MCB 135E: Discussion

Discussion Topics Lactation Gastrointestinal System Liver

Lactation Mammary Gland Development Milk Production, Ejection, Cessation Benefits of Breast Feeding

Mammary Gland Development 6 th week of gestation –Formation of mammary ridges Further development under influence of E (pre- natal) Female breasts develop further at puberty –Again primarily under influence of E –Enlargement due to fat deposits and connective tissue –Further growth and branching of ductal system

Mammary Gland: Pregnancy Higher levels of E lead to more ductal elongation Influenced also by GH, PRL, Insulin, and glucocorticoids Final development of gland due to influence of P –Causes branching and formation of alveoli buds at ends of ducts –Alveoli are lined with milk secreting epithelium

Benefits of Breast Feeding Infant –Reduction in infections –Initial increased growth –Decreased obesity in adulthood –Positive effects on mental development Mother –More rapid and sustained weight loss –Lactational amenorrhea Decreased Breast Cancer ? –Psychological benefits

G.I. System GI Functions –Digestion and Absorption –Defense –Endocrine –Mechanical and Chemical Nutrition of the Infant

G.I. System Development Smaller size = Shorter duration of food in GI Developing Stomach –Spitting, Regurgitating, burping are a result of peristalic waves in opposite direction –Emptying time First Month – 1-4 Hours Adult – 5-6 Hours –Size (Volume) much smaller at birth with continual increase in size until adulthood

Nutrition Proteins –Synthesized in alveolar cells –Casein and lactalbumin are predominant proteins –Have antigenic properties Vitamins –No supplements required for infant while breast feeding Minerals –Mother needs to take calcium supplements Fats (Breast Milk) –High in essential FA required for brain and retina development –Secreted in droplets pinched off from cell into alveolus CHO –Lactose –Glucose –Galactose

Liver Functions –Formation of Bile –CHO storage –Formation of Urea –Cholesterol Metabolism –Make plasma proteins –Regulates fat metabolism –Metabolizes some polypeptide hormones –Reduction and conjugation of steroid hormones –Vitamin D3 metabolism –Detoxification

Bile Functions –Emulsification of lipids –Activation of enzymes for digestion of lipids –Conjugation of bilirubin to form a water soluble product for excretion –Excretion of cholesterol –Excretion of drugs, heavy metals, and environmental toxins –Neutralization of acid delivered to duodenum from stomach Constituents –Water (97%) –Bile Salts –Bile Pigments (Bilirubin and Biliverdin) –Cholesterol –Inorganic Salts –Fatty Acids –Lecithin