The absorb of nutrients occurs partly by diffusion with the wall surface of the small intestine.

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Key Points

digested food is able to pass into the blood ship in the wall of the small intestine with the process of diffusion. The within wall, or mucosa, that the tiny intestine is covered in wrinkles or folds dubbed plicae circulares that job microscopic finger-like piece of tissue called villi, i beg your pardon in turn have finger-like projections recognized as microvilli. The role of the plicae circulares, the villi, and the microvilli is to rise the lot of surface ar area obtainable for the absorption of nutrients. Each villus transports nutrients to a network the capillaries and also fine lymphatic vessels dubbed lacteals close come its surface.

Key Terms

villi: Tiny, finger-like projections the protrude from the epithelial lining the the minister wall. plicae circulares: this circular folds (known as the valves that Kerckring or the valvulae conniventes) room large, valvular flaps the project into the lumen the the bowel. diffusion: The act of diffusing or dispersing something, or the building of being diffused or dispersed; dispersion.


Examples that nutrients soaked up by the little intestine incorporate carbohydrates, lipids, proteins, iron, vitamins, and also water.

The small Intestine

The small intestine is the part of the gastrointestinal tract in between the stomach and the big intestine where much of the digestion of food takes place. The primary role of the little intestine is the absorption of nutrients and minerals discovered in food.


Intestinal villus: picture of a simplified structure of the villus. The thin surface ar layer appear over the capillaries that are associated to a blood vessel. The lacteal is surrounding by the capillaries.

Digested nutrients pass right into the blood ship in the wall surface of the intestine through a process of diffusion. The inside wall, or mucosa, the the small intestine is lined with simple columnar epithelial tissue.

Structurally, the mucosa is covered in wrinkles or folds called plicae circulares—these space permanent attributes in the wall of the organ. They are unique from the rugae, which are non-permanent attributes that allow for distention and also contraction.

From the plicae circulares task microscopic finger-like pieces of tissue dubbed villi (Latin because that shaggy hair). The individual epithelial cells also have finger-like projections known as microvilli. The function of the plicae circulares, the villi, and also the microvilli is to increase the quantity of surface ar area accessible for the absorb of nutrients.

Each villus has a network the capillaries and fine lymphatic vessels referred to as lacteals close to its surface. The epithelial cells of the villi deliver nutrients native the lumen that the intestine right into these capillaries ( amino acids and also carbohydrates) and also lacteals (lipids).

The took in substances room transported via the blood ship to various organs of the body whereby they are offered to build complicated substances, such as the proteins compelled by ours body. The food that continues to be undigested and unabsorbed passes into the huge intestine.

Absorption that the majority of nutrient takes place in the jejunum, with the following notable exceptions:

iron is soaked up in the duodenum. Vitamin B12 and bile salt are soaked up in the terminal ileum. Water and lipids are absorbed by passive diffusion throughout the little intestine. Sodium bicarbonate is took in by energetic transport and glucose and amino acid co-transport. Furustos is took in by helped with diffusion.

See more: How Much Celery Salt Equals One Stalk, 11 Celery Substitutes

Section that duodenum: section of duodenum through villi at the optimal layer.

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