Block 1 Flashcards
What is the process for Human Digestion?
6 points
o Mechanical homogenization and mixing of solids with fluids secreted by GI tract glands
o Secretion of digestive enzymes- Hydrolyses macromolecules to oligomers, dimers, or monomers
o Secretion of electrolytes, acid, base to provide the appropriate environment- For optimal enzyme digestion
o Secretion of bile to enable lipid absorption
o Hydrolytic digestion of oligomers and dimers on the intestinal surface
o Import of nutrient molecules and electrolytes from the gut lumen into gut epithelial cells
Why must Polymers be broken down into monomeric components?
2 points
To allow absorption.
Transport from the lumen of the gut into the blood.
What bulk of ingested nutrients consist of?
1 point
Polymers
What components ensure efficient digestion of food and how does it help?
(4 points)
o Peptides
o Amino Acids
o Fatty Acids
They stimulate the coordinated release of pancreatic juice & bile into the lumen of the small intestine.
What is the function of Salivary glands in Digestion and Absorption?
(1 point)
Elaboration of fluid and digestive enzymes
What is the function of the Stomach in Digestion and Absorption?
(1 point)
Elaboration of HCL and digestive enzymes
What is the function of the Pancreas in Digestion and Absorption?
(1 point)
Elaboration of NaHCO3 and enzymes for intraluminal digestion
What is the function of the Liver in Digestion and Absorption?
(1 point)
Elaboration of bile acids
What is the function of the Gallbladder in Digestion and Absorption?
(1 point)
Storage and concentration of bile
What is the function of the Small-Intestine in Digestion and Absorption?
(2 points)
Terminal digestion of food. Absorption of nutrients and electrolytes
What is the function of the Large-Intestine in Digestion and Absorption?
(1 point)
Absorption of electrolytes
Where are the Digestive enzymes secreted from?
3 points
o Salivary Glands
o Stomach
o Pancreas
Where are the pancreatic enzymes and bile secreted together?
1 point
Duodenum
The pancreatic duct joins the common bile duct, where both flow into the duodenum
what are the pancreatic enzymes?
3 points
o Amylase
o Protease
o Lipase
After digestion, what do carbohydrates and peptides remain as?
(1 point)
Dimers and Oligomers
Where are the hydrolytic enzymes located?
1 point
The outer surface of epithelial cells lining- forming the ‘brush border’
What is covered on the outer surface of the brush border membrane?
(3 points)
o di- and oligosaccharides
o amino- and dipeptidases
o esterase
Why do Surface enzymes not get digested by Soluble proteases?
(2 points)
o Surface enzymes have heavy glycosylation that prevents access of proteases to relevant peptide bonds
What do carbohydrates break down into during digestion?
1 point
Monosaccharides for absorption
What are the two barriers in the transcellular pathway?
2 points
o Luminal plasma membrane
o Contra luminal plasma membrane
The small intestinal epithelial cells provide examples of the differentiation and specialisation of the two different membranes. In what way do two membranes differ?
(3 points)
o Morphological appearances
o Chemical compositions
o Different enzymes and transporters
What is the main function of the intestinal epithelial cells?
(2 points)
It is the active absorption of…
o Nutrients
o Electrolytes
o Vitamins
Define Chyme.
1 point
The semifluid mass of partially digested food
What is the luminal membrane specialised for?
2 points
o For terminal digestion of nutrients through hydrolytic enzymes on its external surface and o For nutrient absorption through transporter or channels for monosaccharides, amino acids, peptides, fatty acids, cholesterol and electrolytes.
What is the contra-luminal plasma membrane in contact with?
2 points
The intracellular fluid and hence indirectly with capillaries and lymph vessels.
What is the role of nutrient transporters in the contra-luminal membrane?
(2 points)
o They serve to release nutrients into blood or lymph after a meal.
o As well as providing nutrients to enterocytes in between meals.
The nutrients transporter in the contra-luminal membrane are…
(1 point)
…Bidirectional
Describe the morphological appearance of Luminal plasma membranes?
(1 point)
Microvilli arranged as brush border
What enzymes are present in the luminal plasma membrane?
6 points
o Di- and oligosaccharides o Aminopeptidase o Dipeptidases o γ-Glutamyltransferase o Alkaline Phosphates o Guanylate Cyclase C
Describe the morphological appearance of Contra-Luminal plasma membranes?
(1 point)
Few microvilli
What enzymes are present in the contra-luminal plasma membrane?
(2 points)
o Na+/K+ ATPase
o Adenylate cyclase
