CARDIOVASCULAR SYSTEM and Exercise PHYS Flashcards
*Describe the organization of the circulatory system, explain how the systemic and pulmonary circulations are linked physically and physiologically; describe the distribution of pressure in the circulatory system
CV system plays roles of delivering blood flow and nutrients to exercising muscle, deliver blood pulmonary capillary an take up O2, get CO2, and dissipation of heat (divert blood from deeper tissue to surface of skin); regulate temperature
systemic circulation-blood flow to body and brain
pulmonary circulation- perfusion of blood to right and left side of lungs
most of blood is on venous side
heart muscle needs a great amount of blood flow during exercise
Arterial side- higher pressure, Low volume
Venous side- Lower pressure, Higher volume
*Describe the interrelationships among cardiac output, total peripheral resistance, arterial blood pressure and venous return
Arterial blood pressure= cardiac output x total peripheral resistance
Cardiac output= HR x Stroke volume
during exercise, blood pressure goes up and peripheral resistance goes down.
Blood pressure increases since you increase cardiac output more than you decrease total peripheral resistance .
When venous return is reduced, you also limit blood pressure and cardiac output
A decrease in TPR, leads to increase in venous return as it increases right atrial pressure (more blood flow back to the heart)
*Describe the role of the venous system as an active blood reservoir. Explain the effects of changes in intrathoracic pressure on venous return, cardiac output, arterial blood pressure and heart rate
venous return must always match or equal cardiac output value for sustained exercise.
venous side has the higher percent of blood volume. in exercise, valves helps increase even our return, and bring blood back to heart as quickly as possible.
come back to this slide?
*List the anatomical components of the baroreceptor reflex, including: sensors, afferent neural pathways, medullary centers, efferent neural pathways, and sites of efferent cardiovascular regulation. Describe the role of the baroreceptor reflex in the integrated cardiovascular response to exercise
Baroreceptors are activated due to exercise
they response to high or low pressure and help maintain normal blood pressure levels.
Afferent pathway: receptors in aortic arch and carotid sinus; sense increase or decrease in stretch of vessels
Efferent pathway: innervates heart, blood vessels, regulates sympathetic tone
-stretch receptors in afferent sense amount of stretch in blood vessels, aorta, and increase in stretch will cause increased rate of firing in vagus nerve; firing inhibits sympathetic nerve in medulla
decrease sympathetic tone, decrease heart rate, decrease release of NE, contract less and decrease stroke volume (hence cardiac output decreased)
*Discuss the changes in blood pressure that occur during resistance exercise, steady state exercise, graded exercise and upper body exercise; explain the hypotensive response following exercise
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*Know how cardiac function (output) curves are generated and how factors (ex: autonomic nervous system, exercise, etc) which causes increase or decrease in contractility of the heart can alter the shape and position of cardiac function curves compared to normal .
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*Define venous return, understand the importance of central venous pressure as it relates to venous return and cardiac filling during exercise
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*Explain the integrated cardiovascular response to warming the surface of the skin by 10 degrees centigrade over 45 minutes; describe how the thermoregulatory function of the skin is integrated into the cardiovascular response during exercise
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*contrast the neural and local control of skeletal muscle blood flow at rest and during exercise. Contrast the effect of phasic and sustained skeletal muscle contraction on extravascular compression of blood vessels on venous return
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*Outline the roles and important interactions of respiratory and cardiovascular systems in supporting the metabolic needs of the body during exercise
*summarize the key concepts underlying the physiology of exercise in terms of two pumps (respiratory and cardiac) and two gas exchangers (pulmonary capillary and systemic capillary); include the interactions and control mechanisms of the cardiovascular and respiratory systems starting with generation of carbon dioxide.
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How does blood pressure change during exercise? What other factors are important?
During exercise, blood pressure increases; temperature regulation is important because you are dissipating heat (Cardiovascular system helps reduce heat during exercise)
Also, with exercise for people with high blood pressure blood pressure will decrease to lower blood pressure
Which factors regulate ventilation during exercise?
Factors that regulate ventilation during exercise:
- Valsava maneuver
- Chemical control- maximal expiatory movements (breathing out) against a closed glottis; ex; Seen in weight lifting.
- intrathoracic pressure may increase to 150 mm Hg - Non-chemical influences
What occurs during a valsava maneuver?
Valsava maneuver- breathing method, where one performs forceful attempt of exhaling against an open airway (by closing mouth and pinching nose shut, while expelling air out).
it helps to slow your heart rate if it is beating too fast
-helps people lift more weights during exercise
it helps increase pressure in the chest
Where can valsava maneuver be seen during exercise? Why does pulse pressure drop significantly when lifting weight? How does this affect other aspects of Cardiovascular system?
Valsava maneuvers occur when you lift a heavy weight
ex: Person who is exercising lifts weights and does arm curls. Their pulse pressure is being measured based on each heartbeat
when you lift weight, person is straining against closed glottis to do curl exercise, and pulse pressure drops more than 50%. This occurs because when you are straining your muscles, your intrathoracic pressure (pressure inside chest) is increasing significantly and becomes POSITIVE
High positive intrathoracic pressure will COMPRESS the blood vessels (Vena cava; since it has lower pressure) and venous return will decrease, less blood filling ventricle, reduced stretch on ventricle
when ventricle blood contracts to eject more blood, less blood.
normally your intrathoracic pressure is lower.
What is pulse pressure? What are the highest and lowest pressures in the aorta?
Pulse pressure- systolic pressure - diastolic pressure
systolic presssure- highest pressure in the aorta
diastolic pressure- lowest pressure in aorta.
What is causing the pulse pressure? What leads to aortic pressure in the heart to change from 80 mm Hg 120 mm Hg
pulse pressure due to moving blood from left ventricle into aorta
pulse pressure is caused by the pumping one stroke volume of blood out into aorta; causing aorta to stretch and pressure to rise from 80 to 120 mm Hg,
Describe the relationship between pulse pressure and stroke volume
pulse pressure and stroke volume are DIRECTLY RELATED (when pulse pressure increases, stroke volume increases also).
What are the two main things that affect pulse pressure?
Compliance of aorta and stroke volume are the main factors that affect pulse pressure
when aorta is Stiffer or LESS compliant it INCREASES pulse pressure
what happens when your vena cava is compressed? What causes this compression?
Lifting weight can increase intrathoracic pressure (high positive pressure) and hence compress vena cava, leading to reduction in venous return, and less End diastolic volume, this will lead to reducing of stroke volume, and pulse pressure; causing some people feel light headed, and possibly faint
Describe the changes that occur in alveolar pressure PO2, alveolar PCo2 and mixed-venous pCo2 during aerobic activity. Explain the reason for these changes
During aerobic activity from rest to a HIGH level of O2 consumption:
Alveolar PO2 stays CONSTANT
Alveolar PCO2- stays CONSTANT
Mixed Venous Co2- INCREASES as we increase oxygen consumption.
The alveolar PO2 and PCO2 stays constant because CO2 in lungs increase but you are increasing ventilation rate and blowing off Co2 into expired air. you are bringing in more Oxygenated air as you ventilate, keeping CO2 and O2 levels constant in lungs.
The Mixed venous CO2 levels increase during exercise because as you are exercising you are using more oxygen and producing more CO2 levels. As CO2 levels in skeletal muscle increases it causes the CO2 levels in venous blood (blood returning back to heart) to increase
What factors normally stimulate increase in ventilation in respiratory system?
- CO2 levels in blood stimulate increase in ventilation through chemoreceptors in carotid artery or aortic arch that can sense low O2 or CO2 and stimulate motor centers to increase ventilation.
- Conscious control of ventilation rate- Ventilation can be increased from motor cortex (breathe more often)- conscious control over breathing
- ex: through hyperventilation, you’re consciously increasing your breathing rate - proprioreceptors influence respiratory centers as you increase muscular activity (receptors in lungs to stimulate increase in ventilation)
what is the A-a gradient? What are normal levels of this gradient? what happens as you increase O2 consumption?
A-a gradient (alveolar-arterial gradient) describes the difference between oxygen concentration in alveoli and arterial system.
Normally, the different in Oxygen concentration between blood and alveoli is small (range of 5-10 mm Hg)
As you increase Oxygen consumption, the partial pressure drops; since you are breathing more and oxygenating less (counterintuitive).
What is Exercise induced hypoxemia? When does this occur?
Exercise induced Arterial hypoxemia (EIH)- when there is a.lower Oxygen concentration in blood (larger A-a gradient) . This occurs as you will breath more, and have less O2 in blood. EIH occurs in Highly trained athletes who over-oxygenate and blow off a lot of CO2, not transferring enough O2 to blood, CO2 levels drop.