Compendium Review Unit 2 Major Topic 2
I.Digestive System and Nutrition
A. Overview
1.ingestion
2. digestion
3. movement
4. absorption
5. elimination
B. Beginning of Digestive tract
1.mouth
2. pharynx
3. esophagus
C. Stomach and Small Intestine
1. lactose intolerance
2. obesity and diabetes
D. Accessory organs and regulation of secretions
1. pancreas
2. liver
3. bladder
4. regulation of digestive secretions
E. Large intestine
1. disorders
F. Nutrition and weight control
1. obesity
2. classes of nutrients
a. carbohydrates
b. lipids
c. proteins
3. minerals and vitamins
4. eating disorders
There are several small processes necessary in order to complete the larger process of digestion. The first of these processes is called ingestion, which is what happens when food is taken in through the mouth. Digestion is the next phase and can be either mechanical or chemical. The mechanical part of digestion occurs in the mouth and stomach, and chemical digestion begins in the mouth and ends when food reaches the small intestine. Next is movement of the GI tract which passes food from one organ to the next. Fourth is absorption as molecules produced by digestion cross the GI tract wall and enter the cells. Finally, is elimination, in which molecules that cannot be digested are eliminated from the body through the anus.
The GI tract begins at the mouth and ends at the anus. The central space of the GI tract is the lumen which contains water, or the food that is being digested. The first layer of the wall is the mucosa. The other three layers are the submucosa, the muscularis, and the serosa.
The digestive tract begins with the mouth. The roof of the mouth has a hard palate, containing several bones, and a soft palate which ends in a projection called the uvula. There are three pairs of salivary glands which send juices to the mouth. Mechanical digestion is performed by our teeth and our tongue, when we chew food to prepare it for digestion. The tongue houses the taste buds which send nerve impulses to the brain.
The mouth leads to a cavity called the pharynx. This is where the food and air passages cross. When you swallow, food enters the esophagus, which takes food to the stomach. We cannot breathe simultaneously to swallowing. Peristalsis is a rhythmic contraction which pushes food along the esophagus.
Our stomach is an organ shaped like the letter J, that is on the left side of the body beneath the diaphragm. The stomach stores the food and initiates the digestion of protein. It also controls how chime moves into the small intestine. The stomach has gastric juice with an enzyme called pepsin, which digests protein, hydrochloric acid, and mucus. The stomach usually empties in two to six hours. The small intestine averages eighteen feet in length. The first twenty five centimeters of the small intestine is the duodenum. A duct brings bile into the duodenum, and emulsifies fat. Digestion is completed, and nutrients are absorbed in the small intestine.
The primary sugar in milk is called lactose. People without the enzyme cannot digest lactose and are known as being lactose intolerant. The nutrients that are absorbed in the small intestine can affect our health. The intake of too much sugar can lead to obesity which can lead to diabetes type two, and cardiovascular disease.
The pancreas is located behind the stomach. It is an endocrine gland that secretes insulin into the blood. The liver is the largest metabolic gland in the body. It is a storage organ, removing the vitamins A, D, E, K, and B12 from the blood and storing them. The liver produces bile salts. Hepatitis is a serious disease that affects the liver. It occurs when the liver is inflamed. Cirrhosis is when the liver becomes fatty and replaced by scar tissue.
Our large intestine absorbs water, helping to prevent dehydration of the body. The large intestine is where feces are formed. Feces are made up of one quarter solids and three quarters water. Indigestible materials are in the solid part of feces. Defecation is the process of ridding the body of feces. There are several common disorders of the colon and rectum. Among these are diarrhea, constipation, diverticulosis, irritable bowel syndrome, and inflammatory bowel disease.
Obesity is a rapidly growing problem in the United States. It is defined as the condition of being grossly overweight. It is recognized as having a body mass index of 32 or greater. Your BMI gives you an idea as to how much of your weight is due to adipose tissue, or fat.
Nutrients are what provide us with energy, promote growth and development, and regulate cellular metabolism. Carbohydrates are one form of nutrients. They are either simple or complex. Any product that is made of refined grains should be limited in intake. Proteins are digested to amino acids. These are not stored in the body, therefore it is important to eat a daily supply. Lipids are fats, oil, and cholesterol. Minerals are divided into two groups : major minerals and trace minerals. Calcium and sodium are two of the major minerals. Calcium is very important for the formation of bones and teeth. Sodium helps regulate the body’s water balance.
Vitamins are organic compounds used for metabolic purposes. The body need these but cannot produce an adequate amount. Antioxidants, such as vitamins C, E, and A defend the body against free radicals. Vitamin D helps with the skin and with calcium absorption.
It is very important to eat nutritious meals to ensure that your body gets what it needs to properly perform all of its functions. The US Department of Agriculture encourages us to eat a variety of foods. People with eating disorders are usually in this state because they aren’t satisfied with the way their body looks. Anorexia nervosa is a fear of getting fat, causing the person to not eat enough food to keep up a healthy body weight. Bulimia nervosa causes a person to binge eat and then purge to avoid gaining weight.
taking my resting pulse rate (I wasn't lying about my daughter pouring a cup of smarties down my shirt)
