MCB 135E: Discussion

MCB 135E: Discussion. Discussion Topics Lactation Gastrointestinal System Liver

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MCB 135E: Discussion

Discussion Topics

• Lactation

• Gastrointestinal System

• Liver


• Mammary Gland Development

• Milk Production, Ejection, Cessation

• Benefits of Breast Feeding

Mammary Gland Development

• 6th 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


• 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


• 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