The Remarkable Body: Nutrients, Cells, Tissues, and Organs

Chapter 3
The Remarkable Body
Sizer and Whitney, Nutrition: Concepts and Controversies, 15th
Edition. © 2020 Cengage. All Rights Reserved. May not be
scanned, copied or duplicated, or posted to a publicly accessible
website, in whole or in part.

Sizer and Whitney, Nutrition: Concepts and Controversies, 15th Edition. © 2020 Cengage. All Rights Reserved.
May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.
Learning Objectives (Slide 1 of 2)
• Name six basic needs of the body’s cells
• Summarize the exchange of materials that takes place as
body fluids circulate around the tissues
• Summarize the interactions between the hormonal and
nervous systems and nutrition
• Summarize how the digestive system provides nutrients
to the body tissues
• Outline the symptoms of eight common digestive
problems related to nutrition

Learning Objectives (Slide 2 of 2)
• Specify the excretory functions of the lungs, liver,
kidneys, and bladder
• Explain how body tissues store excess nutrients
• Compare the effects of moderate and heavy alcohol
consumption

The Body’s Cells
• Body is composed of trillions of cells
• Body needs nutrients
• Cells: The smallest units in which independent life can
exist
• Depend on one another
• Basic needs
• Energy, oxygen, and water
• Cells die at varying rates

Figure 3.1: A Cell (Simplified Diagram)
Hairlike projections
A membrane
Inner membrane
D N A
Membranes
Mitochondrion

Parts of a Cell (Slide 1 of 2)
• Hairlike projections: Typical of cells that absorb nutrients
in the intestines
• Membrane: Encloses each cell’s contents
• Inner membrane: Encloses the cell’s nucleus

Parts of a Cell (Slide 2 of 2)
• D N A: Contains the genes that control the inheritance of
the cell’s characteristics and its day-to-day workings
• Genes are faithfully copied each time the cell duplicates itself
• Mitochondrion: Takes in nutrients and releases energy
from them in a form that the cell can use

Genes Control Functions
• Direct production of proteins such as enzymes and
structural proteins
• Provide instruction for structural components of cells
• Affect the way body handles its nutrients
• Gene variations
• Inborn error of metabolism: Genetic variation present from birth
that may result in disease
• Phenylketonuria (P K U): Inborn error of metabolism that interferes
with the body’s handling of phenylalanine (from dietary protein) and,
left untreated, results in serious harm to the brain and nervous system

Figure 3.2: From D N A to Living Cells
1. Each cell’s nucleus contains D N A—the material of
heredity in all living things.
2. Long strands of human D N A coil into 23 pairs of
chromosomes. If the strands of D N A in all the
body’s cells were uncoiled and laid end to end, they
would stretch to the sun and back four hundred
times. Yet D N A strands are so tiny that about 5
million of them could be threaded at once through
the eye of a needle.
3. Genes contain instructions for making proteins.
Genes are sections along the strands of D N A that
serve as templates for the building of proteins. Some
genes are involved in building just one protein;
others are involved in building more than one.
4. Many other steps are required to make a protein.
5. Proteins do the work of living cells. Cells employ
proteins to perform essential functions and provide
structures.
6. Communities of functioning cells make up the living
tissue.

Cells, Tissues, Organs, and Systems
• Cells are organized into tissues that perform specialized
tasks
• For example, individual muscle cells are joined together to form
muscle tissue, which can contract
• Tissues are grouped together to form organs
• In heart, muscle tissues, nerve tissues, connective tissues, and
others all work together to pump blood
• Organs work together as part of a body system
• For example, the heart, lungs, and blood vessels cooperate as
parts of the cardiorespiratory system to deliver oxygen to all the
body’s cells

The Body Fluids and the Circulatory
System (Slide 1 of 2)
• Body fluids
• Supply energy, oxygen, nutrients, and water to tissues
• Deliver fresh supplies and pick up wastes
• Circulating fluids
• Blood
• Travels within arteries, veins, capillaries, and heart’s chambers
• Plasma: Cell-free fluid part of blood and lymph
• Lymph
• Fluid that moves from the bloodstream into tissue spaces and then
travels in its own vessels, which eventually drain back into the
bloodstream

Figure 3.3: Blood Flow in the Cardiovascular
System
Lungs
Heart
Liver
Kidneys
Intestines
Head and
Arms
Aorta
Lungs
Heart
Liver
Intestines
Kidneys
Pelvis and
Legs
1. The blood is routed
through the body as
follows:
• Heart to tissues to
heart to lungs to heart
(repeat)
2. The portion of the blood
that flows through the
blood vessels of the
intestine travels from:
• Heart to intestine to
liver to heart

Blood Flow in the Cardiovascular System
• Aorta: Channels blood from the heart to the tissues
• Lungs: Oxygenate blood, remove carbon dioxide from
blood, and return blood to heart
• Heart: Right side pumps blood to lungs and left side
pumps oxygenated blood to body
• Liver: Filters toxins from blood; stores, transforms, and
mobilizes nutrients
• Intestines: Absorb nutrients
• Kidneys: Filter wastes from blood and form urine and
deliver it to the bladder for excretion

Figure 3.4: How the Body Fluids Circulate
around Cells
1. Fluid filters out of blood through
the capillary, whose walls are
made of cells with small spaces
between them.
2. Fluid may enter a capillary and
rejoin the bloodstream.
3. Fluid may enter a lymph vessel to
join the lymphatic fluids. Lymph
flows through the vessels and
ultimately into the bloodstream
through a large lymph vessel that
empties into a large vein.

The Body Fluids and the Circulatory
System (Slide 2 of 2)
• Extracellular fluid: Resides outside the cells and
transports materials to and from the cells
• Permits exchange of material
• Forms lymph
• Intracellular fluid: Resides inside the cells and provides
the medium for cellular reactions
• All cell reactions take place here
• Holds cellular shape

Blood Circulation
• Blood circulates to the lungs
• Picks up oxygen
• Releases carbon dioxide
• Blood returns to heart
• Pumped to rest of body via the aorta
• Blood passes through digestive system
• Delivers oxygen and picks up nutrients
• Routed directly to the liver
• Cleansed of wastes in the kidneys

Lymph Circulation
• Picks up most of the fat
• Critical in the body’s immune system
• Lymphocytes that defend against microbes
• Lymphocytes: White blood cells that participate in the immune
response
• Microbes: Bacteria, viruses, fungi, or other organisms invisible to the
naked eye, some of which cause diseases
▶ Also called microorganisms

The Hormonal and Nervous Systems
• Hormones
• Chemical messengers
• Secreted and released directly into blood by glands
• Stimulate organs to take action
• Glands monitor conditions in the body
• Pancreas
• Insulin and glucagon

The Hormonal System Affects Nutrition
• Some functions of hormones
• Regulate the digestive system in response to meals or fasting
• Inform the brain about the degree of body fatness
• Help regulate hunger and appetite
• Influence appetite changes during a woman’s menstrual cycle and
in pregnancy
• Regulate the body’s reaction to stress, suppressing hunger and
digestion

Figure 3.5: Cutaway Side View of the Brain
Showing the Hypothalamus and Cortex

How Does the Nervous System Interact
with Nutrition?
• Cortex and hypothalamus
• Perceive hunger, appetite, and availability of nutrients and water
• Fight-or-flight reaction or stress response
• Neurotransmitters
• Epinephrine and norepinephrine
• Metabolism speeds up
• Muscle and organ response
• Eyes, heart, liver, and stomach

The Digestive System
• Five basic chemical tastes
• Sweet, sour, bitter, salty, and umami
• Other factors affect our experience of food flavor as well
• Sweet, salty, and fatty foods
• Provide energy and minerals
• Almost universally desired
• Can lead to drastic overeating of these substances

Figure 3.6: The Innate Preference for Sweet
Taste
a b c
d e
Source: Courtesy of Classic studies of J. E. Steiner, in Taste and Development: The Genesis of Sweet Preference, ed. J. M. Weiffenbach, H H S
publication no. N I H 77-1068 (Bethesda, M D: U.S. Department of Health and Human Services, 1977), pp. 173–189, with permission of the author.

The Digestive Tract
• The digestive system is directed to digest and absorb
by the nervous system and hormones
• Flexible, muscular tube
• Extends from mouth to anus
• Total length: About 26 feet
• Human body surrounds digestive canal
• Function of the digestive tract
• Breaks down food to its components, absorbs nutrients, and
excretes waste
• Works mechanically and chemically

Figure 3.7: The Digestive System
Digestive Tract Organs
through which Food
Passes
Mouth
Esophagus
Stomach
Small intestine
Large intestine (Colon)
Rectum
Anus
Accessory Organs
that Aid Digestion
Salivary glands
Liver
Gallbladder
Bile duct
Pancreatic duct
Pancreas

The Digestive System (Slide 1 of 3)
• Mouth: Chews and mixes food with saliva
• Esophagus: Passes food to stomach
• Stomach
• Adds acid, enzymes, and fluid
• Churns, mixes, and grinds food to a liquid mass
• Small intestine: Secretes enzymes that digest
carbohydrate, fat, and protein
• Cells lining intestine absorb most nutrients into blood and lymph

• Large intestine (Colon): Reabsorbs water and minerals
• Passes waste (fiber, microorganisms, any unabsorbed nutrients)
and some water to rectum
• Rectum: Stores waste prior to elimination
• Anus
• Holds rectum closed
• Opens to allow elimination
• Pancreas
• Manufactures enzymes to digest all energy-yielding nutrients
• Releases bicarbonate to neutralize stomach acid that enters small
intestine

• Pancreatic duct: Conducts pancreatic juice into small
intestine
• Bile duct: Conducts bile to small intestine
• Gallbladder: Stores bile until needed
• Liver: Manufactures bile, a detergent-like substance that
facilitates digestion of fats
• Salivary glands
• Donate a starch-digesting enzyme
• Donate a trace of fat-digesting enzyme (important to infants)

The Mechanical Aspect of Digestion
(Slide 1 of 2)
• Begins in the mouth
• Chewing
• Saliva to soften food
• Stomach and small intestine
• Liquefy foods through various mashing and squeezing actions
• Peristalsis: Wavelike muscular squeezing of the
esophagus, stomach, and small intestine that pushes
their contents along
• Chyme travels through pyloric valve
• Chyme: Fluid resulting from the actions of the stomach upon a meal

The Mechanical Aspect of Digestion
(Slide 2 of 2)
• Large intestine
• Portion of the intestine that completes the absorption process
• Digestion is virtually continuous
• Slows during sleep and exercise

Figure 3.8: Peristaltic Wave Passing Down the
Esophagus and Beyond

Figure 3.9: The Muscular Stomach

The Chemical Aspect of Digestion (Slide 1 of 2)
• Digestive juices
• Released by salivary glands, stomach, pancreas, liver, and small
intestine
• Saliva functions in the mouth
• Enzymes break down starches and fat
• Maintains teeth health
• Stomach
• Gastric juice initiates protein digestion
• Includes water, enzymes, and hydrochloric acid
• Intestine
• Gallbladder releases bile

Figure 3.10: p H Values of Digestive Juice and
Other Common Fluids

The Chemical Aspect of Digestion (Slide 2 of 2)
• Bicarbonate in the pancreatic juice neutralizes stomach acid
• Digestive enzymes in intestinal wall further break down chemical
bonds for absorption
• Water, fiber, and some minerals remain
• Microbes in the digestive tract
• Ferment many indigestible fibers
• Break down undigested protein or amino acids
• Break down and help recycle bile components
• Chemically alter certain drugs
• Communicate with muscle, adipose tissue, the brain, and the
immune system

If “I Am What I Eat,” Then How Does A
Peanut Butter Sandwich Become “Me”?
(Slide 1 of 2)
• Within 24 to 48 hours of eating, body digests and
absorbs 90% of carbohydrate, fat, and protein in a meal
• Digestion in the mouth
• Food is crushed, mashed, and mixed with saliva
• Carbohydrate digestion begins
• Each swallow triggers a peristaltic wave
• Digestion in the stomach
• Food is collected, and it continues to be digested
• Gastric juice mixes with food
• Acid unwinds proteins

If “I Am What I Eat,” Then How Does A
Peanut Butter Sandwich Become “Me”?
(Slide 2 of 2)
• Enzyme clips the protein strands into pieces
• Chyme forms and enters the small intestine
• Small intestine
• Bile from the liver blends fat with digestive fluids
• Enzymes from pancreas and small intestine break down the fat,
protein, and starch
• Large intestine
• Fiber fragments, fluid, and some minerals are absorbed
• Partly digested by the bacteria living in the colon
• Most fiber is not digested, and it passes out of the colon to be
excreted as feces

Figure 3.12: Typical Digestive System Transit
Times
Time in mouth,
less than a
minute.
Time in stomach,
about 1 to 2
hours.
Time in small
intestine, about 7
to 8 hours.*
Time in colon,
about 12 to 14
hours.*
*Based on a 24-hour transit time. Actual times vary widely.

Absorption and Transport of Nutrients (Slide
1 of 2)
• Nutrient molecules traverse the cells of the intestinal
lining
• Water-soluble components are deposited in the blood
• Fat-soluble components are deposited in the lymph
• Cells of small intestine are selective and efficient in
absorption of nutrients

Absorption and Transport of Nutrients (Slide
2 of 2)
• Intestine’s absorbing surface
• Villi
• Fingerlike projections of the sheets of cells lining the intestinal tract
• Villi make the surface area much greater than it would otherwise be
• Microvilli: Tiny, hairlike projections on each cell of every villus that
greatly expand the surface area available to trap nutrient particles
and absorb them into the cells

Figure 3.14: Details of the Small Intestinal
Lining
The walls of the small
intestine are wrinkled
into thousands of folds
covered with villi.
Each villus contains a
network of capillaries
and lymphatic vessels
for transporting nutrients
out of the intestinal cells.
Each villus is made of
absorptive cells that are
covered with even smaller
projections—the
microvilli—that trap and
absorb the nutrients.
Bill Crew/Superstock

Nutrient Transport
• Lymph vessels
• Transport products of fat digestion and fat-soluble vitamins
• Blood vessels: Directly transport:
• Products of carbohydrate and protein digestion
• Most vitamins
• Minerals

Figure 3.15: Lymph Vessels and the
Bloodstream—Nutrient Flow through the
Body
1. Nutrients are absorbed via two
kinds of vessels in the intestines:
blood capillaries and small lymph
vessels. The capillaries lead to
larger blood vessels that lead to
the liver.
2. The lymph in the lymph vessels
carries most of the absorbed
dietary fat to the large vein near
the heart. From there, the fat-laden
lymph flows into the bloodstream.

A Letter from Your Digestive Tract
• Hiccups
• Breakdown of fiber by bacteria produces gas
• Heartburn
• Use of antacids and acid reducers
• Gastroesophageal reflux disease (G E R D)
• Masks the symptoms of ulcers and hernias
• Constipation and diarrhea
• Hemorrhoids
• Irritable bowel syndrome (I B S)

Figure 3.16: Normal Swallowing and
Choking
A normal swallow. The epiglottis
acts as a flap to seal the entrance to
the lungs (trachea) and direct food to
the stomach via the esophagus.
Choking. A choking person cannot
speak or gasp because food lodged in
the airway (trachea) shuts off airflow.
The red arrow points to where the food
should have gone to prevent choking.

Figure 3.17: First Aid for Choking
The universal signal for choking alerts others to the need for assistance.
Stand behind the person with your arms wrapped around him. Make a fist with
one hand and place the thumb side snugly against the body, slightly above
the navel and below the breastbone.
Grasp the fist with your other hand and make a quick upward and inward
thrust. Repeat thrusts until the object is dislodged.
To perform abdominal thrusts on yourself, make a fist and place the thumb
below your breastbone and above your navel. Grasp your fist with your other
hand and press inward with a quick upward thrust. Alternatively, quickly thrust
your upper body against a table edge, chair, or railing.

The Excretory System
• Organs involved in waste removal are lungs, liver,
kidneys, and bladder
• Kidneys
• Nephrons collect waste materials dissolved in water
• Urine stored in bladder
• Excrete or retain sodium
• Sodium regulates blood pressure
• Regulate fluid volume and concentrations of substances in the
blood and extracellular fluid

Storage Systems
• Eating intervals: Four to six hours
• Major storage sites
• Liver: Stores glycogen, for cellular use
• Muscles: Stores glycogen, for its own use
• Adipose tissue: Fat and fat-related substances for long-term
energy needs
• Body stores exist for many other nutrients

Controversy 3 – Alcohol Use: Risks and
Benefits
• U.S. alcohol consumption
• Average adult drinker consumes about 16% of total calories from
alcoholic beverages
• Percentage of alcohol differs among beverages

What Is Alcohol?
• Names end in –ol
• Acts as lipid solvents
• Uses vary based on levels
of toxicity
• Alcoholic beverages
• Disinfectants
• Antiseptics
© Polara Studios, Inc

Immediate Effects of Alcohol
• The body gives special attention to alcohol
• Diffusion through stomach walls
• Reaches brain within a minute
• Affected by presence of food in the stomach
• Liver metabolizes most alcohol
• Alcohol dehydrogenase (A D H)
• Absorption in small intestine takes place promptly
• Penetrates and dehydrates all tissue

Table C3.2: Drinking Behaviors of Moderate
and Problem Drinkers
Moderate Drinkers Typically Problem Drinkers Typically
Drink slowly, casually Gulp or “chug” drinks
Eat food while drinking or beforehand Drink on an empty stomach
Don’t binge drink; know when to stop Binge-drink; drink to get drunk
Respect nondrinkers Pressure others to drink
Avoid drinking when solving problems or
making decisions
Turn to alcohol when facing problems or
decisions
Do not admire or encourage
drunkenness
Consider drunks to be funny or admirable
Remain peaceful, calm, and unchanged
by drinking
Become loud, angry, violent, or silent
when drinking
Cause no problems to others or
themselves by drinking
Physically or emotionally harm
themselves, family members, or others
when drinking

Drinking Patterns
• Moderate drinking
• Amounts different for women and men
• Excessive drinking
• More than half an ounce of alcohol per hour
• Heavy episodic (binge) drinking
• Cause serious health and social consequences

Does Moderate Alcohol Use Benefit
Health?
• Some studies suggest reduced risk of heart attacks,
strokes, and diabetes
• Associated with moderate drinking
• Health benefits of red wine
• Correlates with a lower-than-average risk of heart attacks
• Some of the phytochemicals seem to oppose certain cancers

Alcohol in the Brain
• Sedates inhibitory nerves
• Lethal dose
• Depends on speed and amount consumed
• Could cause respiration and heartbeat to cease
• Can severely and irreversibly damage brain functions
• Vision, memory, learning, reasoning, and speech

Figure C3.2: Effects of Rising Blood
Alcohol Levels on the Brain
Source: Centers for Disease Control and Prevention.

Figure C3.3: Alcohol Damage to the Liver
• Alcohol metabolism
generates damaging free
radicals
• Diseases and organ damage
• Fatty liver
• Liver fibrosis
• Cirrhosis Arthur Glauberman/Science Source

Hangover
• Symptoms: Headache and nausea
• Dehydration of the brain
• Several chemicals contribute to a hangover
• Time alone can cure a hangover

Alcohol’s Long-Term Effects on the Body
• Effects in pregnancy
• Prolonged, excessive drinking can cause irreversible
damage to body systems
• Such as the brain, the liver, kidneys, heart, and all other systems

Alcohol’s Effects on Nutrition
• Causes disturbances in nutrition
• Fattening power of alcohol
• Alcohol promotes fat storage
• Vitamin and mineral imbalance
• Malnutrition
• Wernicke-Korsakoff syndrome
• Folate gets expelled

[Author Name], [Book Title], [#] Edition. © [Insert Year] Cengage. All Rights Reserved. May not be scanned,
copied or duplicated, or posted to a publicly accessible website, in whole or in part.
Table C3.5: Calories in Alcoholic Beverages and
Mixers (Slide 1 of 2)
Labels of alcoholic beverage containers need not list calorie amounts, but
calories in alcoholic drinks, such as cocktails, may soon appear on many
restaurant menus.
Beverage Amount
(Ounces)
Energy
(Calories)
Malt beverage (sweetened, such as hard
lemonade)
16a 350
Malt beverage (unsweetened) 16 175
Wine cooler 12 170
Pina colada mix (no alcohol) 4 160
Beer 12 150
Dessert wine 3.5 140
Fruit-flavored soda, Tom Collins mix 8 115
aTypical container size, but up to 32-oz containers are common.

Table C3.5: Calories in Alcoholic Beverages and
Mixers (Slide 2 of 2)
Beverage Amount
(Ounces)
Energy
(Calories)
Gin, rum, vodka, whiskey (86 proof) 1.5 105
Cola, root beer, tonic, ginger ale 8 100
Margarita mix (no alcohol) 4 100
Light beer 12 100
Table wine 3.5 85
Tomato juice, Bloody Mary mix (no alcohol) 8 45
Club soda, plain seltzer, diet drinks 8 1

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