Fluid and Electrolytes in Intestines Flashcards
How does the diffusion of water and ions occur?
Phago/endo-cytosis of larger particles
Digestion and absorption in lysosomes
What is the important of hollow shapes?
Maximises surface area for exchange (Dig and Abs)
What are the 4 GI Processes?
Secretion, Digestion, Motility and Absorption
What 2 things are Epithelial cells involved in?
1) Secretion of water and electrolytes
2) Absorption of water and electrolytes
How is energy supplied for moving against concentration gradients?
Sodium gradients (Sodium pump) and Proton gradients
What are the 2 stages of Sodium coupled nutrient absorption?
1) Membrane transport protein
2) Na+/K+ ATPase transporter
What 5 factors help Intestinal Secretion?
1) Na+/K+ ATPase
2) Na+/K+/2Cl- Cotransporter
3) K+ channel
4) Cl- Channel
5) Physiological control of secretion
What factors influence absorption?
1) Number/structure of enterocytes
2) Blood and lymph flow
3) Nutrient Intake
4) GI Motility
What factors influence secretion?
1) Irritants
2) Bile
3) Bacterial Toxins
How do toxins induce diarrhoea?
Released from bacteria in infected intestine
2) Bind to intestinal cells
3) Stimulate adenylate cycle to produce cAMP
4) Efflux of ions and water
What is the definition of Digestion?
Breakdown of large, complex organic molecules that can be used by the body
How is fat digested?
1) Fat and water separate
2) Bile emulsification with affinity for both fat and water(Fat into water)
3) Fat mixed in water solution, so fat-digesting enzymes have access
What is the fat pathway?
Large fatty molecule broken down by lipase
FA etc converted into micelles and absorbed into intestinal epithelia as TG etc
Released via exocytosis as Chylomicron/VLDL and into Lymph vessel
What is exocrine function of pancreas?
Secretion of pancreatic juice and enzymes
How is pancreatic secretion regulated? (3)
1) Acid in duodenum release secretion, and fats CCK
2) Vagal stimulation cause release of pancreatic enzymes
3) Secretin: Bicarbonate secretions, CCK enzyme secretion