Digestive system of gastropods

The Mucosa

Digestive System Model Demonstrating Sequence and Length of Organs
All living systems are based. Transport of the iron from the enterocyte is achieved by binding to a carrier, a plasma protein called transferrin. The process is slow; it takes three hours from its presentation in food to its appearance in the peripheral blood via the enterohepatic circulation and hepatic veins. It functions to control blood glucose levels releasing insulin to reduce blood glucose levels, and glucagon to increase blood glucose levels , but it also releases many digestive enzymes into the small intestine that help chemically digest food proteins, carbs, etc. First, under the influence of photosynthesis made possible by ultraviolet rays from the Sun, a sterol compound from the liver dehydrocholesterol is converted to vitamin D 3.

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Students who understand how different stages of digestion occur as food travels throught he system, will better learn the sequence through which food passes. An overarching theme in biology is the connection between structure and function. I often stress this with my students. Please see Sarah Hughes' recent blog, " From Tactile Models to Tactile Graphics " for an excellent model that includes both the structure and the length of the organs of the digestive system.

Large due to the larger diameter of the large intestine. Materials 6 large popsicle sticks Permanent marker 26' rope braille label paper braille writer. Procedure Explain to students that the model you will show them represents the length of the parts of the digestive system.

Have students stand up and walk along the length of the rope beginning with the label for mouth. But it is part of the digestive system and sits where the small and large intestines connect.

Sketch the large intestine. Extending from the end of the small intestine, right above the appendix, draw the large intestine.

It should look like two squiggly tubes side by side and should go straight up on the left side of the small intestine, then go across the body below the stomach, and then go straight down towards the bottom of the body on the right.

It should form the top three sides of a squiggly, tubelike- square. The passage of food is slower through the large intestine in order to allow for fermentation by bacteria and other microorganisms, called gut flora. The large intestine processes whatever cannot be used in digestion.

It absorbs whatever it can, especially water, but then the rest will expelled as waste after about 12 hours. To make a more advanced model, distinguish between the different parts of the large intestine. The cecum is attached to the appendix and connects it to the ascending colon. The ascending colon goes straight upwards and connects to the transverse colon, which goes across the body.

The transverse colon connects to the descending colon, which carries food down into the sigmoid colon, which goes directly to the rectum. Draw the rectum and anus. At the end of the large intestine is the rectum. The rectum connects the large intestine to the anus. To draw these, simply draw a wide tube that is the rectum leading to a narrower tube that is the anus. This should go to the bottom of your sheet of paper. Congratulations, you have drawn a digestive model!

The rectum stores feces until expulsion. The anus then expels waste. Now that your model is finished, take a black pen or marker and draw over it to create the final version. This is a nice finishing touch that will make it look more professional and will help it to really stand out. Simply trace over all of the pencil marks that you wish to keep.

Color each organ a different color. This helps your model to stand out and also helps to distinguish between the organs. For some of the organs, simply by looking at the drawing, it can be hard to tell where one ends and another begins, but if you color code them, it will be clear.

For overlapping organs, try using using lighter and darker shades of the same color. The areas where they overlap will be darker, and the areas where it is a single organ will be lighter. Draw a thin line to each organ and write its name at the end of the line, outside of your model. This is great for reference so that you can study your model and learn which organ is which. If you prefer not to write the names of the organs on your model, you could instead make a key at the bottom or on another piece of paper where you draw a little square of each color and write the name of the organ next to it.

If you wish to make your model more advanced, you can differentiate the parts of the small intestine. Simply draw a small line towards the beginning of the small intestine to show where the duodenum turns into the jejunum and then draw a small line towards the end of the small intestine to show where the jejunum becomes the ileum.

If you wish to make your model more advanced, you can also differentiate the parts of the large intestine. Simply draw a small line to divide each part. The ascending colon is the part that goes straight upwards. It connects to the transverse colon which goes across the body and is the largest part of the large intestine. The transverse colon connects to the descending colon, which carries food downward. Finally, there is the sigmoid colon which goes directly to the rectum.

To learn even better, you can write a short description of each organ either with the labels or with your key. This will reinforce their functions and help your model to be very educational.

The main function of the epiglottis is to seal off the windpipe during eating, so that food is not accidentally inhaled. Not Helpful 0 Helpful 5. Inflamed sore or lesion on the skin or a mucous membrane of the body.

Fingerlike projections found in the small intestine that increase the absorption area of the intestine. At the junction of the esophagus and stomach there is a powerful muscle—the esophageal sphincter—that acts as a valve to keep food and stomach acids from flowing back into the esophagus and mouth. Chemical digestion begins in the stomach. The stomach is a large, hollow, pouched-shaped muscular organ.

Food in the stomach is broken down by the action of gastric juice, which contains hydrochloric acid and pepsin an enzyme that digests protein. The stomach begins its production of gastric juice while food is still in the mouth. Nerves from the cheeks and tongue are stimulated and send messages to the brain.

The brain in turn sends messages to nerves in the stomach wall, stimulating the secretion of gastric juice before the arrival of food. The second signal for gastric juice production occurs when food arrives in the stomach and touches the lining. Gastric juice is secreted from the linings of the stomach walls, along with mucus that helps to protect the stomach lining from the action of the acid.

Three layers of powerful stomach muscles churn food into a thick liquid called chyme pronounced KIME. From time to time, chyme is passed through the pyloric sphincter, the opening between the stomach and the small intestine.

The small intestine is a long, narrow tube running from the stomach to the large intestine. The small intestine is greatly coiled and twisted. Its full length is about 20 feet 6 meters. The small intestine is subdivided into three sections: The duodenum is about 10 inches 25 centimeters long and connects with the lower portion of the stomach.

When chyme reaches the duodenum, it is further broken down by intestinal juices and through the action of the pancreas and gall bladder. The pancreas is a large gland located below the stomach that secretes pancreatic juice into the duodenum through the pancreatic duct.

There are three enzymes in pancreatic juice that break down carbohydrates, fats, and proteins. The gall bladder, located next to the liver, stores bile produced by the liver. While bile does not contain enzymes, it contains bile salts that help to dissolve fats.

The gall bladder empties bile into the duodenum when chyme enters that portion of the intestine. The jejunum is about 8. The digested carbohydrates, fats, proteins, and most of the vitamins, minerals, and iron are absorbed in this section.

The inner lining of the small intestine is composed of up to five million tiny, fingerlike projections called villi. The villi increase the rate of absorption of nutrients into the bloodstream by greatly increasing the surface area of the small intestine.

The ileum, the last section of the small intestine, is the longest, measuring 11 feet 3. Certain vitamins and other nutrients are absorbed here. The large intestine is wider and heavier than the small intestine. However, it is much shorter—only about 5 feet 1. It rises up on the right side of the body the ascending colon , crosses over to the other side underneath the stomach the transverse colon , descends on the left side, the descending colon , then forms an s-shape the sigmoid colon before reaching the rectum and anus.

The muscular rectum, about 6 inches 16 centimeters long, expels feces stool through the anus, which has a large muscular sphincter that controls the passage of waste matter.

ADDITIONAL MEDIA