Fluid and Electrolytes in Intestines

Question 1

How does the diffusion of water and ions occur?

Answer 1

Phago/endo-cytosis of larger particles

Digestion and absorption in lysosomes

Question 2

What is the important of hollow shapes?

Answer 2

Maximises surface area for exchange (Dig and Abs)

Question 3

What are the 4 GI Processes?

Answer 3

Secretion, Digestion, Motility and Absorption

Question 4

What 2 things are Epithelial cells involved in?

Answer 4

1) Secretion of water and electrolytes

2) Absorption of water and electrolytes

Question 5

How is energy supplied for moving against concentration gradients?

Answer 5

Sodium gradients (Sodium pump) and Proton gradients

Question 6

What are the 2 stages of Sodium coupled nutrient absorption?

Answer 6

1) Membrane transport protein

2) Na+/K+ ATPase transporter

Question 7

What 5 factors help Intestinal Secretion?

Answer 7

1) Na+/K+ ATPase
2) Na+/K+/2Cl- Cotransporter
3) K+ channel
4) Cl- Channel
5) Physiological control of secretion

Question 8

What factors influence absorption?

Answer 8

1) Number/structure of enterocytes
2) Blood and lymph flow
3) Nutrient Intake
4) GI Motility

Question 9

What factors influence secretion?

Answer 9

1) Irritants
2) Bile
3) Bacterial Toxins

Question 10

How do toxins induce diarrhoea?

Answer 10

Released from bacteria in infected intestine

2) Bind to intestinal cells
3) Stimulate adenylate cycle to produce cAMP
4) Efflux of ions and water

Question 11

What is the definition of Digestion?

Answer 11

Breakdown of large, complex organic molecules that can be used by the body

Question 12

How is fat digested?

Answer 12

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

Question 13

What is the fat pathway?

Answer 13

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

Question 14

What is exocrine function of pancreas?

Answer 14

Secretion of pancreatic juice and enzymes

Question 15

How is pancreatic secretion regulated? (3)

Answer 15

1) Acid in duodenum release secretion, and fats CCK
2) Vagal stimulation cause release of pancreatic enzymes
3) Secretin: Bicarbonate secretions, CCK enzyme secretion

Question 16

What are the 3 functions of the liver?

Answer 16

1) Metabolic regulation: Store and release nutrients when needed
2) Haematological Regulation: Plasma protein production and remove old RBC’s
3) Production of Bile: Required for fat digestion and absorption