section 4.3 blood flow
Essential Questions
1.What types of muscle help move blood around the body?
Cardiac muscle pumps blood throughout the body and skeletal muscle creates contractions that help blood flow to the heart within the veins.
2.What is the relationship between the heart and the lungs?
The heart pumps blood through the body including the lungs. The lungs oxygenate the blood so that the blood that is sent by the heart to the body is full of oxygen as fuel.
3.What is the pathway of blood in and out of the heart in pulmonary and systemic circulation?
Unoxygenated blood enters heart by inferior and superior vena cava into right atrium > Passes through tricuspid valve > Right Ventricle > Enters the pulmonary artery by way of the pulmonary valve > Sent to the lungs to be oxygenated > Gets back to the heart by the pulmonary veins > Enters left atrium > Enters left ventricle by way of the bicuspid valve > Sent to body by the aorta
4.How do the structure of arteries, veins and capillaries relate to their function in the body?
Arteries have very thick walls to be able to withstand the high pressure placed on them by the heart pumping blood through them. Veins are very thin because the blood has a lower pressure going back to the heart. Veins also have valves to prevent blood from flowing backwards. Capillaries are very, very small and very thin to allow for gas exchange within the extremities.
5.What unique features of veins help move blood back to the heart?
Valves that open to allow blood to pass through, but close so that blood doesn't flow backwards.
6.What are varicose veins?
Distended and bulging veins that make the legs very gnarly and knotted.
7.Why don’t we ever hear about varicose arteries?
Arteries lack valves because blood does not have to fight against gravity in arteries, which means that blood cannot pool in arteries and cause them to swell.
8.What are the major arteries and veins in the body and which regions do they serve?
Coronary Arteries: Heart
Aorta: Blood to brain and body
Femoral Artery: Femur/leg
Pulmonary Artery: Unoxygenated blood to lungs
Pulmonary Veins: Oxygenated blood to heart
9.What is cardiac output?
The amount of blood (usually in Liters) that your heart can pump in a minute
10.How does cardiac output help assess overall heart health?
It can determine whether or not your heart is pumping the amount of blood that is needed for your body to function properly.
11.How does an increased or decreased cardiac output impact the body?
An increased Cardiac Output is usually generated during exercise and allows for more blood to get to the muscles so that more work can be done. A decreased Cardiac Output may occur when you are sleeping and does not allow as much blood and oxygen to get to your muscles.
12.What is blood pressure?
The pressure exerted by the flow of blood upon the walls of the veins or arteries.
13.How can the measurement of blood pressure in the legs be used to assess circulation?
If the blood pressure in your legs is very high, then the doctor might be able to deduct that a blockage could be forcing the blood to work harder to flow and so generate a high blood pressure.
14.What is peripheral artery disease?
A circulatory problem that occurs when narrowed arteries reduce blood flow to the limbs
15.Why can smoking lead to peripheral artery disease?
Smoking increases the chances of atherosclerosis, which is a disease that decreases the diameter of the artery and so, decreases blood flow in the artery.
4.3.1 Conclusion Questions
1. How does the structure of smooth and cardiac muscle differ from the structure of skeletal muscle?
Smooth muscle lacks the striations of skeletal muscle; Cardiac muscle is highly branched with cells and produces its own action potential.
2. Explain how each of the three types of muscle assist with moving blood around the body.
Cardiac muscle pumps the blood from the heart; Skeletal muscle generates contractions that aid blood flow back to the heart; Smooth muscle can be found around veins and contracts to move blood back to the heart.
3. What role do valves play in the heart?
Valves allow for blood to flow from each chamber of the heart to the next without allowing it to flow backwards.
4. Which structure in the heart functions as the natural pacemaker? What does this term mean?
The Sinoatrial Node. The electrical impulse that forces the heart to contract comes from this node. The heart beats as fast as this node allows it to beat.
5. How does the movement of the electrical impulse relate to the contraction of the chambers of the heart?
The impulse starts by the atria, allowing them to contract and get blood to the ventricles before spreading to the ventricles and forcing them to contract and send blood to the body.
6. What is the difference between pulmonary circulation and systemic circulation?
Pulmonary circulation deals with blood flowing to the lungs to be oxygenated; Systemic circulation deals with blood flowing to the body and back to the heart.
7. Thinking about function, explain why the left ventricle is much more muscular than the right ventricle.
The left ventricle has to pump blood to the entire body.
8. Describe the role of smooth muscle in two human body systems other than the cardiovascular system.
Smooth muscle in the esophagus forces contraction to allow food to move from the oral cavity to the stomach. Smooth muscle in the bladder allows for urine to be squeezed from the body.
9. How does electrical communication in the heart compare to electrical communication in skeletal muscles?
Cell junctions in the heart that conduct electrical signals can remain in their active, or open state, or be turned off when the heart is not contracting.
4.3.2 Conclusion Questions
1. What do you notice about the width of an artery wall versus the width of a vein wall? Why does this make sense given the function of the vessels?
Artery walls are much thicker so that they can withstand the higher blood pressure of blood flowing from the heart.
2. Capillaries function in gas exchange. Describe at least two ways capillary structure is related to this function.
Very thin walls make gas exchange and diffusion much easier.
They are very numerous, which means that they have a high surface area so that more blood can be diffused at once.
3. How do capillaries interact with the respiratory system?
Capillaries are responsible for gas exchange in the body. Whenever the lungs oxygenate blood, the oxygen gets to the muscles and the carbon dioxide in the muscles switches with the oxygen in the capillaries.
4. Which artery do you think is made of thicker muscle, the aorta or the pulmonary artery? Why? Refer back to your heart box to visualize the path of these vessels.
The aorta comes directly off of the left ventricle which is the most muscular chamber of the heart.
5. Describe two ways blood is helped back to the heart in veins. Mention relevant body systems.
The valves found in the veins close after blood passes through so that the blood cannot flow backwards. Also, muscles that are found beside the veins contract involuntarily to push the blood back to the heart.
6. Explain why a person who spends most of the day on his/her feet is more likely to develop varicose veins.
Blood in the veins has to fight against gravity in order to get back to the heart. The valves, if put under too much pressure, the valves might not work well and allow the blood to flow backwards.
4.3.3 Conclusion Questions
1. Why do you think the clay used to represent veins is thinner than the clay used to represent arteries?
Arteries tend to be thicker and have thicker walls because the blood flowing through them is under a much higher pressure.
2. What do you think would happen in the body if blood flow to right femoral artery was blocked? How would this change impact movement of blood and movement of the body?
The right leg would not be able to function anymore. It would be very difficult or at least a big pain to move around. The blood in the body would not be used nearly as much as it would have with a functioning right femoral artery.
3. Suggest a reason why the veins of a bodybuilder “pop out” more than a person who does not lift weights. Why don’t we see arteries “pop out”?
Arteries are much deeper than veins are.
4. Why do you think arteries, veins and nerves always travel together? Provide an example that illustrates your reasoning.
Nerves travel with veins and arteries in order to stimulate the muscles found on either side of arteries and veins in order to help the blood inside flow in the body to where it needs to be.
4.3.4 Conclusion Questions
1. Which do you think are the two, most common places to detect pulse and count the heart rate? Why?
The Carotid and the Radial. They both have a strong and steady pulse that is easy to feel and count.
2. What are some factors that can increase or decrease the heart rate and the beat you feel at each pulse point?
Factors to increase pulse: Physical activity, stress, and near-death situations
Factors to decrease pulse: Rest, sleep, calming noises.
3. Athletes often have a very low resting heart rate. What does this tell you about the health of their heart? Explain.
Their heart is very healthy. It has gotten used to an increased activity level and the heart is able to work more efficiently.
4. What are consequences of having a low cardiac output? How will other body systems be affected?
A low cardiac output will result in a decreased blood flow throughout the body. This means that you might be more lethargic than the average person. The kidneys could be affected because they would not be able to filter as much blood as they normally would.
5. Dehydration reduces blood volume. How would this affect cardiac output? Explain.
Dehydration makes it more difficult for blood to be pumped through the heart. This means that the heart would have to work extra hard to pump blood which would decrease cardiac output.
6. Describe how each of the following could impact stroke volume.
o Damage to the conduction system of the heart
If the conduction system of the heart was compromised, then the heart would not pump in the way that it should, so it could either decrease or increase the cardiac output depending on how the conduction system was compromised.
o A blockage in one of the coronary arteries
If the coronary arteries were blocked, the blood might not flow to a certain part of the heart. This could result the death of heart cells, which would damage the heart and decrease cardiac output.
4.3.5 Conclusion Questions
1. What is your ABI? What does this value tell you about your risk of peripheral artery disease?
ABI is the Brachial Ankle Index. It is a test that compares the blood pressure of your arm to the blood pressure of your legs. It determines whether or not your legs are receiving the proper amount of blood.
2. Explain how PAD might impact other body systems.
PAD can lead to the blockage of important arteries that supply blood to certain parts of the body. This can lead to cell death in the tissues that lack blood supply, which damages how your body functions as a whole.
3. How do the chemicals in smoke relate to the development of atherosclerosis?
Chemicals in smoke can damage the inside layer of arteries, creates gashes and scratches where cholesterol and other materials in the blood can blood up and block the blood flowing in the artery.
4. Why do you think diabetics are also at increased risk for PAD?
Diabetics have a large amount of glucose in their blood, which can damage the walls of arteries and make them more susceptible to PAD.
5. Explain why untreated PAD can lead to the loss of a leg. Make sure to mention the specific arteries of the leg.
PAD can damage and block the blood flow in the femoral arteries, or the arteries that feed blood to the femur and rest of the leg. If left untreated, PAD can lead to the total blockage of an artery, which results in a total lack of blood flowing to the leg which would cause cell death and the loss of the leg.
6. Explain how the endocrine system and the kidneys help play a role in regulating blood pressure.
The kidneys help balance the water levels in the blood. They can either pull out more or less water with would help the blood thicken or be more dilute. The endocrine system, specifically the pituitary gland, releases the hormone that tells the kidneys to release more or less anti-diuretic hormone which will help thicken the blood or dilute it.
1.What types of muscle help move blood around the body?
Cardiac muscle pumps blood throughout the body and skeletal muscle creates contractions that help blood flow to the heart within the veins.
2.What is the relationship between the heart and the lungs?
The heart pumps blood through the body including the lungs. The lungs oxygenate the blood so that the blood that is sent by the heart to the body is full of oxygen as fuel.
3.What is the pathway of blood in and out of the heart in pulmonary and systemic circulation?
Unoxygenated blood enters heart by inferior and superior vena cava into right atrium > Passes through tricuspid valve > Right Ventricle > Enters the pulmonary artery by way of the pulmonary valve > Sent to the lungs to be oxygenated > Gets back to the heart by the pulmonary veins > Enters left atrium > Enters left ventricle by way of the bicuspid valve > Sent to body by the aorta
4.How do the structure of arteries, veins and capillaries relate to their function in the body?
Arteries have very thick walls to be able to withstand the high pressure placed on them by the heart pumping blood through them. Veins are very thin because the blood has a lower pressure going back to the heart. Veins also have valves to prevent blood from flowing backwards. Capillaries are very, very small and very thin to allow for gas exchange within the extremities.
5.What unique features of veins help move blood back to the heart?
Valves that open to allow blood to pass through, but close so that blood doesn't flow backwards.
6.What are varicose veins?
Distended and bulging veins that make the legs very gnarly and knotted.
7.Why don’t we ever hear about varicose arteries?
Arteries lack valves because blood does not have to fight against gravity in arteries, which means that blood cannot pool in arteries and cause them to swell.
8.What are the major arteries and veins in the body and which regions do they serve?
Coronary Arteries: Heart
Aorta: Blood to brain and body
Femoral Artery: Femur/leg
Pulmonary Artery: Unoxygenated blood to lungs
Pulmonary Veins: Oxygenated blood to heart
9.What is cardiac output?
The amount of blood (usually in Liters) that your heart can pump in a minute
10.How does cardiac output help assess overall heart health?
It can determine whether or not your heart is pumping the amount of blood that is needed for your body to function properly.
11.How does an increased or decreased cardiac output impact the body?
An increased Cardiac Output is usually generated during exercise and allows for more blood to get to the muscles so that more work can be done. A decreased Cardiac Output may occur when you are sleeping and does not allow as much blood and oxygen to get to your muscles.
12.What is blood pressure?
The pressure exerted by the flow of blood upon the walls of the veins or arteries.
13.How can the measurement of blood pressure in the legs be used to assess circulation?
If the blood pressure in your legs is very high, then the doctor might be able to deduct that a blockage could be forcing the blood to work harder to flow and so generate a high blood pressure.
14.What is peripheral artery disease?
A circulatory problem that occurs when narrowed arteries reduce blood flow to the limbs
15.Why can smoking lead to peripheral artery disease?
Smoking increases the chances of atherosclerosis, which is a disease that decreases the diameter of the artery and so, decreases blood flow in the artery.
4.3.1 Conclusion Questions
1. How does the structure of smooth and cardiac muscle differ from the structure of skeletal muscle?
Smooth muscle lacks the striations of skeletal muscle; Cardiac muscle is highly branched with cells and produces its own action potential.
2. Explain how each of the three types of muscle assist with moving blood around the body.
Cardiac muscle pumps the blood from the heart; Skeletal muscle generates contractions that aid blood flow back to the heart; Smooth muscle can be found around veins and contracts to move blood back to the heart.
3. What role do valves play in the heart?
Valves allow for blood to flow from each chamber of the heart to the next without allowing it to flow backwards.
4. Which structure in the heart functions as the natural pacemaker? What does this term mean?
The Sinoatrial Node. The electrical impulse that forces the heart to contract comes from this node. The heart beats as fast as this node allows it to beat.
5. How does the movement of the electrical impulse relate to the contraction of the chambers of the heart?
The impulse starts by the atria, allowing them to contract and get blood to the ventricles before spreading to the ventricles and forcing them to contract and send blood to the body.
6. What is the difference between pulmonary circulation and systemic circulation?
Pulmonary circulation deals with blood flowing to the lungs to be oxygenated; Systemic circulation deals with blood flowing to the body and back to the heart.
7. Thinking about function, explain why the left ventricle is much more muscular than the right ventricle.
The left ventricle has to pump blood to the entire body.
8. Describe the role of smooth muscle in two human body systems other than the cardiovascular system.
Smooth muscle in the esophagus forces contraction to allow food to move from the oral cavity to the stomach. Smooth muscle in the bladder allows for urine to be squeezed from the body.
9. How does electrical communication in the heart compare to electrical communication in skeletal muscles?
Cell junctions in the heart that conduct electrical signals can remain in their active, or open state, or be turned off when the heart is not contracting.
4.3.2 Conclusion Questions
1. What do you notice about the width of an artery wall versus the width of a vein wall? Why does this make sense given the function of the vessels?
Artery walls are much thicker so that they can withstand the higher blood pressure of blood flowing from the heart.
2. Capillaries function in gas exchange. Describe at least two ways capillary structure is related to this function.
Very thin walls make gas exchange and diffusion much easier.
They are very numerous, which means that they have a high surface area so that more blood can be diffused at once.
3. How do capillaries interact with the respiratory system?
Capillaries are responsible for gas exchange in the body. Whenever the lungs oxygenate blood, the oxygen gets to the muscles and the carbon dioxide in the muscles switches with the oxygen in the capillaries.
4. Which artery do you think is made of thicker muscle, the aorta or the pulmonary artery? Why? Refer back to your heart box to visualize the path of these vessels.
The aorta comes directly off of the left ventricle which is the most muscular chamber of the heart.
5. Describe two ways blood is helped back to the heart in veins. Mention relevant body systems.
The valves found in the veins close after blood passes through so that the blood cannot flow backwards. Also, muscles that are found beside the veins contract involuntarily to push the blood back to the heart.
6. Explain why a person who spends most of the day on his/her feet is more likely to develop varicose veins.
Blood in the veins has to fight against gravity in order to get back to the heart. The valves, if put under too much pressure, the valves might not work well and allow the blood to flow backwards.
4.3.3 Conclusion Questions
1. Why do you think the clay used to represent veins is thinner than the clay used to represent arteries?
Arteries tend to be thicker and have thicker walls because the blood flowing through them is under a much higher pressure.
2. What do you think would happen in the body if blood flow to right femoral artery was blocked? How would this change impact movement of blood and movement of the body?
The right leg would not be able to function anymore. It would be very difficult or at least a big pain to move around. The blood in the body would not be used nearly as much as it would have with a functioning right femoral artery.
3. Suggest a reason why the veins of a bodybuilder “pop out” more than a person who does not lift weights. Why don’t we see arteries “pop out”?
Arteries are much deeper than veins are.
4. Why do you think arteries, veins and nerves always travel together? Provide an example that illustrates your reasoning.
Nerves travel with veins and arteries in order to stimulate the muscles found on either side of arteries and veins in order to help the blood inside flow in the body to where it needs to be.
4.3.4 Conclusion Questions
1. Which do you think are the two, most common places to detect pulse and count the heart rate? Why?
The Carotid and the Radial. They both have a strong and steady pulse that is easy to feel and count.
2. What are some factors that can increase or decrease the heart rate and the beat you feel at each pulse point?
Factors to increase pulse: Physical activity, stress, and near-death situations
Factors to decrease pulse: Rest, sleep, calming noises.
3. Athletes often have a very low resting heart rate. What does this tell you about the health of their heart? Explain.
Their heart is very healthy. It has gotten used to an increased activity level and the heart is able to work more efficiently.
4. What are consequences of having a low cardiac output? How will other body systems be affected?
A low cardiac output will result in a decreased blood flow throughout the body. This means that you might be more lethargic than the average person. The kidneys could be affected because they would not be able to filter as much blood as they normally would.
5. Dehydration reduces blood volume. How would this affect cardiac output? Explain.
Dehydration makes it more difficult for blood to be pumped through the heart. This means that the heart would have to work extra hard to pump blood which would decrease cardiac output.
6. Describe how each of the following could impact stroke volume.
o Damage to the conduction system of the heart
If the conduction system of the heart was compromised, then the heart would not pump in the way that it should, so it could either decrease or increase the cardiac output depending on how the conduction system was compromised.
o A blockage in one of the coronary arteries
If the coronary arteries were blocked, the blood might not flow to a certain part of the heart. This could result the death of heart cells, which would damage the heart and decrease cardiac output.
4.3.5 Conclusion Questions
1. What is your ABI? What does this value tell you about your risk of peripheral artery disease?
ABI is the Brachial Ankle Index. It is a test that compares the blood pressure of your arm to the blood pressure of your legs. It determines whether or not your legs are receiving the proper amount of blood.
2. Explain how PAD might impact other body systems.
PAD can lead to the blockage of important arteries that supply blood to certain parts of the body. This can lead to cell death in the tissues that lack blood supply, which damages how your body functions as a whole.
3. How do the chemicals in smoke relate to the development of atherosclerosis?
Chemicals in smoke can damage the inside layer of arteries, creates gashes and scratches where cholesterol and other materials in the blood can blood up and block the blood flowing in the artery.
4. Why do you think diabetics are also at increased risk for PAD?
Diabetics have a large amount of glucose in their blood, which can damage the walls of arteries and make them more susceptible to PAD.
5. Explain why untreated PAD can lead to the loss of a leg. Make sure to mention the specific arteries of the leg.
PAD can damage and block the blood flow in the femoral arteries, or the arteries that feed blood to the femur and rest of the leg. If left untreated, PAD can lead to the total blockage of an artery, which results in a total lack of blood flowing to the leg which would cause cell death and the loss of the leg.
6. Explain how the endocrine system and the kidneys help play a role in regulating blood pressure.
The kidneys help balance the water levels in the blood. They can either pull out more or less water with would help the blood thicken or be more dilute. The endocrine system, specifically the pituitary gland, releases the hormone that tells the kidneys to release more or less anti-diuretic hormone which will help thicken the blood or dilute it.