Nutrition Chapter 3: Digestion

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a psychological desire to consume specific food
a psychological sensation that prompts us to eat
a region of the forebrain below the thalamus where visceral sensations, such as hunger and thirst, are regulated
chemical messenger that is secreted into the bloodstream by one of the many glands of the body and acts as a regulator in the physiological processes at a site remote from the gland that secrete it.
group of cells that perform particular set of functions; ex. muscle tissue
two or more tissues performing specific function; ex. esophagus
a group of organs that work together to perform unique function; ex. Gastrointestinal system
Gastrointestinal (GI) tract
a long, muscular tube consisting of several organs: the mought, esophagus, stomach, small intestine, and large intestine; process of digestion, absorption and elimination take place here
a tight ring of muscle separating some of the organs of the GI tract and opening response nerve signals indicating that food is already to pass into the next section
Cephalic phase
earliest phase of digestion in which the brain thinks about and prepares the digestive organs for the consumption of food
a mixture of water, mucus, enzymes and other chemicals that moisten the mouth and food, binds food particles together, and begins the digestion of carbohydrates
salivary glands
a group of glands found under and behind the tongue and beneath the jaw that release saliva continually, as well as in response to thought, sight, smell or presence of food
a mouthful of chewed moistened food that has been swallowed
muscular tube of the GI tract connecting the back of the mouth to the stomach
waves of squeezing and pushing contractions that move food in one direction through the length of the GI tract
a J-shaped organ where food is partially digested, churned, and held until its release in the small intestine
Gastric juice
acid liquid secreted within the stomach; it contains hydrochloric acid, pepsin, water, and other compounds
a term used to describe the action of unfolding proteins. Proteins must be denatured before they can be digested
semi fluid mass consisting of partially digested food, water, and gastric juices
Small intestine
the longest portion of the GI tract, where most digestion and absorption takes place
a tissue sac beneath the liver that concentrates and stored bile and secretes it into the small intestine
fluid produced by the liver and stored in the gallbladder; it emulsifies fats in the small intestine
an accessory organ located behind the stomach; it secretes digestive enzymes that break down proteins, carbohydrates, and fats
a small lymph vessel located inside of the villi of the small intestine
Brush border
term that describes the microvilli of the small intestines lining. these microvilli tremendously increase the small intestines absorptive capacity
the largest accessory organ of the GI tract and one of the most important organs of the body. Its functions include producing bile, processing nutrient-rich blood from the small intestine, and detoxifying harmful substances
Large intestine
the final organ of the GI tract, consisting of the cecum, colom, rectum, and anal canal, and in which most water is absorbed and feces are formed

•Very little digestion takes place •Material is stored 12-24 hours prior to elimination •Water and some nutrients are absorbed
Enteric nervous system
the nerves of the GI tract
the painful sensation that occurs over the sternum when hydrochloric acid backs up from the stomach into the lower esophagus
Gastroesophageal reflux disease (GERD)
a painful type of heartburn that occurs more than twice per week
Peptic ulcer
an area of the GI tract that has been eroded away by the acidic gastric juices of the stomach. the two main causes of peptic ulcers are an H Pylori infection of use of non- steroidal anti-inflammatory drugs
Food allergy
an allergic reaction to food caused by an activation of the immune system
Food intolerance
gastrointestinal discomfort caused by certain foods that is not a result of an immune system reaction
Celiac disease
a genetic disorder characterized by a total intolerance for gluten that causes an immune reaction that damages the lining of the small intestine
Inflammatory bowel disease
a term that includes two different diseases with unknown causes that trigger inflammation and swelling of the intestine: Crohn's disease and ulcerative colitis
Irritable bowel syndrome
a disorder that interferes with normal functions of the colon. Symptoms include abdominal cramps, bloating, and constipation or diarrhea
a condition characterized by the frequent passage of loose, watery stools
a condition characterized by the absence of bowel movements for a time that is significantly longer than normal for the individual. When a bowel movement does occur, stools are usually small, hard, and difficult to pass
Stimulate food intake
neuropeptine Y and galanin
Stimulate satiety
leptin, cholecystokinin (CKK) and serotonin
Food provides us with
•Energy for body processes •Heat for body temperature regulation •Building blocks for growth and maintenance of body tissues
Food goes through three processes
1.Digestion 2.Absorption 3.Eliminationall occur in gastrointestinal tract - the "food processor"
1. Mechanical: physical breakdown2. Chemical: enzymatic breakdown
illeocecal valve
name of sphincter undigested food moves through to get to large intestines
•Synthesize small amts of fatty acids, some B vitamins & vitamin K •By product of bacterial metabolism is gas (200 to 2000mL per day!)
•Undigested matter, dead cells, secretions from the GI tract, water and bacteria
Constipation Myths!
1.Poisonous substances are absorbed from stools & cause ‘autointoxication’ disease 2.Extra long colons cause constipation 3.All cases of constipation are caused by inadequate fiber intake 4.You can treat it by drinking plenty of fluid 5.You can lose weight & stay healthy if you take laxatives regularly 6.If you do not have a bowel movement everyday there is something wrong with you