591. Which of the following organ has the highest O2 extraction ratio?
A. Heart
B. Brain
C. Kidney
D. Skin
E. Gastrointestinal tract

592. Which of the following organ has the largest relative blood flow?
A. Kidney
B. Brain
C. Heart
D. Skin
E. Carotid bodies

593. Cerebral blood flow is increased with:
A. 1’PaC02
B. 1’Pa02
C. 1’pH
D. All of the above
E. None of the above

594. Which of the following is the most effective at constricting renal efferent arteriole in normal physiologic doses?
A. Adrenaline
B. Angiotensin II
C. Angiotensin III
D. EDRF
E. Prostaglandin

595. Which of the following is FALSE regarding carbohydrate digestion & absorption?
A. Salivary amylase is inhibited by gastric acid
B. Deficiency of one or more brush border oligosaccharidase leads to osmotic diarrhoea
C. All oligosaccharides are broken down by oligosaccharidase before absorption can occur.
D. Glucose enters cells using Na/glucose cotransport (SGLT)
E. Insulin has little effect on gastrointestinal glucose transport systems.

596. Which of the following pairing of carbohydrate & mechanism of absorption is CORRECT?
A. Glucose -2° active transport
B. Fructose – facilitated diffusion
C. Pentose -simple diffusion
D. Hexose -2° active transport
E. All of the above

597. Which of the following is FALSE?
A. Pepsinogen is only activated in acid environment
B. Pepsin is inactivated by bile salts in duodenum.
C. Pepsin acts to hydrolyze the bond between aromatic amino acid & other amino acids.
D. Enteropeptidases act to hydrolyze interior peptide bonds
E. Pancreatic carboxypeptidases act to hydrolyze amino acids at either ends of the peptide.

598. Which ofthe following is TRUE?
A. Amino acid absorption mainly occurs at ileum
B. 50% of digest protein is from ingested food, 25% from digestive juices & 25% from desquamated cells
C. 5% of ingested protein is not absorbed & is excreted in stool
D. None of the above
E. All of the above

599. Which of the following is FALSE?
A. Lingual lipase is inactivated at gastric pH.
B. Pancreatic lipase is I 0-60x more active than bile salt activated lipase
C. Bile salt lipase hydrolyses cholesterol esters, esters of fat-soluble vitamins, phospholipase & TAG.
D. Lingual & pancreatic lipase hydroyse TAG
E. Bile salt is important in aiding formation of micelles.

600. Which of the following is FALSE?
A. Rate of fat absorption depends on the rate of esterification inside enterocytes
B. Free fatty acids has less than 10-12 carbon atoms
C. Chylomicrons are phospholipid & cholesterol coated with protein
D. Long chain fatty acids -maximum absorption is in the ileum
E. All of the above