The digestive system is responsible for the ingestion, mechanical breakdown, and digestion of food, as well as the secretion of digestive enzymes, absorption of nutrients, and excretion of waste. The alimentary canal (GI tract) links the mouth, stomach, and intestines as well as the rectum. Chemical digestion begins with the salivary glands in the mouth while mechanical breakdown begins with the motion of the teeth and tongue. Once food is swallowed, the stomach stores and breaks down food both mechanically and chemically with the aid of gastric juices and enzymes such as pepsin. The small intestine continues digestion with additional enzymes and also allows for the absorption of some nutrients. The large intestine regulates the reabsorption of water. Accessory organs include the liver, pancreas, and gallbladder.
The small intestine does a great deal of absorption, has 4 layers of tissue, and has sections called the duodenum, jejunum, and ilium
Intestinal villi and microvilli increase the surface area available for absorption of nutrients
The vermiform appendix is a small vestigial sac in the beginning of the large intestine
The large intestine is made up of the cecum and colon segments (ascending, transverse, descending, sigmoid) and its primary function is to reabsorb water and make solid feces
The rectum and anus are involved with the storage and elimination of fecal matter
The liver has many functions: organic compound metabolism, glycogen storage, waste removal, bile production, vitamin storage, breakdown of toxins, and removal of excess amounts of molecules from the blood
The gall bladder stores bile from the liver and sends it through a duct to the duodenum for emulsification of fats
The pancreas secretes digestive enzymes into the duodenum
Digestive conditions/disorders include ulcers, gallstones, hepatitis, and diarrhea
Did you know…
Q: How much fecal matter could the colon possibly store (if the rectum got backed up)?
A: The world’s largest colon on record is found in the Mütter Museum in Philadelphia, PA. The man who had this colon was born without adequate motor nerve networks in his large intestine, so his brain did not stimulate peristalsis to move along the forming fecal matter. By his early twenties, he was so backed up with fecal matter that he became known as “balloon man”. The preserved colon is close to 27 inches wide at its greatest circumference and stretches out to about 8 feet in length. Suffice it to say, he did not have a typical life span.
Lecture Slides are screen-captured images of important points in the lecture. Students can download and print out these lecture slide images to do practice problems as well as take notes while watching the lecture.
This green projection, this lactile enables your lymphatic system, the immune system to have access to these villi.1941
That is important in the case something traveling through your digestive tract is a potential harm in terms of it containing bacteria or viruses. This lactile is another way that your body can defend yourself from foreign particles or pathogens that entered your digestive tract.1952
When you get to the end of the small intestine and later on we will come back to how bile factors into the small intestine through the breaking down of fats.1971
But when you get to the very end of the small intestine, the ileum, you have reached the appendix.1984
You can see from this Gray’s anatomy diagram here is the ileum and this is the end of the small intestine.1993
Here is the entrance into the colon or the large intestine.1998
Here is what is called the vermiform process or vermiform appendix.2003
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This book includes updated examples, references, and dozens of illustrations. Readers of the new edition will come to understand the meanings of terms in anatomy and physiology, get to know the body's anatomical structures, and gain insight into how the structures and systems function in sickness and health. It also features updated information on how systems function in illness and in health.