midterm 2 lactation 1
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What is exterior gestation
What happens to estrogen and progesteron after birth and what does it do?
- - there is a significant decrease in estrogen and progesteron
- - this is essential for the infant to begin sucking at breast
What initiates the secretion of milk?
- hormone cascade
- nerves and hormones are involved
- nipples send signals to the hypothalamus and pituitary glands via the spinal cord
- stimulates milk production (prolactin) and release (oxytocin)
what hormone stimulates milk production
what hormone stimulates the release of milk
what can cause decreased milk flow in the mother?
- psychological issues cause decreased milk flow
- womens support system is crucial
- in cases of poor suckling response in LBW infants leads to insufficient milk production
What is done for neurological impaired LBW infants with poor suckling response?
milk polypropylene tube feeding at the same time as breast feeding
What cells in mammary glands produce milk and what is milk production stimulated by?
- alevolar cells
- stimulated by prolactin (anterior pituitary)
Describe the process that occurs in the posterior pituitary that leads to the release (let-down) of milk
oxytocin release in the posterior pituitary -> contraction of the myoepithelial cells in the mammary glands -> squeeze ducts -> ejection of milk
What are the functions of oxytocin?
- milk let down
- mothering response in mammals
- increased maternal child bonding
- stimulates contraction (involution) of the uterus to help control blood loss
What hormone combination suppress ovulation?
- decreased estrogen and progesteron
- increased prolactin
What are the advantages of breast feeding over formula feeding?
- may aid in proper jaw and tooth development
- bacteriologically safe and always fresh
- contains a variety of anti-infectious agents and immune cells
- breast milk is nutritionally superior
- associated with a decreased risk of food allergy
- cost less than infant formula
What is a disadvantage of bottle feeding in developing countries?
increased risk of infection esp. in developing countries with contaminated water supplies
What are the effects anti-infectious agents and immune cells in breast milk?
- breast feeding significantly decreases rates of respiratory illnesses (protection until 7 years of age)
- partially breast fed babies fared better than non-breast fed
- early introduction of foods (<15 weeks) --> increased likelihood of wheezing during childhood
What numer of constituents are present in breast milk?
- >200 constituents
- more have been discovered with increasing sophistication of analytical techniques
What are the compartments of milk constituents?
- membrane bound globules
- live cells
- protein and non-protein nitrogenous components (NPN)
- trace elements
What are three sources of milk components?
- transferred from maternal plasma
- synthesized from maternal secretory (aveolar) cells from maternal plasma precursors
- synthesized from other mammary cells in situ
What factos can affect milk composition?
- other maternal physiological changes
What are the three phases of milk production and when does each occur?
- Clostrum (5-7 days)
- Transitional milk (7 days to 3-4 weeks)
- Mature milk (4 weeks on)
What are the characteristics of colostrum milk
- intense transparent yellow fluid due to high carotenoid content (10x higher than mature milk)
- only 2-10 mL feeding/day
- compared to mature milk it had an:
- -increased protein and mineral content (Na,K,Cl)
- - decreased energy, fat and lactose content
What are the characteristics of transitional milk?
protein content drops to consistent level with increases in lactose and fat
What are the characteristics in mature milk?
changes according to the changing infant's needs
What are the immunological properties of human breast milk?
- direct action against pathogens
- modulation of immune response
- promotion of growth and maturation of GI tract
- some of the immunological factors are highest in colostrum
What are the anti-infectious agents in human breast milk?
- whey proteins
- antibodies (IgA, IgM, IgE, and IgG)
- Bifidus factor
- antistaphylococcus factor
- B12-binding protein
What conditions destroy immune factors?
- heating and freezing (milk banking)
- not availible in infant formula and cow milk
how do whey proteins protect proteins?
- protect proteins by preserving their disulfide bonds- maintain protein conformation and activity
- resistant against proteolysis/acid via anti-proteases (eg sulfhydryl oxidases)
- anti-proteases protect bioactive proteins, enzymes, and immunoglobulins
What are the immunological functions of antibodies in breast milk?
- directed against specific bacteria, bacterial toxins, viruses, fungi, and food proteins (which may cause allergies)
- important as infant immune system takes several months to mature fully
- IgA, IgM, IgE, IgI produced locally from mammary gland
- IgG absorbed from maternal plasma
- Act against bacterial invasion of the mucosa
- inhibit colonization of the gut via their bacterial and viral neutralizing capacities
Which Ig accounts for 90% of the secretory Igs? And what is its characteristics?
- originates from the B cells from the maternal small intestines or respiratory tract and enter the maternal blood
- lactogenic hormones stimulate B cells to travel to mammary gland
- decreased but significant concentrations in mature milk
- IgA acts on mucosal surfaces of GI tract and is resistant to proteolysis.
What are the characteristics and immunological functions of bifidus factor?
- N containing CHO
- promotes the growth of lactobacilli (bifidobacteria)
- lactobacilli antagonize the survival of enterobacteria (diarrheal diseases in childhood)
- secrete organic acids such as acetic acid- inhibit pathogenic bacterial overgrowth
What are enterobacteria?
- dominant bacteria in of the lower GI of breast fed infants
- diarrheal disease in childhood
- necrotizing enterocolitis- infects and destroys intestinal tissue--> acute inflammation of intestinal mucosa
What is antistaphylococcus factor immunological functions?
N-acetylglucosamine (gangliosides) decreases the risk of diarrheal diseases
What are the immunological functions of lysozymes?
- high concentrations throughout lactation
- beak down susceptible bacteria by breaking down proteoglycans from cell walls
What are the characteristics and immunological functions of lactoferrin?
- produced by milk lymphocytes
- inhibits siderophilic (Fe-absorbing) bacteria
- competes for Fe as it is 80% in Apo form
What are the immunological functions of lactoperoxidases/lipases?
- kills streptococci and enteric bacteria
What are the functions of lipases?
enhance fat breakdown in the gut leads to products of FFA and monoacylglyecrols which have antiviral properties
What are the characteristics and immunological functions of Interferon?
produced by milk lymphocytes and inhibits intracellular viral replication
What are the immunological functions of lactoferrin?
renders vitamin B12 unavailable for bacterial growth
What is the composition of white blood cells?
- neutrophils and macrophages = 90%
- lymphocytes = 10%
What are the characteristics and immunological functions of Macropgahes?
- synthesize compliment, lactorferrin, lysozymes
- carry out phagocytosis activated when secreted -> antigen-processing properties for presentation of T lymphocytes (recognition of foreign material)
What are the immunological functions of lymphocytes?
synthesize secretory IgA and other Igs
What are the immunological functions of fibronectin?
What are the immunological functions of compliment?
promotes opsinization which makes rendering bacteria in other cells more susceptible to phagocytosis
What are the growth factors in human breast milk?
How does cortisol/thyroxine/insulin function as growth factors in human breast milk?
- stimulate synthesis of intestinal enzymes and maturation of gut mucosa
- Insulin-like growth factor increases the rate of gut maturation
How do prostoglandins function as human growth factor?
- stimulate mucus secretion and cell division
- important as the mucosal barrier is immature in newborns
What are examples of polyamines and what are their functions?
- ex- spermine and spermidine
- growth factors increase cell replication
What are the 2 main proteins in milk and what are their characteristics?
- caseins: complexes of casinates found in micelles in combination with Ca,Mg, and Phosphates - calles phosphoproteins
- whey: thin liquid remaining after removal of the acid precipitate of the curd (casein) and removal of cream
why do humans have one of the slowest growth rates?
- growth rates in animal species is related to milk protein content
- humans habe one of the slowest growth rates because of their low protein content in breast milk
What is the role of micelles in milk?
micelles carry much larger quantities of Ca, Mg, P than in a simple aqueous solution
What are the advantages of human milk vs bovine milk in terms of nutrient content>
- human milk: whey casein ratio = 60:40
- cows milk: casein ration = 40:60
- higher proportion of nucleotides
- better balance of essential amino acids
- decreased risk of allergic reactions
Why is a higher whey:casein ratio desirable for infants?
- whey is a softer more easily digestible curd
- better absorbability (in newborns, acidity and pepsin secretions are immature)
- some cow's milk formulas have been manufactured to have higher whey:casein ratio
Which proteins are present in a higher amount in human milk than cow's milk?
- lactoferrin (not in cows milk)
- serium albumin (more in human milk but only by 10 mg/dl)
Which proteins are persent in a lower amount in human milk than cows milk?
- Beta-lactoglobulin (not present in human milk)
What proteins are synthesized in the mammay glands and what are their functions?
- Lactalbumin (part of lactose synthetase)
- loactorferrin Lf (Fe binding protein)
What protein is synthesized in the plasma cells of the mammary gland and then transported to milk?
What proteins are transported from plasma to milk?
hormones (insulin), serum albumin
whey proteins are major suppliers of _________.
the whey protein lactalbumin supplies which minerals?
the whey protein Xanthine oxidase supplies which minerals?
the whey protein glutathione peroxidase supplies which minerals?
the whey protein Lactoferrin supplies which minerals?
What are other proteins in milk other then whey and casein?
- proteases, lipases, and amylases
- play a role in digestion
What are the major whey proteins in human milk?
lactalbumin, IgA, and serum albumin
What are the major whey proteins in cows milk?
IgG, ß-lactoglobulin and BSA
what protein is responsible for the allergic reaction to cow's milk?
What is the potential effects of BSA intake in the 1st 6-9 months
- may cause autoimmune response
- homologic similarity between p69 antigenic site on BSA and on the pancreas
- Antibody BSA is present in most type 1 diabetes but only 2.5% of most non-diabetic population
IgG is closely associated with infant ________.
__________% of nitrogen in human milk is in the form of nonprotein nitrogen (NPN)
What does a higher proportion of NPN in human milk do compared to cows milk?
- provides better digestion
What are examples of NPN
- N-acetyl sugars
What compounds may play a role as growth factors in the human gut to aid in GI maturation?
- nucleotides (eg orotic acid)
Human milk is rich in Taurine. What effect does this have on it?
- membrane stabilizer
- inhibitory neurotransmitter
- bile acid conjugator
- conditionally essential for newborns
Why is taurine added to formula milk?
they will have abnormal retinograms
Why is taurine supplemented to premature infants?
increase maturation response (auditory, visual, etc.)
what does the higher whey content of human milk result in vs higher casein content of cows milk?
better balance of essential amino acids
Human milk has a lower methionine and is rich in cystine, what does this do?
- cysteine can be used without methionine metabolism
- this prevents methionine build up as there is a developmental delay in cystathionase which is necessary for methionine metabolism
- methionine build up is the most toxic AA
- may adversely affect the CNS
Human milk has a lower phenylalanine and tyrosine content why is this beneficial?
- there are enzymatic delays in metabolizing as tyrosine aminotransferase and para-hydroxyphenyl pyruvate oxidase are late to develop
- excess phenylalanine and tyrosine in the blood can be neurotoxic more of a potential problem for premature infants
What precent of infants does cow's milk allergy occur in?
What are the clinical signs of cow's milk allergy?
- GI tract (vomiting, nausea)
- Respiratory (sneezing, wheezing, chronic cough)
- Skin (dermatitis)
- Neurological (headaches)
What reaction occurs with milk allergy?
- Interaction b/w IgE and food proteins is complex
- protein binds to Fc receptor on mast cell/ blasophils leads to a release of cytoknes, interleukins and platelet activating factor
- resulting in inflammatory response via increased histamine release and increased susceptibility to histamine release
What side effects does histamine cause?
bronchial hyperactivity, asthma, dermatitis, vomiting, diarrhea
There is a cross reactivity between milk and ____ proteins
How does breast feeding protect against milk allergy?
- IgA from human breast milk aids in the blockage of whole food proteins from absorption by binding them
- the IgA food protein complex promotes mucus release from goblet cells and proteolysis at the mucosal surface
- blood IgA binds to food proteins and clear them out via the reticuloendothelial system
- infants have leaky junctions in the GI tract --> antigens can pass through
- colostrum hastens closure of leaky junctions
What are the disadvantages of soy milk formula?
- soy protein associated with poorer bioavailability of Zn, Ca, Fe (phytic acid-protein complexes)
- 25% more Ca and 50% more P but lower bone density and lower Ca and P retention with soy formula
What is Heiner's Syndrome?
- Hypersensitivity to cow's milk protein in infants fed unheated cow's milk:
- -GI blood loss and Fe deficiency anemia
- -failure to thrive
What is hypersensitivity?
an immunologically mediated response but not necessarily an allergy
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