Lactation Physiology

Lactation Physiology

• Lactation cycle: The process of milk production in mammary glands, divided into three stages:
  • Mammogenesis: Development of mammary glands during pregnancy
  • Lactogenesis: Initiation of milk production after parturition
  • Galactopoiesis: Maintenance of milk production during lactation
• Hormonal regulation: Hormones involved in lactation:
  • Prolactin: Stimulates milk production
  • Oxytocin: Stimulates milk letdown
  • Progesterone: Inhibits milk production
• Milk secretion: Milk is produced in alveoli and secreted into ducts through the process of apocrine secretion

Milk Composition

• Milk components: Water, carbohydrates, proteins, fats, and minerals
• Carbohydrates: Lactose (milk sugar) is the primary carbohydrate in milk
• Proteins: Casein and whey proteins are the two main types of proteins in milk
• Fats: Triglycerides are the primary form of fat in milk
• Minerals: Calcium, phosphorus, and potassium are essential minerals in milk
• pH and acidity: Milk has a natural pH of around 6.5-6.7, with a buffering capacity to maintain acidity

Cheese Production

• Cheese making process: Milk is converted into cheese through:
  • Coagulation: Acidification or addition of rennet to form curds
  • Curdling: Separation of curds and whey
  • Shaping: Curds are molded into desired shape
  • Aging: Cheese is allowed to ripen and develop flavor
• Types of cheese: Based on moisture content, fat content, and ripening process:
  • Fresh cheese: High moisture, low fat, and short ripening period (e.g., ricotta)
  • Soft cheese: High moisture, medium fat, and short ripening period (e.g., brie)
  • Semi-hard cheese: Medium moisture, medium fat, and medium ripening period (e.g., cheddar)
  • Hard cheese: Low moisture, low fat, and long ripening period (e.g., parmesan)
• Ripening and flavor development: Enzymes, microorganisms, and chemical reactions contribute to the development of flavor and texture in cheese during the aging process

Lactation Physiology

• The lactation cycle consists of three stages: mammogenesis, lactogenesis, and galactopoiesis
• Mammogenesis is the development of mammary glands during pregnancy
• Lactogenesis is the initiation of milk production after parturition
• Galactopoiesis is the maintenance of milk production during lactation
• Prolactin stimulates milk production, while oxytocin stimulates milk letdown
• Progesterone inhibits milk production
• Milk is produced in alveoli and secreted into ducts through apocrine secretion

Milk Composition

• Milk is composed of water, carbohydrates, proteins, fats, and minerals
• Lactose is the primary carbohydrate in milk
• Casein and whey proteins are the two main types of proteins in milk
• Triglycerides are the primary form of fat in milk
• Calcium, phosphorus, and potassium are essential minerals in milk
• Milk has a natural pH of around 6.5-6.7, with a buffering capacity to maintain acidity

Cheese Production

• Cheese making involves coagulation, curdling, shaping, and aging
• Coagulation occurs through acidification or the addition of rennet
• Curds are separated from whey during curdling
• Curds are molded into shape during shaping
• Cheese is allowed to ripen and develop flavor during aging
• Cheese types are classified based on moisture content, fat content, and ripening process
• Fresh cheese has high moisture, low fat, and a short ripening period
• Soft cheese has high moisture, medium fat, and a short ripening period
• Semi-hard cheese has medium moisture, medium fat, and a medium ripening period
• Hard cheese has low moisture, low fat, and a long ripening period
• Enzymes, microorganisms, and chemical reactions contribute to flavor and texture development during the aging process

Lactation Physiology

Lactogenesis

• Initiated by hormonal changes during pregnancy, specifically the increase in progesterone and placental lactogen
• Divided into two stages:
  • Mammogenesis: growth and differentiation of mammary epithelial cells during pregnancy
  • Lactation differentiation: differentiation of mammary epithelial cells into milk-secreting cells

Milk Synthesis

• Occurs in mammary alveoli, clusters of milk-secreting cells
• Involves uptake of nutrients from bloodstream, synthesis of milk components, and secretion of milk into alveoli
• Regulated by hormones: prolactin, insulin, and cortisol

Milk Secretion

• Process of releasing milk from mammary alveoli into ducts
• Regulated by oxytocin, stimulating contraction of myoepithelial cells surrounding alveoli
• Influenced by frequency and efficiency of milk removal

Mammary Gland Function

• Composed of several lobes, each with a duct and cluster of alveoli
• Ducts converge to form lactiferous duct, opening at the nipple
• Innervated by nerves regulating milk secretion and ejection

Hormonal Regulation

• Prolactin: stimulates milk synthesis and secretion
• Oxytocin: stimulates milk ejection and contraction of myoepithelial cells
• Insulin: regulates glucose uptake and metabolism in mammary gland
• Cortisol: regulates metabolism of nutrients in mammary gland
• Progesterone: inhibits milk synthesis and secretion during pregnancy