Intestino delgado 3: Absorción | Fisiología del sistema gastrointestinal | Khan Academy en Español

How Do Monomers Get Absorbed into the Bloodstream?

The Process of Absorption

• The absorption process begins with monomers, specifically amino acids, which are transported into intestinal cells via primary active transport.

• Primary active transport requires energy from ATP (adenosine triphosphate), which is essential for moving substances against their concentration gradient.

• In intestinal cells, a protein in the cell membrane breaks down ATP to allow amino acids to enter through a specific transporter.

• Once inside the intestinal cell, amino acids can undergo various processes before entering capillaries and subsequently the bloodstream for distribution throughout the body.

Transport Mechanisms for Sugars

• Monosaccharides (simple sugars) utilize secondary active transport instead of primary. This involves using an ion gradient established by previous ATP expenditure.

• Sodium ions flow down their concentration gradient into the intestinal cell, facilitating the entry of monosaccharides through a shared transporter mechanism.

• As sodium enters the cell, monosaccharides exit into capillaries, allowing them to join the bloodstream for further use in bodily functions.

Lipid Absorption Process

• Lipids also follow a unique absorption pathway; they passively diffuse across cell membranes due to their non-polar tails without needing active transport mechanisms.

• Inside intestinal cells, fatty acids reorganize into chylomicrons—large lipoprotein particles that cannot directly enter blood capillaries due to their size.

• Instead of entering blood vessels directly, chylomicrons are absorbed into lymphatic capillaries (lacteals), where they are further digested and eventually released into circulation via veins.

Summary of Macromolecule Digestion