LACTATION

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LACTATION
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Topics to be covered

• What is lactation
• Anatomy of the breast
• Development of the breast
• Histology of the lactating mammary gland
• Hormonal control of Breast growth and lactation
• Composition of milk

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What is lactation?

• Feeding human breast-milk to provide for the
  nutritional needs of infants
• An alternative to human breast milk is by using
  formula feeding which is food products designed
  to provide for the nutritional needs of infants.
  They include powders, concentrates or
  ready-to-use forms

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Milk Formula

• Should contain the right balance of nutrients
  according to the age of the infant or child and
  formulated as close as possible to breast milk
  i.e.,
• nutrient contents automatically changes with
  babies needs
• DHA (Docosahexaenoic Acid), Protein, Sialic acid,
  choline, taurine, other omega 3 and 6, inulin
  dietary fibr, calcium, iron, essential vitamins
  and vital minerals in quantities appropriate for
  infants and children developmental needs.
• Some also contains L Bifidus, a type of friendly
  and beneficial bacteria found in the intestinal
  tract which enables the child to obtain all the
  goodness from food for growth development.
• Available in either regular, honey, mild
  chocolate or fine cereals
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• Some powders which are soya based are formulated
  for lactose intolerance babies. Soya based milk
  is quite expensive.

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Examples of milk formula/powder in Malaysia
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Breast milk is the best!!!!
Milk glands
Areola
Proper latching on
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Anatomy of breast

• External structure
• Breast situated on the anterior chest wall
  between 2nd and 6th ribs, extended to the sternum
  and axilla
• In the centre-erectile structure-nipple
• Has 15-29 opening of lactiferous duct.
• The areola is area of loose skin with 18-20
  sebaceous gland.

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Anatomy

• Internal structure
• Mature breast consist of glandular tissue, ductal
• tissue, fibrous tissue and fatty tissue
• A. Glandular tissue
• Produce milk
• Acinar secretory cell are arranged to alveolus
• Alveolus will form lobules
• Lobules will form lobes
• There are 15-20 lobes, each consist of 20-40
  lobules which include 10-100 alveoli

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• B. Ductal tissue
• Transport milk
• Group of alveoli empty their milk into distal
  lactiferous duct
• Many lactiferous duct units to form major duct.
• Each major duct widen to form an ampulla
  (lactiferous sinus) as it reach the areola
• Each ampulla narrow to form separate opening on
  the nipple

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• C. Fibrous tissue
• Support the breast
• Chest wall superficial fascia condenses to form
  multiple fascial bands ( Cooper ligaments)
• D. Fatty tissue
• comprises of 85 of breast
• Responsible for bulk and shape

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Picture 1 Breast structure
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Formation of mammary glands

• During birth, mammary glands consists of sparse
  alveoli and abundant lactiferous ducts
• After puberty, under the influence of estrogen,
  these ducts will produce branches which ends in
  polyhedral granular cells that are dense, small
  and circular (true alveoli)
• E and P4 will stimulate the growth of
  ductal-lobular-alveolar system and breast
  enlargement with fat deposition and growth of
  connective tissue

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Breast changes during pregnancy

• Breast hypertrophy occur with pregnancy
• Size increase 400g each
• Blood flow double
• Areola enlarged and pigmented
• Montogomery glands becomes prominent.
• Increase fat deposition and retention of fluid
  and electrolyte

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Hormonal control of breast and lactation

• Breast growth during pregnancy is associated with
  increase levels of oestrogen, progesterone, hPL
  and prolactin from maternal pituitary
• Oestrogen promote duct growth
• However alveolar development require full complex
  of hormones
• Oestrogen and progesterone inhibit lactogenic
  effects of hPL and prolactin
• After delivery, rapidly decreasing level of
  steroids?milk secretion occur

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Histology of lactating breast

• Alveolar epithelium consists of short columnar
  cells with microvillous surface
• There is a prominent endoplasmic reticulum and
  golgi apparatus at the base of cells
• Both fat droplet and vesicle(lactoseprotein)
  from GA fuse with the cell membrane and
  discharged into lumen.
• Milk are stored alveoli, duct and cistern
• When lactation ceases? extensive degeneration of
  lactogenic cells, a phagocytic reaction and fatty
  tissue infiltration

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Milk ejection reflex

• Suckling stimulates release of prolactin and
  oxytocin via neurological pathways between nipple
  and the hypothalamus.
• Milk ejection is brought about by the contraction
  of myometrial cells around the alveoli and ducts
  under influence of pituitary oxytocin.

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• This sharp increase in prolactin secretion,
• diminishes progressively over 3 months of BF
• No direct relationship between prolactin level
  and milk yield
• The most important factors are removal of the
  milk?promotes further milk production
• In the absence of suckling, maternal level of
  prolactin reduced slowly to reach non pregnant
  value after 2-3 weeks

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Milk ejection reflex

• MER a neuroendocrine reflex and a conditioned
  reflex
• Apart from touch and pressure on the nipple,
  stimulation from a babys cry for milk, thoughts
  of your baby and lactation times can cause milk
  let-down
• This conditioned reflex is more for release of
  oxytocin and not prolactin
• Stimulation to vagina and cervix can also cause
  milk let-down

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• MER can be inhibited due to pain after labour,
  anxiety and worries whether you are feeding the
  baby enough
• All these will cause inhibition of oxytocin
  release

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Fertility during lactation

• Some women assumes their menstrual cycle right
  after puerperium
• Some women may have no menses for almost a year
  or as long as baby is breast-feeding (Prolactin
  inhibits the hormones for control of regular
  menstruation)
• May be use as a natural contraceptive

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Advantages of breast milk

• Free
• Comes at the right temperature
• Release on demand
• Changes to suit babys needs
• Comes in an attractive package

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Stage of lactation(Summary)
Stages Defination Onset Initiating events Ostrogen, progesterone, prolactin
Mammogenesis Preparing breast for milk secretion Puberty Increasing level of oestrogen and progesterone Oestrogen Progesterone Prolactin, GH, insulin, cortisols
Lactogenesis Initiation of milk secretion in alveoli Post partum Declining O, P, hPL prolactin
Galactopoiesis Maintanace of established milk secretion After each emptying of duct and alveoli Periodic suckling Oxytocin prolactin
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Colostrum

• Is a yellow fluid containing fat laden cells and
  large quantity of protein and minerals.
• Secreted first 24 48 hours of life
• Highest absorption occurs in first 24 hours of
  life
• Contains relatively higher levels of IgG, IgM,
  and IgA including antibodies to bacteria esp
  E.coli
• After 1st week, predominant IG is secretory IgA

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Composition of human milk (produced 2 to 3 days
post delivery)
Component Human
Water 85
Carbohydrate 7 (Lactose)
Protein 1-1.5 (40 casein)
Lipids 3.5 (palmitic, oleic acid)
Enzymes Amylase, catalase, peroxidase, lipase to help in digestion
Mineral Vit A abundant
Immunology IgA protect against enteric bacteria, T and B cell lymphocytes provides active immunity
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• When lactation stops, the involution of the
  mammary glands occur after three months
• Distension and mechanical atrophy occurs to the
  epithelial
• structure, rupture to the alveoli wall and
  formation of cavities in the mammary tissue
• Alveolar distension will cause alveolar hypoxia
• After phagocytosis of dead cells, the
  lobular-acinar structure becomes smaller and the
  ductular system predominates
• The alveolar lumen decreases and dissapears and
  the surface changes to a double non-secretory
  layer
• Milk production can also be terminated by a
  lactation depressant using bromocriptine, an
  agonist receptor Dopamine D2 that inhibits
  prolactin release

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Other Breast milk benefit