Anatomy of the Breast and the Physiology of Lactation, Including Mother-Infant Skin to Skin Contact

Question 1

Identify the nipple, nipple ducts, areola, and Montgomery’s tubercles on the surface of the breast

Identify the ribs, pectoral muscle, Cooper’s ligaments, lobes, lobules, acini cells, myo-epithelial, and lactiferous ducts

Answer 1

See print out

Question 2

What are breasts?

Answer 2

Bilateral compound secretory glands aka mammary glands. Positioned between the 2nd and 6th rib of the thorax, extending laterally from the sternum to the Adila and lying anterior to the pectoralis major muscle

Question 3

Describe the anatomy of the breast

Answer 3

Each breast is composed of varying proportions of fat and glandular tissue separated by connective tissue, into lobes
Each lobe is subdivided into lobules
Lobules consist of alveoli and ducts

Question 4

Describe lobes and lobules

Answer 4

Lobes: approximately 4-18 lobes in each breast composed of glandular tissue- divided by connective tissue and adipose layer

Lobules: subdivision of each lobe consisting of alveoli and lactiferous ducts- collections of 10-100 alveoli from one lobule

Question 5

Describe alveoli and their function

Answer 5

Alveoli are the basi glandular unit of the breast. Contain acini cells responsible for secreting milk, and are surrounded by myo-epithelial cells composed of smooth muscle.
Lymphocytes or monocytes are found wedged between the secretary (acini) cells of the alveoli and have migrated there. They play a role in local production of antibodies in the form of immunoglobulin A (igA) for secretion into the breast milk

Question 6

Describe the ductal system

Answer 6

Complex network of lactiferous ducts
Lactiferous ducts arise from alveoli and unite to form larger ducts
Transport milk to the nipple
Resting diameter 1-1.4mm but during milk ejection can dilate up to 58%
Ducts near to nipple are more superficial and easily compressed
Lactiferous sinuses (thought to be permanently dilated part of the duct where the milk pools) do not exist. In fact, the dilation of the ducts is transient

Question 7

What is the typical glandular tissue to fat ratio in the breasts?

Answer 7

2:1

Question 8

Describe the blood and nerve supply in breasts

Answer 8

Blood supply:
Internal and external mammary arteries
Intercostal arteries
Venous return corresponding veins

Lymphatic drainage:
Lumpy drains between both breasts into lymph nodes in axillae and mediastinum

Nerve supply:
4th, 5th, 6th thoracic nerves

Question 9

Describe mammogenesis during the fetal and neonatal stage (breast development)

Answer 9

Fetal:
Branching morphogenesis: development of the ducts system in utero. Mammary- specific cells present from 4-6 weeks gestation. Irrespective of fetal sex.

Neonatal:
From birth, some glandular tissue is present, and milk may be produced, known as ‘galactorrhea of the newborn’.

There are a few changes from age 2 to puberty.

Question 10

Describe the breast development at puberty

Answer 10

Sexually dimorphic breast development i.e. female breast development, occurs under the influence of sex hormones, particularly oestrogen and progesterone
Breast development is usually the first secondary sex characteristic, usually preceding pubic hair by 6 months
For the onset of breast development, the typical age range is 8 1/2 to 13 1/2 years
Ductal development and branching, and lobular development occurs
Nipple size increases, and the primary areola becomes pigmented
Cyclical changes occur

Question 11

Describe the breast development in pregnancy

Answer 11

Glandular development occurs under the influence of progesterone
Ductal development occurs under the influence of oestrogen
Colostrum is synthesised, but lactation is suppressed under the influence of placental hormones

Question 12

Describe the breast development in pregnancy, from 3 weeks to late pregnancy

Answer 12

3-4 weeks: prickling, tingling sensation due to increased blood supply, particularly around the nipple
6-8 weeks: breasts increase in size, becoming painful, tense and modular due to hypertrophy of the alveoli; delicate bluish surface veins become visible just beneath the skin
8-12 weeks: montgomery tubercles become more prominent on the areola; these hypertonic sebaceous glands secrete sebum, which keeps the nipple soft and supple; pigmented areas around the nipple (the primary areola) darken, and may enlarge and become more erectile
16 weeks: colostrum can be expressed; the secondary areola develops, with further extension of the pigmented areas that is often mottled in appearance
Late pregnancy: progesterone causes the nipple to become more prominent and mobile. Colostrum may leak.

Question 13

How is milk made?

Answer 13

Lactogenesis
Milk is synthesised in the acini cells (lactocytes) under the influence of the hormone prolactin
Milk is synthesised from glucose and amino acids in the blood stream
Milk is secreted from the acini cell, across the cell membrane, into the lumin of the alveoli

Question 14

Describe the initiation of lactation

Answer 14

Hormone prolactin is released from the anterior pituitary gland
Prolactin is produced in pregnancy, but milk production is suppressed by oestrogen and progesterone (placental hormones)
Once the placental is birthed, and oestrogen and progesterone drop, the prolactin activates milk production in the acini cells
Prolactin levels are higher at night time
Prolactin’s is also released when the baby suckles

Question 15

Describe the maintenance of lactation

Answer 15

The ‘order’ of milk to be made is sent to both breasts even if only one is stimulated

Early, frequent access to the breast is needed for milk production to be stimulated and maintained

Question 16

Describe prolactin

Answer 16

Produces calmness and reduces stress
Stimulates mothering behaviour
Triggered through touch
More secreted at night
Suppresses ovulation
Level peaks after the feed, to produce milk for the next feed

Question 17

Describe the prolactin receptor theory

Answer 17

Surges of prolactin prime the receptor sites
Expulsion of placenta opens receptor sites
Unprimed receptor sites shut down, reducing potential for milk production
Prolactin receptor sites open when placenta delivered
Prolactin surges ‘prime’ sites to begin milk production
Receptor sites start to close if not primed
Skin contact and lots of feeds in early days increase potential for long-term milk privation

Question 18

Describe oxytocin

Answer 18

Works on muscle (myo-elithelial) cells to expel milk
Pulsatile action
Induces feeling of love and well-being
Levels are higher when baby is near
Can be temporarily inhibited by stress
Creates a feelings of wellbeing

Question 19

Describe the difference between endogenous and synthetic oxytocin

Answer 19

Endogenous oxytocin crosses the blood-brain barrier; it invokes the feelings of lobe and protectiveness; it is stimulated by nurture and touch

Synthetic oxytocin does not cross the blood brain barrier and does not evoke the same feels of lobe and protectiveness

Question 20

Describe the milk ejection reflect aka neuro-endocrine reflect or ‘let down’ reflex

Answer 20

Tactile stimulation of the breast stimulates release of oxytocin from the posterior pituitary
Oxytocin stimulates contraction of the myo-epithelial cells surrounding the alveoli
Milk is expelled into the lactiferous ducts
Initially an unconditioned reflex- later becomes a conditioned reflex

Question 21

What helps and hinders the milk ejection reflex?

Answer 21

Helped by sight, sound and smell of baby
Becomes conditioned over time
Hindered by anxiety, stress, pain and doubt
Works before or during the feed to make the milk flow

Question 22

Describe the process of FIL

Answer 22

Feedback inhibitor of lactation

FIL is secreted as part of milk
Build up of FIL blocks milk production
Removing FIL allows milk production

So, frequent milk removal ensures ongoing milk production

Question 23

Describe and compare the control of lactation from an endocrine and autocrine perspective

Answer 23

Endocrine control:
Pituitary gland
Oxytocin (milk ejection for this feed)
Prolactin (milk production for next feedback)
Systemic (both breasts)

Autocrine control:
Feedback inhibitor of lactation
Build up (inhibits production)
Removal (stimulates production)
Local (one breast)

Question 24

Why is lactation and breastfeeding important?

Answer 24

Keeps mother and baby together
Helps mothers to recognise feeding cues
Allows unrestricted, frequent feeds
Support mothers to breastfeed at night
Avoid supplements
Use dummies with caution

Question 25

What makes human milk different to infant milk?

Answer 25

It is matched to the needs of the baby (change dependent upon when the baby is born, it’s age and the environment that it lives in)
It has live constituents (as it hasn’t been pasteurised, it has live microbes which are essential in colonising the baby with healthy bacteria)
Protects the baby’s gut (newborn babies have a ‘leaky’ gut, which harmful bacteria can latch onto; human milk coats the gut wall to prevent harmful bacteria from colonising

Transfer of immunoglobulins to support baby’s immune system:
IgM: IgM present in breast milk increases responsiveness to the vaccination compared to formula fed babies
IgA: the first line of defence against pathogens that invade humans from mucosa. Coats the gut wall and protects the mucosal surfaces against entry of pathogenic bacteria and enteroviruses. It affords protection against: Escherichiacoli (E. Coli), salmonellae, shigellae, streptococci, staphy lococci, pneumococci, poliovirus and the rotaviruses
IgD: combats disease without causing inflammation
IgG: transfers across the placenta and through breast milk, therefore passive immunity will be maintained while the baby is being breastfed by its mother
IgE: small quantities in breast milk for a longer period than in cows milk; implications unknown

Question 26

What happens immediately after a baby is born?

Answer 26

Baby is handled (received)
Baby is dried thoroughly and stimulated
Baby transitions to extra- uterine life by breathing and crying
Baby is placed on its mother’s abdomen

Question 27

How is a baby assessed at birth?

Answer 27

Apgar scoring, out of 10- performed at 1 and 5 minutes of age (and 10 minutes if low)

Question 28

Describe skin to skin contact

Answer 28

Skin to skin contact involves placing the dried, naked baby prone on the mother’s bare chest, often covered with a warm blanket

All mothers have skin to skin contact with their baby after birth, at least until after the first feed and for as long as they wish

Question 29

Describe the benefits of skin to skin contact

Answer 29

Stimulates release of prolactin and oxytocin
Calms and relaxes baby and mother
Regulates baby’s heart rate and breathing
Regulates baby’s temperature
Stimulates breast-seeking behaviour and interest in feeding
Stimulates endorphin release
Protects baby from infection- colonises their microbiome

Question 30

Describe the physiology of skin to skin contact

Answer 30

Skin to skin contact in the first hour encourages:
Thermal regulation-> avoiding hypothermia
An early first feed and higher blood glucose levels-> counteract physiological drop in blood glucose after birth
The baby to familiarise itself with its mother’s chest, and learn how to locate and self-attach to the breast
Normal transition to extra utero life-> more stable heart rate, respiratory rate and oxygen saturation
Reduction in mean time for placental expulsion

Question 31

Name 3 aspects of the energy triangle for babies

Answer 31

Hypothermia
Hypoglycaemia
Hypoxia

Question 32

What are nine stages of neonatal behaviour during skin to skin contact?

Answer 32

1. Birth cry
2. Relaxation
3. Awakening
4. Activity
5. Rest
6. Crawling
7. Familiarisation
8. Suckling
9. Sleep

Question 33

Describe the value of colostrum

Answer 33

Colostrum is a concentrated version of breastmilk:
Packed with protective factors
Concentrated nutrition
Small volumes-intentionally
Laxative effect- to clear meconium

Question 34

Describe how breastmilk provides protection from infection

Answer 34

Pathogens inhaled
Broncho-mammary pathway
Antibodies produced and sent to breasts
Antibodies incorporated into breastmilk
Milk- producing cells in breast

Pathogens ingested
Entero-mammary pathway
…

Question 35

Describe the placental hormones post-birth for the mum

Answer 35

Immediate drop in levels of placental hormones:
Human placental lactogen (hPL)
Human chorionic gonadotropin (hCG)
Oestrogen (7 days)
Progesterone (24-48 hours)

Question 36

Describe the oxytocin hormone post-birth for the mum

Answer 36

Levels peak during labour and birth
Elicits feelings of love, attachment and contentment
Plays a key role in mother-infant bonding and feelings of protectiveness
Stimulated by touch, feeding and skin to skin contact

Positive feedback loop: mothers are awarded with this feel-good hormone when they ‘mother’ their baby

Question 37

Describe the prolactin hormone post-birth for the mum

Answer 37

It is no longer suppressed by the progesterone being secreted by the placenta, so prolactin receptors are activated
High circulating levels of prolactin can now lock into the receptor sites to stimulate milk production
Ongoing prolactin production is stimulated by the baby suckling at the breast
When the bay suckles, prolactin is released from the anterior pituitary gland

Positive feedback loop: the more the baby feeds, the more prolactin is released, the more milk is made