Post on 25-Feb-2016
description
MCB 135E: Discussion
Discussion Topics
• Lactation• Gastrointestinal System• Liver
Lactation
• 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
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