what happens to prolactin levels during a feed.

Answer 75

Prolactin levels rise within 10 minutes of suckling. They peak at 30 minutes. Levels return to base levels within 4 hours of the start of the feed.

Question 76

Prolactin circadian rhythms exist throughout lactation. When are levels highest?

Answer 76

At night.

Question 77

In non-breastfeeding mothers, when should their prolactin levels return to normal?

Answer 77

Within two weeks of giving birth.

Question 78

Prolactin concentrations are highest in which type of breastmilk?

Answer 78

Transitional breastmilk.

Question 79

When absorbed by the neonate, what effect does prolactin have on the intestine?

Answer 79

It influences fluid, sodium, potassium and calcium transport.

Question 80

What is dopamine also known as?

Answer 80

Prolactin-inhibiting factor.

Question 81

Where is prolactin-inhibiting produced?

Answer 81

The hypothalamus

Question 82

What determines whether the hypothalamus produces prolactin-inhibiting factor?

Answer 82

Catecholamine levels

Question 83

List three factors that affect prolactin release.

Answer 83

Physiological stimuli, pharmacological stimuli, and pharmacological suppressors.

Question 84

According to the prolactin receptor theory, when are the specialised prolactin receptor sites most sensitive?

Answer 84

Immediately after the birth of the placenta.

Question 85

According to the prolactin receptor theory, where can the specialised prolactin receptor sites be found?

Answer 85

Surrounding the acini cells.

Question 86

According to the prolactin receptor theory, receptor sites that are not primed shut down. What effect does this have?

Answer 86

The receptor sites lose their sensitivity to prolactin. If insufficient sites are primed, the resultant milk supply will be lower for the duration of that lactation.

Question 87

When a baby suckles at the breast, _____ impulses pass from the nipple via the ______ to the _____.

Answer 87

sensory spinal cord brain

Question 88

Sensory impulses from the newborn suckling at the breast stimulates the hypothalamus to produce what?

Answer 88

Prolactin-releasing factor.

Question 89

Prolactin-releasing factor stimulates the _____________ to produce ________.

Answer 89

anterior pituitary gland prolactin

Question 90

Prolactin is transported via the _____ to the ______, where it directs _____ cells to produce milk.

Answer 90

blood breast acini

Question 91

Suckling (possibly via prolactin release) suppresses which three hormones implicated in menstruation and ovulation?

Answer 91

Gonadotrophin releasing hormone, luteinising hormone and follicle-stimulating hormone

Question 92

If a mother is exclusively breastfeeding (including at least once at night) and her baby is less than 6 months old, how effective is lactation amenorrhoea as a method of contraception?

Answer 92

98% effective.

Question 93

Where is oxytocin produced?

Answer 93

The posterior pituitary gland

Question 94

Oxytocin binds to receptors on _____________ cells and to __________ cells in the duct walls, causing ________.

Answer 94

myoepithelial longitudinal contractions

Question 95

Does the milk ejection reflex increase or decreases intraductal mammary pressure?

Answer 95

Increase

Question 96

Describe what happens to oxytocin levels during a feed.

Answer 96

Levels rise within one minute of breast stimulation. Levels remain elevated during stimulation due to pulsatile release at one minute intervals. Levels return to baseline within 6 minutes of cessation of stimulation.