Unit 6A Part 5 and 6 - Screencasts Flashcards
Why are fats difficult to digest and absorb?
a) They are water-insoluble
b) They are protein-bound
c) They are acidic
d) They denature enzymes
a) They are water-insoluble
Explanation: Fats do not dissolve in aqueous environments, making enzymatic access and transport more challenging.
What is the role of bile salts in fat digestion?
a) Neutralize acid
b) Increase stomach churning
c) Digest triglycerides
d) Emulsify fat droplets
d) Emulsify fat droplets
Explanation: Bile salts coat large fat droplets and break them into smaller micelles to increase surface area for lipase activity.
Which nutrients are absorbed in a regulated manner by the GI tract?
a) Iron and calcium
b) Water and sodium
c) Carbs and fats
d) Bile salts and proteins
a) Iron and calcium
Explanation: Iron and calcium absorption is hormonally regulated, unlike most other nutrients.
Where are chylomicrons formed and where do they go?
a) Stomach; capillaries
b) Enterocytes; lymph
c) Liver; bile ducts
d) Gallbladder; portal vein
b) Enterocytes; lymph
Explanation: After fats are absorbed, they are reassembled into chylomicrons in intestinal epithelial cells and enter the lymphatic system.
How is dietary DNA processed by the GI system?
a) Digested by nucleases to nucleotides
b) Stored in lymph nodes
c) Incorporated into host genome
d) Triggers immune reaction
c) Digested by nucleases to nucleotides
Explanation: DNA is broken down and absorbed as nucleotides/nucleosides, not incorporated into our genome.
Which enzyme is responsible for most fat digestion in the small intestine?
a) Amylase
b) Pepsin
c) Pancreatic lipase
d) Phospholipase
c) Pancreatic lipase
Explanation: This enzyme hydrolyzes triglycerides into monoglycerides and free fatty acids.
What is required for vitamin B12 absorption?
a) Vitamin D
b) Intrinsic factor
c) Chylomicrons
d) Pepsin
b) Intrinsic factor
Explanation: B12 binds intrinsic factor (from parietal cells) in the stomach and is absorbed in the ileum.
Where are fat-soluble vitamins absorbed?
a) In the colon
b) With lipids in micelles
c) With nucleic acids
d) In the stomach
b) With lipids in micelles
Explanation: Fat-soluble vitamins follow the fat digestion pathway and are packaged into micelles and chylomicrons.
What is a micelle?
a) A hormone
b) A vesicle from the ER
c) A fat-soluble vitamin transporter
d) A small droplet of digested fats + bile salts
d) A small droplet of digested fats + bile salts
Explanation: Micelles are emulsified units that carry lipids to the intestinal brush border for absorption.
What transporter brings iron across the apical membrane of enterocytes?
a) Ferritin
b) SGLT1
c) GLUT2
d) Divalent metal transporter (DMT1)
d) Divalent metal transporter (DMT1)
Explanation: DMT1 is responsible for absorbing divalent ions like Fe²⁺, and can also carry toxic metals.
