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Home , Circulatory system, Gas exchange, Human body, Pulmonary circulation, Respiration (physiology), Trachea

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Q What can take your breath away? This photograph shows a resin cast of the thousands of vessels that supply blood and air to your . As you take a breath every three to five seconds, this network takes in oxygen and expels . Pollution, disease, or can damage this intricate network, literally taking your breath away.

R e a d i N G T o o lb o x This reading tool can help you learn the material in the following pages.

USING LANGUAGE Your Turn Recognizing Main Ideas A main idea is a statement Find the main idea in the paragraph below. that tells you about the main point of a paragraph. It Cardiovascular diseases include high blood , summarizes what the paragraph is about. The main idea clogged and hardened , heart attack, and . is often, but not always, one of the first few sentences High causes the heart to work harder of a paragraph. than normal, weakening the heart. Clogged and hard- ened arteries raise blood pressure and can also lead to heart attack and stroke.

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30.1 Respiratory and Circulatory Functions

4B, 10A, 10C Key Concept the respiratory and circulatory systems bring oxygen and nutrients to the cells. VOCABULARY MAIN IDEAs circulatory system The respiratory and circulatory systems work together to maintain . The respiratory system moves gases into and out of the blood. The circulatory system moves blood to all parts of the . alveoli diaphragm Connect to Your World heart You have thousands of kilometers of blood vessels in your body and several hundred million tiny air sacs in your lungs. Blood circulates constantly through the vessels, while air continually fills and empties from the tiny air sacs. Your heart keeps beating and your lungs keep working 24 hours a day, every day of your . Even more amazing, everything works without your having to think about it. 4B investigate and explain cellular processes, including homeostasis, conversions, of , and synthesis of new molecules; 10A describe the interactions that occur among systems that perform the functions of regulation, absorption, reproduction, and defense from injury or illness in MAIN IDEA 4b, 10a, 10c ; 10C analyze the levels of organization in biological systems and relate the levels to each other The respiratory and circulatory systems work and to the whole system together to maintain homeostasis. Every in your body needs nutrients and oxygen to function and needs to get rid of its waste products. The circulatory system is the body system that blood and other materials. It brings vital supplies to the cells and carries away their wastes. The organization of the blood vessels in the circula- tory system also keeps oxygen-poor blood from mixing with oxygen-rich blood. READING TOOLBox The respiratory system is the body system in which takes place. You can think of your respiratory system as a supply depot where the blood TAKING NOTES can pick up oxygen (O2) and deposit excess carbon dioxide (CO2). The lungs Use a supporting main ideas strategy to help you remember of the respiratory system are the only place in your body where gases in the the respiratory and circulatory blood are exchanged with gases from the . structures and their functions. The respiratory and circulatory systems work closely together to maintain respiratory system homeostasis in the of constant change. Every time you , lie down –brings gases into and out of the body to rest, or simply stand up, you change your needs for oxygen and nutrients. , sinuses As a result, your heart speeds up or slows down and you breathe faster or – warm and moisten air slower, depending on your activity. This section gives you an overview of the trachea major structures of the respiratory and circulatory systems and their func- tions. Sections 2 through 5 provide a closer look at the organs of each system, how they work, and what can damage them. Apply When you stand up after lying down, why do your and rate increase?

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FIGURE 1.1 Respiratory Organs and Tissues Specialized structures move air into and out of the body.

sinus nose

bronchiole trachea alveoli

lungs bhspe-093001-002 bhspe-093001-003 Infer How do the structures in the lungs increase their surface area?

MAIN IDEA 4b, 10a, 10c The respiratory system moves gases into and out of the blood.

The function of the respiratory system is to bring O2 into the body and to CONNECT TO expel CO and vapor. The structures of this system bring the gases in 2 close contact with the blood, which absorbs O . The circulatory system then 2 You learned in Cells and Energy carries O2 to all of the body’s cells and transports CO2 from the rest of the that eukaryotic cells require a body to the lungs, where it is exhaled. constant supply of oxygen to produce ATP, which is the main The specialized structures of the respiratory system are shown in FIGURE 1.1. energy source for cells. The nose and mouth are the entry points to the system. When air enters the nose, that lines the nasal passages warms and moistens the air. The mucus and tiny called cilia, help filter and pathogens from the air. At the back of the , a small piece of , the epiglottis, regulates airflow into the trachea, or windpipe. The trachea (TRAY-kee-uh) is a long structure made of soft tissue reinforced with C-shaped rings of . It resembles the hose of a cleaner. When you swallow, the epiglottis closes the entrance to the trachea to keep food or saliva from entering the airways. The trachea divides into the two bronchi, with one branch going to each lung.

The lungs are the organs that absorb O2 from the air you inhale. Inside the lungs, the bronchi divide into smaller and smaller branches that resemble the limbs and twigs of a tree. The smallest branches, the , end in clusters of tiny air sacs called alveoli (al-VEE-oh-ly). One is called an alveolus. The lungs have a huge number of alveoli—from 300 to 600 million.

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Biology HMDScience.com GO ONLINE How You Breathe Air inhaled. Air exhaled.

Muscles contract and Muscles and expands. cage relax.

Figure 1.2 When you inhale, movements of the rib cage and diaphragm produce lower pres- sure in the lungs, and air flows in. Diaphragm flattens Diaphragm relaxes When you exhale, rib cage and and moves downward. and rises. diaphragm movements produce higher pressure in the lungs, and air flows out. This huge number of alveoli gives the lungs a massive surface area for absorb-

ing O2 and releasing CO2 and . Lung tissue is spongy and elastic, which allows the lungs to expand and contract as you breathe. Lung mucus and cilia help trap and remove foreign materials and pathogens. The mechanics of breathing involve the muscles of the rib cage and the READING TOOLBox diaphragm, as FIGURE 1.2 shows. The diaphragm is a dome-shaped muscle at the base of the rib cage. When you inhale, the muscles of the rib cage contract, VOCABULARY causing the rib cage to expand. The diaphragm then flattens and moves The word diaphragm is based on the Latin diaphragma, downward. The volume of your lungs increases, and the air pressure decreases, which means “.” The falling below the air pressure outside your body. Gases move from areas of midriff extends from below greater pressure to areas of lower pressure, so air flows into the lungs. the to the . The diaphragm is located in When you exhale, the rib cage muscles relax, and the rib cage becomes this area. smaller. The diaphragm also relaxes, causing it to rise and regain its domelike shape. Now the air pressure inside your lungs is greater than the air pressure outside your body, so air flows out. Predict How might damaged alveoli affect the oxygen level in the blood? 10c

MAIN IDEA 10a, 10c The circulatory system moves blood to all parts of the body.

The function of the circulatory system is to transport O2 and nutrients to body

cells and to carry oxygen-poor blood and CO2 back to the heart and lungs. To Biology do its job, the system must keep blood constantly circulating. HMDScience.com The main parts of the circulatory system are the heart, the blood, and the GO ONLINE blood vessels. The heart is a muscular pump, about the size of your fist, that Build the Circulatory and Respiratory Systems keeps the blood moving to every part of the body. The blood circulates through a closed system—that is, blood in the circulatory system stays inside the vessels. The average body contains about 5 liters (more than 5 qt) of blood. On average, your blood circulates from your heart, throughout your body, and back to your heart about every 60 seconds.

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The circulatory system has three types of blood vessels: arteries, , and . Arteries are blood vessels that carry blood away from the heart to the rest of the body. Veins are blood vessels that carry blood from the rest of the body back to the heart. As illustrated in Figure 1.3, arteries carry oxygen- rich blood (red) and veins carry oxygen-poor blood (blue). Blue is used for heart illustration purposes only. In your body, oxygen-poor blood is not actually blue but a darker red color. You can think of arteries and veins as a system of roads. Large arteries and veins are like major highways. Smaller arteries and veins are like streets that route traffic through local neighborhoods. Arteries and veins are connected by a system of capillaries. Capillaries are the tiny blood vessels that transport blood to and from the cells of the body. These vessels are so small that blood cells must move through them in single file. The walls of these tiny blood vessels are only one cell thick. Materials can easily diffuse into and out of them. In addition to transporting vital supplies to the cells, the circulatory system performs two other important functions that maintain homeostasis. • The circulatory system collects waste materials produced by and cell , and delivers them to the and kidneys to be filtered out of the body. For example, muscle cell activity produces a waste product known as urea. As blood moves past the muscle cells, urea is moved into the bloodstream and carried to the kidneys to be excreted. • The circulatory system helps maintain body by distributing the heat produced in the muscles and internal organs. When you are active, your organs and muscles produce more heat. The heart pumps harder, and Figure 1.3 The circulatory the blood vessels expand, or dilate, to bring excess heat to the , where it system is composed of the heart, can escape. In weather, the blood vessels constrict to conserve heat. arteries carrying oxygen-rich blood (red), veins carrying oxygen- The heart, the blood vessels, and the blood are described in more detail in poor blood (blue), and capillaries. Sections 3 through 5. Infer If a person has a weak heart, how might his or her ability to maintain a stable body temperature be affected? 10a

Self-check Online HMDScience.com GO ONLINE 30.1 Formative Assessment CONNECT TO Reviewing Main Ideas Critical thinking Science and 1. How do the respiratory and 4. Apply Why can’t you breathe Technology circulatory systems help maintain through your mouth while you are 6. A mechanical homeostasis in the body? 10a food? What would breathes for a paralyzed 2. List the main parts and functions of happen if you could do this? person. During , the the respiratory system. 5. Infer Arteries and veins are equally machine air under 3. Describe the basic parts and func- distributed throughout the body. pressure into the lungs. tions of the circulatory system. How does this arrangement help to During , the maintain the functions of each cell? pressure drops and air moves 10c out of the lungs. How does this machine compare with natural breathing?

Chapter 30: Respiratory and Circulatory Systems 873 CorrectionKey=A DO NOT EDIT--Changes mustbemadethrough “File info” Unit 874 CO (colored SEM; magnification 150 magnification SEM; (colored F emphysema cell blood red VOCABULARY maintenance ofhomeostasis feedback mechanismsinthe 11A describe therole ofinternal and to thewhole system; and relate thelevels to each other organization inbiological systems animals; 10Canalyze thelevels of defense from injuryorillness in absorption, reproduction, and ofregulation,the functions nutrient occur amongsystems that perform 10A describe theinteractions that synthesis ofnew molecules; transport ofmolecules, and homeostasis, energy conversions, cellular processes, including cell whichallows thick, O alveoli. Alveoli walls are about one shows abronchiole andseveral alveoli igure 2 to diffuse easily across them.

9: 4Binvestigate andexplain

2.1 Human Biology 30.2

This micrograph 11A 4B, 10A, 10C, bronchiole 2 and Respiration andGasExchange 3 ) ca Gas exchangeGas occurs alveoli the in lungs. ofthe the blood, whichmeans less O that burnfossil fuels.What makes CO so deadly? Your bodyreadily absorbs itinto (CO) gas intheirhomes.Thiscolorless, odorless gas escapes from leaks infurnaces Nearly every winter, newspapers carry stories ofpeople killed by Your to World Connect K oxygen starved. You mustquickly get to anarea where you can breathe fresh air. ey

O unable enough to extract O square meters. Without huge this area for gas exchange, lungs the would be of sand, but of all alveoli the together give lungs the area asurface of about 100 several alveoliseveral is shown in bronchioles and to alveoli. the finally Across-section of abronchiole and process of gas exchange. When you inhale,air flows from bronchi the to the In alveoli, the respiratory the and circulatory systems come together inthe O out that cells inyour the cellularRecall carry respiration, body which requires tration of O O of based on threebased principles: in asteady supply of O only places where gas exchange with atmosphere the The lungs occurs. bring an area of high alveoli inthe to an area of low concentration in shown in

rbon dioxide. rbon • • • MAI MAI

C 2 2

and produces CO and must get of rid CO o The lin centration to an area of lower concentration. Gas O A com Respiratory diseases interfere withgas exchange. Gas exchange occurs inthealveoli ofthelungs. N n N 2 and CO ID ce IDEAS es move by diffusion—that move is, they from an area of highercon- pt EA FIGURE 2.2. FIGURE plex network of capillaries surrounds and penetrates alveoli, the as ing of alveoli the must moist be to help diffuse. gases t 2

than does the air thanthe alveoli. does inthe As aresult, O the 2 he respiratory system exchanges oxygen and and oxygen exchanges system respiratory he are by carried blood. the 2 and CO and Blood entering Blood capillaries these contains alower concen- 2 4B, 10A, 10C, 10A, 11A4B, as awaste product. needs body inthe cell Thus, every

2

and excess expel CO 2 FIGURE 2.1. FIGURE 2 . However, alveoli the and capillaries their are the isabsorbed. time,your Withinashort cells become 2

2 from air the to keep you alive. Each alveolus Each is about sizeof the agrain 2 . Gas exchange lungs inthe is 2 diffuses from diffuses

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FIGURE 2.2 Gas Exchange in the Alveoli Diffusion of gases into and out of the alveoli

maintains O2 and CO2 homeostasis.

alveoli Gas Exchange

capillary alveolus

CO2 diffuses into alveolus. CO2

O2 diffuses O2 into blood.

capillaries

Predict How might a sudden rise in CO2 in the blood affect the gas exchange process? 4b

the capillaries. The blood in the capillaries contain red blood cells, a type of cell that picks up oxygen in the lungs and delivers it to all of the body’s cells.

In red blood cells, most of the O2 molecules bind to an -rich called hemoglobin (HEE-muh-gloh-bihn). Each of hemoglobin

binds with four O2 molecules. The iron in hemoglobin is what gives blood its reddish color. Blood becomes bright red only when it absorbs oxygen. The

blood leaving the alveoli carries almost three times the amount of O2 that it had coming into the lungs. T’ ing! In contrast, CO2 are higher in the blood than in the alveoli. A maz As a result, CO2 diffuses into the alveoli. The higher concentration of CO2 in Video Inquiry

the blood is due to the fact that every cell produces CO2 and water as waste HMDScience.com

products. The CO2 and water combine in the blood to form the compound GO ONLINE carbonic acid. The more carbonic acid there is in the blood, the more acidic Breath the blood becomes. When carbonic acid diffuses into the alveoli, the com-

pound separates into CO2 and water, which are exhaled. Gas Exchange and the Gas exchange is so critical to the body that it is an autonomic function regulated by the medulla and pons in the stem. These centers monitor CONNECT TO

dissolved gases in the blood, particularly CO2 concentrations. As you become Nervous System

more active, CO2 levels increase and the blood becomes more acidic. Sensors As you read in Nervous and in the respiratory and circulatory systems signal this change to the brain stem. Endocrine Systems, the brain stem is located at the base of The medulla sends messages through the nervous and endocrine systems that the brain. The brain stem is stimulate the diaphragm and rib cage muscles to work harder. The medulla involved in regulating breathing regulates how often and how deeply you breathe based on your activity. and other autonomic functions that help maintain homeostasis. Analyze How does the alveoli’s structure relate to the function of gas exchange? 10c

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MAIN IDEA 10a, 10c Respiratory diseases interfere with gas exchange. Figure 2.3 Healthy lung tissue Damage to the respiratory system makes gas exchange more difficult, which in is free of any deposits. When a turn affects every cell in the body. is the leading cause of respiratory person smokes for several years, black tar deposits first invade diseases such as and emphysema. Tobacco smoke contains more and then the tissue, and than 4800 chemicals that can paralyze cilia, damage alveoli, and cause genetic greatly reduce gas exchange. mutations leading to cancer. In FIGURE 2.3, you can see the effects of smoking 3 (LM; magnification 250 ) on lung tissue. When a person smokes for several years, the lung tissue is slowly coated by tars and other chemicals. Eventually, the tissue becomes almost solid black. The sooner people stop smok- Healthy lung tissue ing, the sooner such damage to the lungs can be reversed. Emphysema (ehm-fih-SEE-muh) is a lung disorder caused mainly by smoking. Over time, many alveoli are destroyed. This process gradually reduces the surface area for gas exchange, and not enough oxygen can enter the blood. People with advanced emphysema must use supplemental oxygen, but eventually their lungs fail. At present, this disease has no cure. The best way to prevent emphysema is to refrain from smoking. Smoker’s lung tissue Asthma (AZ-muh) causes the bronchioles to constrict due to muscle spasms. This condition makes it hard to move air in and out of the lungs. A person having a severe asthma attack can die from lack of oxygen. Attacks may be triggered by , , exposure to smoke and chemicals, or exercise. The attacks can be relieved by drugs that relax the bronchioles. Web (CF) is a genetic disease that causes the lungs to produce a thick, sticky mucus. This mucus blocks the airways and allows microorgan- HMDScience.com isms to thrive in the lungs. People with CF have frequent, sometimes fatal, GO ONLINE lung . Treatments focus on preventing the mucus from building up. Asthma Synthesize How does smoking affect gas exchange? 4b

Self-check Online (t) ©Dachez/Photo Inc.; Researchers, (b) Inc. Wood/Photo Researchers, ©Kent HMDScience.com 30.2 Formative Assessment GO ONLINE CONNECT TO Reviewing Main Ideas Critical thinking Forensic Science 1. Explain how diffusion allows gases to 3. Synthesize Explain how your 5. When police find a body in move into and out of the alveoli of breathing rate would change if your a lake or river, they must 11a the lungs. Use the term red blood blood became more acidic. determine if the person was cell in your explanation. 4b 4. Apply People poisoned by CO are drowned or was killed in 2. In what ways can respiratory diseases often given 100 percent O2 in a room some other way and then

reduce the level of O2 in the blood? with two to three times normal thrown into the water. How . Explain why would examining the lungs more oxygen would enter their blood of the person help them to under these conditions. solve the mystery?

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30.3 The Heart and Circulation

11a Key Concept The heart is a muscular pump that moves the blood through two pathways. VOCABULARY MAIN IDEAS The tissues and structures of the heart make it an efficient pump. The heart pumps blood through two main pathways. pacemaker Connect to Your World systemic circulation Lub-dub, lub-dub. This is the sound of your heart beating. The lub sound occurs when the between the upper and lower chambers of the heart snap shut. 11A describe the role of The dub sound is made by valves closing the two arteries that carry blood out internal feedback mechanisms in of the heart. If a valve does not close properly and allows blood to leak backward, the maintenance of homeostasis the sound of the heart changes. A heart with a leaky valve might sound like this: Lub-dub-shhh, lub-dub-shhh. The sounds your heart makes can tell a a great deal about how it is performing.

MAIN IDEA The tissues and structures of the heart make it an efficient pump. Each day your heart beats about 100,000 times, circulating blood through nearly 96,000 kilometers of blood vessels—roughly one-quarter of the distance to the moon. Over 70 years, your heart will beat about 2.5 billion times. How can it keep going? One reason is that cardiac , unlike tissue, can work continuously without Figure 3.1 Heart Chambers and valves becoming tired. Also, the structures of the heart make this an efficient pump.

Structures of the Heart The largest structures in your heart are the four left atrium chambers. As shown in FiGURE 3.1, the two smaller pulmonary chambers are the right atrium and left atrium valve (plural, atria), and the two larger chambers are the right and left ventricles. The ventricles are separated by the septum, a thick wall of tissue. right atrium The heart valves are flaps of tissue that prevent left blood from flowing backward. They open when ventricle the atria or ventricles contract, and close when the atria or ventricles relax. After blood fills a chamber, the right ventricle septum contracts and pumps the blood out of the cham- ber. The heart is an amazingly powerful pump.

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The reason has to do with the small size of the heart, which allows the strong cardiac muscles to exert a great deal of on the chamber. The combination of small size and large force results in a powerful pumping action. The heart is also an efficient, self-regulating pump. It can respond to signals from the SA node nervous system to change the speed and force of its pumping action. For (pacemaker) example, if you increase your level of activity, your heart will pump faster. The Heartbeat The heartbeat consists of two contractions: the first takes place in the atria and the second in the ventricles. The contractions occur partly because the cardiac muscle fibers of the chambers have a unique property. Whenever one fiber is stimulated to contract, all of the fibers contract at the same time. The first contraction of the heart begins in the right atrium at a signal from AV node the sinoatrial (SA) node, shown in FIGURE 3.2. The SA node is known as the heart’s pacemaker because the cells in this node generate an electrical signal that starts the wave of contractions. Once the atria have contracted, the Figure 3.2 An electrical signal electrical signal spreads through conducting fibers to the atrioventricular (AV) from the SA node causes both atria to contract. The AV node node, located in the wall of the right ventricle. The AV signal stimulates both then picks up the signal and trans- ventricles to contract at the same time. mits it to both ventricles, causing them to contract. If the SA node is seriously damaged by injury or disease, it can be replaced with an artificial pacemaker that is implanted into the heart. This device, like the SA node, sends electrical signals to the muscle fibers of the atria.

Biology IDEO Blood Flow in the Heart V CLIP Once you know the basic structures and actions of the heart, you can follow HMDScience.com how oxygen-rich and oxygen-poor blood flow through this organ. Study

GO ONLINE FiGURE 3.3, which illustrates this pathway. Notice that blood always enters the Heart and Function heart through an atrium and the heart through a ventricle. The contrac- tions of the atria and then of the ventricles keep blood moving in this sequence. 1 Oxygen-poor blood from the body enters the right atrium. The SA node signals the atria to contract, and blood flows into the right ventricle. 2 When the AV node signals the ventricles to contract, blood is pumped from the right ventricle into the . This artery, which R E ADI N G TO OLB ox goes to the lungs, is the only artery in the body that carries oxygen-poor

VOCABULARY blood. The blood enters the lungs, where CO2 and water vapor diffuse

The word pulmonary comes into the alveoli and O2 diffuses into the blood. from the Latin root pulmo, meaning “lung.” The suffix 3 Oxygen-rich blood returns to the heart through the pulmonary vein and -ary means “belonging to or enters the left atrium. This is the only vein in the body that carries connected with.” Therefore, oxygen-rich blood. As the atria contract, blood is pumped into the left pulmonary means something ventricle, the largest chamber in the heart. “belonging to or connected with the lung.” 4 When the ventricles contract, blood is pumped from the left ventricle into a large artery, the , and is circulated to the rest of the body. After oxygen has been delivered to the cells, the oxygen-poor blood returns through the veins to the heart, and the sequence begins again. Analyze The left ventricle is the largest chamber of the heart. How is its size related to its function?

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FIGURE 3.3 Blood Flow in the Heart Biology HMDScience.com The structures of the heart keep oxygen-poor blood GO ONLINE separated from oxygen-rich blood. Heart Pumping Blood

Oxygen-poor blood

Oxygen-rich blood

from body from lungs to lungs to body

1 The right atrium 3 The left atrium receives receives oxygen- oxygen-rich blood from poor blood from the the lungs and pumps it body and pumps it to the left ventricle. to the right ventricle. 4 The left ventricle pumps 2 The right ventricle oxygen-rich blood to all pumps oxygen-poor parts of the body. blood to the lungs.

Normal Human Heart

CRITICAL If the valves in the right ventricle do not close properly, VIEWING where in the body might circulation be affected the most? ©Custom Medical Stock Photo

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MAIN IDEA 11a The heart pumps blood through two main pathways. Circulating blood follows two separate pathways that meet at the heart, as shown in FIGURE 3.4. These pathways are called pulmonary and systemic pulmonary circulation. All of your blood travels through both of these pathways. Pulmonary circulation (PUL-muh-nehr-ee) occurs only between the heart and the lungs. The main function of this circulation is to carry oxygen-poor

blood to the lungs, where it picks up O2, expels excess CO2 and water, and carries oxygen-rich blood back to the heart. Each lung is supplied by its own pulmonary artery and pulmonary vein. Systemic circulation (sihs-STEHM- ihk) occurs between the heart and the rest of the body, except for the lungs. The main function of this circulation is to carry oxygen-rich blood to all cells and transport oxygen-poor blood back to the heart. Systemic circulation begins when blood leaves the left ventricle, the largest chamber of the heart. The blood then circulates through the , , legs, and , and then systemic returns to the heart. As the body’s need for oxygen changes, sensors in the walls of major arteries in the pulmonary and systemic pathways send information to the medulla in the brain stem. The medulla coordinates this information with signals from the respiratory system. Homeostasis is maintained by matching heart rate and respiration rate with the oxygen needs of the body. In extreme conditions, such as severe cold, the pulmonary and systemic circulation systems serve another vital function—making sure the body’s brain, heart, and other major organs remain at a constant temperature. When Figure 3.4 The circulatory the body is exposed for any length of time to a cold environment, blood vessels system has two general pathways. Pulmonary circulation moves to the arms and legs begin to constrict. The blood flow to the arms and legs is blood between the heart and the reduced in order to keep the torso and head warm. Once you reach a warmer lungs. Systemic circulation moves environment, these blood vessels dilate and normal circulation resumes. blood between the heart and the rest of the body. Infer Why is it important to have two separate pathways for circulation?

Self-check Online HMDScience.com 30.3 Formative Assessment GO ONLINE Reviewing Main Ideas Critical thinking CONNECT TO Animals 1. Is the feedback loop that maintains 3. Predict Explain how leaky heart homeostasis in severe cold a positve valves might damage the heart 5. Unlike a human heart, an loop or a negative loop? Explain. over time. heart has two atria 11a 4. Predict How might a high fever but only a single ventricle. How might living in a watery 2. Briefly describe the pulmonary affect a person’s heart and breathing environment help reduce the and systemic circulation pathways. rates? Explain your answer. work that an amphibian heart needs to do?

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With the

T’ ng Biology VIDEO zi ! CLIP A ma Video Inquiry Web Body’s Blood Usage Find Turtle Breath Asthma Learn what causes out which parts of your How can sea hold their breaths asthma, what triggers an body use the most blood. for so long? Learn more about these episode, and why people fascinating creatures, and analyze data with asthma can still live on their diving and breathing patterns healthy, active . to help answer this question. (r) ©Michael Newman/PhotoEdit

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30.4 Blood Vessels and Transport

VOCABULARY Key Concept The circulatory system transports materials blood pressure throughout the body. systolic pressure MAIN IDEAS diastolic pressure Arteries, veins, and capillaries transport blood to all parts of the body. Lifestyle plays a key role in circulatory diseases.

Connect to Your World The last time you visited a doctor, you may have had your blood pressure measured. You can feel the pulsing of the blood under the cuff on your . Your blood pressure indicates how hard your heart is working. We’ve come a long way in our understanding of blood flow. In the 1600s, most scientists that the lungs were responsible for the movement of blood. , court physician to the king of England, changed this perception with his studies. Harvey’s work on circula- tion is regarded as one of the greatest advances in the history of .

MAIN IDEA Arteries, veins, and capillaries transport blood to all parts of the body. As you read in Section 1, the circulatory system includes three types of blood vessels—arteries, veins, and capillaries—that act as transportation networks for the blood. Each of the three vessels has its own structure and function, as illustrated in FIGURE 4.1. Arteries R E ADI N G TO OLB ox Arteries need to be strong and flexible because the blood they carry from the heart is under great pressure. An artery’s thick wall is composed of three layers. TAKING NOTES The innermost layer consists of coated with a protein that prevents A two-column chart can help blood from clotting. The middle layer is a thick band of and you organize your notes about different blood vessels and elastic fibers. The outer layer consists of and elastic fibers. The circulatory pathways. elastic fibers allow the arterial walls to expand and contract to help move blood arteries - Thicker, more through the arteries. , or smaller arteries, contain the same three muscular layers, but the outer and middle layers are much thinner. than veins - Blood under greater Veins pressure The structures of veins reflect the fact that blood is under much less pressure when it is returning to the heart. Veins have larger diameters and thinner walls than do arteries and contain valves that prevent blood from flowing backward. However, the walls of the veins are not as thick as those of arteries and do not expand and contract to keep blood moving. Instead, they need the activity of skeletal muscles to help maintain circulation. As you walk, skeletal muscles in your legs push against the veins. The valves open, and blood moves toward the heart. If you sit for too long, the lack of exercise makes it harder for the blood to move upward. are small veins that join larger veins to capillaries.

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FIGURE 4.1 Three Types of Blood Vessels Arteries, veins, and capillaries transport the blood to every cell.

endothelium valve

smooth muscle

connective tissue

artery Vein capillaries

Analyze Explain why arteries do not need valves to keep blood moving in one direction.

Capillaries Capillary walls are made of , but they contain no muscle cells or elastic fibers. The thinness of capillary walls allows materials to diffuse into and out of the blood quickly and easily. In areas of high metabolic activity, such as CONNECT TO the lungs, kidneys, and liver, capillaries form dense networks called capillary beds. These beds move a great deal of blood into and out of these organs. Differentiated Cells In Human Systems and Circulation and Blood Pressure Homeostasis, you learned that epithelial cells line most organs Blood pressure is the force with which blood pushes against the wall of an and structures in the body. These artery. A healthy resting blood pressure for a young adult is around 120/70 cells provide a protective layer mm Hg (read as “120 over 70 millimeters of mercury”). The top, and higher, that helps each organ or structure to do its job. number is known as the systolic pressure (sih-STAHL-ihk). This is the amount of pressure on the walls of an artery when the left ventricle contracts to pump blood through the body. The bottom, and lower, number is known as the diastolic pressure (dy-uh-STAHL- VISUAL VOCAB ihk). This is the pressure in the artery when the left ventricle relaxes. Systolic pressure occurs when the left ventricle contracts. Diastolic pressure Blood pressure depends on how occurs when the ventricle relaxes. You Biology IDEO elastic and unblocked the arteries are can write these numbers as a fraction in V CLIP and on the strength of the heart which systolic pressure is always on top. HMDScience.com contraction. The less elastic the systolic = numerator GO ONLINE arteries and the more blockages that 120 reduce blood flow, the harder the 70 diastolic = denominator Blood and Blood Vessels heart must pump. As a result, blood pressure rises. Blood pressure also rises naturally with activity, stress, and strong emotions, but it should drop again with rest. If the pressure remains high, there could be a problem in the circulatory system.

Chapter 30: Respiratory and Circulatory Systems 883 DO NOT EDIT--Changes must be made through “File info” CorrectionKey=A

People with permanently high blood pressure have a condition called Biology IDEO V CLIP , which can lead to a heart attack or stroke. A heart attack occurs when the arteries to the heart muscle are damaged or blocked. A stroke can HMDScience.com occur when blood flow to the brain is interrupted. Most people can lower their GO ONLINE blood pressure through loss, proper diet, and exercise. If these rem- Circulatory System edies fail, people can use medications to reduce blood pressure. Infer Why do you think that blood moving from the heart to the lungs must be carried by an artery and not by a vein?

MAIN IDEA Lifestyle plays a key role in circulatory diseases. Lifestyle choices strongly influence the health of your circulatory system. artery wall Smoking, lack of exercise, excessive weight, long-term stress, and a diet low in plaque fruits and vegetables but high in saturated are all linked to an increased risk of developing circulatory diseases. These diseases mainly affect the heart and the arteries. For example, in arteriosclerosis (ahr-teer-ee-oh-skluh-ROH- sihs), the artery walls become thick and inflexible. In (ath-uh- roh-skluh-ROH-sihs), blood flow is partially or fully blocked by sticky mate- rial, called plaque, that collects on the walls of the arteries, as FIGURE 4.2 shows. High blood pressure is often the only warning sign of these problems. Both diseases can lead to a heart attack, stroke, or damage. Some blocked arteries supplying the heart muscle can be opened using a surgical technique known as a balloon (AN-jee-uh-plas-tee). A device is threaded into the artery and then inflated so that it squeezes the obstruction against the artery wall. If this procedure does not work, bypass may be necessary. In this operation, a healthy from another part of the body (usually the leg) is attached to the artery on either side of the blockage. Figure 4.2 This micrograph Blood can then bypass the obstruction. clearly shows fatty deposits, called plaque, building up on an artery To reduce the risk of circulatory diseases, urge people to not wall. If such deposits block blood smoke, to maintain a healthy weight, and to exercise regularly. Medications flow, they can cause a heart attack or stroke. (LM; magnification 253) can also help reduce the risks of heart disease. Apply How can lifestyle choices affect the function of the arteries? ©ISM/Phototake

Self-check Online HMDScience.com 30.4 Formative Assessment GO ONLINE Reviewing Main Ideas Critical thinking CONNECT TO 1. How do the structures of arteries, 3. Infer People who smoke often have veins, and capillaries relate to their cold and feet. What might 5. The hard of an functions? explain this condition in terms of exerts pressure on the ’s circulatory 2. How can lifestyle choices help blood flow? system. In what way does reduce the risk of heart disease? 4. Apply Explain why narrowing of the arteries decreases blood flow but the exoskeleton serve the increases blood pressure. same function as the heart does in ?

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CorrectionKey=A DO NOT EDIT--Changes must be made through “File info” info” “File through be made must EDIT--Changes DO NOT CorrectionKey=A DO NOT EDIT--Changes mustbemadethrough “File info” Unit 886 white blood cells, F cells blood white factor Rh group blood ABO plasma VOCABULARY maintenance ofhomeostasis feedback mechanismsinthe 11A describe therole ofinternal blood, muscle, andepithelium; plants; andanimal cells suchas including roots, stems, andleaves of 5B examine specialized cells, synthesis ofnew molecules; transport ofmolecules, and homeostasis, energy conversions, cellular processes, including and . gases, nutrients, waste products, control andtransport , that helpto fight infections, is composed ofseveral parts igure red blood cells, and

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Human Biology 30.5 plasma

Whole blood 4B, 5B, 11A Blood mat fragments, and plasma. fragments, and Blood composed is mainly ofcells, cell substance accomplish all ofthese functions? help fightinfections andcontrol bleeding from damaged blood vessels. How can one gets ridofwaste products from your cells. Blood also hasother components that supplies your organs withgases andnutrients,helps you keep warm orcool off, and The adult humanbodycontains about5liters (more than5qt)ofblood. Thisfluid Your to World Connect Ke

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fragments, produced inbone marrow, that help clotting. inblood main as shown parts, in put inatest blood tube and spin it inacentrifuge, separate it will into two fluid, along with of particles , other nutrients, and dissolved If gases. you stance. Whole is asticky actually blood mixture of fragments, cells, cell and When you at look with naked the eye, it blood appears asingle to sub- be clotting factor that works with platelets to stop bleeding the after an injury. not that out does so leak blood inthe fluid of vessels. the Fibrinogen is a mostthe abundant plasma protein. Its main role is to stabilize volume blood help maintain homeostasis. Albumin, same the substance white, as inegg is enters cells. the capillaries, it moves outward to an area of lower concentration and eventually homeostasis. For instance, as concentration the of increases glucose inthe capillaries the between and cells plays the role acritical inmaintaining moves through capillaries. the The movement of water, nutrients, gases, and plasma determines into which substances diffuse and will out ofthat blood the waste products. include molecules These amino acids, glucose, hormones, , salts, and of dissolve molecules inplasma and transported can be throughout body. the about 55percent of Plasma blood. the is roughly 90percent water. Many types contains cells, white red cells, and blood blood platelets. MAI MAI C erials.

o At th Pla Why i Platelets anddifferent typesofblood cells have different functions. Blood iscomposed mainly ofcells, cell fragments, andplasma. N n N sma such as albumin, fibrinogen, and immune proteins also ID c ID ept e top of tube the is s plasma important? The concentration of dissolved molecules in E E A AS

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cells and carry CO cells and carry crescent shapes, as shown in effectively. In for disease, sickle cell example, cells are red blood distorted into commonly found inpeople of descent. African 20 days, and tend to clump vessels. inblood This genetic disorder is most also knownalso as the mon markers are Aand B, which produce fourA,B, types: AB, blood and O, clump. The clumped vessels can block blood blood vital and result indeath. your attack will foreign the cells, causing blood to them sions. If you receive with aprotein blood marker different from your own, important is very type people when giveBlood or receive for blood transfu- cells have blood Red protein surface markers that your define type. blood Factors Rh and ABO Blood Group and recycle them. cells are toDegraded liver the carried and , which break up cells the circulate throughfor body the about 120days before to degrade. begin they nuclei, cannot they undergo division. cell cells blood Red globin and nuclei their lose and other . Without marrow. As cells mature, these with hemo- gradually fill they with asolidcenter. are They produced from stem cells inbone Matureblood. cells are red blood shaped like an inner tube cells make up blood Red 40to 45percent of cells inthe all Red Blood Cells cells, and platelets, as photograph the in containsBlood of types white cells, several red blood blood proteins chapter inthe on immune the system and disease. or attacks foreign materials You blood. inthe more learn will about these A group proteins of specialized made by immune the system fights marrow. shape one Each and has aspecialized function. componentsthree blood are manufactured mostly inthe returning toit heart, the picks up CO hemoglobin cells and inred blood is transported cells. When to is all blood Type can receive Bblood only orOblood. own their type blood protein markers and can accept any of People type blood. with Type Aand donatedbe to aperson with any Type othertype. blood has both ABblood MAI hydrated? lls have different functions. havells different If re Pro The m N

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Q U I C K L A B observing 5B

Blood Cells Materials In this lab, you will examine different types of blood cells • slide of blood cells under the . • microscope Problem What are the different characteristics of blood cells? Procedure 1. Examine the slide under low power and high power on the microscope. Identify a red blood cell, a , and a platelet. Notice the proportion of each type of cell on your slide. 2. Draw each type of cell and label its structures. Analyze and conclude 1. explain What is the general shape of a red blood cell? How is this shape related to the function of a red blood cell? 2. Infer Based on the proportion of each type of cell on your slide, which type of cell is the most numerous in the blood of a healthy person? Which is least numerous?

Another blood protein, known as the Rh factor, is also critical in making a successful transfusion. People either are Rh positive (Rh+) and have this protein or are Rh negative (Rh–) and do not have it. Anyone can receive CONNECT TO Rh– blood without harm. However, if you are Rh– and receive Rh+ blood, your immune system will make proteins that cause the Rh+ blood cells to and In Extending Mendelian burst. As a result, blood must be matched for both the ABO group and the Rh Genetics, you read about the alleles that produce the group. The possible ABO/Rh blood combinations are shown in FIGURE 5.4. different phenotypes in the ABO blood group. Figure 5.4 ABO Rh BLOOD COMBINATIONS blood type can donate to can receive from A A, AB A, O B AB, B B, O VIRTUAL Lab AB AB A, B, AB, O HMDScience.com O A, B, AB, O O GO ONLINE Rh factor can donate to can receive from Blood Typing Rh+ factor Rh+ Rh+, Rh– Rh– factor Rh+, Rh– Rh–

White Blood Cells White blood cells, which contain no hemoglobin, are cells that defend the body against infection and that remove foreign material and dead cells. Different kinds of white blood cells defend the body in different ways. Some surround and ingest . Others produce proteins that act to destroy pathogens. Unlike red blood cells, white blood cells are not limited to the circulatory system. Some of these cells are able to pass through capillary

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(t) ©Photo Researchers, Inc.; (cr) ©CNRI/Photo Researchers, Inc. se Apply 30.5 2. 1. Re help seal the wound.help the seal injured, must they have missing the clotting factor injected into to blood their As aresult, must they guard against slightest the scrape or bruise. When people with hemophilia, even aminor cut can cause life-threatening bleeding. is agenetic disorder inwhich akey clotting factor is missing For blood. inthe thin the blood or dissolve clots can help prevent these circulatory problems. arteries to the heart or brain can cause a heart attack or stroke. Medications that and present serious risks to aperson’s For health. example, clots that block B otherheals, chemicals are released that dissolve clot. the ratethe of change inclotting until wound the Once injury the is sealed. clotting are example agood of apositive feedback loop. increases The body woundthe and prevents any loss of The further blood. steps inblood ce platelets and white blood cells, as the top photo shows in converts fibrinogen into fibrin. Sticky threads of fibrin form a web that traps converts prothrombin, a plasma protein, into thrombin. Thrombin, in turn, which begin the process of repair. One of the factors platelets then release proteins known as clotting factors, spiky extensions that intertwine into a complex net. The R platelets quickly cluster around wound. the control bleeding. When you cut or vessel, tear ablood Platelets are fragments cell that help form clots that P consideredalso of part immune the system. body’sthe tissues. For reason, this white cells are blood intowalls lymphatic the system and attack pathogens in als an injury? an als

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30.6

4B, 10A, 10C Key Concept the lymphatic system provides another type of circulation in the body. VOCABULARY MAIN IDEAS lymphatic system is collected from tissues and returned to the circulatory system. lymph The lymphatic system is a major part of the immune system. node Connect to Your World 4B investigate and explain cellular processes, including Your body has two transport networks that circulate fluids. The first is the circulatory homeostasis, energy conversions, system, which brings gases and nutrients to every cell. The second is the lymphatic transport of molecules, and synthesis of new molecules; system. While this system also helps to distribute nutrients, its main jobs are to 10A describe the interactions that absorb excess fluid, to fight disease, and to carry waste products away from the cells. occur among systems that perform the functions of regulation, nutrient These two systems work so closely together that almost everywhere there are blood absorption, reproduction, and vessels, there are also lymph vessels. defense from injury or illness in animals; 10C analyze the levels of organization in biological systems and relate the levels to each other MAIN IDEA 4B, 10A, 10C and to the whole system

tonsils Lymph is collected from tissues and returned to the circulatory system. The lymphatic system (lihm-FAT-ihk) consists of a complex network of organs, vessels, and nodes throughout the body, as shown in FIGURE 6.1. The heart system collects excess fluid that leaks out of the blood capillaries into the area between the cells. This fluid, called interstitial (ihn-tuhr-STIHSH-uhl) fluid, spleen brings nutrients to the cells and removes their wastes. Although 90 percent of the fluid returns to the capillaries, up to 3 liters (3.2 qt) per day remain outside the blood vessels. Without the lymphatic system, your body would begin to swell as more fluid becomes trapped in your lymph nodes tissues. The system prevents this problem through a two-step process: • It collects the fluid and filters it to remove dead cells and microorganisms. lymph • It returns the cleaned fluid to the circulatory system. vessels Lymphatic circulation begins when the fluid between the cells enters the lymphatic capillaries, where it becomes known as lymph. The lymph then flows into larger vessels within the lymphatic system. Without a heart to pump the fluid, the vessels rely on contractions of skeletal and smooth muscles to circulate the lymph. One-way valves similar to those in veins keep the fluid from flowing backward. From the vessels, lymph collects in small rounded structures called lymph nodes. The nodes filter the lymph and trap , viruses, fungi, and cell Figure 6.1 The lymphatic system fragments. Specialized immune cells ingest and destroy this organic material. collects fluid that leaks from the Vessels then carry the lymph out of the nodes. In the last stage of the journey, blood vessels and returns it to the the lymph returns to the circulatory system. Two large vessels, one on either heart. The spleen recycles old red blood cells; white blood cells side of the body, enter veins located just under the collarbones. The lymph is mature in the thymus. returned to the blood and becomes part of the circulatory system again.

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CHAPTER 30 G N I D A E R

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IDEAS ood group 4b o know your blood type? 10a 2 ood andthe 5b rises. How doyour s. 2 andO 2 are able 10a 10c

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Critical Thinking 25. Infer When people lift or push a heavy weight, their Analyzing Data Form a Null Hypothesis veins often puff up and become visible under their skin. A scientist is investigating the relationship between age Why do you think this happens? and rates of smoking—light, medium, or heavy. Use the 26. Synthesize A person who is exposed to high levels of graph below about age and smoking rates to answer the smoke during a fire may be taken to a hospital for a test next two questions about accepting or rejecting a null to determine whether he or she has enough oxygen in hypothesis the blood. Would you test the blood from an artery or a age groups and rates of smoking vein in this case? Explain your answer. 40 27. Analyze In volcanic areas, certain depressions in the 30 ground are filled with high levels of CO2. Animals wandering into these areas die so quickly that they have 20

no chance of getting out. Use your knowledge of Percent diffusion and circulation to explain why death might 10 occur so quickly. 4b 0 16–24 25–34 35–44 45–54 55–64 65–74 28. Apply If someone has a heavy weight on his or her Heavy smoker Age (years) chest, explain why after a short time it becomes difficult to breathe, even though the person’s mouth and nose Medium smoker are not affected. Light smoker 29. Predict A stroke occurs when the blood supply to the brain is interrupted. What immediate impact would this event have on the brain cells? 10c 33. Evaluate One null hypothesis for this investigation might be: “There is no relationship between age and Interpreting Visuals smoking rates.” Based on the data, would you accept or Use the diagram of the heart to answer the next three reject this null hypothesis? Explain your answer. questions. to body 34. Apply Form another null hypothesis for this investiga- tion based on age and smoking rates. Explain whether the data would cause you to accept or reject your from body hypothesis.

to lungs to lungs Making Connections 35 . Write a Proposal Suppose you are asked to make an from lungs from lungs animated film about the journey of an oxygen molecule from the time it is inhaled until it reaches a cell. Write a left atrium proposal describing your concept for the film. Include in your description the names of structures in the circula- right atrium tory and respiratory systems, such as trachea, alveoli, left ventricle atrium, ventricle, and so on. 4b right ventricle 36. Synthesize The heart and lungs work very efficiently, but they can be strengthened by exercise to work even from body to body better. For instance, the heart rate of an athlete at rest is actually lower than the resting heart rate of a person 30. Identify Describe the path of blood in the heart. who does not regularly exercise. Why do you think this is so? Use your knowledge of the muscular, circulatory, 31. Infer Why does the heart need two openings leading and respiratory systems in your answer. 10c into the right atrium?

32. Analyze Which chamber(s) and valve(s) do you think would be under the most stress from high blood pressure? Explain.

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Biology End-of-Course Exam Practice

Record your answers on a separate piece of paper. 4B, 11A, 11B MULTIPLE CHOICE 3 In order for the body to maintain homeostasis, the intake of oxygen into the lungs must be 5B, 10A, 10C followed by — 1 The chart below shows compatibility between A an increase in blood pressure different blood types. What would happen if a B the exhalation of carbon dioxide person with type O blood received a blood C a decrease in gas exchange transfusion of any other blood type? D a decrease in blood flow

Blood Type Compatibility 4B, 10C Blood Type Can Receive Blood From 4 A A or O B B or O AB A, B, AB, O O O

A There would be no complications because any blood type can be exchanged for another. B Complications would result as the immune As shown above, gas exchange occurs between system attacks the foreign blood cells. the alveoli and the capillaries of the lungs. C A larger amount of the different blood type What process is this diagram illustrating? would be needed to supply the missing protein. A circulation D There would be complications only if type AB B absorption were given. C diffusion D exhalation 4B, 10A, 10C 2 The circulatory and respiratory systems work 10A, 10C, 11B together to provide cells with oxygen and 5 The circulatory system helps to maintain a stable nutrients and remove wastes such as carbon body temperature as you exercise. Which dioxide. When the body needs more oxygen, how statement best describes this process? does the circulatory system respond? A Heat produced by the muscles is absorbed by A More blood is sent to the lungs and less to the the surrounding blood, where it cools. rest of the body. B Blood carries excess heat from the muscles to B The blood vessels to the arms and legs the skin, where heat can escape the body. constrict to conserve oxygen. C The circulatory and lymphatic systems work C The heart beats faster to match the rise in together to remove heat from the muscles. breathing rate. D Excess heat from the muscles is transported to D Blood moves more slowly through the organs the heart and lungs, where it cools. to carry away more wastes.

Chapter 30: Respiratory and Circulatory Systems 895