Download Unit 2 Digestion, Basic Chemistry, and Carbohydrates

Unit 2
Digestion, Basic Chemistry, and Carbohydrates
Chapter 3
The Human Body: Are We Really What We Eat?
Why Do We Want to Eat?
Food is intimately connected to our sense of ________________, but also stimulates our senses of
Sight
Smell
Touch
Hearing
This ultimately impacts:
_________________ and _____________________
Hunger vs. Appetite
Hunger: ____________________ drive for food
Nonspecific
Can be satisfied by a variety of different foods
Appetite: ______________________ desire to consume specific foods
Aroused by environmental cues
Additional terms
__________________: feeling of being full
__________________: physiological need for food yet no appetite
How are these factors controlled?
________________ System and ______________________ System
Signals from the brain cause hunger and satiation (___________________ phase of nervous system)
Nerve receptors in the stomach and small intestine send signals to the brain to indicate if they are full or empty
Blood glucose levels trigger the release of hormones called insulin and glucagon
The ____________________________ region of the brain receives these signals
_________________________ triggers feelings of hunger or satiation (__________________)
Integrates signals from nerve cells in other body regions and from chemical messengers
Special cells lining the stomach and small intestine send signals to the brain to indicate if they are full or empty
The hypothalamus can do these functions by releasing __________________.
Hormones
Hormones: chemical ___________________ secreted into the bloodstream by ________________________ to
help regulate body functions
Pancreatic hormones, insulin and glucagon, maintain blood glucose levels
Feeling full (satiated) results from signals from the stomach and rise in blood glucose
Nervous System
“________________________” - Stomach distension by food stimulates the release of gastric juices and other
hormones.
Not all foods have the same effects on our feelings of hunger
Proteins have the _________________ satiety value
Carbohydrates have a ______________ satiety value than fats
__________________ foods provide a sense of satiety
_________________ foods are more filling than semi-solid foods or liquids
What Happens to the Food We Eat?
Food undergoes three processes:
_____________________—large food molecules are broken down to smaller molecules, mechanically and
chemically
_____________________—process of taking these products through the intestinal wall
_____________________—undigested portions of food and waste products are removed from the body
Gastrointestinal (GI) tract:
A series of organs arranged in a long tube that work together to ________________ foods
The GI tract includes:
Organs such as the stomach, intestines
______________________: muscles that control the passage of food material from one organ to the next
The Flow of Digestion
Digestion begins in the ________________
__________________ phase of digestion:
Hunger and appetite work together to ________________ the GI tract for digestion
First thought of food (_______________ system) stimulates the release of digestive juices
___________________ moistens the food and mechanically breaks it into smaller pieces
____________________ contains digestive juices secreted by the salivary gland in the mouth
Bicarbonates neutralize ____________
Mucus ___________________ the food and oral cavity
Antibodies and lysozymes fight oral bacteria
___________________ are complex chemicals that induce chemical changes in other substances to speed
up bodily processes
Salivary amylase begins _______________ digestion
________________ receptors detect distinct tastes:
Bitter, sweet, salty, sour, and umami
__________________ receptors detect aromas of foods
The mass of food chewed and moistened in the mouth is called ____________________
The ____________________ covers the opening to the trachea during swallowing
Food travels from the mouth to the stomach through the ____________________
How does food travel through the Esophagus to the Stomach?
____________________ is the muscular contractions moving food through the GI tract
Digestion in the Stomach
__________________ - a hormone secreted by stomach lining cells that stimulates gastric juice
Gastric juice contains
___________________________ (HCl) denatures proteins and activates pepsin
___________________ – enzyme to digest protein
_______________________________ – enzyme to digest fat
_______________________________ – protein to absorb vitamin B12
Stomach does more than help with chemical digestion
___________________: semi-solid product of mechanical and chemical digestion in the stomach
How is the stomach protected from the gastric juices or more specifically HCl?
The pH Scale
Acid?
Base?
pH ?
Pure water is neutral/human blood is close to neutral
Tissues lining the stomach are generally protected from the effects of acidity
____________________ layer protects the stomach lining from the acid in gastric juices
Digestion in the Small Intestine
From the stomach, chyme is slowly released through the _______________ sphincter to the small intestine
Small intestine is composed of 3 sections
______________________ valve (sphincter) connects the small intestine to the large intestine
Most of the digestion and absorption take place in the small intestine
Digestion in the Large Intestine
The large intestine is also referred to as the ____________ or ________________
_____________ assist with final digestion
Its main function is to store undigested food material and absorb water, short chain fatty-acids, and
electrolytes
Are we forgetting something?
________________ and ___________________
How is Chemical Digestion Accomplished?
Enzymes Speed Up Digestion
_____________________ guide digestion through ___________________, a chemical reaction that breaks down
substances by addition of water
Enzymes are _______________ to carbohydrate, protein, and fat digestion
Hormones Assist in Digestion
Hormones are released into the bloodstream to _________________________________ that contain the
_______________ protein for that given hormone
____________________________________: Hormones bind to the receptor on the cell membrane for activation
Key hormones involved in digestion:
Accessory Organs Produce, Store, and Secrete Chemicals that also Aid in Digestion
Accessory Organ: ___________________
Gallbladder stores __________________, a greenish fluid, produced by the liver
_________________ signals the gallbladder to release bile
Bile _________________________ the lipids
Lipids are dispersed into smaller globules and become more accessible to digestive enzymes
Accessory Organ: _________________
Manufactures, holds, and secretes ____________________________________
Stores enzymes in the _____________________ form
_____________________________ digests carbohydrates
_____________________________ digests fats
_________________________ digests proteins
________________ and ___________________ (hormones) are produced to regulate blood glucose
_______________________ is secreted to neutralize chyme
Accessory Organ: ______________________
The liver is one of the most important organs in the body
____________________ chemicals for metabolism
__________________ bile for emulsification of fats
Receives the products of digestion via the portal vein (also called the portal venous system)
____________________ glucose from glycogen stores
Stores vitamins
_____________________________ blood proteins
Absorption
Process of taking molecules ________________ a cell membrane and into cells of the body
A small amount of absorption occurs in the ________________
Most absorption of nutrients occurs in the ____________________________
Types of Absorption
Passive Diffusion
_____________________________ - nutrients simply pass through the enterocytes and into the blood stream
without the use of a __________________ or ______________________
Going from ______________ to ______________________ concentration
No ____________________ expended
Facilitated Diffusion
Requires a _____________________________
Going from ___________________ to _______________________ concentration
No ______________________ expended
Active Transport
Requires ___________________ and a _____________________ carrier to transport nutrients
Endocytosis
________________________________, the lining of the GI tract, has special structures to facilitate absorption
_________________ are folds in the lining that allow it to absorb more nutrients
___________________ are absorptive cells in the villi
Capillaries and a ____________________ (small lymph vessel) are inside each villus
The brush border is composed of ____________________, which greatly increase the surface area
What happens to the nutrients after absorption?
Transport of Nutrients and Wastes
_____________________ travels through the cardiovascular system
_____________________ travels through the lymphatic system
___________________ pick up most lipids and fat-soluble vitamins
___________________ nodes are clusters of immune cells that filter microbes and other harmful agents
Digestive Disorders
____________________ (burping) is primarily caused by swallowed air, eating too fast, improperly fitted dentures,
and chewing gum
____________________ (intestinal gas) is a normal process that may be caused by
Foods rich in fiber, starches, and sugar
Bacteria that act on partially digested carbohydrates
The fat substitute olestra and sugar alcohols
Beano can offer some relief
The lining of the stomach is designed to cope with hydrochloric acid, but other regions of the GI tract are not
____________________ is caused by hydrochloric acid in the esophagus
____________________________________________ (GERD) is painful, persistent heartburn
Causes of GERD include
Hiatal hernia
Cigarette smoking or alcohol use
Being overweight
Pregnancy
Chocolate, citrus, spicy or fried foods
Large high-fat meal
Lying down soon after a meal
_______________________ are areas of the GI tract that have been eroded by HCL and pepsin
Bacterium ___________________________ plays a key role in development of both gastric and duodenal ulcers
___________________________________ is a cluster of GI symptoms (gas, pain, diarrhea) that occur following
consumption of a particular food
_______________________________ is a hypersensitivity reaction of the immune system to a particular component
(usually a protein) in a food
____________________________ (celiac sprue)
Damaged small intestine lining (decreased villi and enzymes) reduces nutrient absorption
Offending component is gliadin (a protein in ________________), which is found in wheat, rye, and barley
__________________ reflex is triggered when substances stimulate brain cells to signal "backwards" peristalsis
_____________________________ (CVS) is a chronic condition of recurring cycles that can last for hours or days
_________________________
This inflammatory bowel disease can affect any area of the GI tract
Possible cause is immune system reaction to a virus or bacteria
Symptoms include diarrhea, abdominal pain, rectal bleeding, weight loss, fever, anemia
Children can experience delayed growth
_______________________________
Chronic disease characterized by inflammation and ulceration of the mucosa, the innermost lining of the colon
Possible cause is an immune response to a virus or bacteria
Symptoms are similar to Crohn's disease
Although not caused by food, patients may have to avoid foods that cause GI discomfort
_______________________________
Frequent passage of loose, watery stools
Usually caused by infection of the GI tract, stress, food intolerances, reactions to medications, or bowel disorders
Can lead to severe dehydration
More dangerous for children and the elderly
____________________________—common concern; also called ________________________
______________________________
Infrequent hard, small, difficult-to-pass stools
Prevention includes increasing fiber-rich foods and fluids, and regular exercise
______________________________ (_______) is a disorder that interferes with normal colon function
Symptoms include abdominal cramps, bloating, and either diarrhea or constipation
Associated with stress, caffeine, large meals, chocolate, alcohol, dairy, wheat
Treatment includes stress management, smaller meals, high-fiber diet, fluids, and regular physical activity
Probiotics and Human Health
______________________
Live microorganisms which, when administered in adequate amounts, confer a health benefit on the host
Bacteria in the Colon
Protection against invading microorganisms
Synthesizing vitamins (Vit K)
Reduce ulcers
Reduce inflammation
Prevention of diarrheal diseases
Intro to Chemistry
Chemistry
_____________________
The smallest “piece” of an element that retains the characteristics of that element.
Composed of 3 subatomic particles:
Draw the structure of the atom and describe the characteristics of the subatomic particles
How do we calculate the # of subatomic particles in each atom?
Atomic _________________
# _____________ in nucleus of an atom (establishes identity of the atom)
Since most atoms are electrically neutral, atomic number indicates # of electrons as well.
Atomic _____________________
# __________________ plus # ___________________ in nucleus of an atom
How can we determine the number of neutrons in an atom?
Do all carbon atoms have the same number of protons?
Do all carbon atoms have the same number of neutrons?
___________________________
Atoms having the same number of protons, but differing numbers of __________________.
Ex. Carbon isotopes
carbon 12 (12C)  6 neutrons
carbon 13 (13C)  7 neutrons
carbon 14 (14C)  8 neutrons
Molecule
An accumulation of ________________ of different types to form a specific association.
Smallest piece of a _____________________ that retains characteristics of that _____________________.
Examples:
4CO2
4 molecules of carbon dioxide
2C6H12O6
2 molecules of glucose
6O2
6 molecules of oxygen
How do they come together?
Chemical Bonds
Type of bond formed is determined by the number of ___________________ electrons in the interacting atoms
[_____________ rule].
____________________ bonds - form when atoms ___________________ electron pairs.
strongest type of bond
___________________ bonds - form when oppositely charged _______________ are attracted to each other.
weaker than covalent bonds
form salts
Ex. NaCl
____________________ bonds - form when opposite charges on two ________________ are attracted to each
other.
weakest type of bond*
Chemical Reactions
When compounds or set of compounds (________________) is converted into another compound or set of
compounds (_________________). It is usually accompanied by a release or absorption of energy
Dehydration vs. Hydrolysis
Dehydration reactions
A ______________ molecule is _______________
Hydrolysis reactions
A ______________ molecule is _______________
Oxidation vs. Reduction
Oxidation: _________________ of ___________________ (in atoms)
Reduction: __________________ of ____________________
Acids and Bases
___________ – substances that add H+ to a solution
___________ – substances that remove H+ from a solution
What does pH scale measure?
Carbohydrates: Plant-Derived Energy Nutrients
What Are Carbohydrates?
One of the three _____________________
Important source of ___________________ for all cells
________________ energy source for nerve cells
Composed of ______________, ___________________, ________________
Good sources: fruits, vegetables, grains
Glucose
The most abundant carbohydrate
Produced by plants through _________________________
Simple carbohydrates
Contain _______ or ___________ molecules
Commonly referred to as ___________________
____________________ contain __________ molecule
____________________ contain __________ molecules
Complex carbohydrates
___________________ contain 3 to 10 monosaccharides
Most _______________________ consist of hundreds to thousands of glucose molecules
Starch, glycogen, most fibers
Starch
______________ store carbohydrates as starch
________________—straight chain of glucose
_____________________—branched chain of glucose
Sources: grains, legumes, fruits, vegetables
Glycogen
Storage form of glucose for ____________________ (humans)
Not found in _______________ and therefore not a source of dietary carbohydrate
Stored in the liver and muscles
Fiber
Composed of long polysaccharide chains
___________________ fibers are non-digestible parts of plants
___________________ fibers are non-digestible forms of carbohydrates extracted from plants or
manufactured in a laboratory and have known health benefits
______________ fiber = Dietary fiber + Functional fiber
_______________ fibers
_________________ in water; viscous and gel-forming
Fermentable, digested by intestinal bacteria
Associated with risk reduction of cardiovascular disease and type 2 diabetes
Examples: pectin, gum, mucilage
Found in citrus fruits, berries, oats, beans
________________ fibers
Do not dissolve in water, ___________________
Cannot be fermented by bacteria in the colon
Promote regular bowel movements, alleviate constipation, and reduce diverticulosis
Examples: lignins, cellulose, hemicelluloses
Good sources: whole grains, seeds, legumes, fruits, and vegetables
Carbohydrate Digestion
Digestion breaks down most carbohydrates into _________________________
__________________________
Enzyme that begins carbohydrate digestion in the mouth
Breaks starch down to __________________
Carbohydrate digestion does ________ occur in the stomach
Stomach acids __________________ salivary amylase
Most chemical digestion of carbohydrates occurs in the small intestine
______________________________
Enzyme produced in the pancreas and secreted into the small intestine
Digests starch to ________________
Additional enzymes in the microvilli digest disaccharides to monosaccharides
Monosaccharides are ___________________ into the cells lining the small intestine and then enter the bloodstream
All monosaccharides are ___________________ to glucose by the liver
Glucose circulating in the blood is our ________________ energy source
Excess glucose is stored as ____________________ in the liver and muscles
We do not have the enzymes necessary to digest _______________
_______________ in the large intestine can break down some fiber
Most fiber remains undigested and is excreted in the ________________
Blood Glucose Regulation
Blood glucose must be closely regulated
Hormones control blood glucose levels:
Blood Glucose Regulation: ________________________
Secreted by _________ cells of the pancreas
Stimulates glucose transporters (______________________) to help take glucose from the blood across the
cell membrane
Stimulates the liver to take up glucose and convert it to ____________________
Blood Glucose Regulation: _______________________
Secreted by ____________ cells of the pancreas
Stimulates the liver to convert glycogen to glucose
Stimulates _______________________, the production of glucose from amino acids
Blood Glucose Regulation: _____________________ and _____________________
Secreted by the adrenal glands and nerve endings when blood glucose is low
Increase glycogen breakdown in the liver, releasing glucose into the blood
Responsible for our "fight-or-flight" reactions to danger
Blood Glucose Regulation: _________________ and ______________________
Secreted by the adrenal glands to act on the liver, muscle, and adipose tissue
Cortisol increases gluconeogenesis and decreases muscle glucose use
Growth hormone decreases muscle glucose uptake, increases fatty acid mobilization and use, and increases
liver glucose output
Blood Glucose Regulation: __________________ Index
A food's potential to raise blood glucose
Foods with a ________________ glycemic index cause a sudden surge in blood glucose, triggering a large increase
in insulin, which may be followed by a dramatic fall in blood glucose
Foods with a low glycemic index cause low to moderate fluctuations in blood glucose
Not always easy to predict
Food's absorption rate varies with type of carbohydrate, preparation methods, and its fat and fiber content
Most foods are eaten in combination in a meal
Blood Glucose Regulation: _______________________ Load
Used to determine the effect of a food on a person's glucose response
Grams of carbohydrates in a food are multiplied by the glycemic index
Glycemic index and glycemic load remain controversial
Evidence of health benefits is weak
Value of Lower Glycemic Index
Less fluctuations in blood glucose
Risk reduction for heart disease and colon cancer
High fiber intake helps to improve fat levels in the blood (higher HDL and lower LDL)
Foods with lower glycemic index:
Beans, fresh vegetables, whole wheat
The Role of Carbohydrates
__________________
Each gram of carbohydrate: ___kcal
Red blood cells use only glucose for energy
Both carbohydrates and fats supply energy for daily activities
Glucose is especially important for energy during exercise
Ketosis
Fat breakdown during fasting forms ______________
Excess ketones increase blood acidity and cause _______________________________
Sufficient energy from carbohydrates prevents ketone production as alternate energy source
Carbohydrates Spare Protein
___________________________ occurs when a diet is deficient in carbohydrate
The body will make its own glucose from protein
Amino acids from these proteins cannot be used to make new cells, repair tissue damage, support the immune
system, or perform any of their other functions
Complex Carbohydrates Have Health Benefits
Fiber
May reduce the risk of _______________ cancer
Helps prevent hemorrhoids, constipation, and other intestinal problems
May reduce the risk of _________________________
May reduce the risk of heart disease
May enhance weight loss
May lower the risk of type 2 diabetes
How Much Carbohydrate?
Recommended Dietary Allowance (RDA) is 130 grams/day to supply adequate glucose to the brain
Acceptable Macronutrient Distribution Range (AMDR) is 45% to 65% of daily calories
Focus on fiber-rich carbohydrate foods
Simple Carbohydrates
Diets high in simple sugars:
Can cause tooth decay
May increase "________ cholesterol"
May decrease "________ cholesterol"
May contribute to obesity
Complex Carbohydrates
Most Americans eat too little complex carbohydrates
________________ foods are foods in which nutrients that were lost during processing have been added back so
the food meets a specified standard
Fortified foods have nutrients added that did not originally exist in the food (or existed in insignificant amounts)
Fiber
Adequate Intake (AI) for fiber
25 g per day for women
38 g per day for men, or
14 g of fiber for every 1,000 kcal per day
It is best to get fiber from food (also a source of vitamins and minerals)
An adequate fluid intake (at least 8 oz/day) with high-fiber diets is recommended
Alternative Sweeteners
Nutritive sweeteners
Sucrose, fructose, honey, and brown sugar contain 4 kcal energy per gram
Slow-absorbing sugar alcohols: 2−3 kcal/gm
Non-nutritive (alternative) sweeteners
Provide little or no energy
Safe for adults, children, people with diabetes
______________________
180-200x sweeter than sucrose
Heat tolerable
______________________
K for potassium
200x sweeter than sucrose
Not digested by the body
Heat stable
AKA Sunette
________________________
180-200x sweeter than sucrose
4 kcals/g, but only a trace amount is needed to sweeten foods
Not heat stable
Complaints of sensitivity to aspartame
headaches, dizziness, seizures, nausea, etc.
Not recommended for people with phenylketonuria (PKU)
___________________________
600 x sweeter than sucrose
Heat stable
Excreted in feces (small amount in urine)
“Made from sugar so it tastes like sugar"
__________________________
~7000 –13000 times sweeter than sucrose
Structure is similar to aspartame (but not a risk for PKU)
Heat stable
Safe for use by the general population (including children, diabetics, pregnant and lactating women)
Used in a variety of products
_________________________
200 sweeter than sucrose
extract from stevia plant
Aka Truvia or Purevia
Diabetes
Inability to regulate blood glucose levels
Types
Type 1 diabetes
Type 2 diabetes
______________________ diabetes
Uncontrolled diabetes can cause nerve damage, kidney damage, blindness, and can be fatal
________________________ = higher-than-normal blood glucose levels
Diabetes—Type 1
Accounts for 10% of all cases
Body does not produce enough insulin
Causes hyperglycemia (high blood glucose)
Once known as juvenile-onset diabetes or insulin dependent diabetes mellitus (IDDM)
May be an autoimmune disease
Carbohydrate intake must be coordinated with insulin injections to maintain Blood-Glucose levels
Diabetes—Type 2
_________________________ (insulin resistance): cells become less responsive to insulin
_________________________: a cluster of risk factors that increase the risk for type 2 diabetes
Once known as adult-onset diabetes
Increasing in children and adolescents
Cause is unclear, but genetics, obesity, and physical inactivity play a role
Treat with weight loss, healthy eating, regular exercise, and, if necessary, medications
Healthy lifestyle choices may prevent or delay the onset of type 2 diabetes
Hypoglycemia
Low blood glucose may cause shakiness, sweating, anxiety, weakness
_______________ hypoglycemia: pancreas secretes too much insulin after a high-carbohydrate meal
_______________ hypoglycemia: pancreas produces too much insulin, even when someone has not eaten
Lactose ___________________
Insufficient enzyme lactase to digest the lactose-containing foods
Symptoms: gas, bloating, cramping, diarrhea
Extent of intolerance: mild to severe
Persons with lactose intolerance may need to find alternate sources of calcium
Lactose ______________________
Coping with lactose maldigestion
Determine tolerated amount
Eat dairy with fat
Cheese and yogurt more easily tolerated
Lactase pills
Health Concerns: Dental Caries
Tooth decay or dental cavities
Infectious disease which damages the structures of Teeth
Bacteria collect around the teeth and gums in a sticky, creamy-coloured mass called plaque
Prevented by eating sugar-free products
Personal hygiene care consists of proper brushing and flossing daily