The female breast and lactation

Question 1

Each mature breast consist:

Answer 1

One areola → provides lubrication during lactation
One nipple → milk production is excreted
Alveoli → milk is produced
Tubules and ducts → milk passes from the alveoli to the nipple

Question 2

External Structure of the breast.

Answer 2

Areola- area of pigmentation.
Montgomery’s tubercles- secrete substance to lubricate the nipple during pregnancy and breastfeeding
Nipple- highly sensitive erectile structure within it are plain muscle fibres that act like a sphincter to avoid leakage

Question 3

Internal Structure of the breast

Answer 3

Lobes- 16-20 and are divided by bands of fibrous tissue. Each lobe contains a lactiferous ducts leading to a lactiferous sinus. It is here that that milk is stored.
Lobules- each lobe is divided into lobules each of which contains a lactiferous duct and alveoli is situated.
Alveoli- are composed of milk-secreting cells → acini. Enclosing each alveoli are myoepithelial cells which have the ability to contract under the influence of hormones → oxytocin. Squeezing milk into the lactiferous ducts.

Question 4

OXYTOCIN

Answer 4

expels milk from muscle cells
Pulsatile action
Inhibited by stress
Feeling of loves and wellbein

Question 5

THE FEEDBACK INHIBITOR OF LACTATION

Answer 5

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

Question 6

PROLACTIN

Answer 6

tells lactocytes to make milk
Produces calmness and reduces stress
Mothering behaviour stimulated
Needs to be stimulated early and frequently to ensure long term production
When baby attaches properly - sensory impulses pass from the nipple to the brain → prolactin secreted → acini cells produce milk

Question 7

What are the two main hormones are involved in lactation?

Answer 7

Prolactin from the anterior lobe of the pituitary gland influences the production of milk
Oxytocin from the posterior lobe controls the ejection of the lobe

Question 8

Steps of what occurs with breastfeeding

Answer 8

Neuroendocrine Response: BABY SUCKLES/CRY/THOUGHT OF BABY ← stimulation → NERVE IMPULSES → PITUITARY GLAND STIMULATED → HORMONES (OXYTOCIN/PROLACTIN) -oxytocin acts on the myoepithelial cells surrounding the alveoli→ BOTH BREAST RECEIVE MESSAGE

Frequent breastfeeding including night feeds will maintain good prolactin levels

Question 9

Physiology of lactation

Answer 9

• Lactogenesis is the initiation of milk production

• There are three phases of lactogenesis – the first two are
• Autocrine: a cell secretes a hormone chemical that acts on itself
Lactogenesis I
• Lactogenesis I occurs around 16 weeks gestation when colostrum production by lactocytes begins
• Prolactin, although present during pregnancy, is inhibited by increased levels of progesterone and oestrogen, as well as HPL and prolactin-inhibiting factor (PIF)
• Therefore milk production is suppressed
Lactogenesis II
• Lactogenesis II is the onset of milk production, and occurs following expulsion of placenta and membranes
• Prolactin levels increase and bind with prolactin receptors in walls of lactocytes, which are no longer deactivated by HPL and PIF
• Skin to skin and early and regular breastfeeding inhibits PIF and stimulates prolactin
Lactogenesis III
• Lactogenesis III: autocrine regulation where supply and demand regulate milk production
• As well as neuroendocrine response, breast milk supply is controlled by milk removal, through autocrine or local control
• Feedback Inhibitor of Lactation (FIL) is increasingly secreted by lactocytes as alveoli distend with milk, inhibiting lactogenesis
Baby suckles
Both breasts receive message

Question 10

Changes through pregnancy?

Answer 10

From the 6th week of pregnancy undergo enlargement and develops in response to the increasing levels of the hormones of pregnancy.

Oestrogen → responsible for the growth of lactiferous ducts and tubules.

Progesterone, prolactin and human placental lactogen (HPL) → result in the proliferation and enlargement of the alveoli

Blood supply to the breast increases → visible veins appearing on surfaces.

12th week: nipples and areola have become more pigmented

Montgomery’s tubercles have become more pronounced and begin secreting lubricants.
16th week: colostrum (highly nutritious and contains many immunoglobulins) has been formed under the influence of HPL and prolactin → high levels of oestrogen and progesterone prevent milk productions.
Because colostrum is formed in early pregnancy, it is available to the neonate after delivery.

Question 11

Labour - Breastfeeding

Answer 11

After the third stage of labour has been completed and the placenta is out oestrogen and progesterone level drops and initiates lactation.

Question 12

Postnatal - Breastfeeding

Answer 12

Colostrum continues to be produced for the first day or two delivery and gradually changed in composition to milk
Encouraged by suckling the neonate from birth.
By the 3rd or 4th day postnatal, the breasts become full and colostrum changes to milk which may make breasts sore.

Question 13

During pregnancy, stimulation of milk production by prolactin is inhibited by

Answer 13

Progesterone

Question 14

The anterior pituitary gland secretes

Answer 14

Prolactin

Question 15

Acini cells in breast tissue are stimulated to secrete milk by

Answer 15

Prolactin

Question 16

Myoepithelial cells in breast tissue are stimulated to contract by

Answer 16

Oxytocin

Question 17

The posterior pituitary gland secretes

Answer 17

Oxytocin