Download 28.1 Levels of Organization

SECTION 28.1
28.1
Plan and Prepare
Objectives
Levels of Organization
KEY CONCEPT
MAIN IDEAS
VOCABULARY
determination, p. 852
differentiation, p. 853
tissue, p. 854
• Specialized cells develop from a single
zygote.
• Specialized cells function together in
tissues, organs, organ systems, and the
whole organism.
• Describe cell specialization and
levels of organization.
• Identify how levels of organization
work together in an organism.
organ, p. 854
organ system, p. 854
Review
cell, stem cell, zygote
Connect Climbing a wall of ice requires careful interaction among all parts of
Section Resources
the body. You probably know that the brain and muscles work together to
coordinate the climber’s movements. The heart and lungs also have to work
together to help provide energy for the climb. Yet every human body starts out as
a single cell, a fertilized zygote. How does a single cell give rise to all the different
types of cells, tissues, and organs in the human body? Further, how do such
different parts coordinate their activities to keep the body functioning?
Unit Resource Book
Study Guide pp. 1–2
Power Notes p. 3
Reinforcement p. 4
Pre-AP Activity pp. 15–16
Interactive Reader Chapter 28
Spanish Study Guide pp. 283–284
MAIN IDEA
Specialized cells develop from a single zygote.
Biology Toolkit pp. C6, C19, D3, D9
Technology
Power Presentation 28.1
Media Gallery DVD
Online Quiz 28.1
Activate Prior Knowledge Have
students think about the way employees in a large company are organized.
Ask, How would you describe the
relationship between different jobs,
divisions, and levels of responsibility in
a company? Every part of the company
is dependent on every other part
functioning properly and efficiently. Tell
students that in this section, they will
learn about how the body levels of
organization work together.
FIGURE 28.1 The disk-shaped red
blood cells (top) carry oxygen to
all parts of the body. The neuron
(bottom), through its extensions,
receives and transmits messages
from and to other neurons.
(colored SEMs; magnifications: blood
cells 2800⫻; neuron about 1600⫻)
Teach
TEACH FROM VISUALS
The human body has five levels of organization.
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If you were to watch an emergency medical team in action, you would quickly
notice that each person has a special job. One keeps in radio contact with the
main hospital. Another monitors the patient’s vital signs. Still others perform
life-saving procedures. All emergency teams are made up of people, but each
person within the group has a different job.
Likewise, multicellular organisms are made up of cells, but different cells
in the organism have different functions. Take a moment to study the images
of the blood cells and nerve cells, or neurons, in FIGURE 28.1. You will notice
that the red blood cells are round with a concave center. This structure gives
them more surface area to help deliver oxygen to all parts of the body. In
contrast, neurons develop extensions that transmit and receive messages
from other neurons.
Humans, like almost all multicellular organisms, are collections of specialized cells that work together. These cells arise from a single cell, the zygote,
which is formed by the union of an egg and sperm. The zygote divides and
differentiates into more than 200 different types of human cells. These cells
allow you to do everything from lifting a glass, to learning people’s names, to
maintaining your body temperature on a cold day. Cell specialization involves
two main steps: determination and differentiation.
Determination
The cells produced during the first few divisions of the zygote are known as
embryonic stem cells. These cells have the potential to become any type of
specialized cell in the body. Within a few weeks, however, a process called
determination occurs in which most stem cells become committed to develop
Unit 9: Human Biology
Differentiated Instruction
FIGURE 28.1 Have students observe the
differences in appearance of the cells.
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ENGLISH
LEARNERS
Ask
Have students preview the chapter by having
• In what way are all the cells in the
them look at headings, illustrations, and key
body alike? have the same DNA
terms. Ask them to predict what will be
• What accounts for the differences
important and why they think so. Set up a
in these two cells? Different genes
four-column table with the headings: What I
are turned off and on depending on
Know I Know, What I Think I Know, What I
cell type.
Think I’ll Learn, What I Learned. Have
Remind students of the Hox genes they
students fill in the first three columns, leaving
learned about in genetics.
the last column empty until they complete
the chapter.
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Biology Toolkit, DRTA, p. C6
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Unit 9: Human Biology
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into only one type of cell. For instance, a stem cell might become a cardiac
muscle cell or a spinal neuron. These committed cells still retain all of the
genetic information needed to build an entire organism. However, during
determination, they lose their ability to express some of this information.
Once a cell is committed to becoming a specialized cell, it will develop into
only that type of cell. For instance, a cell that will become a neuron can only
be a neuron, even if it is transplanted into another part of the body. During
normal development, determination cannot be reversed.
Differentiation
Differentiation is the process by which committed cells acquire the structures
and functions of highly specialized cells. Differentiation occurs because
specific genes in each cell are turned on and off in a complex, regulated
pattern. The different structures of these specialized cells, such as those shown
in FIGURE 28.2, allow them to perform specific functions within the body.
TAKING NOTES
Vocabulary
Use a supporting main ideas
strategy to take notes about
processes such as cell
specialization.
Greek and Latin Word Origins Students
know the word species, which shares the
same Latin root as the word special,
meaning “of a certain kind.” Tell students
that it is possible to think of specialized
cells as belonging to a species. A “species”
of muscle cell is distinct from a “species” of
skin cell, in a similar sense that one species
of bird is different, yet similar, to another.
Specialized cells develop
from embryonic stem cells.
determination—cells
are committed to be
one type of cell
differentiation
supporting detail
The Inside Story
The function of muscle cells, for example, is to produce movement by
contracting and relaxing. However, skeletal muscle and smooth muscle cells
have different structures. Skeletal muscle cells align in bands of orderly rows
and contain many nuclei. They are responsible for nearly all voluntary muscle
movements, such as lifting your
foot to kick a ball. In contrast,
FIGURE 28.2 Cell Differentiation
smooth muscle cells are shorter
Cells develop specialized structures and functions during differentiation.
and have only one nucleus. They
perform involuntary movements,
such as raising the hairs on your
Connective cells
Smooth muscle cells in
in skin
intestinal wall
arms and legs.
Other cells have even more
specialized structures and functions. Sperm cells, for instance,
develop whiplike tails that enable
Bone
Skeletal
them to swim. Cells lining the gut
cells
muscle
are elongated and tightly packed to
O
G
T
E
cells
ZY
provide more surface area for the
absorption of nutrients.
Not all cells continue to develop
into specialized cells. The process
of programmed cell death, called
apoptosis (AP-uhp-TOH-sihs), is
also a normal part of development.
For example, when your hands
Epithelial cells
Epithelial
in skin
cells in stomach
first formed, your fingers resemlining
bled a mitten. The death of cells
between the fingers allowed
Sperm cells
individual fingers to develop.
A Analyze What are some of the
reasons that multicellular organisms
need specialized cells?
What does it mean that you are 16
or 17 years old if your cells regularly
replace themselves? Dr. Jonas Frisén, a
stem-cell biologist at the Karolinska
Institute in Stockholm, has developed
a way to estimate the ages of human
cells. He developed a scale for converting the carbon-14 in tissues into
calendar dates. Using this dating
technique, Dr. Frisén estimates the
average age of all the cells in an adult’s
body may be seven to ten years.
A hotly debated topic is whether
the brain generates new neurons. Using
his technique, Dr. Frisén has shown that
cells from the visual cortex in the brain
are the same age as the individual.
These are the cells that enable you to
see and interpret what you see. Still to
be determined are whether the cells
associated with the cerebral cortex,
involved with memories and consciousness, are also as old as you are.
Answers
B Contrast How do the structures of sperm cells and epithelial cells in
the stomach differ?
Chapter 28: Human Systems and Homeostasis 853
BELOW LEVEL
M
Have students note how key vocabulary are
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used in the text. In their notebooks, have
them write what each word means based on
their reading of the text. Have them check
the definition in the Glossary. Then have
students use the word in a sentence and draw
a picture that will help them remember the
meaning.
Biology Toolkit, Student Vocabulary, p. D3
PRE-AP
Tell students that there are about 25 trillion8/13/08
red blood cells in the human body, each with
a life span of about 100–120 days. Red blood
cells that are worn out and die are replaced
by new cells produced in the bone marrow
and stored in the spleen. Have students calculate the number of blood cells the human
body loses due to natural cell death each
second. 25 trillion cells ⫼ 10.4 million seconds
⫽ 2.4 million cells per second This is about
half the number of red blood cells in one
cubic millimeter of blood.
2:22:23
A Analyze Multicellular organisms
need specialized cells to build specialized tissues and organs that carry out
functions such as respiration, digestion,
and elimination. Specialization also
allows multicellular species to become
M much larger than unicellular species can.
B Contrast Sperm have a head and a
long tail that enables them to move.
Epithelial cells are elongated, are tightly
packed, and have hairlike cilia at the
surface to move materials.
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MAIN IDEA
Specialized cells function together in tissues,
organs, organ systems, and the whole organism.
Teach continued
ONLINE BIOLOGY Go to
the chapter Resource Center at
ClassZone.com for additional
resources and information on levels
of organization.
Specialized, or differentiated, cells are only the first level of organization in a
multicellular organism. Scientists organize multicellular structures into five
basic levels, beginning with cells and moving to increasingly complex levels—
tissues, organs, organ systems, and the whole organism. These five levels in the
human body are shown in FIGURE 28.3.
1
Cells Each type of specialized cell has a particular structure and a
chemical makeup that enable it to perform a specific task. Some cells in
the lungs, for instance, are involved in the exchange of gases. Others
secrete mucus that helps to trap foreign particles and to protect the lungs
from pathogens, such as bacteria and viruses.
2
Tissues Groups of similar cells that work together to perform a specialized
function are known as tissues. The human body is made up of four general
types of tissues.
• Epithelial tissue consists of protective sheets of tightly packed cells
connected by special junctions. The skin and the membranes that line
the stomach, the lungs, and other organs are epithelial tissues.
• Connective tissue serves to support, bind together, and protect other
tissues and organs. Tendons, ligaments, bone, and cartilage are all
connective tissues.
• Muscle tissue is capable of contracting to produce movement. The
human body contains skeletal, cardiac, and smooth muscle tissues.
• Nervous tissue transmits and receives impulses in response to
stimuli, processes information, and regulates the body’s response
to its environment.
3
Organs Different types of tissue that function together form an
organ. For example, the lungs are organs composed of all four types of
tissues. Muscle and connective tissues expand and contract the lungs.
Nervous tissue sends and receives messages that help regulate gas exchange in the lungs and the rate at which a person breathes. Epithelial
tissue forms the inner lining of the lungs.
4
Organ systems Two or more organs working in a coordinated way form
an organ system. The organ system that allows you to breathe includes
not only the lungs but also the sinuses, the nasal passages, the pharynx,
and the larynx (the voice box). Organ systems perform the most complex
activities in the body.
5
Organism Together, the organ systems make up the entire organism. For
you or any other organism to stay alive, all of the systems must interact
and work together. As a result, anything that harms one organ or organ
system will affect the health of the entire body.
Science Trivia
• Skin is the largest organ of the
human body.
• Unlike other organs that are distinct
•
•
•
•
•
and separate structures, skin covers
the entire body.
Adults have about 1.7 square meters
(20 ft2) of skin.
Skin makes up about 15–20 percent
of a person’s body weight.
Every minute approximately 30,000–
40,000 dead skin cells are removed
from the body.
In a person’s lifetime, he or she will
lose around 18 kilograms (40 lb) of
dead skin.
Your body will produce an entirely
new layer of skin in one month’s
time.
Connecting
CONCEPTS
Digestion and Elimination In
addition to serving as a protective layer, epithelial tissue can
absorb materials and secrete
special types of fluids. Your
ability to digest food and eliminate waste depends in part on
the specialized functions of
epithelial tissue, as you will
learn in Chapter 32.
A
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Unit 9: Human Biology
Differentiated
Instruction
TEACH WITH TECHNOLOGY
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Students might enjoy viewing a portion of
the 1966 film Fantastic Voyage. In this science
fiction film, a miniaturized medical team is
inserted into the human bloodstream with
the goal of removing a blood clot in the brain
of an important scientist. The film was made
long before the advent of computer animation yet provides an entertaining realization
of the body.
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PRE-AP
d d
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Biology Toolkit, Analogies, p. D9
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Unit 9: Human Biology
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AM
The human body, with its five levels of
organization, can be compared to the
structure of an ecosystem with its different
levels of organization. Have students explore
this analogy by developing a visual presentation that illustrates their interpretation of this
idea. Students should provide a written
explanation of the thinking behind their
interpretation.
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FIGURE 28.3 Five Levels of Organization
All levels of organization interact and work together to maintain the body’s health.
1
CELLS
BIOLOGY
Explore the human
organ systems at
ClassZone.com.
Epithelial Lung Cell
These cells have tiny
hairlike structures
(cilia) at the top.
2
TISSUES
Epithelial Lung Tissue
Cells with cilia are packed together
in the lung’s inner lining. They
act like a conveyor belt to
move foreign particles
and pathogens out of
the lungs.
3
ORGANS
Lungs
The lungs are composed
of four types of tissue.
The lungs are the site
where gases are
exchanged.
TEACH FROM VISUALS
FIGURE 28.3 Point out to students that
the numbers in the diagram correspond
to the numbered list on page 854. Ask
• What cells are featured in the figure,
and what system do they belong to?
epithelial cells of the lung and
respiratory system
• Looking at the drawing of the girl
and the organs identified in
caption 4, what parts of the respiratory system lead from the nose to
the lungs? nose leads to pharynx and
larynx, then to trachea and into lungs
• What is the primary function of the
respiratory system? exchange of
gases, supply oxygen needed to
release energy, remove waste carbon
dioxide
Science Trivia
• The size of an average human body
cell is ten micrometers.
• It would take over 39 million cells to
4
ORGAN SYSTEMS
Respiratory System
This system includes the
lungs, trachea, larynx,
pharynx, sinuses, and nose.
The nose and sinuses filter,
moisten, and warm the air
before it enters the lungs.
5
•
•
ORGANISM
Human
The respiratory system is one of several
organ systems that work together to keep
the human body functioning properly.
Answers
A CRITICAL How might a sinus infection affect the rest
VIEWING of the respiratory system?
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cover the floor of a high school
basketball court.
It would take 6000 cells to cover a
sheet of notebook paper.
Roughly 1000 cells would be needed
to cover a dollar bill.
BELOW LEVEL
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A Critical Viewing Air first enters
through the nose and sinuses, where it is
filtered, moistened, and warmed. If the
sinuses were blocked by infection, the
person would have to breathe through
the mouth and there would be a greater
chance of harmful pathogens or foreign
matter entering the lungs. Drainage from
the sinuses could also spread pathogens
to the airways, producing a lower
respiratory infection.
Have students look at the full list of systems
in FIGURE 28.4. Point out that the first letter
of each system can be used to make the
words miners and cider. After reviewing the
information, have students close their books.
Give them five minutes to write down as
many systems as they can remember and a
function for each. To help them remember,
remind them that miners like cider.
Biology Toolkit, Quick-Write, p. C19
Chapter 28: Human Systems and Homeostasis 855
FIGURE 28.4 Major Organ Systems
Teach continued
Take It Further
In 1989, the National Library of Medicine
set out to create a digital atlas of the
human body called the Visible Human
Project. The University of Colorado
Heath Sciences Center created the atlas
by combining CT and MRI images of
cross sections of a male and a female
cadaver. Both bodies, from a 39-year-old
male and a 59-year-old female, had been
donated to science. The Visible Human
Project provides medical, research, and
educational communities with the
unique opportunity to see organs and
systems in relation to one another, along
the entire length of the human body.
SYSTEM
MAJOR TISSUES AND ORGANS
PRIMARY FUNCTION
Circulatory
heart, blood vessels, blood, lymph nodes,
lymphatic vessels
transports oxygen, nutrients, wastes; helps regulate body temperature; collects fluid lost from blood vessels and returns it to
circulatory system
Digestive
mouth, pharynx, esophagus, stomach, small⁄large
intestines, pancreas, gallbladder, liver
breaks down and absorbs nutrients, salts, and water; eliminates
some wastes
Endocrine
hypothalamus, pituitary, thyroid, parathyroid,
adrenals, pancreas, ovaries, testes
influences growth, development, metabolism; helps maintain
homeostasis
Excretory
skin, lungs, kidneys, bladder
eliminates waste products; helps maintain homeostasis
Immune
white blood cells, thymus, spleen
protects against disease; stores and generates white blood cells
Integumentary
skin, hair, nails, sweat and oil glands
acts as a barrier against infection, injury, UV radiation; helps
regulate body temperature
Muscular
skeletal, smooth, and cardiac muscles
produces voluntary and involuntary movements; helps to circulate blood and move food through digestive system
Nervous
brain, spinal cord, peripheral nerves
regulates body’s response to changes in internal and external
environment; processes information
Reproductive
male: testes, penis, associated ducts and glands
female: ovaries, fallopian tubes, uterus, vagina
produces reproductive cells; in females, provides environment
for embryo
Respiratory
nose, sinuses, pharynx, larynx, trachea, lungs
brings in O2 for cells; expels CO2 and water vapor
Skeletal
bones, cartilage, ligaments, tendons
supports and protects vital organs; allows movement; stores
minerals; serves as the site for red blood cell production
Answers
The major organ systems in the human body, including their main parts
and primary functions, are listed in FIGURE 28.4. Keep in mind that all of the
organs in these systems developed from specialized cells and tissues that arose
from a single cell, the zygote. The major parts and functions of each organ
system are examined in greater detail in Chapters 29 through 34.
How do these complex organs and organ systems keep functioning and
working together properly? As you will read in Section 28.2, the body has
sophisticated mechanisms for maintaining a stable internal environment.
A Compare and Contrast Tissues are
composed of one specific type of
differentiated cell. Organs consist of two
or more types of tissues. Organ systems
are composed of two or more organs
working in a coordinated fashion. Organs
and organ systems perform more
complex activities than tissues do.
A Compare and Contrast How do tissues differ from organs and organ systems?
28.1
Assess and Reteach
REVIEWING
Assess Use the Online Quiz or Section
Quiz (Assessment Book, p. 553).
Reteach Have students make a graphic
organizer that shows the hierarchical
relationships among cells, tissues, organs,
organ systems, and organism.
28.1 ASSESSMENT
MAIN IDEAS
1. How does the process of cell
determination differ from the
process of cell differentiation?
2. Briefly define and give an example of each of the five levels of
organization in multicellular
organisms.
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ONLINE QUIZ
A SS ESS M E N T
ClassZone.com
CRITICAL THINKING
3. Apply What organ systems must
work together to bring oxygen to the
body’s cells?
4. Predict A cell has undergone determination to become an endocrine gland
cell. If it is transplanted to a leg muscle,
what do you think will happen to
this cell?
CONCEPTS
5. Cell Cycle In the spring,
tadpoles lose their tails as part
of their life cycle. At a certain
stage in development, the
human fetus acquires individual
fingers and toes. What occurs
in some cells of both species
to explain these changes?
Unit 9: Human Biology
1. In cell determination, stem cells commit to
tissues that function together (example:
becoming a certain type of cell, such as a
brain). Organ systems consist of two or
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muscle cell. In cell differentiation, cellsb10hspe-092801.indd more
organs working together (example:
develop the actual structures and funcbrain and spinal cord).
tions that make them specialized cells.
3. The respiratory system brings oxygen into
2. A cell is the smallest unit of life (example:
the body. Part of the muscular system
neuron). A tissue is a group of similar cells
coordinates the movement of the lungs.
that work together to perform a specialThe circulatory system picks up oxygen
ized function (example: nerve tissue).
from the lungs and delivers it to body cells.
Organs consist of two or more types of
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Connecting
4. Because determination is usually not
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reversible, the cell and its daughter cells
will continue to develop as endocrine cells.8/13/08
5. Both are examples of programmed cell
death, or apoptosis.
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CHAPTER 28
MATERIALS
• jump rope
• stop watch
PROCESS SKILLS
• Observing
• Collecting data
I N V E S T I G AT I O N
I N V E S T I G AT I O N
Homeostasis and Exercise
Your body’s temperature, heart rate, and blood pressure need to remain within
certain set ranges. In this lab, you will work in groups to examine the effects of
exercise on the circulatory and respiratory systems and on perspiration level.
Time 45 minutes
PROBLEM How does exercise affect a person’s heart rate, breathing rate, and
Teacher Preparation
perspiration level?
Student Difficulty
PROCEDURE
1. Choose one person to jump rope. Measure the person’s heart rate by taking his or
her pulse for 15 seconds. Multiply this number by four to calculate beats per
minute. (Caution: If the person exercising feels discomfort at any time, stop the
experiment and inform your teacher.)
2. Measure the person’s breathing rate by counting the number of breaths taken in
15 seconds. Multiply this number by four to calculate breaths per minute.
3. Rate the person’s perspiration level from 1 to 5 (1 = none; 5 = droplets dripping
down the face).
4. Design a data table like the one shown below. Write a hypothesis about the
effect of exercise on the dependent variables that you are measuring.
5. Have the person jump rope for 2 minutes. When the person stops, measure heart
rate, breathing rate, and perspiration level and record the data. Repeat step 5
three more times and record your data at each point.
6. After the final recording of the dependent variables, wait 1 minute and measure
all of the variables again.
Lab Binder Human Bio, pp. 1–4
Purpose Measure the effects of
exercise on body systems.
Overview Student teams will test the
effect of exercise on the circulatory,
respiratory, and integumentary systems.
They will
• predict the effect of exercise on
heart rate, breathing rate, and
perspiration level
• graph the relationships between the
independent and dependent
variables, using the data collected
TABLE 1. EFFECTS OF EXERCISE
Time
(Min)
Heart Rate
(Beats/Minute)
Breathing Rate
(Breaths/Minute)
Perspiration Level
LAB PREPARATION
0
Move furniture to create an open space.
2
4
LAB MANAGEMENT
6
8
Ask for one or two volunteers to jump
rope for the experiment.
Extend the readings at the end of the
investigation to see how long it takes to
return to the resting rates.
Safety Caution students to stop
jumping if they feel uncomfortable and
to inform you right away. Any student
who has a health problem that could be
exacerbated by physical activity should
not be allowed to jump rope.
9
ANALYZE AND CONCLUDE
1. Identify Variables What is the independent variable in this experiment?
2. Organize Data Graph the relationship between the independent and dependent
variables. You may choose one graph to display all of your data, or you may use
separate graphs for each of the dependent variables. Explain your graph choice.
3. Summarize What are the effects of exercise over time on the circulatory and
respiratory systems and on perspiration level?
4. Synthesize What other processes could you have measured to determine the
external and internal effects of exercise on the body?
5. Infer How is perspiration level related to body temperature? How is perspiration
related to homeostasis?
POST-LAB DISCUSSION
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Answers
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Sample Data
For a sample of student graphs from this lab,
go to page R108.
Analyze and Conclude
1. amount of time spent exercising
2. Graphs can be line graphs, bar graphs, or a
combination of both. Heart and breathing
rates can be placed on one y-axis with
perspiration level on a second.
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A
3. Exercise leads to increased heart rate,
breathing rate, and perspiration level.
4. Sample Answer: blood pressure and body
temperature
5. Higher perspiration level indicates higher
body temperature. Perspiration is one way
the body cools itself to maintain a fairly
constant body temperature.
Relate the variables tested to homeostasis. Ask, Why do heart rate and breathing rate increase with exercise? During
exercise, muscle cells demand more
energy. More oxygen must be taken in
for cellular respiration to produce
energy, so the breathing rate increases.
The heart rate increases so that the
blood can quickly deliver oxygen to the
muscles.
Teacher Note “Students are able to
make connections beyond homeostasis
and inquire about relationships between
breathing and heart rate.”
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