Special Sub-Topic: You've Eaten.... Now What?
|The enzyme salivary amylase begins breaking down this type of food in the mouth.|
Carbohydrates. Salivary amylase is secreted by the 3 pairs of salivary glands in the mouth. The broken down carbohydrates can then begin to be absorbed in the mouth. That is why cotton candy melts in your mouth.
|What type of muscle movement is required by the esophagus to move a bolus (ball of chewed or liquid food) to the stomach?|
Peristaltic wave. A sweeping waveline motion of smooth muscle moves behind the bolus, pushing it to the gastroesophageal sphincter. Like squeezing toothpaste out of the tube. The peristaltic wave is so strong that you can stand on your head and eat or drink something and it will go up to your stomach. There are esophageal spasms, however they are not associated with swallowing. The tongue swallowing motion moves the bolus out of the mouth into the oropharynx where the esophagus begins moving it to the stomach. Jumping up and down could result in choking if the bolus goes down the wrong pipe.
|When the bolus enters the stomach a number of enzymes are secreted including hydrochloric acid, pepsin and alkaline mucus. What is the function of pepsinogen?|
It begins the digestion of proteins in the stomach. Pepsinogen is activated by the release of hydrochloric acid, not to protect the stomach but to begin protein digestion. The alkaline mucus is secreted to protect the stomach from acid and pepsin. It also helps protect the stomach wall from self-digestion and mechanical injury. Mechanical injury isn't an injury incurred by power tools. The stomach moves violently during digestion. The contents of the stomach can cause injury to the wall lining if it isn't protected.
|After being processed in the stomach the bolus changes chemical composition and its name. What is it called when it moves out of the stomach into the small intestine?|
Chyme. Chyme is a thick, pulverized, liquid mixture of food and gastric juices. Digestion continues and absorption begins in the small intestine. Rugae are folds in the stomach lining that increase the surface area and allows the strong mixing movements of the stomach. The fundus is the top area of the stomach. Enterikinase is an enzyme in the brush border of the small intestine that aides in digestion.
|Where are fats digested and what breaks them down?|
In the small intestine by lipase and bile salts. Fat is not digested until it reaches the small intestine. After being attacked by bile salts and lipase it is absorbed into the lymph vessels. The digested product is to large to cross the blood capillary membrane. Carbs and proteins must be digested further in the brush border of the small intestine before they can be absorbed into the blood. The incorrect answer items are all reabsorbed in the small intestine.
|What is the total volume entering the small intestine per day? Total volume includes foods, drinks, saliva and digestive juices.|
Approximately 9500 ml. Of the 9500 ml of total volume only 1250 ml is ingested foods, 1250 ml is fluid drink, 1500 ml is saliva and 2000 ml is gastric juices. Pancreatic juice, bile and intestinal juice make up the remaining 3500ml.
Only about 500 ml of total volume moves into the large intestine. Approximately 350 ml of that is reabsorbed leaving roughly 150 ml of feces to be excreted. Some perspective; 9500 ml is equal to almost 5-two liter soda bottles, while 150 ml only comes to about 3/4 of a cup. Our bodies don't let much go to waste.
|What type of muscle movement occurs in the colon to move the contents towards the rectum?|
Haustral contractions. Haustral contractions move the contents through the large intestine at about 1 contraction every 30 minutes. Segmentation occurs in the small intestine at a rate around 9-12 movements per minute. Peristaltic wave takes about 5-9 seconds to move from the oropharynx down to the end of the esophagus. Enterogastric reflexes are intrinsic and autonomic nerve plexuses that regulate the rate and amount of chyme that enters the small intestine. The stomach stores the chyme until the duodenum has room to receive and process it.
|What purpose does the appendix serve?|
The appendix is a lymphoid tissue that houses lymphocytes that help defend the digestive tract. The appendix does serve a purpose. If the appendix were removed it would not have any affect on the function of the lymphoid or digestive systems. The large intestine extracts the remaining water and salt from the chyme with an feces as the end result. The appendix is not a storage facility. It is possible for hard feces to get stuck in the 3 1/2 inch long finger shaped appendix which could result in appendicitis. The appendix may need to be removed.
|What are the only two things that the stomach can absorb?|
Alcohol and aspirin. Alcohol and aspirin are quickly absorbed into the blood stream through the stomach. The incorrect answers are all absorbed through the brush border of the small intestine.
|These two things cannot absorb or reabsorb anywhere but the terminal end of the ileum portion of the small intestine. What are they?|
Bile salts and vitamin B-12. There are special carriers that transport bile salts and vitamin B-12 into the blood. They are only located in the ileum. Everything else can be absorbed anywhere along the small intestine. The spaghetti and garlic toast are just a craving.
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