ANATOMY 201 Lecture Notes - Lecture 9: Intestinal Gland, Pylorus, Circular Folds

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harlequinrhinoceros187

22 May 2018

School

UC-Irvine

Department

Anatomy and Neurobiology

Course

ANATOMY 201

Professor

Richard

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The Lower Digestive Tract: Small and large intestines

Small Intestines:

-From mouth to bottom of stomach is about 50 cm

-750 cm length of small intestine

-Large intestine is only about 4 ft or 5 ft long

-Upper digestion is 2.5 feet long

Organization:

Small intestine divided into three major parts:

A. Duodenum: First region of small intestine that you hit as you leave the

stomach. Once you go through pyloric sphincter you enter small intestine,

specifically the duodenum.

B. Jejunum: After Duodenum

C. Ilium: Closest to stomach vs furthest away from stomach

Ends at the iliosecal valve- A sphincter that divides the small intestine from the

large intestine.

Structures:

Primary function of small intestine is nutrient absorption. That paste (food) enters

small intestine where it is being absorbed as nutrients inside your blood.

-A lot of different little ridges called circular folds. Circular folds that are on lumen

side of small intestine serves a purpose to give small intestine a larger surface

area, therefore more absorption of nutrients.

-Inner layer of small intestine are epithelial cells.

-First you have epithelial layer

-The you have submucosa layer

-Then you run into a layer of circular muscles which will help with contractions

and push food along through digestive system so it does not stay in one place for

too long

-Outside of it you have a serosal layer that creates fluid so your intestines can

move around your gut without rubbing against stuff and damaging itself. It

provides lubrication so intestie does’t ru agaist itself.

-Inner side of luminal wall of small intestine you see small structures that are

microscopic. Finger like projections sticking up from wall. The wall in the inside of

your intestines has all these fingers sticking up that gives it a soft appearance.

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These fingers are called villi, and are there to serve another purpose- to further

increase the surface area of the small intestine.

-These villi are going to be covering everything. The picture here shows a circular

fold underneath the villi. Circular folds are big and visible to naked eye while villi

are very small

-Villi are made up of epithelial cells. The primary function of epithelial cells are for

absorption. These specific cells we are talking about are Enterocytes which are

really good at absorbing nutrients (fats, proteins, sugars, etc.). The enterocyte has

microvilli which are FURTHER WAYS that the body can increase surface area.

-Three major structures that increase surface area

Circular folds

Villi- finger like projections

Microvilli- Absorbs nutrients

In between the villi are called Crypts. A crypt is going to be like a pit like in the

stomach. The intestinal crypts are similar to pits, they function like glands and a

lot of secretion goes on.

You have a lot of endocrine cells in the crypts to better absorb or absorb less

nutrients from your food.

-Besides enterocytes, we also see goblet cells to lubricate the food so stuff

does’t get stuk to strutures, et.

-Below the surface are crypts

-Paneth cells: Kills stuff before they enter in your bloodstream

Lacteal:

Inside each villus you have a lot of blood flow.

There is fat that the body handles differently with fats- it absorbs them but

does’t put it diretly i lood syste

It enters in the lymphatic system. (Yellow tube is a lymphatic vessel known as a

lacteal, which is a lymphatic vessel whose primary function is to absorb fats and

transport fats to lympathic system for further processing before it enters the

blood)

Enters into a lymph node- takes white blood vessels, cleans it, and spits it out.

Fats get absorbed in lacteal, which is a vessel that transports fat to lymphatic

vessel before it gets in blood.

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Histology:

Fingerlike projections: Villi

Grooves in surface going down to tissue are: Crypts

White dots: Goblet cells

On every villi and crypt there are enterocytes that allow for nutrient absorption

Layer of epithelium is known as the mucosal layer

Then you have the submucosa

And then you have smooth muscle layer

And then connective tissue of serous membrane

Celiac Disease

-An allergy to the gluten protein which is found in grains and wheat.

-If you have an allergy to it it can make you sick

-If you eat a lot of gluten and you have celiac disease, gluten will get to small intestines and it

will cause all the cells in your small intestine to get inflamed.

-Everything Is inflamed, a lot of blood flow in there, increased cell death, buildup of scar tissue

over time

-If you are consistently eating wheat and have gluten allergy, you will damage the wall of your

intestines. The finger projections will go away and it will be a mess

-Losing villi over time will decrease the efficiency of nutrient absorption

Large intestine: Short and fat

Three finger widths in diameter

Has a very specific purpose

Major components first-

• Enter large intestine after you are done going into large intestine through ileocecal

valve, which will close off the opening to your large intestine (opening from ilieum, last

part of small intestine, to opening of secum).

• Cecum is large fat part of large intestine and it is a food collecting area. It will fill in and

sit inside the cecum.

• As food enters into the cecum, it just hangs out there for a while

• The cecum is first area you enter, and then after you leave the ceum, you get to the

ascending colon.

• Right angle turn known as the Right colic flexure

• Transverse colon

• Left colic flexure

• Descending colon runs downwards until you run into S shaped curve called sigmoid

colon

• Get to rectum, holding area for poop

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Document Summary

The lower digestive tract: small and large intestines. From mouth to bottom of stomach is about 50 cm. Large intestine is only about 4 ft or 5 ft long. Small intestine divided into three major parts: duodenum: first region of small intestine that you hit as you leave the stomach. Once you go through pyloric sphincter you enter small intestine, specifically the duodenum: jejunum: after duodenum, ilium: closest to stomach vs furthest away from stomach. Ends at the iliosecal valve- a sphincter that divides the small intestine from the large intestine. Primary function of small intestine is nutrient absorption. That paste (food) enters small intestine where it is being absorbed as nutrients inside your blood. A lot of different little ridges called circular folds. Circular folds that are on lumen side of small intestine serves a purpose to give small intestine a larger surface area, therefore more absorption of nutrients. Inner layer of small intestine are epithelial cells.

Related Questions

2. General questions about the digestive tract A. Mechanical digestion of all foods begins in the oral cavity. Describe how food is digested mechanically in the oral cavity. B. What is the scientific name for swallowing? Which portions of the pharynx does food pass through when swallowing? What is the function of the esophagus? C. Cells lining the stomach release hydrochloric acid (HCl). How does HCl assist in food digestion? How are the cells lining the stomach protected from being auto-digested by HCl? D. Carbohydrates, fats, and proteins must be broken down into their smallest subunits (AKA building blocks) in order to be absorbed through the epithelial lining of the small intestine. Name the building blocks of each of the major classes of nutrients: complex carbohydrates (AKA polysaccharides), fats, and proteins. E. About 99% of all nutrients are absorbed in the small intestine. Name the 3 portions of the small intestine. In which of these 3 portions does the greatest amount of nutrient absorption occur (think about the location and length of each segment)? Which type(s) of nutrient(s) is/are absorbed into blood capillaries? Which type(s) of nutrient(s) is/are absorbed into lymphatic capillaries? F. The last portions of the digestive tract are the rectum, anal canal and anus. Name the 2 muscular sphincters located at the anus. When the rectum fills, the defecation reflex is initiated. Describe the events that occur during the defecation reflex. Name the 2 sphincters located at the anus. Which sphincter undergoes involuntary relaxation during the defecation reflex? Which division of the autonomic nervous system causes this sphincter to relax and open? Name the sphincter that you control consciously to stop or initiate defecation.

violetwombat627

The digestion process begins at the mouth. Food enters and then accessory digestive organs like the tongue, teeth, and salivary glands break down the substance. It then travels through the pharynx and esophagus into the stomach, where the stomach acid further breaks down the food (UXL Complete Health Resource). After that, the food travels through the small and large intestines where a majority of its nutrients are absorbed. The waste then exits through the end of the large intestine which is made up of the rectum and anus. After the teeth assist in chewing, food rolls over the tongue and reaches stomach through the esophagus within 8 seconds. General Tsoâs Chicken and Rice consist of carbohydrates, fats and proteins. However, carbohydrates are digested easily than the fats and proteins. After broken down in the stomach, most of the nutrients are absorbed from the small intestine, and it takes 6 to 8 hours to pass through small intestine. The remaining unabsorbed material, âmoves very slowly through the large intestine where the final absorption of water and other nutrients take placeâ (UXL Complete Health Resource). The parasympathetic nervous system encourages the food to move through the digestive tract and motivates digestion process. The sympathetic nervous system works against the parasympathetic nervous system by decreasing the contraction and relaxation of the digestive tract (Taylor). Mouth produces saliva, which contains amylase. Amylase is key in digesting carbohydrates. The stomach produces hydrochloric acid, pepsinogen, intrinsic factor, and mucus (Taylor). Hydrochloric acid kills the bacteria and other organisms that enter the stomach, and then continues to activate pepsinogen. Pepsinogen then changes into pepsin, which digests protein peptides. The pancreas produces trypsin, chymotrypsin, carboxypeptidases, lipases, and phospholipases. Trypsin, chymotrypsin, and carboxypeptidases digest proteins, whereas lipases, phospholipases digest lipid molecules. Small intestine produces lactase, sucrase, maltase, lipases, and peptidases. Lactase, sucrase, and maltase digest carbohydrates (UXL Complete Health Resource). Saliva glands, pancreas, liver, and gallbladder are the accessory organs of the digestive process. Saliva glands produce mucus and amylase which digests starch into simple sugars and binds food particles together, while lubricating the palette when one swallows. The pancreas produces amylase, lipases, and proteinases etc. These digestive juices are responsible for breaking down carbohydrates, proteins, and fats. The liver is the largest gland in the body, âIt produces bile salts to emulsify lipids. It detoxifies metabolic end products to protect the bodyâ (UXL Complete Health Resource). Gallbladder stores bile juice. The chicken in the General Tsoâs contains proteins. Proteins cannot be digested in mouth. However, the mouth can physically digest chicken into smaller pieces. These partially digested chicken pieces travel to stomach, where it is digested by pepsin. The pancreas produces trypsin, chymotrypsin, carboxypeptidases, lipases, and phospholipases (UXL Complete Health Resource). The chicken is then digested by trypsin, chymotrypsin, and carboxypeptidases in the duodenum of the small intestine. After the complete digestion, the chickenâs proteins change into amino acids, which are then absorbed into blood. The rice of the General Tsoâs is a carbohydrate. Carbohydrates are partially digested inside the mouth by amylase. The rest of the rice travels to the stomach where it is digested by pancreatic juices and enzymes that are produced by small intestine. The digestion of the rice produces monosaccharides that absorb into the blood stream. The left over, and undigested parts of the chicken and rice that are useless to the body are excreted by large intestine through rectum.

1) Based on your finding in the Module 3 Report, begin the Module 4 Report by identifying which metabolites are being absorbed and specifically which vessels of the cardiovascular or lymphatic system are the initial vessel of transport from the digestive system. 2) From the point that the specific metabolites are absorbed from the GI tract, trace the path of the resulting metabolites to the following locations in the body for incorporation into the body structure: Metabolites of protein for use in the Gastrocnemius muscle for muscle maintenance. Metabolites of the carbohydrates for energy to contract the cardiac muscle cells. Metabolites of fat to incorporate into the myelin sheaths of the Schwann cells of the Trigeminal nerve that innervates the Masseter muscle. Water for incorporation into the synovial fluid of the hip joint. Iron for incorporation into red blood cells in the bone marrow of the sternum.

maroonguinea-pig686

Food that we consume is composed of very complex molecules. During the digestive process these compounds are broken down into smaller and smaller subunits in preparation for use by the body as building blocks needed for the many components of the human body. The digestion process begins at the mouth. Food enters and then accessory digestive organs like the tongue, teeth, and salivary glands break down the substance. It then travels through the pharynx and esophagus into the stomach, where the stomach acid further breaks down the food (UXL Complete Health Resource). After that, the food travels through the small and large intestines where a majority of its nutrients are absorbed. The waste then exits through the end of the large intestine which is made up of the rectum and anus. After the teeth assist in chewing, food rolls over the tongue and reaches stomach through the esophagus within 8 seconds. General Tsoâs Chicken and Rice consist of carbohydrates, fats and proteins. However, carbohydrates are digested easily than the fats and proteins. After broken down in the stomach, most of the nutrients are absorbed from the small intestine, and it takes 6 to 8 hours to pass through small intestine. The remaining unabsorbed material, âmoves very slowly through the large intestine where the final absorption of water and other nutrients take placeâ (UXL Complete Health Resource). The parasympathetic nervous system encourages the food to move through the digestive tract and motivates digestion process. The sympathetic nervous system works against the parasympathetic nervous system by decreasing the contraction and relaxation of the digestive tract (Taylor). Mouth produces saliva, which contains amylase. Amylase is key in digesting carbohydrates. The stomach produces hydrochloric acid, pepsinogen, intrinsic factor, and mucus (Taylor). Hydrochloric acid kills the bacteria and other organisms that enter the stomach, and then continues to activate pepsinogen. Pepsinogen then changes into pepsin, which digests protein peptides. The pancreas produces trypsin, chymotrypsin, carboxypeptidases, lipases, and phospholipases. Trypsin, chymotrypsin, and carboxypeptidases digest proteins, whereas lipases, phospholipases digest lipid molecules. Small intestine produces lactase, sucrase, maltase, lipases, and peptidases. Lactase, sucrase, and maltase digest carbohydrates (UXL Complete Health Resource). Saliva glands, pancreas, liver, and gallbladder are the accessory organs of the digestive process. Saliva glands produce mucus and amylase which digests starch into simple sugars and binds food particles together, while lubricating the palette when one swallows. The pancreas produces amylase, lipases, and proteinases etc. These digestive juices are responsible for breaking down carbohydrates, proteins, and fats. The liver is the largest gland in the body, âIt produces bile salts to emulsify lipids. It detoxifies metabolic end products to protect the bodyâ (UXL Complete Health Resource). Gallbladder stores bile juice. The chicken in the General Tsoâs contains proteins. Proteins cannot be digested in mouth. However, the mouth can physically digest chicken into smaller pieces. These partially digested chicken pieces travel to stomach, where it is digested by pepsin. The pancreas produces trypsin, chymotrypsin, carboxypeptidases, lipases, and phospholipases (UXL Complete Health Resource). The chicken is then digested by trypsin, chymotrypsin, and carboxypeptidases in the duodenum of the small intestine. After the complete digestion, the chickenâs proteins change into amino acids, which are then absorbed into blood. The rice of the General Tsoâs is a carbohydrate. Carbohydrates are partially digested inside the mouth by amylase. The rest of the rice travels to the stomach where it is digested by pancreatic juices and enzymes that are produced by small intestine. The digestion of the rice produces monosaccharides that absorb into the blood stream. The left over, and undigested parts of the chicken and rice that are useless to the body are excreted by large intestine through rectum. 1) Based on your finding in the Module 3 Report, begin the Module 4 Report by identifying which metabolites are being absorbed and specifically which vessels of the cardiovascular or lymphatic system are the initial vessel of transport from the digestive system. 2) From the point that the specific metabolites are absorbed from the GI tract, trace the path of the resulting metabolites to the following locations in the body for incorporation into the body structure: Metabolites of protein for use in the Gastrocnemius muscle for muscle maintenance. Metabolites of the carbohydrates for energy to contract the cardiac muscle cells. Metabolites of fat to incorporate into the myelin sheaths of the Schwann cells of the Trigeminal nerve that innervates the Masseter muscle. Water for incorporation into the synovial fluid of the hip joint. Iron for incorporation into red blood cells in the bone marrow of the sternum.

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ANATOMY 201 Lecture Notes - Lecture 9: Intestinal Gland, Pylorus, Circular Folds

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