www.neatsolutions.com/Curriculum%20Resources/. Google search for nutrition images
Chapter Eight: Digestive System and Nutrition
Chapter concepts :
8.1 Overview of Digestion
8.2 First Part of the Digestive Tract
8.3 The Stomach and Small Intestine
8.4 Three Accessory Organs and Regulation of Secretions
8.5 The Large Intestine and Defecation
8.6 Nutrition and Weight Control
Chapter concepts :
8.1 Overview of Digestion
8.2 First Part of the Digestive Tract
8.3 The Stomach and Small Intestine
8.4 Three Accessory Organs and Regulation of Secretions
8.5 The Large Intestine and Defecation
8.6 Nutrition and Weight Control
http://science.nationalgeographic.com/science/enlarge/small-intestine-blood-vessels.html
This colored scanning micrograph shows a cast of blood vessels from the external wall of the small intestine. Measuring about 22 feet (6.7 meters) in length, the small intestine performs most of the major digestion and absorption of nutrients. The walls of the small intestine are lined with millions of projections called villi, which absorb and transmit nutrients into the bloodstream. Photograph by Susumu Nishinaga
8.1 Overview of Digestion
The digestive system is located in the gastrointestinal tract, called the GI tract.
The purpose of digestion is to hydrolyze the macromolecules, which are carbohydrates, fats, and proteins. Digestion of these macromolecules into “unit molecules” must occur because the macromolecules are too large to pass over the plasma membranes.
Unit Molecules:
Sugars
Amino Acids
Fatty Acids
Glycerols
Accessory Organs include: Salivary Glands- Liver- Gall Bladder- Pancreas
Digestive Tract Organs include: Mouth- Pharynx- Esophagus- Stomach- Small Intestine- Large Intestine- Rectum- Anus
Ingestion- is our mouth taking in food.
Digestion- can be mechanical or chemical
Mechanical- food is divided into pieces and can be acted upon by the digestive enzymes-occurs mainly in the mouth and the stomach
Chemical- begins in the mouth and ends in the small intestines-thick semi fluid mass is called chyme as it reaches the small intestines-excludes the large intestine as there are no digestive enzymes present -
Movement- within the GI tract is vital for the tract to fulfill the other bodily duties/functions within the body -
Absorption- unit molecules produced digestion enter cells lining the tract as they cross the GI tract wall- nutrients then enter blood stream to go to cells next -
Elimination- Molecules that can not be digested- waste that passes through the anus-
Wall of the Digestive Tract
The actual GI tract begins at the mouth and ends at the anus.
The central space that contains digestion is the Lumen.
The wall of the GI tract has four layers.
Layer one- next to the lumen- Mucosa-commonly called mucous membrane- produces mucous, which protects the wall from enzymes-Diverticulosis is a condition where portion of mucous membrane has pushed through the layers to make pouches where food can then collect.
Layer two-Submucosa- broad band and loose connective tissue-contains blood vessels, lymphatic vessels, and nerves- carries nutrients- a disorder that can begin in layer two is IBD (Inflammatory Bowel Disease).
Layer three- Muscularis- contains two layers of smooth muscle-contractions occur to help movement of digested food-This layer can be the area where IBS (Irritated Bowel Syndrome) begins- stress may be underlying cause of IBS.
Layer four- Serosa- secretes a serous fluid- are is connected to internal lining of abdominal cavity-appendix inflammation (called Peritonitis) can be life threatening condition in which the appendix must be removed.
8.2 First Part of the Digestive Tract
The mouth, pharynx, and esophagus are parts of the first part of GI tract.
The Mouth
Mechanical and chemical digestion begins in the mouth.
Parts of the interior of the mouth are hard palate and the soft palate.
There are three pairs of salivary glands.
Teeth play an important role in the mechanical breakdown of food to be digested.
When food is swallowed the tongue works in conjunction with the soft palate by closing off the nasal passages.
The epiglottis closes off larynx so bolus of food enters esophagus.
Swallowing can be voluntary but it is also a reflex when food/drink pushes against the pharynx. Rhythmic contraction pushes food along esophagus and all other organs of digestive tract, called Peistalsis.
Sphincters are muscles that encircle tubes and act as valves.
Heartburn is the result of acid reflux. This happens when some of the food escapes into the esophagus. Vomiting occurs when there is contraction of the thoratic and abdominal cavities.
http://science.nationalgeographic.com/science/enlarge/digestive-system.html
Once food is swallowed, it passes through the esophagus into the stomach, the pink organ shown here above the yellow pancreas. A large, muscular chamber, the stomach produces digestive juices like pepsin, lipase, and hydrochloric acid, which digest and dissolve stomach contents.
Illustration by PureStock
8.3 The Stomach and Small Intestine
The stomach and small intestine finish the digestion responsibility in the body.
Stomach is thick walled and lies beneath the diaphram.
The stomach is continuous from esophagus to small intestine.
Stomach stores food, initiates the digestion of protein, controls movement in the small intestine.
Stomach has four layers.
http://highered.mcgraw-hill.com/sites/dl/free/0072986867/391204/chapt08_lecture.ppt#257,1,Chapter 8 from the powerpoint presentation for chapter 8
Stomach muscles have three muscle layers and mucosa has folds called rugae.
Gastric glands put out mucus, HCL, pepsin, which is an enzyme that digests protein.
Peristalsis controls secretion of chyme into small intestines at pyloric sphincter.
Small intestine is approx. 18 feet long and the large intestine is only about 4 ½ feet long.
Small intestine contains enzymes to digest all foods, especially carbohydrates, proteins, and fats.
Enzymes are secreted by the pancreas.
Small intestinal wall absorbs the molecules of sugar, amino acids, fatty acids, and glycerol.
The mucosa is modified for absorption.
Lactose Intolerance
The brush border enzyme, Lactase, is used to digest lactose. People who do not have this enzyme are “lactose intolerant”.
Characteristics of ‘lactose intolerance” are:
Diarrhea
Gas
Bloating
Abdominal cramps
The indigestible lactose causes fluid retention.
Digestion/Absorption of Nutrients:
Carbohydrates are ingested-pancreatic amylase-maltase-glucose-to blood capillary/ph balance =basic
Proteins are ingested-trypsin-peptides-peptidase-flows w/amino acids-to blood capillary/ph balance=basic
Fats are ingested-bile salts+fat globules form into emulsification-lipase-monoglycerides and free fatty acids-chylomicron-lymphatic capillary/ph balance =basic
Figure 8.7 page 151
Starch is digested to glucose
Proteins are digested to amino acids
Fats are emulsified by bile/digested to monoglycerides
Obesity: Diabetes Type 2 and Cardiovascular Disease
Absorption of nutrients in the small intestine impact our health greatly.Too much sugar leads to obesity and can also lead to Type 2 Diabetes.
Health Improvement can occur with a healthy nutritional diet, exercise, and losing weight. The hormone insulin operates within our bodies much more efficiently when we choose a healthy life style.
Cardiovascular Disease is more probable with high fatty acid levels of Type 2 Diabetes.By choosing a healthy eating and behaviors, the chance of blindness, kidney disease, and cardiovascular disease decrease.
8.4 Three Accessory Organs and Regulation of Secretions
Three Accessory Organs
Pancreas- pancreatic cells produce pancreatic juice. Pancreatic Amylase digests starch, Trypsin digests protein, and lipase digests fats.
The pancreas is an endocrine gland. It secretes the hormone insulin.
“Hormones” are substances created by one set of cells and used by another set of cells within the body.
Liver- the largest metabolic and major gland in the body-The liver contains 100,000 lobules. The liver receives blood via hepatic portal vein from capillary bed of GI tract. Liver filters blood in capillaries of lobules. The liver is a storage organ. The liver removes these things from blood: iron, vit. A,D,E,K, and B12. The liver makes plasma proteins and regulates quantity of cholesterol in blood. Bile salts are produced using cholesterol.
Bile is stored in the gall bladder. Gall stones result when the liquid hardens in the gall bladder. The liver can convert glycerol from fats and also amino acids to glucose molecules.
Liver disorders: Hepatitis and cirrhosis are two extremely serious liver disorders that affect the entire liver and also prevent repair from damage/disease. Both of these ailments can and are life threatening.
Regulation of Digestive Secretions
The nervous system is in control of the digestive juice secretion along with digestive hormones. The parasympathetic nervous system responds immediately to the sight or the smell of food by stimulating gastric juice production. Gastrin hormone is produced in the stomach when a person eats a high proteined meal. Gastrin enters the blood stream and activates the gastric glands. Cells within the duodenal wall produce CCK and HCI and assist with food digestion by entering blood stream and activating the pancreas to produce more pancreatic juice.
8.5 The Large Intestine and Defecation
http://highered.mcgraw-hill.com/sites/dl/free/0072986867/391204/chapt08_lecture.ppt#257,1,Chapter 8 from powerpoint presentation for chapter 8
The large intestine includes cecum, colon, rectum, and anal canal. The cecum is the blind end of the large intestine. The cecum is thought to help fight off infections in humans. The colon includes ascending colon-works its way to the rectum-rectum opens at anus where defecation takes place.
Functions of the Large IntestineThe large intestine absorbs water which prevents dehydration in our bodies. Large intestine absorbs vitamins produced by bacteria. The large intestine forms feces. Feces are ¾ water and ¼ solids. Defecation is also a function of the Large intestine.
Disorders of the Colon and Rectum
There are many disorders that can occur in the Large intestine and many of these are avoidable with good life choices such as good diet and good bowel habits.
Diarrhea/mainly caused by infections in the lower intestinal tract.
Constipation/feces are dry and hard/chronic constipation is often associated with hem raids
Diverticulosis/ occurrence of small pouches of mucosa that push through weak spots of muscular tissue.
IBS/muscular is contracts powerfully but without the normal coordination.
IBD (Colitis) inflammatory disorder-
Polyps/ Cancer- small growths arising from epithelial lining.
8.6 Nutrition and Weight Control
Obesity has doubled in our country in the past 20 years.
Almost 1/3 of adults are considered obese.
Obesity is now much more common in children and teens.
Obesity is rising world-wide.
Experts believe the correct way to address obesity is to eat balanced kinds of food and to get enough exercise.
How Obesity is Defined
Below is my BMI estimated value from:http://www.findmybmi.org
We have calculated your Body Mass Index based on your weight of 165 pounds and your height of 5 feet and 9 inches. In the report below you will see personalized information on where your BMI stands compared to others, as well as an explanation of what your BMI number means. In addition we will show you common health problems that women of age 47 and older experience with similar BMI levels to yours.
You have a BMI of 24.36. This BMI puts you under the body classification of "Average" according to the CDC (US Center for Disease Control & Prevention).Your risk for the following health conditions is: Very Low
Hypertension
Dyslipidemia
Type 2 diabetes
Coronary heart disease
Stroke
Gallbladder disease
Osteoarthritis
Sleep apnea
Endometrial, breast, and colon cancer
Obesity is defined as Body Mass Index (BMI) of 32 or higher-
Healthy BMI is 19.1-26.4
Overweight BMI is 26.5- 31.1
Obese BMI is 32.3- 39.9
Morbidly obese BMI is 40 or more
The BMI number is how much of your weight is due to adipose tissue, which means fat. The taller a person is the more weight a person can generally carry on their frame without it being considered body fat. The BMI number should only be used as a general guide.
The BMI does not consider a persons fitness, bone structure, or gender.
Health Focus page 157
The most sensible/healthy way to lose weight is simple: eat a variety of foods, watch your weight and caloric intake, and exercise.
http://www.self.com/fitness Google picture from Self Magazine on exercise
Trendy Diets:
The Pritikin Diet follows high amounts of carbohydrates and fiber in whole grains and vegetables consumption. Diet is very low fat.The Atkin’s Diet follows a very low carbohydrate intake. Philosophy is by consuming high amounts of protein and fats our bodies will burn stored body fat. Scientifically believed to threaten homeostasis with a strain on maintaining glucose levels and stressing the kidneys with excretion of protein breakdown.
The Zone Diet follows “healthy” fats and sugar carbs-bringing back these two extreme diets to a middle balance.
Prescription drugs have been manufactured to fight obesity and help with weight loss. Dangers and side effects are common with many prescriptions .Heart problems, and elevated blood pressure are two health concerns associated with diet drugs.
Surgical procedures are becoming more common in todays society for the morbidly obese. Gastroplasty, gastric by pass, and gastric banding are three types of procedures that are routinely recommended today.
These types of procedures produce results however there can be lifetime post surgery problems as well. Chronic diarrhea, vomiting, intolerance to dairy, dehydration, and nutritional deficiencies are common.
Liposuction is also becoming more common for over weight people to choose to remove fat cells from localized areas. Liposuction is not a long term solution.
People who are looking for quick fixes may be on an unending merry go round but may get positive long term results with the old fashioned-Eat right, Watch food intake, Exercise!
Classes of Nutrients
Carbohydrates are simple or complex- Glucose is a simple carbohydrate the body prefers as an energy source- brain cells require glucose- the body is unable to convert fatty acids to glucose-refined grains should be minimized in the diet-during refinement fiber and vitamins are also removed so basically the starch is all that remains. Complex carbohydrates beans, peas, nuts, and fruits are good source of vitamins, minerals, and fiber-
Proteins are digested to amino acids which cells use to synthesize hundreds of cellular proteins- there are 20 amino acids/8 of these are considered essential amino acids- children can not grow without the essential amino acids-eggs, milk products, meat, poultry, and food derived from animals all contain the essential amino acids needed- amino acids do not store in our bodies-a daily supply is needed-
Lipids include fats, oils and cholesterol- too many lipids can be harmful to health- cardiovascular disease is caused by plaque build up in the arteries-
Minerals are divided into major and trace.
Major minerals are constituents of cells and body fluids and structural parts of tissues-
Trace minerals are parts of larger molecules-
Calcium is a major mineral-
Vitamin D is a partner to calcium-
Sodium helps regulate the water in the body-
Vitamins are organic compounds used for metabolic purposes- Many vitamins are enzyme helpers (co-enzymes)- Vitamins C, E, and A are believed to defend the body against free radicals- Vitamin D is a molecule that is converted in the skin by sun exposure-
How to Plan Nutritious Meals
A person cannot normally become fat without taking in mre food energy (calories) than is needed by the body to burn- Typical amount of calories for a woman is 2000 a day/For a man it is 2500 a day-
Eat a food variety-
Eat more of these; fruit, vegetables, and whole grains-
Eat less of saturated/trans fats, high sugar and salts-
Physical activity each and every day!
Eating Disorders
askville.amazon.com Cat seeing himself as a lion/self esteem and perception tool for self care and positive self imag
People with eating disorders are unsatisfied with their body image- Many have a skewed perception of what they look like in reality- they often do not see themselves the way the rest of the world sees them-
Obesity, Anorexia nervosa, and Bulimia Nervosa are serious disorders that can lead to malnutrition, disability, and death-
Bulimia results in binge eating and then purging (vomiting) often difficult to spot because their body weight may be close to “normal” and they are experts at concealment of their behaviors-
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