Lecture Notes: Small Intestine and Digestion Process

Key Functions

• Primary Function: Transfer digested food molecules into the blood for distribution to the body.
• Molecules Absorbed:
  • Glucose (from starch)
  • Amino acids (from proteins)
  • Fatty acids and glycerol (from lipids)
  • Essential materials

Structure of the Small Intestine

• Villi and Microvilli: Increase surface area for maximum absorption
  • Singular: Villus
  • Plural: Villi
• Analogy: Compared to a straight line (less surface area) vs. a line with finger-like projections (more surface area)

Villi Details

• Goblet Cells: Lined with microvilli, further increasing surface area
• Blood Supply:
  • Numerous blood capillaries
  • Transfers most materials to the blood
  • Exit vein into the blood = hepatic portal vein
• Lacteal Structure:
  • Absorbs products of lipid digestion
  • Eventually transfers these to the bloodstream at a different point

Visual Aid

• Simplified diagram of a single villus
• Shows the process of food molecule transfer from the intestine to the blood and lacteal