Food intake, Digestion & Absorption Flashcards
Resulting products for
Pyralin (salivary amylase)
Forms dextrine + branched oligosaccharides
Substrate, action and resulting products for
Pepsin
Protein (in the presence of HCL acid)
Hydrolysis
Polypeptides + aa
Substrate, action and resulting products for
Gastric lipase
Fat, esp shorter chain
Hydrolysis
Free FAs
Substrate, action and resulting products for
Lipase
Fat (in presence of bile salts)
Hydrolysis
Monoglycerides + FAs (incorporated into micelles)
Substrate, action and resulting products for
Cholesterol esterase
Cholesterol
Hydrolysis
Esters of cholesterol + FAs (incorporated in micelles)
Substrate, action and resulting products for
a-amylase
Starch + dextrins
Hydrolysis
Dextrine + maltose
Substrate, action and resulting products for
Trypsin (activated trypsinogen)
Proteins + polypeptides
Hydrolysis
Interior peptide bonds to form polypeptides
Substrate, action and resulting products for
Chymotrypsin
Proteins + polypeptides
Hydrolysis
Interior peptide bonds to form polypeptides
Substrate, action and resulting products for
Carboxypeptidase
Polypeptides
Hydrolysis
Terminal peptide bonds to form aa
Substrate, action and resulting products for
Elastase
Fibrous protein
Hydrolysis
Peptides + aa
What is the cause of GI movement?
Coordinated activity of:
- Enteric nerves
- Extrinsic nerves
- Endocrine cells
- Smooth muscle
NEUROTRANSMITTERS
GABA
Site of release + primary action
CNS
Relaxes lower oesophageal sphincter
NEUROTRANSMITTERS
Norepinephrine
Site of release + primary action
CNS, spinal cord, sympathetic nerves
⬇️ Motility
⬆️ contraction of sphincters
Inhibits secretions
NEUROTRANSMITTERS
Acetylcholine
Site of release + primary action
CNS + Autonomic system
⬆️ Motility
Relaxes sphincters
Stimulates secretion
NEUROTRANSMITTERS
NEUROTENSIN
Site of release + primary action
GI tract, CNS
Inhibits release of gastric emptying + acid secretion.
NEUROTRANSMITTERS
SEROTONIN (5-HT)
Site of release + primary action
GI tract, spinal cord
Facilitates secretion + peristalsis
NEUROTRANSMITTERS
NITRIC OXIDE
Site of release + primary action
CNS, GI tract
Regulates blood flow
Maintains muscle tone + gastric motor activity
NEUROTRANSMITTERS
SUBSTANCE P
Site of release + primary action
Gut, CNS, skin
⬆️ sensory awareness + peristalsis.
Where is gastrin secreted from?
Endocrine “G” cells in the antral mucosa of the stomach.
What initiates secretion of gastrin?
Distension of antrum after meal
Impulses from vagus nerve
When is gastrin inhibited?
When acidity in lumen ⬆️
What does gastrin do?
Binds to receptors on parietal cells + histamine-releasing cells
- To stimulate gastric acid
To receptors on chief cells
- To release pepsinogen
To receptors on smooth muscle to ⬆️ gastric motility.
Where is secretin released from?
“S” cells in wall of proximal small intestine into bloodstream
Why is secretin released?
In response to gastric acid + digestive end products in duodenum.
What does secretin stimulate the pancreas to do?
Secrete H20 + bicarbonate into duodenum
What does secretin inhibit?
Gastric acid secretion + emptying.
Where is motilin released from?
Endocrine cells in duodenal mucosa
When is motilin released?
During fasting
Why is motilin released?
To stimulate gastric emptying + intestinal motility.
Substrate for
Pyralin (salivary amylase)
Starch
Action for
Pyralin (salivary amylase)
Hydrolysis
