Transcript Chapter 6 Presentation

Chapter 6
Digestion and
Absorption; Alcohol
What Happens to the Food We Eat?
 The food we eat undergoes three processes:
1)
Digestion
2)
Absorption
3)
Elimination
 These processes occur primarily in the gastrointestinal
tract.
What Happens to the Food We Eat?
 Gastrointestinal (GI) tract: series of organs arranged as a
long tube
 The GI tract includes:
 organs such as the stomach, liver, and intestines
 Table 6.1
 sphincters
 muscles that control the passage of material from one
organ to the next
Gastrointestinal Tract
Digestion
 Digestion
 the process of breaking large food molecules down into
smaller molecules
 Digestion includes breaking food down:
 Mechanically
 Includes peristalsis
 chemically
Digestion Overview – Smell/Taste
Digestion Overview - Mouth
 Digestion begins in the mouth
 Mechanical
 Chewing
 Chemical
 Saliva: lubricates and contains enzymes
 Start to digest CHOs
 Food becomes a bolus
 Bolus enters esophagus
 Peristalsis
 No digestion
Enzymes
 Enzyme
 A protein that induces a chemical change in another
substance
 Enzymes speed up the rate of chemical reactions.
 Typically end in “ase” (amylase)
 Digestion is dependent on many different enzymes.
Digestion Overview - Stomach
 The lower esophageal sphincter separates the esophagus
from the stomach.
 Digestion in the stomach includes:
 extensive mechanical digestion, mixing food with gastric juice to
produce chyme
 chemical digestion of proteins and fats
 Holds food for 2 to 6 hours
Gastric Juice
What It Is
What It Does
Mucus
Keeps stomach from digesting itself
HCl
Denatures PRO; activates pepsin
Intrinsic Factor
Protects vitamin B12 until it can be
absorbed
Proenzyme converted to pepsin (an
Pepsinogen
Hormones
enzyme) for PRO digestion
Regulate digestive process and enzyme
release
Gastric lipase
Enzyme that begins digestion of fat
Anatomy of Stomach
Digestion Overview - Small Intestine
 Duodenum
 Neutralizes stomach
acid (bicarb)
 Pancreatic enzymes
take over
 Gallbladder releases
bile
 Jejunum
 Majority of digestion
and absorption
 Ileum
 Vitamin B12 absorption
and immune functions
Small Intestine Anatomy
Folds
Villi & Microvilli
 Secrete digestive enzymes
and absorb nutrients
Small Intestine Anatomy
Small Intestine Summary
Accessory Organs
 Liver: largest digestive organ
 produces bile
 emulsifies fats
 Receives products of
digestion
 Gallbladder
 Stores and releases bile
 Pancreas
 produces many hormones and digestive enzymes
 produces bicarbonate
Digestion Overview – Large Intestine
 Very little digestion*
 Absorption of water and
sodium
 Formation of waste for
elimination
 Remains 12-24 hours
 *Filled with bacteria!
Bacterial Flora
 About 100 trillion bacteria in large intestines
 They help metabolize remaining nutrients
 Break down some fibers to create short-chain fatty acids
 Fuel supply for colonic cells
 They produce vitamin K and B vitamins
 Why newborns get a vitamin K shot
 Is this why pre/probiotics are important?
Pre/Probiotics
 Probiotics:
 Live microbial products (lactobacillus and Bifidobacterium)
that health of the gut
 Restore microbial balance
 Prebiotics:
 Food for the probiotics and good gut bacteria
 Indigestible CHO sources (inulin)
 Synbiotics
 Combo of pre and probiotics (supplements)
Pre/Probiotics
 Possible health benefits include:
 Decreased diarrhea and constipation
 Decreased growth of H. Pylori
 Enhanced immunity
 Increased nutrient absorption
 Reduced risk of colon cancer
 Fewer allergies in kids
 Improved blood lipids
 Lower blood pressure
© 2013 Pearson Education, Inc.
Pre/Probiotics
Where To Find
Prebiotics:
Where To Find
Probiotics:

Asparagus

Fermented Foods:

Bananas

Yogurt

Oatmeal

Kefir

Jerusalem artichokes

Buttermilk

Legumes

Tempeh

Onions

Miso

Leeks

Sauerkraut

Cabbage

Some pickles
Follow The Path
 Now that we have learned
the basics, let’s look at
what happens when we
eat a turkey sandwich on
whole wheat bread with
lettuce, tomato, cheese,
and avocado
Digestion - Mouth
 Digestion begins in the mouth.
 Chewing is the mechanical digestion that breaks all food
into smaller pieces.
 Some chemical digestion takes place.
 Saliva lubricates and contains amylase – an enzyme
produced by the salivary glands.
 Salivary amylase begins the chemical digestion of
carbohydrates.
 Maltose & dextrins
Salivary amylase
Mouth Summary
Digestion – Through Esophagus
Digestion - Stomach
 Acidic HCl (from gastric juice) stops salivary amylase
activity

No CHO digestion
 HCl activates enzymes that start PRO and fat digestion
 Pepsinogen
Pepsin
 Lingual and gastric lipases (fats)
 HCl denatures PROs
 Mechanical digestion through churning
 Still, minimal digestion takes place
 Absorption of alcohol
Digestion - Stomach
Lingual/Gastric lipase
Pepsin
Minimal digestion
Smaller PRO units
Stomach Summary
Digestion – Small Intestine
 From the stomach, chyme is slowly released through the
pyloric sphincter to the small intestine.
 **Most digestion and absorption occur in the small
intestine.
 Absorption: the process by which molecules of food are
taken from the GI tract into the body.
Small Intestine - CHOs
 Pancreatic amylase
dextrins
maltose
 Intestinal cells release disaccharide-specific enzymes
Enzyme
Digests
Into
Maltase
Maltose
Glucose + glucose
Sucrase
Sucrose
Glucose + fructose
Lactase
Lactose
Glucose + galactose
 Monosaccharides are absorbed into capillaries
 Go to liver
All become glucose
Small Intestine - Fat
 Problem:
 Fats and watery digestive juices do not mix well
Bile
gallbladder
 _______
is released from the _______________
to help
 Process is called:
 Emulsification
Bile
 Very important in lipid digestion
 Sometimes called bile salts
 Acts as an emulsifier
 What is an emulsifier?
 A substance that suspends lipid/fat in a watery solution
Water
Lipid
Emulsification
Lipid does not like
water and sits on top
Fat is emulsified
in watery fluid
E
M
U
L
S
I
F
I
E
R
Small Intestine - Fat
 Now that fats are emulsified
 Pancreatic lipase can digest triglycerides
 Fatty acids and glycerol
Pancreatic
lipase
Small Intestine - Fat
 Now that triglycerides broken down
 Absorbed and reformed in chylomicrons
 With fat-soluble vitamins and cholesterol
 Get transported from lacteal to lymph
 Empty into blood through left subclavian vein
 Go to liver and cells
Small Intestine - Protein
 Pancreas releases peptidases
 Proteins into peptides
 Small intestine releases other enzymes
 Peptides into amino acids
Protein
Peptides
Amino Acids
 Amino acids absorbed into capillaries and go to the liver
Small Intestine Summary
Large Intestine
 Fiber and other undigested particles
 Colonic bacteria digest some fibers
 Short-chain fatty acids
 Make some vitamins (K & B)
 Absorb water and sodium
 Prepare waste for elimination
 After 12-24 hours
Large Intestine Summary
Vitamins & Minerals & Water
 Vits/Mins: Already in the smallest form
 Fat-soluble vitamins need to be transported
in chylomicrons
 A, D, E, K
 Water-soluble nutrients go through blood
 B12 needs intrinsic factor
 Water absorbed in small and large intestines
 Follows sodium, glucose across intestinal wall
Digestion Review
 Digestive System Video
Disorders Related to Digestion
 The lining of the stomach is designed to cope with
hydrochloric acid (HCl), but other regions of the GI tract
are not.
 Heartburn is caused by HCl in the esophagus.
 GERD, or gastroesophageal reflux disease, is painful,
persistent heartburn.
GER or GERD
Disorders Related to
Digestion
Peptic ulcers are
regions of the GI
tract that have
been eroded by
HCl and pepsin.
The bacterium
Helicobacter pylori
contributes to the
production of
both gastric and
duodenal ulcers.
Disorders Related to Digestion
 Food intolerance is a group of GI symptoms associated
with eating a particular food.
 No immune system involvement
 Symptoms may include gas, pain, and diarrhea.
 Lactose intolerance is an example.
Disorders Related to Digestion
Food allergies: a response
of the immune system
caused by a particular
food component
In some people, food
allergies can be mild.
In others, food allergies
can be quite severe and
require immediate
medical attention.
Disorders Related to Digestion
 Celiac disease is an immune
system response to eating
gluten, a protein found in
wheat, rye, and barley.
 The immune response damages
the villi in the small intestine,
leading to decreased
absorption of certain nutrients.
 Celiac disease is considered a
genetic disorder.
 Treatment involves a gluten-free
diet.
Disorders Related to Digestion
 Diarrhea:
 can be caused by infection of the GI tract, chronic disease,
food intolerances, stress, and bowel disorders
 can lead to severe dehydration
 is more dangerous for infants, young children, and older
adults
Disorders Related to Digestion
 Constipation:
 can be caused by the disruption of a person's schedule, a
change in diet, or certain medications
 may be treated by increasing fluid and fiber consumption
Disorders Related to Digestion
 Irritable bowel syndrome (IBS) is a disorder that interferes
with normal colon function.
 Symptoms of IBS include:
 abdominal cramps and bloating
 either diarrhea or constipation
 IBS is more common in women than in men.
Disorders Related to Digestion: IBDs
Ulcerative Colitis
Crohn’s Disease
 Inflammation of the large
intestine
 Inflammation of the small
and large intestines
Alcohol
 Contained in beverages made from fermented fruits,
vegetables, or grains
 High-energy compound: contains 7 kcal/g
 Not a nutrient since it is not essential and impairs body
functions
Alcohol
 Dietary Guidelines for Americans recommends that any
alcohol consumption should be done in moderation.
 What is moderation?
 No more than 1 drink/day for women, 2 drinks/day for men
 There is no safe level for women who are pregnant or
breastfeeding.
 “Legal” BAC limit in AZ <0.08%
 If >0.08% = loss of license
 See Table 6.4
Alcohol
 One drink is the
amount of a
beverage that
supplies ½ fluid ounce
of alcohol:
 1 ½ oz of distilled
spirits
 5 oz wine
 12 oz beer
 1 wine cooler
Metabolism of Alcohol
 Alcohol is not digested but is absorbed directly
through the stomach and intestine.
 Alcohol is transported to the liver, where it is
metabolized at the rate of approximately 1
drink/hour.
 Excess alcohol is released to the blood and
excreted in urine, breath, and sweat.
 Does coffee/caffeine help?
Levels of Consumption
Level
Amount
Moderate
Up to 1 per day women; 2 per day men
Heavy
8+ drinks/week women; 15+ drinks/week men
Binge
3+ drinks/time women; 5+ drinks/time men
Alcohol and Liver Metabolism
 Liver is the ONLY organ that can metabolize alcohol
 Alcohol absorbs faster than nutrients
 Alcohol absorbs faster on empty stomach
 Liver metabolizes at rate of 1 drink per hour
Alcohol and the Brain
 Decreases inhibitions, reasoning, judgment
 Induces relaxed feelings
 Impairs speech, vision, muscle movements
 Impairs breathing, heart rate
 Loss of consciousness
 Kills brain cells
Alcohol and the Brain
Alcohol and Health Benefits
 Moderate alcohol consumption is linked to:
 Improved lipid profiles
 Reduced risk of blood clots in arteries
 Stimulated appetite in the elderly
 Possible lower risk of cognitive impairment and other
forms of dementia
 Stronger bones in older adults
 Red wine contains polyphenols
 Catechin and resveratrol
 Found in grape skins/seeds
Alcohol and Health Risks
 Moderate alcohol consumption is linked to:
 Possible increase in the risk for breast cancer
 Possible increase in the risk for hypertension
 Possible increased total calorie consumption and therefore
increased risk of obesity
 Interactions with medications
 Possible reduced intake/absorption of vitamins/minerals
 Wernicke-Korsafoff syndrome
Alcohol and Health Risks
 Alcohol abuse:
 drinking too much, too often, or at inappropriate times or
situations
 Binge drinking:
 the consumption of five or more drinks on one occasion.
 Alcohol consumption that overwhelms the liver's ability to
detoxify the blood can result in alcohol poisoning.
Alcohol and Health Risks
 Chronic alcohol abuse can lead to alcoholism, a
disease characterized by:
 craving alcohol
 inability to stop drinking
 physical dependence
 tolerance
 Chronic alcohol abuse
severely damages the liver.
fatty liver
hepatitis
cirrhosis
Fetal Alcohol Syndrome
 Alcohol is a teratogen –
 a substance known to cause birth defects.
 Alcohol crosses the placenta and enters the fetus.
 A fetus cannot metabolize alcohol, so it accumulates in
the fetal bloodstream.
Fetal Alcohol Syndrome
 Fetal alcohol syndrome (FAS) is a group of birth defects
found in children whose mothers consumed alcohol
during pregnancy.
 Children with FAS typically have emotional, behavioral,
social, learning, and developmental problems
throughout life.
100% Preventable!!
Don’t Do It!!!