Katie Meyers

Compendium Four – Food and the Body

Cell Respiration and Diffusion

• Diffusion
• Cell respiration
• Glycolysis
• Kreb’s cycle
• Electron transport system
• NAD+
• ATP

Digestion

• Purpose
• 5 steps
• GI tract
• 4 layers
• GI tract organs
• Accessory organs
• Diabetes

Nutrition

• Nutrients
• Carbohydrates
• Proteins
• Lipids
• Minerals
• Vitamins
• Obesity
• Healthy diet approaches
• Eating disorders

Cell Respiration and Diffusion

• Diffusion – how glucose enters a cell
• Insulin – a protein secreted by the pancreas into the blood, usually after a meal
• Insulin stimulates cells to take up glucose, or stimulates GLUT4 in the cell’s plasma membrane
• Glucose diffusion – special protein pore (GLUT4) diffuses glucose through the cell membrane and into the cell
• Here is an image of how glucose is taken in by diffusion

(found on slide 6 of Nutrition – BIO 156 PowerPoint presentation)

• After glucose is taken in by the cell, it is either stored as glycogen or used in the cell’s metabolism (cell respiration)
• Here is an image of the overall cell’s actions with glucose diffusion

(found on slide 6 of Nutrition – BIO 156 PowerPoint presentation)

• Cell Respiration – provides energy by oxidizing food molecules, e.g. glucose; is the primary way that cells make ATP
• Glucose is the main substrate (used chemical) combined with oxygen in cellular respiration
• Glycolysis and the Kreb’s cycle break down food molecules
• 3 phases

(found on slide 5 of Nutrition – BIO 156 PowerPoint presentation)

• Glycolysis – the oxidization of glucose to pyruvate
• Cells get energy (ATP) from oxidizing nutrients like glucose
• Step 1 – add two phosphates, get two ATP
• Step 2 – divide into two 3-carbon sugar phosphates; convert these 3-carbon sugar phosphates into pyruvate
• This step produces ATP as well
• Step 3
• Aerobic – pyruvate is further oxidized, yielding more ATP
• Anaerobic – pyruvate is converted into lactic acid

(found at http://ghs.gresham.k12.or.us/science/ps/sci/ibbio/cellenergy/resp/respirpics/glycolysis2.gif)

• Kreb’s Cycle (or citric acid cycle)
• Occurs in mitochondria
• First converts pyruvate to acetyl-CoA
• Then, acetyl-CoA reacts with a 4-carbon molecule
• This then produces NADH and carbon dioxide
• This production produces one ATP as well
• Cycle ends with 4-carbon molecule being regenerated – starts the Kreb’s cycle all over again

(found at http://www.emc.maricopa.edu/faculty/farabee/biobk/enyld2.gif)

• Electron Transport System and ATP synthesis
• Resulting energy from glycolysis and Kreb’s cycle is transported to the electron transport system in electron form
• Phosphorylation – hydrogen movement into the mitochondrion helps synthesize ATP from ADP and phosphate

(found at http://staff.jccc.net/PDECELL/cellresp/ets.gif)

• NAD+
• Oxidization – the removal of hydrogen from molecules
• Enzymes give NAD+ a hydrogen, making it into NADH
• NADH can then donate its hydrogen to other molecules
• ATP – a high energy phosphate bond that is used all over the cell for different actions; the cell’s currency of energy; produced mainly by glucose

Digestion

• Purpose of digestion – to break down nutrients in food so cells can use them (by crossing the plasma membrane)
• Digestion – 5 steps
• 1) Ingestion – when mouth takes in food
• 2) Digestion
• Mechanical digestion – when food is divided into smaller pieces to be acted on by digestive enzymes (in the stomach); we aid mechanical digestion by cutting up our food before eating it
• Chemical digestion – begins in mouth, ends in small intestine; the partly digested food in between the mouth and small intestine is called chyme
• 3) Movement – of GI tract along the digestive tract; food passes from one organ to the next, while indigestible remains are expelled
• 4) Absorption – nutrients created by GI tract cross GI tract’s wall and enter cells nearby, which then put the nutrients received into the blood to be spread throughout the rest of the body

(found on slide 12 of Nutrition – BIO 156 PowerPoint presentation)

• 5) Elimination – defecation (enough said)
• GI tract – gastrointestinal tract – contains digestive organs
• 4 layers of the GI tract, from innermost to outermost
• Mucosa – modified according to organ type
• Submucosa – loose connective tissue in broad band – contains blood and lymph vessels, as well as nerves
• Muscularis – two smooth muscle layers
• Serosa – thin; made of visceral peritoneum
• Here is an image of the GI tract’s organs, as well as its accessory organs.

(found on slide 13 of Nutrition – BIO 156 PowerPoint presentation)

• GI tract organs – mouth, pharynx, esophagus, stomach, small intestine, large intestine, rectum, anus
• Mouth – receives food, begins chemical and mechanical digestion
• Pharynx – cavity where mouth and nasal passages cross (windpipe goes in front of the esophagus)
• Esophagus – long, narrow tube that takes food to the stomach
• Stomach – has thick walls, is J shaped, on the left side of the body beneath the diaphragm – stores food, initiates protein digestion, controls movement of chyme into the small intestine; its high acidity kills most bacteria in food
• Small intestine – completes digestion, absorbs nutrients through its walls; contains enzymes to digest food
• Names of small intestine parts, in order of the direction of food’s movement (top to bottom, in a sense)
• Duodenum, jejunum, ileum
• Large intestine – absorbs H2O (prevents hydration); does not produce enzymes, does not store nutrients, does absorb vitamins produced by bacteria called flora; aids body in getting rid of indigestible solid remains of food (defecation)
• Names of large intestine parts, in order of the direction of food’s movement (not really top to bottom)
• Cecum, ascending colon, transverse colon, descending colon, sigmoid colon, rectum, anal canal
• Accessory organs (organs that assist the digestive tract’s organs) – salivary glands, liver, gallbladder, pancreas
• Salivary glands – help moisten food and aid swallowing by excreting saliva; 3 pair – sides of face under and in front of ears, beneath tongue, beneath oral cavity floor
• Liver – major metabolic gland located in the upper right of the abdominal cavity
• Detoxifies blood with liver’s lobules and their capillaries
• Stores iron and vitamins A, D, E, K, B12 from blood; stores glycogen
• Regulates cholesterol and glucose levels in blood
• Produces and provides bile for small intestine (bile emulsifies fat in digestion)
• Gallbladder – stores bile, also provides bile for the small intestine
• Pancreas – in the back of the abdomen, behind the stomach
• Produces pancreatic juice made of sodium bicarbonate and digestive enzymes
• Amylase – digests starches
• Trypsin – digests proteins
• Lipase – digests fat
• Secretes digestive enzymes into the small intestine
• Secretes insulin hormone into the bloodstream

(found on slide 7 of Nutrition – BIO 156 PowerPoint presentation)

• Diabetes – two types
• Type I – no insulin is released by the pancreas after eating, leaving the blood sugar high; treated with injections of exogenous insulin

(found at http://images.medicinenet.com/images/ccf/42943_Type1Diabetes.jpg)

• Type II – insulin is released by the pancreas after eating, but cells do not receive the signal; treated with Avandia, which increases cell sensitivity to normal insulin, or treated with metformin if the patient is obese, where metformin blocks the liver synthesis of glucose
• Associated with a diet high in simple carbohydrates; therefore, giving a type II patient insulin is not ultimately helpful
• Long-term exposure to simple carbohydrates reduces the body’s response to insulin

(found at http://images.medicinenet.com/images/ccf/diabetesccf2.bmp)

• Type II is less severe than type I
• Type I occurs in children, type II occurs in adults

Nutrition

• As body runs off glucose, why not just eat sugar? Because the body needs other nutrients, minerals, vitamins, and amino acids (building blocks of protein) to function as well. These are things the body does not produce, so we must be sure to intake a sufficient amount of each in our daily diets to facilitate bodily function.
• Nutrients

(found on slide 10 of Nutrition – BIO 156 PowerPoint presentation)

• Carbohydrates – simple (e.g. glucose) or complex (sugar with several sugar units, digested and broken down into glucose)
• Glucose – energy source at the cellular level; preferred energy source in the body
• Protein – digested into amino acids, which cells then synthesize into cellular proteins
• 8 essential amino acids, 20 total
• Incomplete protein source – a food that does not contain all 8 essential amino acids
• Absence of just one essential amino acids prevents the utilization of the other 19 amino acids
• Daily supply of amino acids needed, as body does not store them

(found on slide 9 of Nutrition – BIO 156 PowerPoint presentation)

• Lipids – fats, oils, cholesterol
• Saturated fats – solid at room temperature
• Usually of animal origin, e.g. butter and meats
• Exceptions: palm oil and coconut oil
• Unsaturated fats – oils
• Do not promote cardiovascular disease
• Polyunsaturated fats – corn oil and safflower oil
• Only lipid to contain linoleic acid and linolenic acid
• These are essential fatty acids
• Body does not supply these, need to be in everyday diet
• Monounsaturated fats – olive oil and canola oil
• Trans fats – found in commercially packaged foods; bad for the body
• Minerals – major and trace
• Some example minerals:
• Calcium – vital to the construction of bones, teeth; vital to nerve conduction and muscle contraction
• Sodium – regulates body’s H2O balance
• Salt intensifies hypertension, so do not have too much sodium in salt form
• Chart of minerals

(found on slide 16 of Nutrition – BIO 156 PowerPoint presentation)

• Vitamins – organic compounds used for the body’s metabolic purposes
• 13 total
• Antioxidants – defend against free radicals (which can mutate DNA) – e.g. vitamins A, C, E
• Vitamin D – becomes calcitriol, which promotes the absorption of calcium by the intestines
• Water-soluble vitamins

(found on slide 18 of Nutrition – BIO 156 PowerPoint presentation)

· Fat-soluble vitamins

(found on slide 17 of Nutrition – BIO 156 PowerPoint presentation)

• Obesity
• The American diet results in excess body fat; 33% of U.S.A. adults are obese
• How to keep weight down
• While dieting, “eat a variety of foods, watch your weight, and exercise” (found in “Human Biology” 10^th ed. By Sylvia S. Mader page 156)
• Remember food – the win-win-win approach; a social/political/ethical issue
• “Bring a spiritual and cultural base back to our diet”, or make food matter more in such ways to each individual
• Ignore the lure that commercial food is trying to cast over the general population; get back to whatever each person considers their home-cooked meals that mean more to the individual and will make them think and care more about what they are eating
• Culturally-based cuisines are usually healthy
• In wealthier areas of the world, “nutritional transition” takes place and draws the wealthier population away from simple, culturally-based cuisines and towards colorfully packaged foods that appeal to people in the fast lane of life
• “Bring long-term health to our lives”
• “What is healthy [food]? Non-packaged; local; home-cooked; culturally-based; spiritually satisfying.”
• “Bring long-term health to our farming and agricultural ecosystems”
• Encourage local farmers by buying their products, as they have standards since their business is at the mercy of their local reputation
• The four above quotes found on slide 23 of Nutrition – BIO 156 PowerPoint presentation)
• The food satisfaction triangle

(found on slide 27 of Nutrition – BIO 156 PowerPoint presentation)

• Eating disorders – dissatisfied with self-body image
• Anorexia nervosa
• Severe psychological disorder
• Refusal to eat enough food to maintain a healthy body weight
• 90% of these cases are young women – 1 in 200 teenage girls have it
• Bulimia nervosa
• Overeating episodes, followed by purging
• Binge/purge cycle can be done several times a day
• Plagues 4% of young women
• Binge-eating disorder
• Overeating episodes, not followed by purging
• Triggered by stress, anxiety, anger, depression
• Muscle dysmorphia
• Patient thinks their body is underdeveloped
• Body-building preoccupation, along with supplements and protein drinks used to body-build
• Affects more men than women