Bio manual 26



36____________________________________________________________________________________________circulationChapter Outline36.1 a shocking save36.2 circulatory systemsOpen and Closed Circulatory SystemsEvolution of Vertebrate Circulation36.3 HUMAN CARDIOVASCULAR SYSTEM The Pulmonary Circuit The Systemic Circuit36.4 The human HeartThe Cardiac CycleSetting the Pace for Contraction36.5 vertebrate BLOODPlasmaCellular ComponentsRed Blood CellsWhite Blood CellsPlatelets36.6 ARTERIES AND ARTERIOLESRapid Transport in ArteriesAdjusting Flow at Arterioles36.7 BLOOD PRESSURE36.8 EXCHANGES AT CAPILLARIES36.9 BACK TO THE HEART36.10 blood and Cardiovascular DisordersAltered Blood Cell CountCardiovascular DiseaseAtherosclerosisHypertensionRhythms and Arrhythmias36.11 interactions with the LYMPHATIC SYSTEMLymphoid Organs and TissuesA SHOCKING SAVE (REVISITED)SUMMARYSelf-Quiz Data analysis activitiescritical thinkingLearning Objectives36.1 Examine the life-saving uses of CPR and automated external defibrillator.36.2 Compare open and closed circulatory systems.36.3 Illustrate the process of blood circulation in humans using diagrams.36.4 Examine the pulmonary and the systemic circuits of the human cardiovascular system.36.5 Describe the components of blood.36.6 Examine the three-phase process of hemostasis.36.7 Examine the significance of blood types.36.8 Illustrate the process of a cardiac cycle using a diagram.36.9 Examine the relationship between the structure and the functioning of the human heart.36.10 Discuss the structure and functions of the different kinds of blood vessels involved in blood circulation.36.11 Examine how blood pressure is measured and regulated.36.12 Examine how materials are exchanged between the blood and interstitial fluid.36.13 Discuss the important functions of veins.36.14 Examine the causes that affect the normal functioning of the circulatory system.36.15 Examine the components of the lymphatic system.Key Termsaortaarteriesarteriolesatrioventricular (AV) nodeatrium, atriabloodblood pressure capillariescardiac cyclecirculatory systemclosed circulatory systemdiastolediastolic pressurehearthemolymphhemostasisinferior vena cavalymphlymph nodeslymph vascular systemopen circulatory systemplasmapulmonary arterypulmonary circuitpulmonary veinspulsered blood cells (erythrocytes)sinoatrial (SA) nodespleen superior vena cavasystemic circuitsystolesystolic pressurevasoconstrictionvasodilationveinsventriclewhite blood cells (leukocytes)Lecture Outline 36.1 A Shocking SaveA.An electrical signal generated by a natural pacemaker in the heart wall causes the heart muscle to contract, creating the heart beat.1.Sudden cardiac arrest is the cessation of the beat, which halts the flow of the blood.2.CPR and defibrillation can restore the heart beat.B.Matt Nader, a high school football player, went into cardiac arrest during a high school game.1.CPR and defibrillation using an automated external defibrillator (AED) saved his life.2.Through his testimony, Texas legislators passed a law requiring high school athletic events to have AEDs readily available.36.2Circulatory SystemsA.Open and Closed Circulatory Systems1.A circulatory system is an internal transport system with three components. a.Blood is a fluid tissue composed of water, solutes, and formed elements. b.Blood vessels are tubes of various diameters through which the blood is transported.c.The heart is a muscular pump that generates pressure to keep the blood flowing.2.Interstitial fluid “bathes” the cells of the body.a.The volume, composition, and temperature of this fluid must be carefully maintained.b.Exchanges between interstitial fluid and blood keep the internal environment tolerable.3.Arthropods and most mollusks have an open system.a.Hemolymph is pumped from a heart into large tissue spaces where organs are “bathed.”b.The hemolymph mixes with interstitial fluid, and after accessing cells, returns to the heart via pores.4.Vertebrates have a closed system.a.All the vessels and the heart are connected so that blood remains enclosed.b.Blood volume is constant and is equal to the heart’s output at any time.c.Flow rate slows as blood moves through the fine capillaries of the capillary beds.B.Evolution of Vertebrate Circulation1.In fishes, blood flows in a single circuit, passing through a heart of two chambers.2.In amphibians the three-chambered heart is partially partitioned into right and left halves, permitting a partial separation into two circuits.3.Birds and mammals have two separate circuits of blood flow.a.The right half of the heart receives deoxygenated blood and pumps it to the lungs of the pulmonary circuit.b.The left half receives blood from the lungs and pumps the oxygen-rich blood to all of the tissues and organs in the systemic circuit.36.3 Human Cardiovascular SystemA.The general route of blood circulation is: heart arteries arterioles capillaries venules veins heart.B.The Pulmonary Circuit 1.In the pulmonary circuit, oxygen-poor blood is pumped to the lungs from the right side of the heart, and oxygen-rich blood is returned from the lungs to the left side. C. The Systemic Circuit1. In the systemic circuit, oxygen-rich blood is pumped from the left side of the heart to all the body.2.Usually a given volume of blood in either circuit passes through only one capillary bed; an exception is blood from the digestive tract, which passes through the liver before entering the general circulation.36.4The Human HeartA.Heart Structure and Function1. The heart tissue is layered.a.The outer covering of the heart is the pericardium, which is partially a fluid-filled sac and the outer part of the heart wall.b.The bulk of the heart wall is the heart muscle—myocardium—serviced by coronary circulation.c.The heart is lined with a smooth endothelium.2.Nutrients and oxygen are delivered to the heart tissues by the coronary arteries.3.The heart has four chambers and four valves.a.Each half of the heart consists of an atrium (receiving) and a ventricle (pumping) separated by an atrioventricular valve.b.Blood exits each ventricle through a semilunar valve. B. The Cardiac Cycle1.The cardiac cycle consists of a sequence of contraction (systole) and relaxation (diastole).a.As the atria fill, the ventricles are relaxed.b.Pressure of the blood in the atria forces the atrioventricular valves to open; the ventricles continue to fill as the atria contract.c.The ventricles contract, the atrioventricular valves close, and blood flows out through the semilunar valves.d.The heart sound “lub” is made by the closing of the AV valves; the “dup” sound is the closure of the semilunar valves.C.Setting the Pace for Contraction1.Cardiac muscle has orderly arrays of sarcomeres, which contract by a sliding-filament mechanism.2.Because of the close junctions of cardiac muscle cells, they contract in unison.3.Excitation for a heartbeat is initiated in the sinoatrial (SA) node (also known as the cardiac pacemaker) then passes to the atrioventricular (AV) node for ventricular contraction; this is the cardiac conduction system.4.The nervous system adjusts rate and strength.36.5 Vertebrate BloodA.Functions of Blood1.It carries oxygen and nutrients to cells, and it carries secretions and wastes away from them.2.It helps stabilize internal pH.3.It contains phagocytic cells that fight infection.4.It equalizes body temperature in birds and mammals.B.Blood Volume and Composition1.In humans, body size and the concentrations of water and solutes dictate blood volume. a.On average, humans have about 5 liters (10 pints).b.In vertebrates, blood is a viscous fluid, thicker than water and slower flowing.c.Blood’s fluid portion is called plasma; the cellular portion consists of blood cells and platelets.d.Stem cells are unspecialized cells that retain the capacity for mitotic cell division.2.Plasma a.About 50–60 percent of blood volume is plasma, which is composed mostly of water.b.Some plasma proteins transport lipids and vitamins; others function in immune responses and blood clotting.c.Plasma also contains ions, glucose, lipids, amino acids, vitamins, hormones, and dissolved gases. It also acts as a solvent for hundreds of different plasma proteins.3.Red Blood Cells (Erythrocytes)a.In mammals, red blood cells are biconcave disks that transport oxygen.b.Red blood cells contain hemoglobin—an iron-containing protein that binds with oxygen.c.They form from stem cells in bone marrow, lose their nuclei, and live about 120 days.d.The number of cells per microliter (about five million) is called the cell count.4.White Blood Cells a.White blood cells, or leukocytes, remove dead or worn-out cells and protect us against invading microbes and foreign agents.b.There are several types of white blood cells. 1)Granulocytes, named for their visible granules in the cytoplasm, are neutrophils, basophils, and eosinophils. 2) Neutrophils undergo phagocytosis to capture bacteria. 3) Eosinophils can combat parasitic worms and are prevalent during allergy season.c. Basophils are active in the inflammatory response. 4) Agranulocytes, white blood cells that lack granules in the cytoplasm, are lymphocytes and monocytes. 5) Lymphocytes, the “B” and “T” cells, are involved in the immune responses. 6) Monocytes become macrophages that destroy foreign particles via phagocytosis.5.Platelets a.These are fragments of megakaryocytes produced by bone marrow stem cells.b.They function in blood clotting and last only 5–9 days.36.6Arteries and ArteriolesA. Blood is distributed by means of arteries, arterioles, capillaries, venules, and veins.1.Blood pressure is fluid pressure of the blood due to ventricular contractions.a.The flow rate is directly proportional to the pressure gradient between the start and end of the vessel; it is high in contracting ventricles and in the beginning of the arteries, and low in relaxed atria.2.The flow rate is inversely proportional to the vessel’s size or resistance to flow.B.Rapid Transport in Arteries1.Arteries are large-diameter vessels that present low resistance to flow as they conduct blood away from the heart.2.Because of their elastic walls, arteries tend to “smooth out” the pulsations associated with the discontinuous pumping cycle of the heart.C.Adjusting Flow at Arterioles 1.Blood flow to organs, except the brain, is a function of activity. a.The brain gets a constant supply. b.When you exercise, blood flow to the kidneys and gut slows. 2.Neural and endocrine signals cause changes in arteriole diameter by stimulating the muscle cells in the walls.a.If the blood pressure increases, the arterioles are instructed to relax (vasodilation).b.If the pressure decreases, the diameter of the arterioles decreases (vasoconstriction).3.Arterioles serve as control points where adjustments can be made in blood volume distribution.D. Following arterioles, the blood enters capillary networks.1. The oxygen is given up to the tissues in the capillary network.2. The blood from several capillaries flows into a venule.3. After the venules, the blood enters veins and travels back to the heart.36.7 Blood PressureA. A special instrument with a cuff surrounding the upper arm is connected to a pressure-measuring device. 1.The peak pressure (systolic) is recorded when the ventricles are contracting—120mm is typical. 2. The lowest pressure (diastolic) is reached when the ventricles are relaxing—80mm.B. Blood pressure is related to blood volume, constriction of the arterioles.1.Receptors on the aorta and in carotid arteries of the neck alert a control center in the brain when blood pressure drops or increases.2.In response the brain calls for changes in cardiac output and arteriole diameter.36.8 Exchanges at CapillariesA.Capillary Function 1.Capillaries are diffusion zones for exchanges between blood and interstitial fluid.a.A capillary is the smallest tube (red blood cells travel single-file) in the path of circulation.b.Total resistance is less than in arterioles, so the drop in blood pressure is not as great.c.Its wall consists of a single layer of endothelial cells, which facilitates diffusion to and from the interstitial fluid.2.Movement across the capillary is by several modes: diffusion (of oxygen and carbon dioxide), endocytosis and exocytosis (of proteins), between the cells (of ions), and bulk flow (of water).a.At the beginning of a capillary bed, there is a movement of plasma out into the interstitial fluid in a process known as ultrafiltration.b.Further on, some tissue fluid moves into the capillary through clefts between its endothelial walls in a process known as reabsorption.36.9 Back to the Heart A.Capillaries merge into venules then into veins.1. Blood pressure and resistance to flow are both low; valves prevent backflow.a. When valves become damaged, varicose veins (in the legs) or hemorrhoids (in the anus) form. b. Clots may develop in a leg vein from valve damage or inactivity. 1) A clot may dislodge from the leg and travel to the heart or lungs.2. Veins are blood volume reservoirs (50–60 percent of blood volume) because their walls can distend or contract.3.The movement of skeletal muscles squeezes the veins and pushes the blood along against the forces of gravity.36.10Blood and Cardiovascular DisordersA.Altered Blood Cell Count1.Anemias are conditions in which there are too few, or deformed, RBCs. a.Hemorrhagic (sudden) and chronic (slow) anemias follow blood loss. b.Certain bacteria and protozoans replicate in RBCs and cause hemolytic anemias. c.Insufficient iron causes iron deficiency anemia. d.Sickle-cell anemia and thalassemias arise from mutations that either alter the hemoglobin or stop its synthesis altogether.2.Polycythemias (far too few RBCs) and blood doping make blood flow sluggish.3.Infectious mononucleosis is a viral disease in which too many monocytes and lymphocytes form; it may last several weeks with a gradual recovery.4.Leukemias are cancers of the bone marrow, which impair WBC formation.5.Lymphomas are cancers that originate from B or T lymphocytes, producing tumors in lymph nodes and the lymphatic system.B. Cardiovascular Disease Major risk factors for cardiovascular disease are genetics, smoking, obesity, lack of exercise, hypertension, high cholesterol level, and diabetes mellitus.2. Atherosclerosis a.In this condition, lipids such as cholesterol build up in the arterial wall. b.Low-density lipoproteins (LDLs) infiltrate the walls, causing an atherosclerotic plaque to form. c.High-density lipoproteins (HDLs) also bind cholesterol, but are more desirable since the liver is able to metabolize them. d.Platelets gather at the site and initiate clot formation. e.Enlarging plaques and blood clots narrow or block arteries. f. With coronary bypass surgery, doctors stitch a section of blood vessel from another part of the body to the aorta and coronary artery below a clogged area.g.Laser angioplasty uses lasers to vaporize the plaques.h.During balloon angioplasty, a small balloon is inflated inside a blocked artery to flatten the plaques. 3. Hypertension a.Hypertension refers to chronically high blood pressure, even at rest.b.It is referred to as the silent killer because people are often unaware they have it.c.Hypertension tends to run in families.d.Diet, lack of exercise, and salt intake increase risk. e.The heart may enlarge enough to pump less efficiently and interfere with the delivery of oxygen to the brain, heart, and other vital organs.4. Rhythms and Arrhythmias a.Electrocardiograms (ECGs) can reveal arrhythmias, an abnormal heartbeat. 1) Bradycardia is a below-average resting cardiac rate, which may be the result of ongoing exercise. 2) Tachycardia, fast heartbeat, is caused by exercise or stress. b.Atrial and ventricular fibrillation are repeated contractions that disrupt the normal cardiac cycle.36.11Interactions with the Lymphatic SystemA.Lymph Vascular System1.The lymph vascular system includes lymph capillaries and lymph vessels.2.It returns excess water and proteins (lymph) to the bloodstream, transports fats, and brings foreign materials to the lymph nodes for disposal.3.Lymph capillaries begin blindly in the tissues of the body; they lead to lymph vessels, which in turn lead to ducts that return the fluid to the bloodstream.B.Lymphoid Organs and Tissues1.Lymph nodes are strategically located at intervals along lymph vessels.a.Before entering blood, lymph trickles through at least one node and gets filtered.b.Masses of white blood cells are located inside the nodes and attack nonself items.2.The organs and functions include: a.The lymph nodes (with resident cells) located along the lymph vessels help remove bacteria and cellular debris.b.The spleen is the largest lymphoid organ and it removes spent RBCs, holds macrophages, and produces red blood cells in human embryos.c.The thymus secretes hormones that regulate the activity of lymphocytes and is a site where they multiply and mature.36.12A Shocking Save (Revisited) Most cardiac arrest cases are not attended to before health professionals arrive.CPR has been replaced with CCR (cardiocerebral resuscitation).CCR involves only chest compressions—enough air moves into the lungs via this method. Automated External Defibrillators (AEDs) are more readily available in public places.Suggestions for Presenting the Material?This chapter includes a discussion of closed and open circulatory systems. Students will be familiar with a closed system because that is the type in the human body; but the open concept implies a great deal of “hemorrhaging,” which sounds terminal, but in this context is normal.?One of the strengths of the Starr and Taggart text is the inclusion of excellent summaries. Use the figures and animations to help the students with these topics. See CengageNOW for additional information and sources.?When discussing the functions of blood, it may be helpful to refer to other lectures that will expand on the topic. Such instances include: white blood cells and immunity, red blood cells and respiration, and nutrient transport.?Because of the complexity of the entire cardiovascular system, the simplified scheme in Figure 36.5 is useful for introducing the concepts of pulmonary and systemic circuits. The concept of oxygen-rich and oxygen-poor blood can be emphasized here. This can be followed by the heart pathways and contraction sequence.?The heartbeat, pulse, and blood pressure are measurable quantities of interest to students; therefore, these deserve as much lecture time as is feasible.?Capillary exchange is a topic that allows you to review previous lectures on diffusion and active transport.?The mechanism of clotting, and the somewhat confusing term hemostasis (not homeostasis) used to describe it, may need special attention and/or simplification.?Blood typing is confusing to students. This is especially true because most believe that the ABO markers and the Rh markers are intimately connected, since blood type is nearly always expressed that way—O+, for example. Stress the independent nature of these two sets of markers. It is also helpful to mention that the ABO and Rh factors are only a few of the antigens that are located on red blood cells. There are over 400 more!?Usually students feel they have a fair grasp of circulation until the lymphatic system is introduced. Then it is a “what’s this for?” expression. Stress the necessity for such a system and the one-way return of fluid to the general blood supply.Make sure that the students understand the difference in pressure between an artery and a vein. The artery has a great deal of pressure, since it is the first type of vessel the blood encounters after leaving the heart. Since veins are located at the end of the trip back to the heart, they are exposed to much-reduced pressure. Explain to the students that if you cut an artery and a vein, there would be very different results. (Do not try this at home!)Typically arteries contain oxygenated blood and veins contain deoxygenated blood. How are the pulmonary veins and arteries different?Mention that the heart exhibits autorhythmicity—it is self stimulating. This is unlike other muscles of the body. -How does this influence the idea of clinical death?Classroom and Laboratory Enrichment?Ask a physician to demonstrate an artificial pacemaker; include comments on the limitations and usefulness of such an artificial device versus the natural SA node.?Borrow a sphygmomanometer and ask a person skilled in its use to explain how blood pressure is determined, using members of the class as volunteers.?Create or acquire a blood cell model with both ABO antigens and Rh factors. Purchase a simulated blood-typing kit (available from Ward’s). This kit utilizes plastic-coated particles, so there is no risk of disease transmission. Have the students type the four patients provided. At the end of the activity, ask questions about who could transfuse to which other patient safely.?Request a cow heart(s) from a local meat processor (be sure to ask them to leave the aorta on it) to use in a lab setting. Students are amazed at the size of the heart! Dissect both the atria and ventricles to show students the similarity in mammal heart structure and function. Show the students the SA node and other key features of the exterior of the heart. If the major vessels are not present, you can poke a glass rod down through each hole to help determine which vessel was originally there.?Determine the resting and active pulse rates for a variety of body types in the class. Can you make any generalizations from your data? ?Obtain a recording of heart sounds as they would be heard through a stethoscope. Relate sounds to events of the normal and abnormal cardiac cycle. Pass a stethoscope around the room so everyone can hear their own heart sounds.?To illustrate cardiovascular disorders, show a video of a heart bypass operation. Using a model, illustrate for students what is “bypassed” in the procedure.?Discuss the role of cholesterol and its contribution to heart disease.Do a demonstration of the dissection of an earthworm. Typically, the students think the earthworm is a primitive organism. They may be surprised to learn that the earthworm has a closed circulatory system and more than one heart.When you examine diagrams of the hearts of various animals, which ones do not mix oxygenated blood with deoxygenated blood? Why is this an important adaptation?Examine prepared slides of blood smears. Try to identify each of the five types of white blood cells. Notice that mature red blood cells do not have a nucleus. How is this explained by their function?A machine that performs cell counts does so based on cell size. When observing red blood cells, white blood cells, and platelets list them in order from largest to smallest.Examine a cutaway view of the heart. Can you tell which of the four chambers of the heart work the hardest by examining the thickness of the chamber walls?If you are feeling brave, take a live goldfish and spread its tail under a dissecting microscope. You will be able to see red blood cells traveling single-file through the capillaries.Explain why they call skeletal muscle action “milking a vein.” How does the movement of skeletal muscles and valve action prevent clot formation? Have everyone in the class choose an artery or a vein from Figure 36.4. Then have each student tell where each vessel supplies blood to or collects blood from, and whether the blood is oxygenated or deoxygenated.If possible, obtain a speaker from the local chapter of the American Red Cross. This representative can discuss the conditions each blood product would treat, expiration dates, and storage requirements. Look up the symptoms of a transfusion reaction. Many of these symptoms resemble those of a tissue rejection. This may make the students more comfortable thinking of blood as a tissue.Have anyone who knows their blood type in the class announce what other blood types they could safely receive and for whom they could serve as a suitable donor.Each student should record their own pulse rate or that of a lab partner. Note: do not use your thumb to measure someone’s pulse, since your thumb has a pulse. What could it mean if the pulse in your leg is different than the pulse in your wrist? Classroom Discussion Ideas?How can you explain the fact that persons who die of heart attack (lack of oxygen to heart muscle) have perfectly adequate amounts of oxygenated blood in their heart chambers??Should CCR training be a required skill taught and learned in high school or college? ?Evaluate the risk to the public of administering first aid (CCR or AED defibrillator) when so many people are “sue happy.”?Would you want to own an AED? Should most public places be required to have one available? The textbook mentions that bystanders are hesitant to perform CPR on a heart attack victim. How will this change with the advent of CCR, where no mouth-to-mouth resuscitation is necessary?Additional Ideas for Classroom Discussion?How can a worker in a police crime lab determine if the blood found at a crime scene is human??The heart is really a “double pump.” It is also, of course, divided into four chambers. Does this mean that one pump consists of atria, the other of ventricles, or does it mean the left and right sides are pumping to separate circulations? Explain your reasoning.?Why is the lymph system such a “highway” for the spread of certain metastatic cancers??Why is hemophilia in females almost never seen??Evaluate the truthfulness of the statement “I’m a blood relative.” Is there a more accurate expression that could replace this one??Have students reflect on and discuss the ceaseless activity of their own heart. Have them complete the simple calculations for how many times per hour, day, month, and year their own heart beats.?In small groups, have students compile a list of common activities of college-age students that are considered risk factors for heart disease. Think about the differences in the composition of hemolymph and blood.In today’s world, there are often severe blood shortages. Occasionally, scientists try to develop artificial blood and ways to utilize animal blood for human use. Look into some of these methods. How are they successful or unsuccessful? Stress to the students that clot formation requires both a series of clotting factors and an adequate platelet count.The Rh factor’s involvement in pregnancy is often a difficult concept for the beginning biologist. Be sure to re-explain it in detail. Now there is a product called RhoGAM? to eliminate this problem —explain its mechanism. Give the students this problem: a mother had 12 pregnancies in the early 1900s. Only one child survived. Which child lived and why?Be sure to stress that valves in the heart and in veins have the same function—to prevent the backflow of blood.How Would You Vote? Classroom Discussion Ideas?Monitor the voting for the online question. There are many good topics that high schools should add to their curricula, including lifestyle education (smoking, birth control, etc.). Most of these topics are concerned with maintaining one’s health and wellbeing. Learning CPR is preparation for helping someone else. It is proven that it does save lives. It seems it would be a worthwhile addition to a required health curriculum.?Have students complete class polling using the JoinIn clickers.Term Paper Topics, Library Activities, and Special Projects?Evaluate the reported links between lipids and cardiovascular diseases.?Survey the various corrective surgical procedures that are routinely performed on the heart and its vessels. Select one or two for an in-depth report.?It is often said that “the heart never rests.” True, it does beat continuously from before birth until death, usually at old age. However, it does rest for 0.3 seconds after each beat. Assuming a steady pulse of 70 beats per minute, calculate the total amount of time the heart has rested in a person 75 years old. ?The Rh factor is named for the Rhesus monkey. Trace the historical discovery of this protein marker in primates and humans.?Death of newborn babies from erythroblastosis fetalis (Rh factor related) have been virtually eliminated since the 1950s. How has this been accomplished??Have students use Thomson’s INFOTRAC to research one type of cardiovascular disorder of interest. Have them report on their results in a short paper.?Have students complete a position paper taking a pro or con position on the trend toward further regulation of activities and foods that are considered prime contributors to cardiovascular disease in the U.S.?Have students consult their medical records and create a short description of their blood type. What would their red blood cells look like? What ABO or Rh elements are present?Look up arteriosclerosis, which is commonly known as hardening of the arteries. How is it related to atherosclerosis?Research the disease malaria. Obtain a photograph of a red blood cell containing the deleterious organism. What is the chemical composition of lymph? How does it differ from plasma? How is it transported around the body?Lymphoid organs such as tonsils and the spleen have definite functions. How do we compensate if those organs are removed?Borrow an AED (automated external defibrillator) from the public safety department at your campus. Show the class the necessary steps for its operation.What is RhoGAM? How and when was it developed? How does it save the lives of many babies?Possible Responses to Critical Thinking Questions1.A blood clot in the leg, or deep vein thrombosis (DVT), that breaks free is more likely to get stuck in the lungs because the embolus that comes from a clot in a leg vein will be returned to the heart along with the deoxygenated blood via the larger leg and body veins to the heart. Since deoxygenated blood is pumped from the heart to the lungs to pick up oxygen, the embolus will get stuck in a smaller blood vessel going to a lung.2.Beta-blockers would be useful for treating high, but not low blood pressure. They work by reducing the heart rate, and hence the amount of blood the heart pumps out. 3.The liver produces proteins necessary for blood to clot (clotting factors). Therefore, individuals with compromised liver function are at risk for not producing these proteins at the levels required for blood to clot properly. Possible Responses to Data Analysis Activities QuestionsThe states in the southeastern U.S. are known as the “stroke belt,” since they have an increased incidence of stroke deaths. This study compares stroke deaths in the Southeast to those in New York state. More black people (~ 85/100,000 people) in the “stroke belt” die from strokes than white people (~60/100,000 people) in that same area.The white population in New York has a slightly higher death rate (~35/100,000 people )than the black population (~30/100,000 people) in the same state.White people living in the “stroke belt” have a higher death rate than black people living in New York.This data show evidence that illustrates that there are more deaths from stroke in the southeastern U.S. than in New York state. It does not definitely prove that this difference in survival rate is due to the proximity of healthcare facilities. Many more factors would need to be explored, such as diet and whether the participants were smokers. ................
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