Please enable JavaScript.
Coggle requires JavaScript to display documents.
Intestinal Absorption Physiology - Coggle Diagram
Intestinal Absorption Physiology
Carbohydrate Digestion & Absorption
Polysaccharides (Starch / Glycogen)
Luminal Amylase
Oligosaccharides
Brush Border Disaccharidases
Monosaccharides (Glucose, Galactose, Fructose)
Apical & Basolateral Membrane Transporters
Apical membrane (Lumen → Enterocyte)
SGLT1
Na⁺-dependent secondary active cotransport
Absorbs Glucose + Galactose
GLUT5
Facilitated diffusion
Basolateral membrane (Enterocyte → Blood)
GLUT2
Facilitated diffusion
Transports Glucose + Galactose + Fructose into portal blood
Liver
Polypeptides & Amino Acids Absorption
Endopeptidases (Internal Cleavage)
Pepsin (Stomach)
Trypsin, Chymotrypsin, Elastase (Pancreas)
Exopeptidases (Terminal Cleavage)
Carboxypeptidases (Pancreatic; C-terminus)
Aminopeptidases (Brush border; N-terminus)
Transporter Mechanics
PepT1 (Proton-Coupled Cotransporter)
Apical uptake
H⁺-dependent cotransport of dipeptides and tripeptides
Intracellular hydrolysis by cytoplasmic peptidases
Free amino acids
Free Amino Acids
Apical entry
Na⁺-dependent secondary active transport
Basolateral exit via amino acid transporters
Portal capillaries
Lipid Digestion, Micelles & Chylomicron Formation
Dietary Triglycerides + Bile Salts ──► Fine Emulsion
Free Fatty Acids (FFA) + 2-Monoglycerides (MAG) ◄── Pancreatic Lipase / Colipase
Mixed Micelles (Bile Salts + FFA + MAG + Cholesterol) ──► Brush Border Diffusion
Intracellular Re-esterification (Triglycerides) + Apolipoproteins ──► Chylomicrons
Exocytosis into Lacteals (Lymphatics) ──► Thoracic Duct ──► Systemic Circulation
Water, Electrolytes & Minerals
Iron (Fe²⁺)
Stored as Ferritin or exported via Transferrin
Enhanced by Vitamin C
Absorbed in reduced Fe²⁺ state in proximal intestine
Calcium (Ca²⁺)
Ca²⁺ extrusion → Via Ca²⁺/Na⁺ and Ca²⁺/Mg²⁺ exchangers/pumps
Vitamin D-dependent apical entry
Absorbed in Duodenum
Sodium & Water
Basolateral Na⁺/K⁺-ATPase → Maintains the Na⁺ gradient (upregulated by aldosterone in the colon)
Apical: SGLT1, Na⁺-AA, Na⁺/H⁺
Water follows solute gradients (Osmosis via aquaporins/gaps)
Vitamins & Folic Acid Assimilation
Folic Acid
Absorbed in Jejunum via active transport (Essential for DNA)
Vitamin B12 (COBALAMIN)
Absorbed in Terminal Ileum (Deficiency → Pernicious Anemia)
Resistant to pancreatic proteolysis
Binds Intrinsic Factor in stomach
Fat-Solule (A, D, E, K)
Incorporated into mixed micelles & chylomicrons with dietary lipids