Lactation Flashcards
Where are the mammary glands found?
Embedded in breasts
Where are the mammary glands found?
Embedded in breasts
What are the mammary glands made up of?
15-24 lobulated masses of tissue, with fibrous and adipose tissue, and blood vessels, in between
What are the lobes of the mammary glands made up of?
Alveoli
Blood vessels
Lactiferous ducts
What is found on the surface of the alveoli of the mammary glands?
Contractile machinery
Where are the lactiferous ducts of the mammary glands found?
Lining the alveoli
What do the sinuses/lacunae of the lactiferous ducts lead to?
The nipple pores
Are mammary tissue and breast tissue the same thing?
No
How does development of the mammary tissue begin?
In utero, with invagination of the epithelium which takes some melanin
Describe the mammary tissue at birth?
Only a few ducts present
What happens to the mammary tissue at puberty?
Ducts sprout and branch, and alveoli begin development
What happens to mammary tissue with each menstrual cycle?
Changes in breast tissue occur with changes in oestrogen and progesterone
What is the result of oestrogen increase in pregnancy on the mammary tissue?
Causes development of ducts and alveoli, and the connection of the myoepithelial cells
What are the physiological stages of lactation?
- Preparation of breasts - mammogenesis
- Synthesis and secretion from the breast alveoli - lactogenesis
- Ejection of milk - galactokinesis
- Maintenance of lactation - galactopoiesis
When does mammogenesis occur?
During pregnancy
What happens in mammogenesis?
Hypertrophy of ductular-lobular-alveolar system
Prominent lobules form
Alveolar cells differentiate
When are the breasts capable of milk production?
From the 2nd trimester
What happens to the milk thats produced by the breasts?
It is secreted into the lumen of alveolar ducts
What happens to the breast towards the end of pregnancy?
Nipple becomes erect
Areola enlarges and becomes darker
Montgomery tubercles form
Breast becomes more sensitive
What is the purpose of the arerola enlarging and becoming darker towards the end of pregnancy?
So baby can see them when feeding
How do montgomery tubercles form?
Fusion of sebaceous glands with mammary lobules
What is the purpose of Montgomery tubercles?
Produce sebum which lubricates the nipples and prevents them from cracking during feeding
Produce pheromones which helps baby determine where the nipple is
Why does the breast become more sensitive towards the end of pregnancy?
Due to production of sensory neurones under the influence of oestrogen
How much milk is secreted during pregnancy?
Little
Why is only a little milk secreted during pregnancy?
Because there is a high progesterone/oestrogen ratio in early gestation which favours growth, not secretion
What does a high progesterone/oestrogen ratio stimulate in the breast?
Proliferation and growth of adipose
What is the importance of the proliferation and growth of breast adipose in pregnancy?
It is the raw material for milk
How does a high progesterone/oestrogen ratio stop milk secretion?
It prevents the production of the prolactin receptor in the alveoli
Where does lactogenesis take place?
In the alveolar cells
Where is the fat for lactogenesis synthesised?
In the SER
How is the protein secreted in lactogenesis?
Via Golgi apparatus
What are the constituents of breast milk?
Fat Protein Sugars Neutrophils Macrophages
How do neutrophils and macrophages get into the breast milk?
Can enter the alveolar space (lumen)
What is the purpose of the neutrophils and macrophages in the breast milk?
Protect against bacterial infection
What is produced soon after birth (0-3 days)?
40ml/day of colostrum
How does colostrum differ from breast milk produced later?
Less water, fat, and sugar
More protein, particularly immunoglobulins (IgA, IgM, IgG)
Contains white cells
How many grams of immunoglobulins are there in colostrum?
19g
What is the purpose of the immunoglobulins in colostrum?
Coat intestinal mucosa preventing bacteria from entering intestinal cells
Why can’t you give a newborn cows milk?
Contains a lot of the protein casein, which the neonate can’t digest, and so gives colic, GI proteins, and watery diarrhoea
What happens to the breast milk over the first two weeks?
Composition gradually changes to mature milk
What is the composition of ‘intermediate milk’?
90% water 7% sugar (lactos) 3% fat Proteins Minerals and vitamins Endocannabinoids
What proteins are found in the intermediate milk?
Lactalbumin
Lactoglobulin
Lacotoferrin
What is the purpose of the endocannabinoids in breast milk?
Binds to cannaboid receptors, causing the baby to feel full, and so stop suckling, and feel sleepy
What stimulates breast tissue growth?
High progesterone and oestrogen in pregnancy
What allows secretion of breast milk?
Fall in steroids
What promotes milk secretion?
Prolactin
What is prolactin?
Polypeptide hormone
What secretes prolactin?
Anterior pituitary gland
What is prolactin secretion controlled by?
Dopamine from hypothalamus (inhibits)
How do factors promoting secretion of prolactin exert their effects?
They reduce dopamine secretion
What factors increase prolactin?
TRH
Oestrogen
How does oestrogen cause the secretion of prolactin?
It causes lactotroph hyperplasia, which means there are more cells producing prolactin
When is TRH produced?
When baby suckling
Other than the anterior pituitary, where else is prolactin produced?
Decidua
What does deciudal prolactin stimulate?
Colostrum
Is decidual prolactin inhibited by dopamine?
No
What is pituitary prolactin secretion promoted by?
Suckling - potent neuroendocrine reflex
What does suckling at one feed do?
Promotes prolactin release, which causes production of the next feed, which accumulates in alveoli and ducts
What is required to maintain milk production?
Sufficient suckling stimulus at each feed
What happens if there is no suckling?
Milk production ceasses gradually, and there is turgor induced damage to secretory cells
How can milk production be maintained by suckling?
Free feeding 1-3 hours apart/day
How do babies get the milk from the breast?
They do not suck milk about of the breast, it is ejected by a ‘let down’ reflex
How does the let down reflex work?
Baby suckling stimulates receptors on nipples, signal to hypothalamus causes oxytocin, which leads to milk ejection
How does oxytocin lead to milk ejection?
Myoepithelial cells surround the alveoli, and are contracted by oxytocin to squeeze milk out of the breast
Where is oxytocin release from?
Posterior pituitary
How does galatopoeisis occur?
Oxytocin release is a neuro-endocrine reflex from suckling/expressing systems
What stimulates the oxytocin neuro-endocrine reflex?
Anticipation of feed
Fondling the baby
