ABSORPTION WAYS IN SMALL

INTESTINEBy Shune Lei ThuCahyuning Isnaini

MSc Food Technology Program School of Agro Industry Mae Fah Luang University

Absorption• Ultimate objective of digestion• After eating, food break down soluble form (nutrients & water)

then absorb in ileum intestinal walls pass through the epithelial cells of

the villi then into the blood capillaries in the villi

fat-soluble substances pass into the lymph from this capillaries and

substances transport to the body by lymphatic system (drains them into the blood near the heart)

Passive Difusion

Digested substances absorbed by simple diffusion include:- the end products of fat digestion – glycerol, monoglycerides and fatty acids;- water-soluble vitamins (B and C); and- water. (The simple diffusion of water across the cell wall is called osmosis.)

Substances that can travel across the cell wall without requiring the cell to use any energy are said to be transported passively. In the digestive system, the main passive transport process is called diffusion. Particles in solution diffuse from an area where they are in high concentration to one where they are in low concentration, until they are evenly distributed.

Facilitated Difusion If a particle is not lipid soluble and is too large to pass through the pores of the cell wall then it needs the help of a carrier protein.1 The particle (a) binds to the protein (b), which straddles the cell wall (c).2 The particle enters the cell through the protein.Digested substances absorbed by facilitated diffusion include fructose (a sugar).

Active TransportActive absorption process faster but requires energyTransport the nutrients from lumen of intestine into cells with the help of ATP molecules that is carrier protein

act as ATPases and hydrolyse provide energy to transport nutrient molecules

across the membraneNutrients like sodium ions, glucose, galactose and amino acids (transported actively)Absorption of sodium ions necessary for the absorption of the other three types of nutrients. This type of absorption fast and almost complete absorption of nutrients from the intestinal lumen into the blood.

EndocytosisThe uptake of material by a cell by the indentation and pinching off its membrane to form a vesicle that carries material into the cell

Most substances either diffuse or are actively transported across cell membranes but some are engulfed and ingested in a process known as endocytosis. A portion of the cell membrane forms a sac around the substance to be absorbed, pulling it into the interior of the cell.Pinocytosis => When cell ingest small molecules and fluidPhagocytosis => used by specialized cell to absorb large particles

Conclusion• There are 3 kinds of absorption in small intestine including Passive

transport (Diffusion and Facilitated Diffusion), Active Transport, and Endocytosis and Exocytosis.

• Passive transport is used only force to simply diffusion and facilitated diffusion that is transport the protein by drivining the force.

• In Passive transport, this way don’t need ATP like Active transport and Endocytosis and Exocytosis.

• Sodium ions is necessary for active absorption because that is help to absorb other nurients.

Reference• http://

samples.jbpub.com/9781284021165/9781449649241_CH03_Insel_4886_1.pdf

• http://www.tutorvista.com/content/biology/biology-iv/animal-nutrition/assimilation.php

• http://www.ivyroses.com/HumanBody/Digestion/Function-of-the-Small-Intestine.php