1. Chapter 23
Circulation 2

2. Blood starts in the Right Atrium, where to next
Blood starts in the Right Atrium, where to next? Put the following in order:
Correct Order
Right Ventricle
Pulmonary Arteries
Capillaries of Lungs
Pulmonary Veins
Left Atrium
Left Ventricle
Aorta
Capillary beds of body
Vena Cava
Left Ventricle
Capillaries of Lungs
Vena Cava
Right Ventricle
Capillary beds of body
Pulmonary Veins
Left Atrium
Aorta
Pulmonary Arteries
s/B23/B2301/st01/frame.html

3. The SA node sets the tempo of the heartbeat
The SA (sinoatrial) node
generates electrical signals in atria
sets the rate of heart contractions.
Called the pacemaker of the heart
SA Node receives nervous signal info from central nervous system and relays these changes in heart rate to rest of heart to coordinate cardiac cycle and heart rate. 1
Signals from the SA node spread through the atria.
SA node (pacemaker)
Right atrium
Student Misconceptions and Concerns
Students often expect that the blood flowing through the heart supplies the heart muscle. The need for coronary arteries and veins is not clear to them. (The thickness of the walls of the heart does not permit efficient diffusion, and furthermore, the oxygen content of the blood in the right atrium and ventricle is very low.)
Teaching Tips
1. The specialized junctions that promote signal conduction between cardiac cells are specifically identified in Figure 20.6 in Chapter 20.
2. Before explaining the functions of the SA node, consider asking your students to explain why the atria contract before the ventricles contract. Posing a question and asking for an explanation rather than simply lecturing students often generates a more active interest in the subject matter.
ECG
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4. The SA node sets the tempo of the heartbeat
The AV (atrioventricular) node
Relays these signals to the ventricles
Causes ventricular contraction
Student Misconceptions and Concerns
Students often expect that the blood flowing through the heart supplies the heart muscle. The need for coronary arteries and veins is not clear to them. (The thickness of the walls of the heart does not permit efficient diffusion, and furthermore, the oxygen content of the blood in the right atrium and ventricle is very low.)
Teaching Tips
1. The specialized junctions that promote signal conduction between cardiac cells are specifically identified in Figure 20.6 in Chapter 20.
2. Before explaining the functions of the SA node, consider asking your students to explain why the atria contract before the ventricles contract. Posing a question and asking for an explanation rather than simply lecturing students often generates a more active interest in the subject matter.
© 2012 Pearson Education, Inc. 4

6. ECG Animations

7. Electrical Activity of Myocardium
Atrial depolarization begins
Atrial depolarization complete (atria contracted)
Ventricles begin to depolarize at apex; atria repolarize (atria relaxed)

8. Electrical Activity of Myocardium
Ventricular depolarization complete (ventricles contracted)
Ventricles begin to repolarize at apex
Ventricular repolarization complete (ventricles relaxed)

9. ECGs, Normal & Abnormal
No P waves

10. ECGs, Abnormal Arrhythmia: conduction failure at AV node
No pumping action occurs

11. Heart Sounds Auscultation - listening to sounds made by body
First heart sound (S1), louder and longer “lubb”, occurs with closure of AV valves
Second heart sound (S2), softer and sharper “dupp” occurs with closure of semilunar valves
S3 - rarely heard in people > 30
Examples

12. A B C A = Pulnomic Stenosis B = Normal C = Aortic Stenosis Early
Which of the following do you think is a normal heart sound? A B C
A = Pulnomic Stenosis
B = Normal
C = Aortic Stenosis Early

13. Where to listen on chest wall for heart sounds.

14. Heart Contractions
Listen to your hearts.

15. What is a Heart Attack?

16. Heart Attack
Atherosclerosis

17. STRUCTURE AND FUNCTION OF BLOOD VESSELS
STRUCTURE AND FUNCTION OF BLOOD VESSELS
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18. 23.7 The structure of blood vessels fits their functions
Capillaries
Function:
only vessels involved in exchange of solutes and fluid between blood and interstitial fluid.
Structure:
have thin walls consisting of a single layer of epithelial cells,
are narrow, about as wide as one red blood cell, and
Structure allows for increased surface area to facilitate gas and fluid exchange
Student Misconceptions and Concerns
Students may need to be reminded of the definitions of an artery and vein, especially when discussing blood flow to and from the heart. Although veins generally carry oxygen-poor blood, the pulmonary artery transports low-oxygen blood to the lungs. The main difference between arteries and veins is the direction of flow (away from or toward the heart). Due to their structure, arteries are better able to resist the higher pressures generated by ventricular contractions. Veins generally experience lower pressure and are structurally less resistant.
Teaching Tips
1. The photo in Figure 23.7A demonstrates the narrow width of capillaries. Notice that the diameter of the capillaries barely permits the passage of red blood cells. (Also note that Figure 23.7B shows a capillary diameter much greater than in the photograph.) Challenge your students to explain why such a small size is adaptive. (Answer: it increases the surface area of capillaries and places red blood cells adjacent to the capillary walls for efficient gas exchange.)
2. One function of the circulatory system that is rarely discussed is the transport of heat. Blood vessels near the surface of the body expand when the body is overheated, releasing some of this excess heat to the environment. Conversely, during periods of exposure to cold, blood is shunted away from the skin to conserve heat.
3. Students may not relate the structure of the walls of arteries to blood pressure. Consider noting the presence of smooth muscle in the walls of arteries (Figure 23.7C). If these muscles contract, they narrow the arteries and increase pressure.
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19. Diffusion of molecules Interstitial fluid
Capillary
Red blood cell
Capillary
Figure 23.7A A capillary in smooth muscle tissue
Diffusion of molecules
Interstitial fluid
Tissue cell 19

20. The structure of blood vessels fits their functions
Arteries and Veins
are lined by a single layer of epithelial cells
connective tissue layer and smooth muscle that allows these vessels to recoil after stretching.
Arteries:
Largest in diameter of all vessels
thickest layer of smooth muscle in their walls
Allows them to constrict and reduce blood flow
Deal with higher blood pressure and exhibit increased elasticity
Veins:
have one-way valves that restrict backward flow of blood.
Student Misconceptions and Concerns
Students may need to be reminded of the definitions of an artery and vein, especially when discussing blood flow to and from the heart. Although veins generally carry oxygen-poor blood, the pulmonary artery transports low-oxygen blood to the lungs. The main difference between arteries and veins is the direction of flow (away from or toward the heart). Due to their structure, arteries are better able to resist the higher pressures generated by ventricular contractions. Veins generally experience lower pressure and are structurally less resistant.
Teaching Tips
1. The photo in Figure 23.7A demonstrates the narrow width of capillaries. Notice that the diameter of the capillaries barely permits the passage of red blood cells. (Also note that Figure 23.7B shows a capillary diameter much greater than in the photograph.) Challenge your students to explain why such a small size is adaptive. (Answer: it increases the surface area of capillaries and places red blood cells adjacent to the capillary walls for efficient gas exchange.)
2. One function of the circulatory system that is rarely discussed is the transport of heat. Blood vessels near the surface of the body expand when the body is overheated, releasing some of this excess heat to the environment. Conversely, during periods of exposure to cold, blood is shunted away from the skin to conserve heat.
3. Students may not relate the structure of the walls of arteries to blood pressure. Consider noting the presence of smooth muscle in the walls of arteries (Figure 23.7C). If these muscles contract, they narrow the arteries and increase pressure.
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21. Epithelium Basal lamina Capillary Valve Epithelium Epithelium
Figure 23.7C
Epithelium
Basal lamina
Capillary
Valve
Epithelium
Epithelium
Smooth muscle
Smooth muscle
Connective tissue
Connective tissue
Artery
Vein
Figure 23.7C Structural relationships of blood vessels
Arteriole
Venule 21

22. Blood pressure and velocity
Blood pressure
is the force blood exerts on vessel walls,
depends on:
cardiac output (volume of blood and heart rate)
resistance of vessels to expansion
decreases as blood moves away from the heart.
Student Misconceptions and Concerns
Students often struggle to explain how blood is propelled up their legs to return to their hearts. Frequently, students will suggest that the heart itself must provide sufficient force to move blood completely around the body. However, such pressures would destroy delicate capillaries. Other student hypotheses might include attributing a negative, siphoning effect to the heart. (Although the heart can generate a small pull, it is not sufficient to return blood up their legs and trunk to the heart.) Let them wonder long enough to stimulate critical thinking and motivate them to learn the answer. After explaining the role of skeletal muscles and one-way valves in veins, you might also note that it has been suggested that students will be more alert in class and even perform better on tests if they wiggle their legs. Challenge students to explain why this might work and why locking their knees when standing might have the opposite effect. (And enjoy watching some of your students deliberately wiggling their legs on the next exam!)
Teaching Tips
1. Students may not relate the structure of the walls of arteries to blood pressure. Consider noting the presence of smooth muscle in the walls of arteries (Figure 23.7C). If these muscles contract, they narrow the arteries and increase pressure.
2. Veins on the back of our hands can reveal many of these same principles of venous blood flow. If students keep their hands down below their heart for several minutes, such as during note taking or typing, they might notice their veins starting to bulge. Students can watch the veins empty by simply lifting their hands up to eye level. As we get older, such phenomena are even easier to see. Some instructors may be comfortable enough (and old enough!) to demonstrate this effect to their students.
3. Contracting the hand into a fist helps propel blood back up the arms to the heart. Skin pulled tight on the back of the hand compresses veins against the underlying ligaments and bones. With this example “in hand,” students may better understand the propulsive forces moving venous blood back to the heart.
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23. Blood pressure and velocity
Blood pressure is
highest in arteries and
lowest in veins.
Blood pressure is measured as
systolic pressure — caused by ventricular contraction
diastolic pressure — low pressure between contractions
Student Misconceptions and Concerns
Students often struggle to explain how blood is propelled up their legs to return to their hearts. Frequently, students will suggest that the heart itself must provide sufficient force to move blood completely around the body. However, such pressures would destroy delicate capillaries. Other student hypotheses might include attributing a negative, siphoning effect to the heart. (Although the heart can generate a small pull, it is not sufficient to return blood up their legs and trunk to the heart.) Let them wonder long enough to stimulate critical thinking and motivate them to learn the answer. After explaining the role of skeletal muscles and one-way valves in veins, you might also note that it has been suggested that students will be more alert in class and even perform better on tests if they wiggle their legs. Challenge students to explain why this might work and why locking their knees when standing might have the opposite effect. (And enjoy watching some of your students deliberately wiggling their legs on the next exam!)
Teaching Tips
1. Students may not relate the structure of the walls of arteries to blood pressure. Consider noting the presence of smooth muscle in the walls of arteries (Figure 23.7C). If these muscles contract, they narrow the arteries and increase pressure.
2. Veins on the back of our hands can reveal many of these same principles of venous blood flow. If students keep their hands down below their heart for several minutes, such as during note taking or typing, they might notice their veins starting to bulge. Students can watch the veins empty by simply lifting their hands up to eye level. As we get older, such phenomena are even easier to see. Some instructors may be comfortable enough (and old enough!) to demonstrate this effect to their students.
3. Contracting the hand into a fist helps propel blood back up the arms to the heart. Skin pulled tight on the back of the hand compresses veins against the underlying ligaments and bones. With this example “in hand,” students may better understand the propulsive forces moving venous blood back to the heart.
© 2012 Pearson Education, Inc. 23

24. Pressure (mm Hg) Velocity (cm/sec)
Figure 23.8A
120
Systolic pressure
100
Pressure (mm Hg) 80 60
Diastolic pressure 40 20
Relative sizes and numbers of blood vessels 50 40
Velocity (cm/sec) 30
Figure 23.8A Blood pressure and velocity in the blood vessels 20 10
Aorta
Veins
Arteries
Venules
Arterioles
Capillaries
Venae cavae 24

25. How does blood travel against gravity, up legs?
Blood pressure and velocity reflect the structure and arrangement of blood vessels
How does blood travel against gravity, up legs?
Veins are squeezed by pressure from muscle contractions between
two muscles or
muscles and bone or skin.
One-way valves limit blood flow to one direction, toward the heart.
Direction of blood flow in vein
Valve (open)
Contracting skeletal muscle
Valve (closed)
Student Misconceptions and Concerns
Students often struggle to explain how blood is propelled up their legs to return to their hearts. Frequently, students will suggest that the heart itself must provide sufficient force to move blood completely around the body. However, such pressures would destroy delicate capillaries. Other student hypotheses might include attributing a negative, siphoning effect to the heart. (Although the heart can generate a small pull, it is not sufficient to return blood up their legs and trunk to the heart.) Let them wonder long enough to stimulate critical thinking and motivate them to learn the answer. After explaining the role of skeletal muscles and one-way valves in veins, you might also note that it has been suggested that students will be more alert in class and even perform better on tests if they wiggle their legs. Challenge students to explain why this might work and why locking their knees when standing might have the opposite effect. (And enjoy watching some of your students deliberately wiggling their legs on the next exam!)
Teaching Tips
1. Students may not relate the structure of the walls of arteries to blood pressure. Consider noting the presence of smooth muscle in the walls of arteries (Figure 23.7C). If these muscles contract, they narrow the arteries and increase pressure.
2. Veins on the back of our hands can reveal many of these same principles of venous blood flow. If students keep their hands down below their heart for several minutes, such as during note taking or typing, they might notice their veins starting to bulge. Students can watch the veins empty by simply lifting their hands up to eye level. As we get older, such phenomena are even easier to see. Some instructors may be comfortable enough (and old enough!) to demonstrate this effect to their students.
3. Contracting the hand into a fist helps propel blood back up the arms to the heart. Skin pulled tight on the back of the hand compresses veins against the underlying ligaments and bones. With this example “in hand,” students may better understand the propulsive forces moving venous blood back to the heart.
© 2012 Pearson Education, Inc. 25

26. CONNECTION: Measuring blood pressure can reveal cardiovascular problems
A typical blood pressure for a healthy young adult is about 120/70.
Hypertension is a serious cardiovascular problem in which blood pressure is persistent at or above
140 systolic and/or
90 diastolic.
Teaching Tips
Students may not relate the structure of the walls of arteries to blood pressure. Consider noting the presence of smooth muscle in the walls of arteries (Figure 23.7C). If these muscles contract, they narrow the arteries and increase pressure.
© 2012 Pearson Education, Inc. 26

27. CONNECTION: Measuring blood pressure can reveal cardiovascular problems
Hypertension causes
the heart to work harder, weakening the heart over time
increased plaque formation from tiny ruptures
increased risk of blood clot formation.
Hypertension can contribute to
heart attacks,
strokes, and/or
kidney failure.
Teaching Tips
Students may not relate the structure of the walls of arteries to blood pressure. Consider noting the presence of smooth muscle in the walls of arteries (Figure 23.7C). If these muscles contract, they narrow the arteries and increase pressure.
© 2012 Pearson Education, Inc. 27

28. Smooth muscle controls the distribution of blood
Blood flow through capillaries is restricted by precapillary sphincters.
By opening and closing these precapillary sphincters, blood flow to particular regions can be increased or decreased.
Only about 5–10% of capillaries are open at one time.
Teaching Tips
Students might wonder why they are discouraged from swimming soon after eating a meal. Blood flow during exercise involves the diversion of blood away from the gut and to major muscle groups likely involved in swimming. This can lead to indigestion or muscle cramping. However, the greatest risk of swimming with a full stomach is more likely that even a small amount of vomit could clog an air passageway.
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29. Precapillary sphincters Thoroughfare channel
Figure 23.10
Precapillary sphincters
Thoroughfare channel
Arteriole
Venule
Capillaries 1
Sphincters are relaxed.
Thoroughfare channel
Figure The control of capillary blood flow by precapillary sphincters
Arteriole
Venule 2
Sphincters are contracted. 29

30. Exchange of materials between blood and interstitial fluid occurs at capillaries
Substances leave blood and enter interstitial fluid by
diffusion (following concentration gradient) and
pressure-driven flow through clefts between epithelial cells.
Blood pressure forces fluid (water) out of capillaries at the arterial end.
Osmotic pressure draws in fluid (water) at the venous end.
Teaching Tips
1. Figure 23.11B depicts the movements of fluid out of and back into capillaries because of changes in osmotic pressure. The text references Module 24.3 for further discussion of the role of the lymphatic system in fluid removal. If you do not plan on addressing Chapter 24, consider including the role of lymphatic vessels in your discussion of Chapter 23.
2. Students who have little practice interpreting electron micrographs might benefit from a closer analysis of Figure 23.11A, in which an electron micrograph is paired with explanatory figure. For example, simply recognizing nuclei in micrographs can be an important starting point in interpreting cellular details and gaining a sense of scale.
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31. Nucleus of epithelial cell
Figure 23.11A
Interstitial fluid
Capillary wall
Capillary lumen
Nucleus of epithelial cell
Clefts between the cells
Figure 23.11A A capillary in cross section
Muscle cell 31

32. LE 42-14 Tissue cell INTERSTITIAL FLUID Net fluid movement out
movement in
Capillary
Capillary
Red
blood
cell
15 µm
Direction of
blood flow
Blood pressure
Osmotic pressure
Inward flow
Pressure
Outward flow
Arterial end of capillary
Venous end

33. Glucose, O2, and other nutrients have greatest concentration in blood at arterial end so they move out by diffusion
Water moves by net effect of blood versus osmotic pressure
CO2 and other wastes have greatest concentration in interstitial fluid at venous end so they move in by diffusion

34. STRUCTURE AND FUNCTION OF BLOOD
STRUCTURE AND FUNCTION OF BLOOD
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35. Blood consists of red and white blood cells suspended in plasma
Plasma (55%)
Cellular elements (45%)
Constituent
Major functions
Cell type
Number per L (mm3) of blood)
Functions
Water
Solvent for carrying other substances
Centrifuged blood sample
Red blood cells (erythrocytes)
5–6 million
Transport of O2 and some CO2
Ions (blood electrolytes)
Osmotic balance, pH buffering, and maintaining ion concentration of interstitial fluid
Sodium Potassium Calcium Magnesium Chloride Bicarbonate
White blood cells (leukocytes)
5,000–10,000
Defense and immunity
Plasma proteins
Student Misconceptions and Concerns
1. Students with limited backgrounds in anatomy and physiology might not appreciate the diverse functions of plasma, instead thinking of blood as a transporter of oxygen and carbon dioxide. Figure lists the many functions performed by plasma.
2. Students might have heard about blood thinners, thinking that somehow these substances make blood more fluid (like watering down syrup). The term actually refers to substances that make blood clotting less likely. Anticoagulants are specifically addressed in Module
Teaching Tips
1. If you have a small fiber-optic lamp available, shining the light through your fingertips in a darkened room creates a red glow. This provides a dramatic example of the abundance of hemoglobin in red blood cells in the capillaries of our bodies.
2. Discuss the relationship between the structure and functions of erythrocytes. In Module 23.12, the authors note that the absence of a nucleus permits these cells to carry a greater amount of hemoglobin. But why is an erythrocyte dented in the middle? Wouldn’t it seem more likely to be shaped like a hockey puck? The indentation in the center of an erythrocyte might increase its flexibility, permitting easier passage through small capillaries. Encourage students to contribute other ideas on the adaptive advantages of this unique shape (including a higher surface-to-volume ratio).
3. You might note that one of the effects of aspirin is to block platelet aggregation. For additional details about the use of aspirin to prevent and treat heart disease, search the American Heart Association website at using the key word aspirin.
Osmotic balance and pH buffering
Basophils
Lymphocytes
Fibrinogen
Clotting
Eosinophils
Immunoglobulins (antibodies)
Defense
Substances transported by blood
Neutrophils
Monocytes
Nutrients (e.g., glucose, fatty acids, vitamins) Waste products of metabolism Respiratory gases (O2 and CO2) Hormones
Platelets
250,000– 400,000
Blood clotting 35

36. Figure 23.13
Figure Human red blood cells 36

37. RED AND WHITE BLOOD CELLS
BLOOD HISTOLOGY

38. New Blood Cells are generated in bone marrow from stem cells
Multipotent stem cells
are unspecialized and
replace themselves throughout the life of an organism.
Multipotent stem cells can differentiate into two main types of stem cells.
Lymphoid stem cells can in turn produce two types of lymphocytes (T- and B-cells), which function in the immune system.
Myeloid stem cells can differentiate into
erythrocytes (RBC)
other white blood cells
platelets
Student Misconceptions and Concerns
Students might have heard about blood thinners, thinking that somehow these substances make blood more fluid (like watering down syrup). The term actually refers to substances that make blood clotting less likely. Anticoagulants are specifically addressed in Module
Teaching Tips
1. Advances in stem cell research continue, along with political controversy over whether or not such research should be funded by the federal government. You may want to consider bringing recent articles about stem cell research to class, or encourage your students to find a recent article about some aspect of stem cells and it to you.
2. You might note that one of the effects of aspirin is to block platelet aggregation. For additional details about the use of aspirin to prevent and treat heart disease, search the American Heart Association website at using the key word aspirin.
© 2012 Pearson Education, Inc. 38

39. Multipotent stem cells (in bone marrow)
Figure 23.15
Multipotent stem cells (in bone marrow)
Lymphoid stem cells
Myeloid stem cells
Basophils
Erythrocytes
Figure Differentiation of blood cells from stem cells
Platelets
Eosinophils
Lymphocytes
Monocytes
Neutrophils 39

40. Cardiovascular Lab
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41. Pulse Pulse – pressure wave of blood
Monitored at “pressure points” where pulse is easily palpated

42. Blood Pressure
Measurements by health professionals are made on the pressure in large arteries
Systolic – pressure at the peak of ventricular contraction
Diastolic – pressure when ventricles relax
Pressure in blood vessels decreases as the distance away from the heart increases

43. Measuring Arterial Blood Pressure