Stephenson 2ed_ch04_lecture_PPT.pptx

HUMAN
NUTRITION
Science For Healthy Living
Second Edition
Tammy J. Stephenson, PhD
University of Kentucky
Wendy J. Schiff, MS, RDN
© 2019 McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior written consent of McGraw-Hill Education.

© 2019 McGraw-Hill Education
2
Chapter 4
Human Digestion, Absorption,
and Transport
Lecture Outline

3
4.1 Overview of the
Digestive System
Learning Outcomes
1. Identify the major components of the digestive
system and the major functions of each component.
2. Describe the distinct layers of the gastrointestinal
tract wall.
3. Identify the location, anatomical name, and function
of each sphincter involved in the digestive system.
4. Explain the differences between chemical and
mechanical digestion.

4
Roles of the Digestive System
The primary roles of the digestive system are:
• The breakdown of food into nutrients
• Absorption of nutrients
• Elimination of solid waste products
Digestion is the process of breaking down large
food molecules into nutrients that the body can use
Absorption is the uptake and removal of nutrients
from the digestive tract (gastrointestinal tract),
alimentary canal, or gut

5
Components of the Digestive System
The digestive system has
two major components:
• GI tract
• Hollow, muscular tube
• Accessory organs
• Assist functioning of GI tract
Jump to long description

6
The Wall of the GI Tract1
The wall of the GI tract has distinct layers:
• Mucosa
• Innermost layer of the digestive tract wall
• Mucus, a watery slippery fluid, is secreted from special
cells here
• Surrounds the lumen, a hollow space through which food and
fluids can pass
• Muscular layer
• Circular
• Longitudinal

7
The Wall of the GI Tract2
By relaxing and
contracting, the
muscles can:
• Mix substances in
the lumen
• Control movement
of material through
the tract

8
Muscle Layers of the Stomach
The wall of the
stomach is the
thickest and
strongest of the GI
tract
• Third type of
muscle, diagonal
muscle

9
Sphincters Control the Flow of
GI Contents
Sphincters - thickened regions of circular muscle
that control the flow of contents at various
points in the GI tract
• When contracted:
• Passageway closed
• Flow is restricted
Essential for normal digestion and absorption

10
Two GI Tract Sphincters

11
Mechanical and Chemical Digestion
Mechanical digestion - the physical treatments
that food undergoes while it is in the intestinal
tract
Chemical digestion - the breakdown of large
molecules in food into smaller components,
primarily by the action of stomach acid and
various enzymes, proteins that speed up the
rate of a chemical reaction without being
altered in the process

12
Assess Your Progress 4.1
1. List the primary and accessory components
of the GI tract.
2. What is a sphincter?
3. Explain the difference between mechanical
and chemical digestion.
4. What is a hydrolytic enzyme?

13
4.2 The Mouth
Learning Outcomes
1. Describe the mechanical and chemical digestion
that occurs in the mouth.
2. Identify and explain the effects of smell and taste
disorders in humans.

14
Digestion Starts in the Mouth
Oral cavity is another term for mouth
• Digestion starts here
Teeth masticate food
• Prepares food for swallowing and chemical digestion
Tongue helps direct food into the pharynx, the
section of alimentary canal that connects the
nasal cavity with the top of the esophagus

15
Salivary Glands1
Salivary glands - structures that produce saliva
and secrete the fluid in the oral cavity
Saliva - the watery fluid that contains mucus and
a few enzymes
• Lysozyme - enzyme in saliva that can destroy some
bacteria that are in food or the mouth
• Salivary amylase - enzyme in saliva that begins
starch digestion
• Lingual Lipase - enzyme secreted in saliva that
begins fat digestion

16
Salivary Glands2

17
Taste Buds
Taste buds have
specialized cells that
help distinguish five
basic tastes:
• Sweet
• Sour
• Salty
• Bitter
• Umami

18
Sense of Smell
The sense of smell
(olfaction) contributes
to the ability to taste
food
Airborne chemicals in
chewed food stimulate
the olfactory region of
the nasal passages

19
Disorders of Taste and Smell
Anosmia - the complete inability to detect odors
Hypogeusia - the diminished ability to taste
substances
Ageusia - the total loss of the ability to taste
substances

20
5. Explain what normally happens to a piece of
food that enters the mouth.
6. Identify the key components of saliva.
7. List the taste sensations that human taste
buds detect.
8. Discuss disorders of taste and smell, including
their causes.

21
4.3 The Esophagus
Learning Outcomes
1. Describe the action of swallowing and what it
accomplishes.
2. Identify the muscular activity that propels a mass of
food through the esophagus.
3. Explain what happens when someone is choking on
food and demonstrate the first aid techniques
employed to save the person’s life.
4. Identify the two esophageal sphincters and their
functions.

22
The Esophagus
After being swallowed, the food bolus travels
through the esophagus
• Muscular tube that extends about 10 inches from
the pharynx to the upper portion of the stomach
• Entrance is near the larynx and opening of trachea

23
What Happens When You Swallow
The epiglottis is a flap of tough tissue that prevents the
food from entering the larynx and trachea

24
First Aid for Choking

25
Peristalsis
Peristalsis - waves of
muscular
contractions that
help move material
through most of the
digestive tract
• Involuntary response

26
Esophageal Sphincters
Upper esophageal sphincter
(UES) - the region of the upper
part of the esophagus that
opens to allow a mass of food
to enter the esophagus
Lower esophageal sphincter
(LES) - the region of the lower
part of the esophagus that
controls flow of material into
the upper part of the stomach
• Gastroesophageal sphincter
• Prevents backflow of stomach
contents

27
9. Describe peristalsis. Explain how peristalsis in
the esophagus transfers a bolus of food from
the throat to the stomach.
10.Explain why choking can occur while eating.
What should you do to save a choking
person’s life?
11.What normally keeps stomach contents from
reentering the esophagus?

28
4.4 The Stomach
Learning Outcomes
1. Identify the types of cells in the gastric glands and
what each secretes.
2. Describe the kinds of mechanical and chemical
digestion that occur in the stomach.
3. List the components of gastric juice.
4. Discuss factors that influence stomach emptying.

29
Secretions of the Stomach1
The stomach is a muscular sac that stores and
mixes food
Gastric glands located in the stomach synthesize
and secrete gastric juice
• A collection of stomach secretions that includes
mucus, hydrochloric acid, intrinsic factor, and
digestive enzymes
Mucous cells secret mucin, a carbohydrate-rich
substance that forms mucus when combined
with water

30
Secretions of the Stomach2
Parietal cells secrete hydrogen and chloride ions, which
form hydrochloric acid (HCl) and intrinsic factor
• Intrinsic factor is a substance necessary for absorbing
vitamin B‒12
Chief cells secrete gastric lipase and some chemically
inactive digestive enzymes like pepsinogen
G cells secrete gastrin, a hormone that stimulates
stomach motility and gastric gland secretions
• Hormones are chemical messengers that convey information
to target cells

31
Gastric Gland and Its Secretory Cells

32
Gastric Gland Cells
Gastric Gland Cells Secretion Major Functions
Mucous Mucus Protects stomach mucosa
from HCl and enzymes
Parietal Components that form
HCl (hydrogen ions [H+]
and chloride ions [Cl-])
Intrinsic factor
Activates pepsinogen,
destroys many food-borne
microbes
Facilitates the absorption of
vitamin B-12
Chief Pepsinogen
Gastric lipase
Digests protein after
conversion to pepsin
Digests small amount of fat
G cell Gastrin Stimulates stomach motility
and gastric gland activity

33
Lower Portion of the Stomach
The main function of the lower portion of the
stomach is mixing food with gastric juice to form
chyme, a semiliquid mass
The pyloric sphincter regulates the flow of
chyme into the small intestine

34
Digestion in the Stomach
The presence of food in the stomach stimulates
peristalsis
• Mixes food with gastric juices
• Some protein and fat is broken down
Few substances are absorbed in the stomach
HCl contributes to low pH of gastric juice
• Acidic solutions have a pH value lower than 7
• pH of chyme is 2.0
• Alkaline solutions have a pH value higher than 7

35
pH Scale
Lemon and Wine: ©Brand X Pictures/Getty Images RF; Cola: ©FoodCollection/StockFood RF; Tomato and Banana:
©Stockbyte/Getty Images RF; Coffee: ©Fuse/Getty Images RF; Milk: ©McGraw-Hill Education. Bob Coyle, photographer; Egg:
©Siede Preis/Getty Images RF; Household items: ©McGraw-Hill Education. Stephen Frisch, photographer; Ammonia:
©McGraw-Hill Education. Jacques Cornell, photographer; Oven cleaner: ©McGraw-Hill Education. Ken Karp, photographer

36
Acid in the Stomach
Acidic environment of stomach causes:
• Salivary amylase to cease
• Lingual lipase to become active
• Pepsinogen to be converted to pepsin, which begins the
enzymatic digestion of protein
Mucus is a slippery secretion that protects the stomach
from being damaged by its acid and digestive enzymes
• Produced by mucous cells
• If the layer of mucus breaks down, HCl and gastric enzymes
contact the stomach wall and gastric or peptic ulcers can form

37
Stomach Emptying
Stomach empties in about 4 hours following a
meal
• Varies with contents and size of meal
Dumping syndrome - a disorder that occurs when
chyme flows too rapidly into the small intestine
• Often occurs after surgeries of the esophagus or
stomach
• Changing the types of food eaten (fewer sugary
foods), eating smaller meals, and taking certain
medications may help

38
12.Identify the four different gastric gland cells
and the secretions they produce.
13.Describe the digestive processes that occur
in the stomach.
14.Explain how the stomach protects itself from
digestion. What conditions might occur if this
protection fails?
15.List factors that influence stomach emptying.

39
4.5 The Small Intestine
Learning Outcomes
1. Identify the three primary digestive sections of the
small intestine.
2. Describe the functions of the digestive system’s
accessory organs.
3. Discuss the functions of intestinal villi.
4. Compare and contrast the ways nutrients may be
absorbed.

40
Parts of the Small Intestine1
The small intestine has three sections:
• Duodenum - first segment of the small intestine
• Jejunum - middle segment of the small intestine
• Ileum - last segment of the small intestine
Chyme moves out of the ileum into the large
intestine, passing through the ileocecal
sphincter, which controls the rate that ileum
contents empty into the large intestine

41
Parts of the Small Intestine2

42
Accessory Organs1
The liver, gallbladder, and pancreas are
accessory organs of the gastrointestinal system
• Chyme does not
pass through them
• Play a major role in
digestion

43
Accessory Organs2
The liver:
• Processes and stores many nutrients
• Synthesizes cholesterol
• Makes bile, a greenish-yellow, bitter-tasting fluid
stored in the gallbladder until it is needed for fat
digestion and absorption
The gallbladder stores and concentrates bile
The pancreas produces and secretes digestive
enzymes and bicarbonate ions to neutralize
acidic chyme when it enters the duodenum

44
Digestion in the Small Intestine
The small intestine is the major site of chemical and
mechanical digestion
• Enzyme activity
• Peristalsis
• Segmentation - regular contractions of circular intestinal
muscles followed by relaxations that mix chyme within a
short portion of the small intestine

45
Major Pancreatic and Intestinal Enzymes
Enzyme Source Action
Pancreatic amylase Pancreas Digests starch
Pancreatic lipase Pancreas Digests fat
Trypsin, chymotrypsin Pancreas Partially digest proteins
Carboxypeptidase Pancreas Breaks down certain
partially digested proteins
Nuclease Pancreas Digests DNA and RNA into
nucleotides
Peptidase Small intestine Breaks down certain
partially digested proteins
Sucrase, maltase, lactase Small intestine Break down certain sugars
into simpler sugars
Intestinal lipase Small intestine Digests fat

46
Villi and Surface Area
Villi - tiny, fingerlike projections of the small intestinal
mucosa that are involved in digestion and nutrient
absorption
• Cover the folds of the mucosa of the small intestine
• Enterocytes - absorptive cells that form the outer layer of a
villus
The end of the enterocyte exposed to chyme contains
microvilli, tiny, hairlike projections that form the brush
border of an enterocyte
• Contain brush border enzymes that help digest protein and
carbohydrates

47
Small Intestinal Absorption
Villi are absorptive structures
Enterocytes remove nutrients from chyme and
enable them to enter the intestinal blood or
lymph vessels

48
Nutrient Absorption
Nutrient absorption
can occur by:
• Simple diffusion
• Facilitated diffusion
• Active transport
• Osmosis
• Endocytosis

49
Core of the Villus
The core of the villus contains:
• Arteriole
• Capillary network
• Venule
• Lacteal - a vessel of the lymphatic system
Nutrients from chyme are absorbed into either the
capillary network or the lacteal
Water-soluble nutrients and certain fats are absorbed
into the capillary network
• Travel to the liver via the hepatic portal vein
Most lipids undergo specialized processing before they
enter the lacteals

50
Transporting Absorbed
Nutrients to the Liver

51
16.List the three primary sections of the small
intestine, and indicate their functions.
17.Where is bile synthesized and stored?
18.Where does most nutrient digestion and
absorption occur?
19.Explain how the structure of villi increases
the surface area available for absorption.
20.Identify five ways that nutrients can enter
enterocytes.

52
4.6 The Large Intestine
Learning Outcomes
1. Identify the sections of the large intestine.
2. Describe the role of the large intestine in nutrient
absorption and waste elimination.

53
Parts of the Large Intestine
After moving through the ileocecal sphincter,
unabsorbed water and undigested remains of chyme
enter the:
• Cecum
• First segment of the
large intestine
• Ascending colon
• Transverse colon
• Descending colon
• Sigmoid colon
• Rectum
• Last segment of the
large intestine
• Anus

54
Functions of the Large Intestine
Little absorption takes place in the large intestine
• Some water and minerals
Goblet-cells are intestinal cells that secrete mucus
• Primary secretion of the large intestine
As food residue passes through the colon, water is
absorbed, forming feces
The external anal sphincter allows feces to be expelled
from the anus and is under voluntary control

55
21.List the main sections of the large intestine
from the ileocecal sphincter to the anus.
22.What happens to chyme when it is in the
large intestine?
23.What is the typical composition of feces?
24.Trace the pathway of food from the mouth to
the anus, including key organs and their
functions.

56
4.7 Microbes in the Digestive Tract
Learning Outcomes
1. Discuss the importance of bacteria in the digestive
tract.
2. Describe the role of prebiotics and probiotics in
human health and provide an example of each.

57
Actions of Intestinal Bacteria
A healthy large intestine is home to vast
numbers of various bacteria (gut microbiota)
• Break down (ferment) undigested food
• Synthesize vitamins K, B‒12, thiamin, and biotin
• Produce substances that colon cells can use for
energy
• Metabolize certain phytochemicals (phenols) into
forms that can be absorbed and used by the body

58
Probiotics and Prebiotics
Probiotics are live microorganisms that promote
good health for their human hosts
• Lactobacillus
• Bifidobacterium
Prebiotics are substances in food that are poorly
digested by humans but support and promote
the growth of probiotics in the colon

59
Gut Microbiota Transplantation
Gut microbiota transplantation (GMT) –
commonly referred to as “fecal transplantation,”
the introduction of fecal material from one
person into another person’s colon
• Used to treat C-diff infection
• May benefit people with chronic intestinal disorders
• Ulcerative colitis
• Crohn’s disease

60
25.Summarize the roles intestinal bacteria play
in human health.
26.Explain the difference between a probiotic
and prebiotic, and give an example of each.

61
4.8 Hormonal Regulation of Digestion
Learning Outcomes
1. Describe how gastrin, secretin, and cholecystokinin
(CCK) regulate digestion.

62
The Hormones of Digestion
Three hormones play key roles in digestion:
• Gastrin - hormone secreted by G cells that stimulates
stomach motility and gastric gland secretions
• Secretin - hormone secreted by the duodenum and
first part of the jejunum that stimulates the pancreas
and liver to release a bicarbonate-rich solution into
the small intestine
• Cholecystokinin - hormone secreted by the mucosa
of the small intestine that stimulates the gallbladder
to contract and the pancreas to release pancreatic
juice into the small intestine

63
Actions of Key Digestive Hormones
in the GI Tract
Hormone
Primarily
Released from Responds to Key Actions
Gastrin Stomach Food entering the
stomach
Triggers parietal cells to release HCl
and chief cells to release
pepsinogen
Stimulates stomach and small
intestinal motility
Secretin Small intestine Acidic chyme
entering the
duodenum and first
part of jejunum
Stimulates the release of a
bicarbonate-rich solution from the
liver and pancreas
Cholecysto-
kinin (CCK)
Small intestine Fat and breakdown
products of proteins
(peptides) entering
the small intestine
Stimulates release of bile from the
gallbladder into the small intestine
Stimulates the release of
pancreatic enzymes, decreases
stomach secretions, and slows
stomach motility

64
27.Identify the three major gut hormones,
including the tissues from which they are
released, the factors causing their release,
and their key actions.

65
4.9 Common Digestive Tract Disorders
Learning Outcomes
1. Identify and describe common gastrointestinal
health problems.
2. Discuss preventative measures and treatments for
constipation, diarrhea, vomiting, heartburn, ulcers,
inflammatory bowel syndrome (IBS), and irritable
bowel disease (IBD).

66
Constipation
Constipation - infrequent bowel movements and
feces that are difficult to eliminate
• Can be caused by
• Lack of dietary fiber
• Low water intake
• Anxiety
• Depression
• Changes in typical routine
• Ignoring the urge to have a bowel movement

67
Hemorrhoids
Hemorrhoids - clusters of
small veins in the anal
canal
Chronic constipation and
straining during bowel
movements can play a
role in the development
of inflamed and swollen
hemorrhoids

68
Diverticulosis and Diverticulitis
Diverticula - Small pouches that form in the wall
of the colon
• Diverticulosis - the condition characterized by the
presence of diverticula
• Diverticulitis - the condition characterized by
inflamed diverticula
• Bacteria or feces become trapped in the little pouches
• Blood vessels may become damaged and cause rectal
bleeding

70
Diarrhea
Diarrhea is a condition characterized by
frequent, watery bowel movements
• More water secreted into GI tract
• Less water absorbed by GI tract
Most cases are caused by bacterial or viral
infections

71
Vomiting
Vomiting is an effective
way of removing
harmful food or
beverages
Vomiting generally does
not last longer than 24
hours
Repeated vomiting can
lead to dehydration
Vomiting Danger Signs
1. Lasts longer than a few hours
(children under 6 years of age)
2. Lasts longer than a day (people
over 6 years of age)
3. Is accompanied by:
Blood in vomit (looks like coffee
grounds)
Signs of dehydration
Diarrhea
Fever
Weakness
Headache or stiff neck
Severe abdominal pain
Confusion or decreased
alertness

72
Acid Reflux (Gastroesophageal Reflux)
Gastroesophageal reflux (GER) - commonly
called heartburn or acid reflux; the pain
generally felt in the upper chest that results from
the passage of acidic contents from the stomach
into the esophagus
Gastroesophageal reflux disease (GERD) - a
chronic condition characterized by frequent
heartburn that can damage the esophagus

73
Acid Reflux Damage
An endoscopic view of
the esophagus near
the opening of the
stomach
The reddened areas
are signs of damage
caused by acid reflux
©David M. Martin, M.D./Science Source

74
Factors That Contribute to or Worsen GER
Having excess body fat, especially around the
waistline
Drinking alcohol and coffee
Overeating
Eating chocolate, peppermint, and greasy or
spicy foods
Eating foods that contain tomatoes
Smoking or inhaling secondhand smoke

75
Recommendations to Reduce the
Risk of Heartburn
1. Lose excess body weight.
2. Do not lie down within 3 hours after eating a meal.
3. Do not overeat at mealtimes.
4. Avoid smoking cigarettes or breathing secondhand
smoke.
5. Elevate the head of the bed so it is about 6 to 8
inches higher than the foot of the bed.
6. Do not wear tight belts or clothes with tight
waistbands.
7. Learn to recognize foods and beverages that cause
heartburn.

76
Peptic Ulcer
A peptic ulcer is a sore
that occurs in the
lining of the stomach
or the upper small
intestine
• Symptoms include:
• Deep, dull upper
abdominal pain
• Feeling of fullness 2
hours after eating
Factors that increase
the risk of peptic ulcers:
• Infection with H. pylori
• NSAIDs
• Alcohol consumption
• Genetics
• Smoking
• Excess stomach acid
production

77
Helicobacter pylori
Responsible for the
development of most
stomach ulcers
People infected with H.
pylori are given
antibiotics, as well as
medications that reduce
stomach acid production
©Science Photo Library RF/Getty Images RF

78
Irritable Bowel Syndrome
Irritable bowel syndrome
(IBS) - a condition
characterized by intestinal
cramps and abnormal
bowel function
• Diarrhea, constipation, or
alternating episodes of
both
• Women are more likely to
suffer than men
• Cause is unknown
Foods and beverages often
eliminated in IBS diets:
• Fatty foods
• Some milk products
• Drinks that contain alcohol
or caffeine
• Drinks that contain large
amounts of artificial
sweeteners
• Beans, cabbage, cauliflower,
and other foods that
contribute to intestinal gas

79
Inflammatory Bowel Disease
Inflammatory bowel disease (IBD) - a condition
that is characterized by chronic inflammation of
the GI tract
• Crohn’s disease - a type of IBD; the body’s immune
system cells attack normal intestinal cells, damaging
parts of the intestines
• Ulcerative colitis (UC) - a type of IBD that causes
ulcers to form in the mucosa of the colon and
rectum

80
28. What are potential long-term consequences of frequent
untreated constipation?
29. Explain why vomiting for 24 hours and longer can be serious
enough to require medical attention.
30. Identify potential health effects of untreated, frequent GERD.
31. What factors contribute to the development of peptic ulcers?
32. What dietary recommendations would you provide to a
person experiencing irritable bowel syndrome (IBS)?
33. Describe the differences between Crohn’s disease and
ulcerative colitis.

81
Case Study1
Annie is a 20-year-old college junior who is taking a full
course load. She is also actively involved in three
student organizations, and she volunteers over 10 hours
a week at the local hospital. Six months ago, Annie
experienced frequent bouts of diarrhea, followed by
several days of constipation.
At first, the diarrhea was mild, only once every few
weeks, but over the past few days, the diarrhea has
become daily, making it difficult for her to continue
attending classes and volunteering at the hospital.

82
Case Study2
After examining Annie and taking her history, a
physician at the university’s Student Health Center tells
the young woman that she has irritable bowel
syndrome (IBS). The physician refers her to a registered
dietician who helps Annie understand how she can
prevent and manage the symptoms of IBS.

83
Case Study3
1. What is IBS, and how does it differ from
inflammatory bowel disease (IBD)?
2. What are the long-term consequences to
untreated IBS?
3. Are there certain foods and/or beverages that
Annie should avoid?
4. What lifestyle changes should Annie consider
to manage IBS?

84
Appendix of Image
Long Descriptions

85
Components of the Digestive System - Appendix
The digestive system includes the salivary glands, teeth, tongue,
and pharynx in the mouth, and the esophagus, pancreas, liver,
stomach, gallbladder, small intestine, large intestine, rectum, and
anus.
Jump to the image

86
Two GI Tract Sphincters - Appendix
This illustration shows the position of the lower esophageal and
the pyloric sphincters. (a). When the lower esophageal sphincter
relaxes, the mass of swallowed food enters the stomach (b). The
sphincter contracts to keep the mass from flowing back into the
esophagus (c).
Jump to the image

87
What Happens When You Swallow - Appendix
(a) While chewing, the epiglottis does not cover the larynx. (b)
When swallowing, the epiglottis prevents the bolus from entering
the larynx and trachea. (c) After swallowing, the epiglottis returns
to its usual position and allows air to enter the larynx and
trachea.
Jump to the image

88
First Aid for Choking - Appendix
A. Choking treatment for adults and children: 1. Stand behind the person and
wrap your arms around his or her waist. 2. Make a fist and place the thumb side
of your fist below the person’s ribcage and above the navel. 3. Hold your fist
with your other hand and press into his or her upper abdomen with a quick
upward thrust. Do not squeeze the ribcage. 4. Repeat thrusts until the object is
dislodged from the trachea and the person is breathing and able to talk. B.
Choking treatment for oneself: 1. Lean over a heavy, fixed structure such as a
chair, countertop, or railing. 2. Press your upper abdomen against the edge to
produce a quick upward thrust. 3. Repeat thrusts until the object that is blocking
the trachea is dislodged. OR, if no fixed large object is available: 1. Make a fist
and place the thumb side of your fist below the ribcage and above the navel. 2.
Hold your fist with your other hand and press into your upper abdomen with a
quick upward thrust. 3. Repeat thrusts until the object that is blocking the
trachea is dislodged. C. Choking treatment for infants: 1. Lay the child facedown
across your forearm. 2. Using the palm of your hand, give five forceful quick
blows on the infant’s back. 3. Repeat until the object is dislodged and the child is
breathing.
Jump to the image

89
Esophageal Sphincters - Appendix
(Top) When the lower esophageal sphincter relaxes, the mass of
swallowed food enters the stomach. (Bottom) The sphincter
contracts to keep the mass from flowing back into the
esophagus (c).
Jump to the image

90
pH Scale - Appendix
0: hydrochloric acid. 0.9 to 3.0: gastric juice. 2.0: chime as it
enters the duodenum. 2.3: lemon juice. 2.4 to 3.5: wine, vinegar,
cola, beer. 4.0: tomatoes. 5.0: black coffee. 6.3 to 6.6: milk,
urine, saliva. 7.0: pure water. 7.4: blood. 8.0: pancreatic juice,
bile, egg white, seawater. 9.5: household bleach, baking soda.
10.0: Great Salt Lake (Utah). 11.0: household ammonia. 13.4:
oven cleaner. 14: sodium hydroxide.
Jump to the image

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