Fatty acids from the GI lumen are moved across the epithelium via _________, and they are absorbed into the ________.
a.Diffusion; mucosal capillaries
b.Diffusion; lacteals
c. Mediated transport; hepatic portal capillaries
or
d.Active transport; hepatic portal system
To determine the correct answer, we need to understand the process of fatty acid absorption in the gastrointestinal (GI) tract.
The absorption of fatty acids occurs in the small intestine. Fatty acids are initially emulsified by bile acids, forming small droplets called micelles. These micelles then come into contact with the epithelial cells lining the small intestine.
From the given options, we can eliminate options c and d because mediated transport and active transport are not the primary mechanisms for the absorption of fatty acids in the small intestine.
Now we are left with two options: a and b. To determine the correct answer between the remaining options, let's consider each of them:
a. Diffusion; mucosal capillaries: Diffusion is the passive movement of molecules from an area of higher concentration to an area of lower concentration. Mucosal capillaries are part of the blood vessels located in the epithelial layer of the small intestine.
b. Diffusion; lacteals: Lacteals are lymphatic vessels located in the center of each villus (projections on the small intestine lining). They are responsible for absorbing dietary fats, including fatty acids.
Considering that fatty acids are hydrophobic molecules and can diffuse across the cell membrane, the correct answer is:
b. Diffusion; lacteals: Fatty acids from the GI lumen are moved across the epithelium via diffusion, and they are absorbed into lacteals.
So, in summary, the correct answer is option b, diffusion; lacteals.