Description
Directions: Rely on the powerpoints attached to answer the following questions.
1. List and discuss the three (3) main groups of lipids. What is the role of each type of lipid in the body? What is the recommended daily intake of lipids? List 4 healthy Lipids.
2. Briefly discuss high and low-density lipoprotein cholesterol.
3. Discuss the nature of proteins. Discuss amino acids. What are the role of proteins in the body? What is the recommended daily intake of proteins? List 4 healthy proteins.
4. List the fat and water soluble vitamins. What are the roles of each in the body?
5. List five (5) minerals. What is the role of minerals in the body?
6. Discuss the functions of body water. Compare water intake versus output.
7. Figure 3.5 (depending on the book edition) listed the structures of the gastrointestinal tract including each structure’s digestive function. For the following structures, discuss their digestive function and percent of digestion for each structure.
a. Mouth
b. Stomach
c. Liver
d. Small intestine
e. Large intestine
8. Figure 3.10 (depending on the book edition) is the overview of human digestion. Please discuss how carbohydrates, proteins, and fats are digested.
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Part 1
Food Nutrients: Structure,
Function, Digestion, Absorption,
and Assimilation
1
Chapter 2
The Micronutrients and Water
2
Micronutrients
Micronutrients Include Vitamins and Minerals
• Micronutrients do not provide energy
• Only needed in small quantities
• Deficiencies and excesses of the micronutrients
affect health
Copyright © 2019 Wolters Kluwer • All Rights Reserved
3
The Nature of Vitamins
Thirteen Fat- or Water-Soluble Vitamins
• Have no common chemical structure
• Except for vit D, body does not make vitamins
• Foods/supplements supply all vitamins
• Plants contain abundant vitamins
– Manufactured via photosynthesis
• Animals obtain vitamins from plants, seeds, grains,
fruits, and meat from other animals
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4
Classification of Vitamins
Vitamins
• Fat soluble
– Vitamins A, D, E, and K
• Water soluble
– Vitamin C
– B-complex
o Thiamine (B1), riboflavin (B2), pyridoxine (B6),
niacin (nicotinic acid), pantothenic acid,
biotin, folic acid, and cobalamin (B12)
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5
Classification of Vitamins
Fat-Soluble Vitamins
• Vitamins A, D, E, and K
– Dissolve and store in fatty tissues
o Dietary lipids provide a source of fat-soluble
vitamins
– Should not be consumed in excess without
medical supervision
– Remain in body tissues; not excreted
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6
Classification of Vitamins
Fat-Soluble Vitamin Toxicity
• Toxicity symptoms
– Nervous system irritability
– Bone swelling
– Weight loss
– Dry, itchy skin
• Other symptoms
– Nausea, headache, drowsiness, hair loss,
diarrhea, bone calcium loss leading to
osteoporosis
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7
Classification of Vitamins
Water-Soluble Vitamins
• Vitamin C and B-complex vitamins
• Act largely as coenzymes
• Disperse readily in body fluids
– Excess intake voided in urine
– Marginal deficiencies develop in 4 weeks of
inadequate intake
• Available in foods, mostly plants
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8
Classification of Vitamins
Vitamin Storage in the Body
• Fat-soluble vitamins not excreted
• Water-soluble vitamins continually excreted by
kidneys
– Must be consumed regularly to prevent
deficiencies
– Vitamin B12 an exception
• Deficiencies appear after 10 to 40 days of no intake
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9
Vitamin’s Role in the Body
• Essential links and
regulators in metabolic
reactions that release
energy from food
• Regulate metabolism
• Protect cells’ plasma
membrane
FIGURE 2.1 Biologic function of vitamins
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10
Defining Nutrient Needs
Dietary Reference Intakes
• Comprehensive approach to nutritional
recommendations
• “DRI” umbrella term
– Recommended Daily Allowance: RDA
– Estimated Average Requirement: EAR
– Adequate Intake: AI
– Tolerable Upper Intake Level
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11
Defining Nutrient Needs
Dietary Reference Intakes (DRIs)
• Recommended Daily Allowance: RDA
– Meets needs of 97% to 98% of healthy people
• Estimated Average Requirement: EAR
– Meets needs of ½ of all healthy people
• Adequate Intake: AI
– Adequate nutritional goals with no RDAs
• Tolerable Upper Intake Level
– Highest average daily intake likely to pose little
risk of adverse health effects
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12
Defining Nutrient Needs
Dietary Reference Intakes (DRIs)
FIGURE 2.2 Theoretical distribution of number of persons adequately nourished by a given nutrient intake
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13
Defining Nutrient Needs
U.S. Govt. 2015–2020 Dietary Guidelines
• Limit saturated fat to 10% daily kilocalories
• Eat a variety of protein including seafood, lean
meats, poultry, eggs, soy, legumes, nuts, and
seeds
• Eat fat-free or low-fat dairy, including milk, yogurt,
and cheese
• Consume ≤10% of kcal·d−1 (about 200 kcal) from
added sugars
• Limit alcohol intake to 1 drink daily for women and
3 drinks daily for men
• Limit daily sodium intake to ≤2300 milligrams
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14
Defining Nutrient Needs
Antioxidant Role of Vitamins
• Vitamins protect against oxidative stress
– Influencing molecular mechanisms and gene
expression
– Provide enzyme-inducing substances to detoxify
carcinogens
– Interrupt uncontrolled cell growth
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15
Defining Nutrient Needs
Antioxidant Role of Vitamins
• Vitamins A, C, E, and β-carotene
– Serve protective functions
– Appropriate vitamin levels of these vitamins
reduce potential for free radical damage
(oxidative stress)
o Protects against heart disease, diabetes,
osteoporosis, cataracts, premature aging, and
diverse cancers
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16
Defining Nutrient Needs
Vitamins and Disease Protection
• Isothiocyanates: natural detoxifier
• Lutein and zeaxanthin: protect eye health
• Lycopene: decreases the risk for heart disease and
cancer risk
• Vitamin E: neutralizes harmful compounds
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17
Homocysteine and CHD
FIGURE 2.3 A. Proposed mechanism for how the amino acid homocysteine damages the lining of
arteries and sets the stage for cholesterol infiltration into a blood vessel. B. Proposed defense against the
possible harmful effects of elevated homocysteine levels
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18
Minerals
The Nature of Minerals
• Consist of 22 mostly metallic elements
• Minerals essential to life
– 7 major minerals
o Required amounts ≥100 mg·d−1
– 14 minor or trace minerals
o Required amounts ≥100 mg·d−1
• Balanced diet provides adequate intake
– Some geographic locations lack specific minerals
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19
Minerals
Kinds of Minerals
• Major Minerals
• Trace Minerals
– Requirement ≥100
mg·d−1
– Requirement ≤100
mg·d−1
o Calcium
o Iron
o Phosphorous
o Fluorine
o Potassium
o Zinc
o Sulfur
o Copper
o Sodium
o Selenium
o Chlorine
o Iodine
o Magnesium
o Chromium
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20
Minerals
Role in the Body
• Provide structure
– Bone and teeth formation
• Maintains normal heart rhythm, muscle
contractility, neural conductivity, and acid-base
balance
• Regulates metabolism
– Enzymes and hormones modulate cellular
activity
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21
Minerals
Role in Catabolism
and Anabolism
FIGURE 2.4 Minerals that function in
macronutrient catabolism and
anabolism
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22
Minerals
Mineral Bioavailability
• Factors affecting mineral bioavailability
– Type of food
– Mineral-mineral interaction
– Vitamin-mineral interaction
– Fiber-mineral interaction
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23
Minerals
Calcium (Ca++)
• Body’s most abundant mineral
• Ca++ + phosphorus (P) forms bones and teeth
• Ca++ + P = 75% of body’s total minerals
• Six important functions
1. Muscle action
2. Blood clotting
3. Nerve impulse transmission
4. Enzyme activation
5. Calciferol (vit D) synthesis
6. Fluid transport across cell membrane
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24
Minerals
Calcium Balance
• Prevents hypercalcemia (higher than normal
blood Ca++) and hypocalcemia (lower than normal
blood Ca++)
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25
Minerals
Calcium Balance
• Two opposing processes control Ca++ balance
1. C++ buildup by its efficient transport from the
small intestine for storage in bone matrix
2. Inadequate C++ intake or ineffective calcium
absorption by intestinal mucosa
o C++ travels opposite from bone into bodily fluids
called C++ resorption
▪ This process negatively impacts males and
females of all ages
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26
Minerals
FIGURE 2.5 Ca++ (blue dots) buildup by its efficient transport from small intestines for storage in bone
matrix (white box upper left). Opposing process of ineffective Ca++ intestinal absorption, denoted by the
smaller white box, occurs where Ca++ leaches from bones leaving them brittle and likely to fracture
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27
Minerals
Osteopenia and Osteoporosis
• Ca++ imbalance can lead to
1. Osteopenia
o
Bone weakens with increased fracture risk
o
Bone density does not achieve peak bone
density or max concentration of bony tissue at
maturation and is not low enough for medical
classification as osteoporosis
2. Osteoporosis
o
Porous bones, with bone density values greater
than 2.5 SD units below normal for age and sex
with significantly increased fracture risk
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28
Minerals
Variation in Bone
Population
FIGURE 2.6 A. Different factors that
affect bone mass. B. Weight-bearing PA
augments skeletal mass during growth
above the genetic baseline. The degree of
augmentation depends on the amount of
bone mechanical loading
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29
Minerals
Osteoporosis Risk Factors
• Advanced age
• Excess sodium intake
• White or Asian woman
• Cigarette smoking
• Underweightness
• Excessive alcohol use
• Anorexia or bulimia
nervosa
• Abnormal absence of
menstrual periods
• Sedentary lifestyle
• Calcium-deficient diet before
and after menopause
• Postmenopause, including
early or surgically induced
menopause
• Family history of
osteoporosis
• Low testosterone in men
• Possible high caffeine intake
• High protein intake
• Vitamin D deficiency
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30
Minerals
Osteogenic Effects
of PA
• Most effective
during growth
– Childhood
– Adolescence
FIGURE 2.7 Osteogenic effects of PA
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31
Minerals
Beneficial Effects of Weight-Bearing
FIGURE 2.8 Beneficial effects of weight-bearing activities
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32
Minerals
Female Triad
• Tightly bound
continuum that
begins with
disordered
eating
(with energy
drain) leading to
amenorrhea and
then
osteoporosis
FIGURE 2.10 The female athlete triad: low energy
availability, menstrual dysfunction, and impaired bone health
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33
Minerals
Female Triad
FIGURE 2.11 Contributing factors
to exercise-related amenorrhea
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34
Minerals
Does Muscle
Strength Relate to
Bone Density?
• Greater maximum
flexion and
extension
strength
in
postmenopausal
women with and
without
osteoporosis
FIGURE 2.12 Comparison of chest press extension and
flexion strength in age- and weight-matched
postmenopausal women with low and normal BMD
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35
Minerals
Reducing Fracture Risk in Osteoporosis
• Risk factor reduction for fracture
1. Strengthen bones by maintaining or increasing
bone density with PA and adequate daily Ca++
intake
2. Reduce spinal forces by avoiding higher-risk PA
to increase spinal and lower-limb joint
compression
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36
Minerals
Phosphorus
• Combines with Ca++ to form hydroxyapatite and
calcium phosphate
• Serves as essential component of AMP, PCr, and
ATP
• Combines with lipids to form phospholipids—part of
cell membranes
• Phosphate enzymes regulate cellular metabolism
• Participates in buffering energy metabolism acid
end-products
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37
Minerals
Magnesium
• Helps regulate metabolism
• Plays vital role in glucose metabolism
• Participates as cofactor in glucose, fatty acids,
and amino acids breakdown
• Affects lipid and protein synthesis
• Preserves proper neurologic system function
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38
Part 1
Food Nutrients: Structure,
Function, Digestion, Absorption,
and Assimilation
1
Chapter 3
Nutrient Digestion and
Absorption
2
Food Nutrient Digestion and Absorption
The Digestive Process
• Digestion = mechanical and chemical food
breakdown of food for absorption into blood for use,
storage, or chemical change
– Requires 24 to 72 hours
– Under involuntary control
o ANS controls GI: PNS increases gut activity:
SNS inhibits activity
– Proteins and CHO degrade and enter intestinal villi
for absorption
– Bile emulsifies lipids, hydrolyze or degrade them
for absorption
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3
Food Nutrient Digestion and Absorption
Beginning of Digestion
• Digestion begins with smell and taste
• In mouth, texture and temperature combine with
odors to produce perception of flavor
• Flavor, sensed through smell, signifies what we eat
Four Hormones Regulate Digestion
• Gastrin, secretin, cholecystokinin (CCK), and gastric
inhibitory peptide (GIP)
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4
Food Nutrient Digestion and Absorption
Four Hormones Regulate Digestion
1. Gastrin
2. Secretin
3. Cholecystokinin (CCK)
4. Gastric inhibitory peptide (GIP)
Digestive Secretions
Organ
Target Organ
Secretion
Action
Salivary glands
Mouth
Saliva
CHO breakdown
Gastric glands
Stomach
Gastric juice
Mixes with food
Pancreas
Small intestine
Pancreatic juice
Degrades CHO, fats, protein
Liver
Gallbladder
Bile
Stored until needed
Gallbladder
Small intestine
Bile
Emulsifies fat
Intestinal glands
Small intestine
Intestinal juice
Degrade CHO, fats, protein
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5
Food Nutrient Digestion and Absorption
Transporting Nutrients Across Cell Membranes
• Two process maintain nutrient transport
1. Passive transport through plasma membranes
without requiring energy
2. Active transport through plasma membrane, which
requires metabolic energy to “power” nutrient
exchange
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6
Food Nutrient Digestion and Absorption
Passive Transport
• Four Types
1. Simple
diffusion
2. Facilitated
diffusion
3. Osmosis
4. Filtration
FIGURE 3.1 A. Simple diffusion. B.
Facilitated diffusion. C. Osmosis. D.
Filtration
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7
Food Nutrient Digestion and Absorption
Active Transport
• Sodium-potassium
pump
– Moves food
through
semipermeable
membranes
– Requires energy
FIGURE 3.2 The dynamics of the sodium–
potassium pump
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8
Food Nutrient Digestion and Absorption
Active Transport
• Coupled transport
– Movement in one
direction
– Requires a
cotransporter
(symport)
FIGURE 3.3 Coupled transport. A molecule of glucose
and a sodium ion move together in the same direction
through the plasma membrane in a symport protein
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9
Food Nutrient Digestion and Absorption
Bulk Transport
• Energy-requiring processes
– Exocytosis: transfers substances through cell
membranes
– Endocytosis: cell’s plasma membrane surrounds
substance, pinches away and moves into
cytoplasm
o Two forms
1. Pinocytosis
2. Phagocytosis
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10
Gastrointestinal Tract Anatomy
FIGURE 3.4 Structures of the gastrointestinal tract and each structure’s digestive function
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11
Gastrointestinal Tract Anatomy
Sphincters
Control Food
Passage
FIGURE 3.5 Propulsion of nutrients through the GI tract. A.
Peristalsis involves the reflex-controlled alternate contraction and
relaxation of adjacent segments of the GI tract, which causes
one-directional flow of food with some mixing. B. Segmentation
contractions involve the alternate contraction and relaxation of
nonadjacent segments of the intestine. This localized intestinal
rhythmicity propels food forward and then backward, causing food
to mix with digestive juices
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12
Gastrointestinal Tract Anatomy
Stomach and Gastric Gland Structures
FIGURE 3.6 Stomach and gastric gland structure. The parietal cells primarily secrete hydrochloric
acid, neck cells secrete mucus, and chief cells produce pepsinogen
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13
Gastrointestinal Tract Anatomy
Stomach
• Volume averages about 1.5 liters
• Expands to 50 milliliters (1.5 oz) when empty to ~6
liters when distended following a large meal
• Contents mix with chemical substances to produce
chyme
• Following meal, stomach usually takes 1 to 4 hours
to empty depending on nutrient concentration and
volume
• Can retain a high-fat meal for up to 6 hours before
small intestine absorbs it
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14
Gastrointestinal Tract Anatomy
Small Intestine
• Three sections
1. Duodenum
2. Jejunum
3. Ileum
• Ninety percentage of all digestion occurs in the
duodenum and jejunum
• Absorption takes place in villi of intestinal mucosa
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15
Gastrointestinal Tract Anatomy
Small Intestine
• Microscopic
structure of small
intestine showing
villi and microvilli
projections
FIGURE 3.7 During digestion, bile produced
in the liver and stored and secreted by
gallbladder increases lipids’ solubility and
digestibility through emulsification
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16
Gastrointestinal Tract Anatomy
Large Intestine (Colon or
Bowl)
•
Includes cecum,
colon, rectum, anus
•
Includes cecum,
ascending colon,
transverse colon,
descending colon,
sigmoid colon,
rectum, anus
•
Serves as a storage
area for undigested
food residue (feces)
•
Absorbs water and
electrolytes
FIGURE 3.8 The large intestine, a 5-foot-long tube,
includes the cecum, colon, rectum, and anal canal.
As chyme fills the cecum, a local reflex signals the
ileocecal valve to close, preventing material from reentering the ileum and small intestine
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17
Digestion of Food Nutrients
Carbohydrate,
Protein, and
Lipid Digestion
FIGURE 3.9 Overview of
human digestion showing
the major enzymes and
hormones that act on
proteins, lipids, and
carbohydrates during their
convoluted journey from
the mouth through the GI
tract
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18
Carbohydrate Digestion and Absorption
• In the mouth, salivary amylase degrades starch to
simpler disaccharides
• Pancreatic amylase continues CHO hydrolysis
• Three enzymes on the brush border complete final stage
of CHO digestion to monosaccharides
– Maltase
– Sucrase
– Lactase
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19
Lipid Digestion and Absorption
• In the mouth, lingual lipase begins lipid digestion of
short-chain and medium-chain SFA
• Gastric lipase continues TG breakdown in the stomach
• Lipid breakdown occurs in small intestine
• Lipid breakdown occurs by emulsifying action of bile and
hydrolytic action of pancreatic lipase
• Cholecystokinin (CCK) releases from duodenum
• Gastric inhibitory peptide and secretin released in
response to high lipid content
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20
Lipid Digestion and Absorption
Fatty Acid Carbon Chain Length Affects Digestive
and Metabolic Processes
• Medium-chain triacylglycerols (MCT)
– MCT rapidly absorb into the portal vein
– Bound to glycerol and medium-chain free fatty
acids
– Bypasses lymphatic system and enters
bloodstream
– Supplements have clinical application for patients
with tissue-wasting disease or with intestinal
malabsorption difficulties
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21
Lipid Digestion and Absorption
Fatty Acid Carbon Chain Length Affects Digestive
and Metabolic Processes
• Long-chain fatty acids (LCFA)
– LCFA absorbed by intestinal mucosa reform into
TGs to form chylomicrons
o Chylomicrons move through lymphatic system
and empty into venous blood
o Lipoprotein lipase allows chylomicrons to
hydrolyze to FFA and glycerol
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22
Lipid Digestion and Absorption
FIGURE 3.10 Digestion of dietary lipids
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23
Protein Digestion and Absorption
• Pepsin initiates protein digestion in stomach
• Gastrin stimulates secretion of gastric hydrochloric acid
• Acidification of ingested food achieves five objectives
1. Activates pepsin
2. Kills pathogenic organisms
3. Improves absorption of iron and Ca++
4. Inactivates hormones of plant and animal origin
5. Denatures food proteins, making them more
vulnerable to enzyme action
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24
Protein Digestion and Absorption
Amino Acids in Liver
• One of three events occurs when AA reach liver
1. Converts to glucose (glucogenic AA)
2. Converts to fat (ketogenic AA)
3. Releases directly into the bloodstream as
plasma proteins or as free AA
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25
Vitamin Absorption
• Occurs mainly by the passive process of diffusion in
the jejunum and ileum
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26
Vitamin Absorption
• Lipids absorb fat-soluble vitamins
• Once absorbed, chylomicrons and lipoproteins transport
vitamins to the liver and fatty tissues
• Water-soluble vitamins diffuse into the blood except for
vitamin B12
– B12 combines with intrinsic factor from stomach and
absorbs it via endocytosis
• Water-soluble vitamins pass into urine when their
concentration exceeds renal capacity for reabsorption
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27
Mineral Absorption
• Fat-soluble vitamins absorbed with lipids
• Once absorbed, chylomicrons and lipoproteins
transport vitamins to liver and fatty tissues
• Water-soluble vitamins diffuse into blood, except for
vitamin B12
– B12 combines with intrinsic factor from stomach
and absorbs via endocytosis
• Water-soluble vitamins pass into urine when
concentration exceeds renal capacity for reabsorption
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28
Mineral Absorption
• Extrinsic (dietary) and intrinsic (cellular) factors control
mineral absorption
• Mineral availability in the body depends on chemical
form
• Excessive dietary fiber negatively impacts mineral
absorption
– Consuming recommended daily 30 to 40 grams of
fiber eliminates this concern
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29
Mineral Absorption
FIGURE 3.11 Absorption of minerals and their common excretion pathways
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30
Water Absorption
• Major absorption of ingested H2O and that contained in
foods occurs by the passive process of osmosis in the
small intestine
• Intestinal tract absorbs about ~9 liters of H2O daily
– 72% absorbed in proximal small intestine
– 20% absorbed from distal segment of small intestine
– 8% absorbed from large intestine
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31
Water Absorption
FIGURE 3.12 Estimated daily volumes of
water that enter the small and large
intestines of a sedentary adult and the
volumes absorbed by each component of
the intestinal tract
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32
PA Effects on Gastrointestinal Functions
• Alters blood flow dynamics
– Different modes, intensities, and durations of PA
acutely affect GI functions
o Mode
▪ Light-to-moderate intensity running results in
faster fluid GER than cycling
o Intensity
▪ Wide variability in GER at less than max
intensities impacted by PA type, training status,
timing of ingestion
o Duration
▪ No duration effects
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33
Health Status, Emotional State, and GI
Tract Disorders
GI Disorders
• Constipation: delay in
stool movement
• Diarrhea: loose,
watery stools
• Diverticulosis: small
pouches that bulge
through tissue
FIGURE 3.13 Diverticulosis and diverticulitis.
Diverticula are pockets that develop in the colon
wall. These small pouches bulge outward through
weak spots in the colon wall
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34
Health Status, Emotional State, and GI
Tract Disorders
GI Disorders
• Heartburn/reflux: sphincter between esophagus and
stomach involuntarily relaxes so stomach’s contents
flow back into esophagus
– Chronic heartburn develops into Gastroesophageal
Reflux Disease (GERD)
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35
Health Status, Emotional State, and GI
Tract Disorders
GI Disorders
• Irritable Bowel Syndrome (IBS)
– Functional GI tract disorder devoid of structural,
biomechanical, radiologic, or laboratory
abnormalities
– Afflicts up to 20% of adults
– Two IBS forms:
o Diarrhea predominant
o Constipation predominant
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36
Health Status, Emotional State, and GI
Tract Disorders
Irritable Bowel Syndrome (IBS)
•
Eight factors cause IBS
1. Increased GI motor reactivity to stress
2. Foods high in fat, insoluble fiber, caffeine, coffee,
carbonation, alcohol
3. Dysfunction of the CCK release system
4. Impaired bowel gas transit
5. Visceral hypersensitivity
6. Impaired reflex control
7. Autonomic dysfunction
8. Altered immune activation
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37
Health Status, Emotional State, and GI
Tract Disorders
Irritable Bowel Syndrome (IBS)
• Four common IBS symptoms
1. Cramping abdominal pain relieved by defecation
2. Altered stool frequency
3. Altered stool form (mucous, watery, hard, or
loose) and passage (strain, urgency, or sense of
incomplete evacuation)
4. Abdominal distension following meals
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38
Health Status, Emotional State, and GI
Tract Disorders
Irritable Bowel Syndrome (IBS)
• Four lifestyle and dietary modifications to counter
IBS
1. Stress reduction
2. Daily small meals
3. High-fiber diet
4. Avoiding foods with lactose and candy with
sorbitol
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39
Health Status, Emotional State, and GI
Tract Disorders
GI Disorders
• Gas: Flatus (lower tract intestinal gas) composition
depends on nutrient intake and the colon’s bacterial
population
– CHO produce most gas; fats and proteins least
– In large intestine, bacteria degrades undigested
CHO to produce H+, CO2, and methane gas, which
exit through the rectum
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40
Health Status, Emotional State, and GI
Tract Disorders
GI Disorders
• Functional Dyspepsia—chronic pain in upper
abdomen without physical cause
– Vague GI symptoms: stomach gnawing or burning,
epigastric pain, nausea, vomiting, belching,
bloating, indigestion, abdominal discomfort
– Three most common causes for dyspepsia
1. Peptic ulcer disease
2. GERD
3. Gastritis (stomach inflammation)
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41
Physical Activity Effects on
Gastrointestinal Functions
• PA alters blood flow dynamics
– Depends on modes, intensities, and durations that acutely
impact GI functions
• Five factors affect gastric emptying rate (GER)
1. Volume: larger food volume increases GER
2. Kilocalorie: content—higher kilocalorie solutions decrease
GER
3. Osmolality: higher food osmolality decreases GER
4. Temperature: cooler foods increase GER
5. pH: higher acidic foods decrease GER
• GER also impacted by emotional state, caffeine, environmental
conditions, menstrual cycle stage, and fitness status
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