digestion and absorption

• Describe the processes involved in the absorption and transport of digested lipid molecules from the ileum into lymph vessels

  • Micelles contain bile salts and fatty acids + monoglycerides
  • Bring fatty acids + monoglycerides to cell/lining of the ileum
  • Fatty acids/monoglycerides absorbed by diffusion (non-polar)
  • Triglycerides reformed in cells golgi apparatus/ SER and chylomicrons form due to addition of protein
  • Vesicles move to cell membrane and release chylomicron via exocytosis
• • Triglyceride decrease because of action of lipase
  • …hydrolysing triglyceride into fatty acids by digesting/ breaking the ester bonds
  • fatty acids increase because of hydrolysis of triglyceride

  
• Describe the role of micelles in the absorption of fats into the cells lining the ileum.

  • Micelles include bile salts, fatty acids and monoglycerides
  • They make the fatty acids more soluble in water
  • Release fatty acids to ileum epithelium
  • Maintain higher concentration of fatty acids to ileum epithelium
  • Fatty acids absorbed by diffusion
• • No significant difference in protein absorption
  • … error bars overlaps.
  • So mean percentage absorbed not affected by percentage in diet [Amount of protein in diet is not a limiting factor]

  
• • undigested protein broken down
  • So more amino acids absorbed
  • Because protein passes again through stomach again

  
• Cells lining the ileum of mammals absorb the monosaccharide glucose by co-transport with sodium ions. Explain how.

  • Sodium ions actively transported from ileum cell to blood
  • Maintains diffusion gradient for sodium to enter cells from gut with glucose
  • Glucose enters by facilitated diffusion with sodium ions - cotransport
• amylase is an enzyme which is a protein that breaks down starch into maltose and will turn biuret solution from blue to purple
• Describe the mechanism for the absorption of amino acids ileum?

  • Facilitated diffusion of amino acids (into cell when higher concentration in lumen)
  • Na+ is actively transported from the cell into the blood
  • this creates a Na+ concentration gradient
  • this allows the co-transport of amino acid alongside the Na+ allowing amino acids be facilitated diffused into the blood