Description
The average length of the small intestine in an adult human male is 6.9 m (22 feet 6 inches), and in the adult female 7.1 m (23 feet 4 inches). It can vary greatly, from as short as 4.6 m (15 feet) to as long as 9.8 m (32 feet). It is approximately 2.5–3cm in diameter.
The small intestine is divided into three structural parts: the Duodenum; Jejunum; and Ileum.
Function
The small intestine is where most chemical digestion takes place.The three major classes of nutrients that undergo digestion are proteins, lipids (fats) and carbohydrates. Digested food then able to pass into the blood vessels in the wall of the intestine through the process of diffusion. The small intestine is the site where most of the nutrients from ingested food are absorbed.
Absorption of the majority of nutrients takes place in the jejunum, with the following notable exceptions:
Colour
White.
Shape
Like a very long coiled snake.
Location
From the duodenum to the large intestine within the abdomen.
The average length of the small intestine in an adult human male is 6.9 m (22 feet 6 inches), and in the adult female 7.1 m (23 feet 4 inches). It can vary greatly, from as short as 4.6 m (15 feet) to as long as 9.8 m (32 feet). It is approximately 2.5–3cm in diameter.
The small intestine is divided into three structural parts: the Duodenum; Jejunum; and Ileum.
Function
The small intestine is where most chemical digestion takes place.The three major classes of nutrients that undergo digestion are proteins, lipids (fats) and carbohydrates. Digested food then able to pass into the blood vessels in the wall of the intestine through the process of diffusion. The small intestine is the site where most of the nutrients from ingested food are absorbed.
Absorption of the majority of nutrients takes place in the jejunum, with the following notable exceptions:
- Iron is absorbed in the duodenum.
- Vitamin B12 and bile salts are absorbed in the terminal ileum.
- Water and lipids are absorbed by passive diffusion throughout the small intestine.
- Sodium bicarbonate is absorbed by active transport and glucose and amino acid co-transport.
- Fructose is absorbed by facilitated diffusion.
Colour
White.
Shape
Like a very long coiled snake.
Location
From the duodenum to the large intestine within the abdomen.
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