Digestion and Absorption in the GI Tract

functions of the stomach

1. mixes saliva, food and gastric juice to form chyme

2. serves

layers of the stomach

1. mucosa

2. submucosa

3. muscularis

4. serosa

cell types of the mucosa

How long does food stay in the stomach?

2-4 h

Factors stimulating HCl secretion

• acetylcholine (parasymphatetic NS)

• histamine

• 3rd thing

parts of the small intestine

duodenum, jejunum, ileum

parts of the large intestine

pancreas

• haima

• head, body, tail

• connected to the duodenum by 1) pancreatic duct 2) accessory duct

pancreatic juice

• 1200 - 1500 ml / day

• clear, colorless liquid

• water, salts, sodium bicarbonate and digestive enzymes

• enzymes digest st

What enzymes does pancreatic juice contain and what do they digest?

• pancreatic amylase: starch

• pancreatic lipase: triglyceride

• ribonuclease and deoxyribonuclease: RNA, DNA into nucleotides

• pancreatic proteases: protein → peptide

How do pancreatic proteases activate?

functions of the liver

• protein, cholesterol, triglyceride synthesis

• immune system

• detoxification

• storage of micronutrients

• metabolism of CH, lipids, proteins

• storage of glycogen

• production of bile

• excretion of bilirubin

• activation of vitamin D

anatomy of liver

• covered by visceral peritoneum

• right and left lobe are separated by the falciform ligament

• receives all gastrointestinal blood through hepatic portal vein

secretion of bile

functions of bile

• bile salts emulsify lipids for further triglyceride digestion

• neutralisation of stomach acids for pancreatic enzymes

• faciitation of absorption

gallstones

hepatic laminae

plates of hepatocytes one cell thick

stellate cells

fat-storing cells, store vitamin A, in the perisinusoidal space, major role in fibrogenesis

digestion and absorption facilitating structures in the small intestine

circular folds

villi

• contain blood capillaries and lacteals

microvilli

cells in villus

absorptive cell

goblet cell

enteroendocrine cell

paneth cell

intestinal juice

a clear yellow fluid 1-2 l / day

water, mucus, high concentration of

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