Lecture
Outline
Chapter 4
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Body Basics
Chapter 4
Chapter Learning Outcomes
1. Define key basic chemistry terms, including atom,
element, ion, chemical bond, solutions, solvent, solute,
acid, base, and enzyme.
2. Explain the basic function of an enzyme.
3. Define tissue, organ, and organ system.
4. Identify the organ systems, major organs or tissues in
each system, and describe primary functions of each
system.
5. Discuss the overall processes of digestion and
absorption.
6. Identify some common gastrointestinal problems, and
discuss preventive measures and treatments for these
conditions.
Quiz Yourself
True or False

1. The atom is the smallest living unit in the body.
T F
2. The stomach produces hydrochloric acid (HCl).
T F
3. Taste buds can be found in the lining of your
mouth. T F
4. The human intestinal tract cannot digest certain
combinations of foods, such as mixtures of
simple carbohydrates and proteins. T F
5. Undigested food rots in your stomach, causing
toxic materials to build up in your tissues. T F
How Did You Do?

1. False The atom is not the smallest living unit in
the body.
2. True The stomach produces hydrochloric acid
(HCl).
3. True Taste buds can be found in the lining of
your mouth.
4. False The human intestinal tract can digest
combinations of foods, including mixtures of
simple carbohydrates and proteins.
5. False Undigested food does not rot in your
stomach, causing toxic materials to build up in
your tissues.
Chemistry and Physiology
Chemistry
Study of composition and characteristics of
matter
Human physiology
Study of how the human body functions
Principles of chemistry and human physiology form
the foundation for the scientific study of nutrition.
Basic Chemistry Concepts
Chemicals make up food and other
aspects of the environment.
Humans are complex collections of
chemicals…mostly organized into living
units — cells.
From Atoms to Compounds
Matter is made of atoms that contain:
Protons — Positively-charged particles in the nucleus
Electrons — Negatively-charged particles that surround the nucleus
in a “cloud”
Element
- A substance that cannot be broken down into smaller components
- Elements are the “building blocks” of matter
Some elements are essential nutrients.
Molecules
Molecule – Matter that forms when 2 or more
atoms interact and are held together by a
chemical bond (such as H20 or C6H12O6)
Chemical bond – Forms when atoms interact,
share electrons, and rearrange themselves
Compounds
Compound – Molecule that contains 2 or more
different elements
Solution – Evenly distributed mixture of 2
compounds
The 2 compounds in a solution are:
Solvent - the greater component
Solute - lesser component
Water is the solvent for many solutions.
Solubility
Describes how easily a substance dissolves in a liquid
Ions
Ion – Electrically-charged atom or group of atoms. Ions
form when the atom or group of atoms gains or loses
1 or more electrons
Negative charge - gain of an electron
OH- (hydroxide ion)
Positive charge - loss of an electron
H+ (hydrogen ion)
What Are Acids and Bases?
Acids – Donate hydrogen ions
Bases – Accept hydrogen ions
pH – Measure of acidity or alkalinity of a solution
What’s a Chemical Reaction?
Chemical Reaction
Process that changes atomic arrangement of
molecules
Digestion
Process by which molecules in food are
mechanically and chemically broken down
Metabolism
Chemical reactions occurring in living cells
Enzymes
Enzyme – Protein that speeds up the rate of a
chemical reaction but is not altered during the
process
Names of most enzymes end in “ase”
sucrase lactase lipase protease
Basic Physiology Concepts
Anatomy
Study of cells and other body structures
Physiology
Study of how cells and body structures
function
The Cell
Cell – Smallest functional
structure in a living
organism
A human has ~ 100 trillion cells.
Organelles – Structures within cells that
perform specialized functions
Organelles include: nucleus, mitochondria, and
ribosomes.
A Cell
What Are Tissues?
Tissues – Collection of cells that perform
specialized functions
Epithelial tissue - Cells that form linings and coverings,
such as skin
Connective tissue - Cells that hold together, protect, and
support organs
From Cells to Systems
Organ: Collection of various types of tissues with related
functions
System: Collection of organs with related functions.
• Insert Figure 4.10
The Organ Systems of the Human Body
Respiratory
System
Lungs enable body
to exchange gases,
mainly oxygen and
carbon dioxide.
Lymphatic
System
Helps maintain
fluid balance,
absorb many fatsoluble nutrients,
and defend the
body against
diseases
Urinary System
Kidneys filter unneeded
substances from blood
and help maintain
proper fluid balance.
Bladder stores urine
until elimination.
Muscular
System
Muscles enable the
body to move, and
they provide support
and protection.
Skeletal
System
Bones provide
support,
movement, and
protection.
Bones also store certain
minerals and produce red
blood cells.
Nervous
System
Nervous system
cells (neurons) in
the brain, spinal
cord, and
throughout the body
transmit information
and responses by
electrical and
chemical signals.
Endocrine
System
Organs and
tissues that
produce hormones
Integumentary System
• Comprised of skin, hair, and nails
Reproductive System
• Main function to produce children
Digestion
and Absorption
GI Tract
Muscular tube that
extends from mouth to
anus
Bioavailability
Extent to which
digestive tract absorbs
nutrients and how well
body uses them
• Insert Figure
4.21
Mouth
Digestion begins in the mouth
Mechanical digestion
– Biting and grinding actions of teeth
breaks and mashes food into smaller
pieces.
Chemical digestion
– Saliva mixes and lubricates food.
– Salivary amylase and lipase begin
breakdown of starch and fat, respectively.
Taste and Smell of Foods
Taste Buds
– Specialized sensory structures
on the tongue and in the lining of
mouth and throat
Five Tastes: Sweet, sour, salty,
bitter, and umami
Smell
– Chemicals in food become
airborne and stimulate nasal
passages, contributing to sense of
taste
• Insert photo of
girl with ice
cream page 96
From the Mouth to the
Stomach
Esophagus – Tube connecting pharynx to
stomach
Epiglottis – Flap that folds down over trachea
(windpipe) when you swallow
Gastroesophageal sphincter – Located at the
end of the esophagus; controls opening into the
stomach
What Happens When You Swallow?
Peristalsis
Muscular
contractions
that move
small amounts
of food and
beverages
through
intestinal tract
Stomach
• Large muscular sack that holds and churns food
• In stomach, food mixes with gastric juice, becoming chyme
• Pyloric sphincter controls the rate that chyme is released into the small
intestine
Insert Figure
4.24
Small Intestine
Where most
nutrients are
digested and
absorbed
• Duodenum
• Jejunum
• Ileum
Accessory Organs
Pancreas – produces
and secretes many
digestive enzymes
Liver – processes and
stores many nutrients
• makes cholesterol
Gallbladder – stores
bile that the liver
makes
Absorbing Nutrients
Villi
Tiny projections that
line the small
intestine
Absorptive cells
Remove nutrients
from chyme and
transfer them into
intestinal blood or
lymph
Water-soluble
nutrients enter the
capillary of a villus,
and travel to the liver
via portal vein.
Most fat-soluble
compounds are
formed into
chylomicrons, that
enter a lacteal of the
lymphatic system
and eventually reach
the bloodstream.
Cystic Fibrosis and
Inflammatory Bowel Disease
Cystic fibrosis
– An inherited, incurable disease
– Thick sticky mucus blocks passageways
– Mucus blocks pancreatic ducts,
interfering with nutrient digestion,
especially fat
Inflammatory bowel disease
– Group of diseases that cause
inflammation and swelling of the intestines
– Crohn’s disease and ulcerative colitis
Large Intestine
Absorption of water
and minerals
Feces – form as
chyme becomes
semisolid
Rectum – lower part
of large intestine
where feces are stored
Microbes in Your Digestive Tract
Bacteria
Vast numbers of bacteria reside in large intestine.
Intestinal bacteria:
 Metabolize undigested food material
 Make vitamin K and biotin
 Produce gas
 Feces contain bacteria
Your Adaptable Digestive Tract
• Humans are omnivores
– Human digestive tract:
• Can handle combinations of foods, such as mixtures of
animal and plant foods
• Can digest foods and absorb nutrients from wide variety of
sources, including:
–
–
–
–
Plants
Animals
Fungi
Bacteria
Chapter 4 Highlight
Gut Reaction
Common Intestinal Complaints
– Constipation
– Diarrhea
– Vomiting
– Heartburn
– Peptic Ulcer
– Irritable Bowel Syndrome
Gut Reaction: Constipation
What is Constipation?
• Difficult and infrequent bowel
movements
• Causes:
– Lack of fiber in diet
– Inadequate water intake
– Anxiety or depression
– Changes in daily routine
– Ignoring need to defecate
Gut Reaction: Diarrhea
• Frequent, loose bowel movements
• Causes are often bacterial or viral
• Treatment:
– OTC medication
– Replacing fluid, sodium, and potassium
to prevent dehydration
– Immediate treatment of severe diarrhea
in infants or the elderly is crucial
Gut Reaction: Vomiting
Contraction of abdominal muscles to expel
toxic stomach and duodenal contents
• Causes:
Ingestion of toxic substances, intense pain, head injury, motion
sickness, pregnancy, or touching back of throat
• Treatment:
- Avoid solid food until resolved
- Sip water or non-carbonated beverages, if tolerated, to prevent
dehydration
Watch for signs of dehydration. Contact physician if signs of
dehydration are present and vomiting lasts longer than a few
hours (children) or a day (adults).
Gut Reaction: Heartburn
Gnawing pain or burning in upper chest
• Occasional heartburn affects about 50% of U.S.
adults
•
Results when stomach acid enters esophagus
• Causes: Pregnancy, smoking, excess body fat,
alcohol, caffeine, citrus juice, onions, chocolate,
mints, fatty foods, spices, and eating too much at
one time
Gut Reaction: Peptic Ulcer
• Sore in the lining of the stomach or
duodenum
• Symptoms:
– Deep, dull upper abdominal pain ~2 hrs after eating
• Often caused by Helicobacter pylori
infection
• Treatment:
– Antibiotics to eliminate Helicobacter pylori
– Identification and avoidance of aggravating foods
Factors That Increase Risk of Peptic
Ulcers
Gut Reaction:
Irritable Bowel Syndrome (IBS)
Affects ~10 to 30% of adults
• Intestinal cramps and abnormal bowel function (ranges
from diarrhea to constipation)
• Unknown causes — linked to stress
• Treatment includes stress management
• Elimination of foods, such as milk and milk products, legumes,
and certain vegetables