Structure Of The Small Intestine - Functions Of The Small Intestine - What Are Villi

In this video we discuss the structure and functions of the small intestine. We also cover the villi and microvilli and the different types of cells of the small intestine.

Structure and functions of the small intestine

Your small intestine is an unbelievable organ that has many important roles in everyday bodily functions. When you chew food, then swallow it, it enters your esophagus, which connects with and passes the food to your stomach, which connects with and passes it to your small intestine.

And, your small intestine is located, just below your stomach as it coils and loops filling a large portion of your abdominal cavity. The small intestine has 3 sections, with the duodenum being the first section and it wraps around the pancreas and connects to the pylorus of the stomach. The jejunum is the 2nd middle region of the small intestine and the ileum being the 3rd section. At the end of the ileum is the ileocecal valve, which controls the entry of materials into the large intestine.

The wall of the small intestine is comprised of a mucosa or mucous membrane, a submucosa , a layer of circular muscle, a layer of longitudinal muscle and a serosa. The mucosa and submucosa have internal circular folds as you can see here in this photo of the duodenum.

These folds are more numerous in the duodenum and jejunum and they increase the surface area which slows down the movement of materials from the stomach, and also provides for more nutrient digestion and absorption.

The structure of these folds is absolutely amazing as they have fingerlike projections called villi.

Each individual villus contains a rich capillary network as well as a lacteal which is a lymphatic capillary. The capillaries absorb most of the nutrients and the lacteal absorbs lipids, or fats, and lipid soluble vitamins. There are mainly 2 types of cells that line the surface of a villus.

Absorptive cells called enterocytes, and mucous producing goblet cells. The enterocyte cells have a rapid turnover, as they are shed and excreted in the feces approximately every 3 to 5 days. The enterocytes have tiny hair like projections called microvilli, also described as the brush border. The brush border contains enzymes that complete chemical digestion or breakdown of nutrients before absorption takes place.

These microvilli increase surface area even more, providing for even greater digestion and absorption. Scattered throughout the surface of a villus are also tuft cells, which are believed to secrete endorphins and enzymes that make prostaglandins, which are a type of fat that enhances the immune system.

Deep in the valleys between villi are depressions called crypts or intestinal glands. These crypts contain enteroendocrine cells that secrete hormones, intestinal stem cells, which produce daughter cells that push upwards and become enterocytes. Paneth cells are also located here, and they protect against bacterial growth.

The small intestine has 2 important functions, digestion of nutrients and absorption of nutrients. The tremendous amount of surface area of this organ makes it perfect for this.

I will cover, in depth, the process of digestion and absorption of all of the different types of nutrients in a future video.

Timestamps
0:00 The path of food to the small intestine
0:27 The 3 sections of the small intestine
0:48 The wall and folds of the small intestine
1:17 Villi in the small intestine
1:36 Enterocyte cells and microvilli in the small intestine
2:44 The functions of the small intestine

[sumehrsinghpasricha]

Did anybody notice that in the description all the words were written that he said . What wonderful commitment
Keep it up
Video was of great help

[bhay]

Hii my all friends I am abhay pratap singh from EDUCATION ACADEMY TAHPUR SITAPUR

[bernarde.balangue]

This is exaclty good we can learn about how to beat covid-19 good job dude

[mikkosrussos]

n I have an ileostomy. My large intestine was removed and my small intestine protrudes through my abdomen. I poo uncontrollably into a bag, which i change each day... at which point i get to say hello to my small intestine (stoma)... it resembles a bit of arctic red salmon sushi poking out my stomach. It wriggles around lots, like it has a mind and personality of its own... its a cool fact that your digestive system has more neurones than the brain. Because i lost my large intestine, I struggle to absorb water and salt... although my small intestine has adapted over time to absorb more water than a normal person. How did i get here? I had ulcerative colitis which got so bad i almost died from toxic megacolon. How did it get this bad? Through misdiagnosis and ignoring worsening symptoms until it was too late... i thank every day that I am alive, and have come to embrace life with a stoma... but if you are reading this, i encourage you to find out about crones and colitis and educate others about these all too common illnesses.

[yessaminparedes]

Very comprehensive. A great help! Btw, I'm a nutrition-dietetics student. Thanks a lot.

[dianagonzalez]

OMG, are you going to post more?? I’m taking human anatomy and physiology and have been watching your videos. They REALLY help me out, especially since your videos are straightforward ☺️ would really appreciate it if you did. Thanks 💕

[ayeshawajahat]

Im an 8th grade student, i cannot understand how FOLDING the wall of the small intestine INCREASES its surface area?

[jonathanj]

I like these straightforward videos. Keep it up!

[mattsheezy]

I’m an atheist, but the more I learn about the natural world, the harder it is to believe that these systems are a product of blind refinement, and engineering over millions of years. Why would the universe even burn the calories in the first place if everything is simply dead matter? What was the point of having a planet that was ruled by dinosaurs for millions of years? This life is stranger than the strangest dream that you could ever possibly imagine.

[tiagolince]

In malaysia, for my badge.. we only cover up 1/10 of the contents in this video