Lactation Anatomy and Physiology PDF

# How a baby breast feeds - Attachment - Attachment is how a baby takes the breast into their mouth to enable them to feed. # Temporomandibular joint (TMJ) a key feature of mammals - 'Hinge' between mandible (lower jaw) and maxilla (upper jaw) known as temporomandibular joint (TMJ) - The jaw is i...

# How a baby breast feeds - Attachment - Attachment is how a baby takes the breast into their mouth to enable them to feed. # Temporomandibular joint (TMJ) a key feature of mammals - 'Hinge' between mandible (lower jaw) and maxilla (upper jaw) known as temporomandibular joint (TMJ) - The jaw is innervated by cranial nerve V, the trigeminal (motor) - Provides base for movements of tongue, lips and cheeks - Downward movement during sucking expands the size of the sealed oral cavity to create suction # What can the baby do? - Rooting reflex - Turns his head and opens his mouth when something touches his cheek, brings his tongue down and forward. - Sucking reflex - When something touches his palate, he sucks to draw it into his mouth. - Swallowing reflex - When his mouth fills with milk, he raises his jaw to swallow. - These reflexes are usually present at birth. # How the baby removes milk - Cups breast with tongue - Lowers jaw to create a vacuum, drawing in milk - Presses upwards with tongue and jaw to close ducts - Swallows # The suck/swallow pattern of a breastfeed - Beginning of feed - short, rapid sucks - Active feeding - long, slow, rhythmic sucking and swallowing, with pauses - End of feed - 'flutter sucking' with occasional swallows # 'Seeing' what the baby is getting - Active feeding (1:1 or 1:2 swallowing) - 'Flutter sucking' (fewer swallows) # Principles of Positioning: - Positioning is about how the mother holds her baby to enable him to attach effectively to the breast. - Baby's head and body in line (with freedom to tilt head back) - Baby held close to mother - Nose to nipple - Sustainable # Physiology of lactation - Lactogenesis is the initiation of milk production - There are three phrases of lactogenesis - the first two are neuroendocrine responses, while the third is autocrine - Neuroendocrine: interaction between the nervous system and the endocrine system - Autocrine: a cell secretes a hormone chemical that acts on itself # Lactogenesis I (neuro-endocrine) - 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 # Special features of colostrum - Packed with protective factors - Concentrated nutrition - Small volumes - intentionally - Laxative effect - to clear meconium # Lactogenesis II (neuroendocrine) - 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 (acini cells), which are no longer deactivated by HPL and PIF - Why does this occur following end of 3rd stage of labour? - Skin to skin and early and regular breastfeeding inhibits PIF and stimulates prolactin – why? # How it works - Baby suckles - The pituitary gland is stimulated by nerve impulses - Hormones are sent from the pituitary gland to both breasts # Counterregulatory compensation in newborn - After delivery, a self-limiting decline in the infant's blood sugar occurs for about the first 3 hours of life. Counterregulatory compensation then occurs, plus the formation of alternative fuels: - Glycolysis - the conversion of glucose to lactate and pyruvate - Glycogenolysis - the release of glycogen from body stores to form glucose - Gluconeogenesis - the production of glucose by the liver and kidneys from substrates such as fatty acids and amino acids # Ketogenic response in newborn - Ketone bodies are an alternative source of fuel for the brain, derived from a brisk ketogenic response to low blood glucose levels through fatty acid mobilization - At low blood glucose levels, breastfed infants show high concentrations of ketone bodies - a response blunted by formula supplementation - Early feeding of human milk/colostrum enhances the process of gluconeogenesis by: - Providing amino acid precursors and fatty acids that enable the formation of an enzyme critical to ketogenesis - Provide lactose that minimizes insulin secretion # Perils of artificial feeding - Artificial supplements in the immediate period after birth: - Increase insulin secretion, which suppresses glucogenesis - Decrease secretion of glucagon (a hormone that stimulates the conversion of glycogen to glucose and encourages the use of fats and amino acids for energy production) - Delay the natural gluconeogenesis and ketogenic processes # Prolactin - Triggered by suckling - Acts on lactocytes to make milk - Peaks about 90 minutes after a feed - Suppresses ovulation - Needs to be stimulated early and frequently to be effective long-term # Biosynthesis of milk within alveoli - The lactocytes/acini cells extract and synthesize the components of milk from the woman's blood (such as lipids) and the extracellular space - Water, electrolytes and water soluble constituents diffuse across the alveolar membrane via pores - The milk is then secreted into the alveolar lumen # The prolactin response - Sensory impulses pass from the nipple to the brain. - Prolactin secreted by pituitary gland goes via bloodstream to the breasts - Prolactin is secreted more at night - Prolactin suppresses ovulation - Prolactin level peaks after the feed, to produce milk for the next feed. - Acinı (milk-secreting) cells produce milk # Setting up milk production - Delivery of placenta opens prolactin receptor sites on acini cells - 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 production # The prolactin receptor theory - Surges if prolactin prime the receptor sites - Expulsion of placenta opens receptor sites - Unprimed receptor sites shut down, reducing potential for milk production - Frequent prolactin release maximises long-term milk supply # Oxytocin - Triggered by suckling and positive thoughts - Acts on the myo-epithelial cells to eject milk - Largest peaks occur early in feed - Effect may be felt as tingling - Basal levels are higher when baby is near - Can be temporarily inhibited by stress # The oxytocin reflex - Sensory impulses pass from the nipple to the brain - Oxytocin secreted by pituitary gland goes via bloodstream to the breasts - Myo-epithelial (muscle) cells contract and expel milk - 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 # Prolactin and Oxytocin ... - ... work together to: - trigger feelings of love and mothering behaviour - induce calmness and a feeling of well-being - enhance the mother-baby bond # Lactogenesis III (autocrine) - 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. # The Feedback Inhibitor of Lactation - FIL is secreted as part of milk - Build-up of FIL blocks milk production. - Removing FIL allows milk production # The feedback inhibitor of lactation - Acini (milk-secreting) cells - Frequency milk removal ensures ongoing milk production - Feedback inhibitor secreted in milk - Presence of feedback inhibitor blocks further milk production # Reversing the effect of FIL - Removal of FIL, through the emptying of the breast, allows milk production to be stepped up again - It is because this mechanism acts locally (i.e. within the breast), that each breast can function independently of the other. - It is also the reason that milk production slows as the baby is gradually weaned from the breast. - Midwives have a key role to play in communicating this physiological mechanism to new mothers, and helping them understand how to build up, maintain and increase their milk supply. # Breastfeeding and health - Reduces the risk of: - Gastroenteritis - Chest infections (Geer et al 2008) - Ear infections - Urinary infections - Diabetes - Allergies (Kull et al 2002) - Childhood cancers and SIDS (Kwan et al 2004) - Heart disease (Rich-Edwards 2004) # Breastfeeding reduces the risk of: - Breast cancer (Stuebe et al, 2009) - Ovarian cancer (World Cancer Research Fund, 2007) - Hip fracture (Chantry et al, 2004; Paton LM et al, 2003). - Heart Disease (Schwarz et al, 2009) # 'Instant' protection from infection - Pathogens inhaled - Pathogens ingested - Broncho-mammary pathway - Antibodies incorporated into breastmilk - Antibodies produced and sent to breasts - Milk-Producing cells in breast - Entero-mammary pathway