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.
What are some possible explanations of Exercise-Induced Arterial Hypoxemia?
Possible explanations of Exercise- induced Arterial Hypoxemia:
1. inequality of ventilation-pefusion rates- in lung, no uniform perfusion (base has greater blood flow, so ventilation-perfusion ratio is better in lower part of lung)
2. Shunting of blood between venous and arterial circulations in lung
3.* Failure to achieve end-capillary equillibrium between alveolar PO2 and pulmonary capillary PO2; Decreased transit time in pulmonary capillaries.
-at high aerobic exercise capacity, your cardiac output has increased (tripled) and the rate at which blood flows around circulatory system is faster than it was at rest (each red blood cell pass through capillaries in less time; less time Oxygen to be picked up by red blood cell)
cardiovascular system is reducing exercise capacity due to rapid transit time
Why do athletes use blood doping?
Blood doping- stimulates bone marrow to produce more red blood cells. These use of erythropoietin increase percent of red blood cells; more red blood cells in blood will allow for pick up more oxygen faster ; better oxygenation of blood (close gap between oxygen in blood and alveoli)
What limits exercise capacity the most?
The CARDIOVASCULAR System- it is limiting factor.
What are the three main roles of circulatory system during exercise?
3 main roles of circulatory system:
- Deliver blood flow with oxygen and nutrients to exercising skeletal muscle (deliver O2 to microcirculation (capillary beds)
- Deliver blood to pulmonary capillaries to take up Oxygen and blow off CO2. (you have to maintain adequate blood flow)
- To dissipate heat in the environment during exercise (the body diverts blood flow from deeper tissues of the body to surface of skin, to radiate heat) . Open up shunt channels in skin, that reduces peripheral resistance, initiates sweating (evaporating cooling helps get rid of heat)
- Temp regulation- important function of Cardiovascular system during exercise.
What is the function of chemoreceptors and baroreceptors?
chemoreceptors- sense CO2, O2, H and regulate respiratory system
Baroreceptors- sense pressure out in carotid sinus and aortic arch; help control blood pressure
What is the role of hypothalamus in the cardiovascular system?
The hypothalamus - where there are temperature sensing cells that sense temperature of blood and help sense the need to dissipate heat
-hypothalamus also involved in integrated response at beginning of exercise
as you exercise muscle, feedback system to cardiovascular center to give information on how to adjust heart rate.
Differentiate between systemic and pulmonary circulation. Where is most of the blood volume in the body?
Systemic circulation- blood flow to all organs of the body and brain
pulmonary circulation - perfusion of blood to right and left lung
most of blood volume is on VENOUS side (70%) in capillaries.
Describe the importance of heart as a muscle
heart needs an significant increase in blood flow through right and left coronary arteries to supply more nutrient blood to heart muscle.
heart is efficient at extracting high amount of O2 from blood
if increase oxygen demand of heart, to get more O2 you have to increase blood flow.
What allows the heart to get greater blood flow during exercise?
The presence of local metabolites (Nitrous oxide, Adenosine) are VASODILATORS that allow for greater blood flow to heart during exercise and help deliver more blood to skeletal muscles to meet demands of exercise
Where is deoxygenated blood and oxygenated blood coming from in the heart.
Deoxygenated blood from the Right atrium is coming from the tissues of the body, which blood passes through tricuspid valve to right ventricle. Then RV passes through pulmonary artery to right and left lung and deoxygenated blood passes through pulmonary capillaries, O2 exchange for Co2 in lungs, and Co2 is blown off.
blood returns from lungs to pulmonary veins as oxygenated blood.
Oxygenated blood through pulmonary veins, passing through mitral valve into left ventricle out into the aorta.
when blood pumps through left ventricles out through aorta, see increase in pulse pressure.
What are the two main phases of cardiac cycle? Differentiate between them and mention which valves are open and closed
Diastole- resting or refilling phase of heart; when heart is refilling, tricuspid and mitral valves are open; blood flows back from atria into ventricles Pulmonic/aortic valves closed
Systole- mitral/tricuspid valves closed; aortic/pulmonic valves open as blood is being pumped into aorta through pulmonic artery.
What part of the cardiovascular system controls the peripheral resistance that occurs in circulation?
as you move through larger vessels to smaller arterioles into capillary beds.
Arterioles is site of determining peripheral resistance that occurs in peripheral circulation; diverting blood flow from one vascular bed to another; depending on whether arterioles dilated or constricted.
arterioles receive sympathetic stimulation and are also affected by adenosine, NO (nitrous oxide) vasodilators. ‘
What happens to blood flow when you reduce blood vessel’s radius?
When you reduce blood vessels radius by half, you reduce the blood flow by 16 fold (2^4)
Describe the capillaries and what occurs there. What happens to excess fluid that does not go back to capillary.
Capillaries are 1 cell thick and with red blood cells flowing through. blood pressure forces fluid from capillary into interstitial space and osmotic pressure out into capillary.
once blood flows through capillary gets from small to larger veins.
excess fluid that does not come back to capillary, will go through lymphatic channels.
lymphatic cahhanels pick up extra fluid and bring back to vena cava.
Differentiate between volume, pressure in arterial side vs venous side.
Arterial side - high pressure, low volume
venous side- LOW pressure, high volume
What would happen to pressure in aorta if you constrict arterioles?
if you constrict arterioles that go to capillary beds, you will INCREASE pressure in aorta
What happens to blood pressure during exercise? What happens to our arterioles during exercise ? What places in the body do arterioles dilate or constrict?
During exercise, blood pressure INCREASES; our arterioles are constricted OR dilated. in some areas of body, arterioles dilate; in many areas they dilate
arterioles dilate in area where METABOLIC Activity occurs (legs and arms)
in arterioles that constrict (intestines, kidney), where there is little to no metabolic activity, you maintain
high sympathetic tone
What happens to blood pressure and peripheral resistance during exercise . Explain why this occurs. Write and equation describing the relationship between these factors.
During exercise- you increase blood pressure and Decrease peripheral resistance
Blood pressure increases due to increasing CARDIAC OUTPUT more than you decrease peripheral resistance
Blood Pressure= Cardiac Output x Peripheral Resistance
Differentiate between the capillary sphincters at rest vs during exercise. What allows the pre-capillary sphincters to open up?
at rest: many capillary sphincters are Closed, not all capillaries are open.
when you begin exercising,; Arteriole dilates and pre-capillary sphincter relaxes, opening and allowing more blood flow through capillaries and deliver more O2 to tissues that need it.
-production of low metabolites (vasodilators; NO, adenosine, CO2) allow pre-capillary sphincters to open up, dilate arterioles, increase blood flow (greater flow to muscle that is exercised).
what side of cardiac system has higher percentage of blood volume? What is the role of Valves in the body, and where are they located?
Venous Side- has HIGHER Percentage of blood volume peripheral veins (arms, legs)- have VALVES
- Valves help direct blood from periphery back toward center of body (ex bicep contracts, it compresses veins, and forces blood to center, keeps blood moving back toward vena cava) when valve is open.
- valves close, and prevent back flow of blood back to periphery.
- Valves helps increase venous return and helps bring back blood to heart as quickly as possible
What must happen to venous return if Cardiac output quadruples?
If cardiac output quadruples (by 4) during exercise, Venous Return must also increase by 4 times to sustain increase in cardiac output Cardiac output (how much blood you pump out of Left ventricle into aorta) venous valves and muscle pumps important to support sustained increased in cardiac output, by maintaining increase in venous return.
What is the role for baroreceptor in exercise? Describe its roles in afferent vs efferent limbs
Exercise activates baroreceptors in different ways
baroreceptors respond to high or low pressure to bring blood pressure back to normal range.
Afferent limb: brings Information back to brain
Efferent limb: innervates peripheral, heart and blood vessels and regulates sympathetic and parasympathetic tone
afferent limb: stretch receptors in carotid sinus and aortic arch, that sense amount of stretch In blood vessels, in carotid artery and aorta
Afferent: increase in stretch cause increase in rate of firing in nerves (vagus)
more stretch, increased rate of firing, in afferent limb, which inhibits sympathetic nerve in efferent limb (medulla); decreased sympathetic tone and increased parasympathetic tone in efferent limb.
what would be the effect of decreasing sympathetic tone to SA node of heart. What would increased parasympathetic tone do?
Heart rate would DECREASE, Contractility would be LESS efficient (decrease contractility)
( due to decrease release of NE) .
reduced sympathetic tone would decrease heart rate and decease stroke volume.
increased parasympathetic tone cause decrease in heart rate and stroke volume. Cardiac output also drops too.
What happens to vascular smooth muscle if you decrease Sympathetic tone to arterioles (relaase NE)?
vascular smooth muscle would DILATE arterioles to decrease resistance, and blood pressure would drop,
decrease cardiac output and decrease resistance, you would decrease blood pressure even more.
What stimulates the reflex response by baroreceptor? What is reflex response? What happens if there is a decrease stretch?
What stimulates reflex? : increase stretch or increase pressure in the carotid baroreceptor
reflex response- baroreceptor will decrease and bring pressure back to control level
if baroreceptor sense decrease stretch, decrease inhibition of sympathetic; increase sympathetic tone and decrease parasympathetic to increase blood pressure and bring bp back to control
which baroreceptors correlate to cranial nerve 9 and cranial nerve 10?
Carotid sinus baroreceptors- cranial nerve 9
Aortic arch baroreceptors- cranial nerve 10
these baroreceptors stimulate parasympathetic and sympathetic functions in medulla.
Explain why during a valsava maneuver (such as lifting weights), the heart rate increases, when the blood pressure drops
Valsava maneuver- occurs when you strain the muscles(while lifting heavy weights which causes heart rate to increase and blood pressure to drop.
The heart rate increases while bp drops due to BARORECPETORS. The Baroreceptors are activated due to a decrease in pressure. The decrease in pressure has caused an increased in Sympathetic tone, which eventually causes increase in blood pressure.
what is the relationship between age and hypertension? Why do patients have hypertension?
As people age, they are more likely to be diagnosed with hypertension (blood pressure over 130 or higher)
Many patients have hypertension due to abnormality in Renin-Angiotensin system which makes vasoconstrictor Ang II
Angiotensin II constricts vasculature causing hypertension for some individuals.
What are the pharmacological treatments for hypertension?
Pharmalogical treatments for hypertension
decrease bp by decreasing CO and decrease peripheral resistance
1. Beta Blockers- slow heart rate, and reduce myocardial contractility (decrease Cardiac output, hence lower bp)
2. Alpha blockers, -block alpha receptors on vascular smooth muscle and causes dilation of blood vessels, which decreases peripheral resistance) decrease peripheral resistance, help decrease bp
3. Calcium channel blockers- cause dilation of arteriole blood vessels
4. Diuretics-get rid of circulation blood volume (help reduce bp in patients who obtain excess fluid due to renal abnormalities)
5. Ace inhibitors (angiotensin converting enzyme) - drugs block formation of Ang II from Ang I (potent anti-hypertensive)
6. Angiotensin II receptor blockers- block ability of and Ii cause constriction arteriole blood vessels.
What are the non-pharmacological therapies for reducing blood pressure?
Non-pharmacological therapies for reducing blood pressure:
-Exercising is recommended to reduce blood pressure
in certain types of exercise- blood pressure increases.
List the different forms of exercise that blood pressure responds to?
Blood pressure responds to:
- Resistance exercise
- Steady-rate exercise
- graded exercise
- Upper Body exercise
- Recovery
How does the blood pressure respond during resistance exercise? What factors play a role in this exercise
Resistance exercise (such as lifting weights) increases total peripheral resistance and decreases perfusion of muscle. magnitude of hypertensive response related to intensity of effort and mass of muscle involved. what muscle groups are used and mass involved skeletal muscle compress vasculature, raise peripheral
How does blood pressure respond during steady-rate exercise?
Steady rate exercise (rhythmic muscular activity like swimming, jogging)
active muscles vasodilate, which reduces peripheral resistance in those kind of exercise
blood pressure still goes up but does not go as high up to max levels (stays 130-160 mm Hg)
how does blood pressure respond during Graded exercise ?
Graded exercise (running of treadmill. the is tilted up)- systolic blood pressure can still go up pretty high due to large increase in cardiac output that occurs in exercise.
Elaborate on the events that occur with blood pressure during graded exercise
Graded exercise:
- initial rapid response in systolic blood pressure from baseline; systolic blood pressure increases Linearly with increased exercise intensity
- systolic blood pressure may increase to 200 mm Hg or higher despite significant reductions in TPR (total peripheral resistance)
- Reflects large increase in cardiac output as subjects approach maximum aerobic capacity
- diastolic pressure remains stable or decreases slightly
How does blood pressure respond during Upper Body exercise? Why does blood pressure respond this way?
Upper body exercise- (with arms)- you get greater increase in blood pressure than exercising with legs.
*Arm exercises produce a larger increase in Systolic and diastolic pressures than leg exercise performed at comparable level of VO2 max.
this occurs because the ratio of muscle mass to vasculature is HIGHER with ARMS compared to legs, leading to Greater Increase in Blood Pressure with upper body.
What determines the change in blood pressure during exercise?
The change in blood pressure is based on the kind of exercise training that occurs (arms vs legs)
What is the similarity of resistant training and upper body exercises?
Resistance training and upper body exercises produces a much higher heart rate and blood pressure response
What is another way of gaging how much stress is put on cardiovascular system
Rate-pressure product- estimate of myocardial work and therefore myocardial O2 consumption
Rate-pressure product- Systolic blood pressure x HR (heart rate)
RPP= SBP x HR
gives you max O2 consumption that heart needs to support exercise.
What happens to blood pressure during recovery from exercise? What is the role of venous pooling?
During recovery from exercise: there is a hypotensive response that can last up to 12 hours.
seen in low and moderate aerobic exercise or resistance exercise.
This occurs due to unexplained Peripheral vasodilation
after exercise, basal sympathetic tone lower than normal, more NO production, less vasconstrictors made and a lot of venous pooling
venous pooling- a lot of blood pools into venous side, which lowers blood pressure, since less venous return and less cardiac output
Describe the study performed in rats that further explained the change in blood pressure during exercise.
The study performed in Rat study:
evidence in animal studies (rats exercise for weeks); analyze complexities of ventrolateral medulla.
noticed reduced complexity of dendritic fields in sedentary animals- complex dendritic make
reduced dendritic field reduces baseline sympathetic tone and baseline bp after exercise
neuron remodeling decreases baseline bp with exercise.
What are the factors that contribute to exercise-induced decrease in blood pressure?
factors that contribute to exercise-induced decrease in blood pressure:
1. Decreased baseline sympathetic nerve activity with training
2. Altered renal function facilitating the elimination of sodium and water (reduced sodium reabsorption and renin release)
-reabsorb less Na+ and excrete more sodium
has great effect on blood volume and lowers blood pressure
3. Increased nitric oxide production (increased prostacyclin; DECREASE endothelin)
-prostacyclin and NO are vasodilators which will decrease total peripheral resistance and help decrease blood pressure.
-Endothelin- vasoconstrictor
-increasing vasodilators and decreasing vasoconstrictors help lower bp.
4. Decreased dendritic density in medullary pre-sympathetic neurons.
-regular exercise helps remodel neural connection in brain stem that decrease sympathetic tone and decrease bp)
What are the changes in cardiovascular system that occurs during Exercise?
During exercise, the CV system:
1. Cardiac output increases - HR increases, by increasing sympathetic and decreases parasympathetic , you increase stroke volume (this increases isotropy and lucitropy)
2. Increase in Mean arterial pressure and pulse pressure
-Cardiac output increases more than peripheral resistance decreases
-stroke volume increases, which increases pulse pressure
3. increase in central venous pressure
-due to venous constriction (increase sympathetic adrenergic activity)
-muscle pump activity- skeletal muscle in legs compress veins and help force blood back to heart
-abdominothroaci pump- abdominal muscles contract and help promote venous return to heart
4. Decrease in systemic vascular resistance
-due to metabolic vasodilation (heart, active muscle) and cutaneous vasodilation (decrease sympathetic adrenergic activity)
and vasoconstriction in nonactive muscle and renal circulation (increase sympathetic adrenergic
what occurs when isotropy is increased, and lucitropy? Why is lucitropy important?
increasing inotropy- means you are increasing contractility (contracting more efficiently, increasing Stroke volume), allowing emptying of blood from ventricle more efficiently.
Lucitropy- refers to increasing relaxation of heart. This helps increase Heart rate, the time for filling ventricle gets SHORTER. So for heart to refill with blood, it has to relax more, quickly and have adequate filling, maintain stroke volume and cardiac output.
lucitropy important for supporting high cardiac output during exercise
During exercise, which events of CV system occur first? How does HR, Cardiac output change?
During exercise (for ex: running on a treadmill), the first event of CV system to occur is Production of local metabolites
you start running and produce O2 and nutrients and for byproducts such as adenosine, CO2, H. These local metabolites produced as you run (in muscle of legs) will DILATE arterioles.
When you dilate arterioles in muscles of legs, you will DECREASE Total peripheral resistance. If TPR drops, blood pressure drops as well.
If blood pressure drops at beginning of exercise, baroreceptors will detect drop in blood pressure (less stretch), reduced inhibition of sympathetic center and decreases parasympathetic. This results in baroreceptor activation to increase in sympathetic tone to SA node, which increases heart rate, and increase stroke volume.
Increase heart rate and stroke volume, and Cardiac output increases. Cardiac output increases more than TPR decreases, increasing blood pressure
*decrease in systemic vascular resistance also imitates events in CV system.
How do you explain central venous pressure increase?
You increase central venous pressure by baroreceptor as they increase sympathetic activity to vein and causes venoconstriction.
Venoconstriction causes constriction of vascular Smooth muscle on veins, DECREASES Compliance of vein and Increases pressure in vein. When pressure in vein increases, you increase venous return and fill ventricles with more blood and stretch to optimal length. Via frank starling, the increase in venous pressure helps increase stroke volume.
What causes systemic vascular resistance to drop? Compare the areas in the body that constrict or dilate arterioles
Systemic vascular resistance drops due to local. metabolites produced during exercise of muscle.
Areas that do not experience high metabolic activity (like kidneys, intestines) will not have a lot local metabolites, and hence vascular resistance will decrease and constriction will occur.
Constriction of arterioles will occur in areas with low metabolic activity and dilation of arterioles in areas of body with high metabolic activity (able to produce local metabolites)
How do you get differential activation of vascular system during exercise?
Differential activation of vascular system due to:
1. some areas in the body constricting arterioles (no metabolites made) due to no metabolic activity
and some areas in the body with high metabolic activity (large muscles) that re able to Dilate arterioles.
What is the exercise pressure reflex? Where is it initiated.
Exercise pressure reflex- initial response that occurs prior to all of the early model events happening.
This reflex is orchestrated in HYPOTHALAMUS
hypothalamic control increases Heart rate and Contractility before baroreceptor reflex is activated
you will get in increase in cardiac output, heart rate and contractility; also increase vasoconstriction in non-active muscle.
baroreceptor will reinforce the initial reflex effect
What factors are included in the integrated cardiovascular response to exercise?
Integrated Cardiovascular response to exercise includes:
- Exercise pressor reflex- kicks starts exercise, in hypothalamus.
- arterial baroreflexes
- Vasodilation triggered by metabolites in skeletal muscle
- Increased venous return
- Histamine release
- Epinephrine release
- Regulation of core body temperature (heat being produced during exercise.
what happens to cardiac output, heart rate, stroke volume, mean arterial pressure (bp) and Vascular resistance during exercise?
During exercise:
Cardiac ouput, heart rate, stroke volume and MAP (blood pressure) ALL INCREASE
Vascular resistance DECREASES
What mechanisms maintain stroke volume at Higher heart rates during exercise? What occurs with high atrial inotropy?
- Increased venous return help maintain venous pressure and (bring back venous at same rate as cardiac output)
- Venoconstriction (decreases venous compliance) and helps maintain high central venous pressure so blood returns to heart
3.increased atrial inotropy- atrial contraction becomes important to augment ventricle filling (deliver high amount of blood to ventricle)
atrial inotropy very important during exercise - Increased ventricular inotropy decreases end-systolic volume, which increases stroke volume and eject fraction (pumping out more blood, and increase SV)
- Enhanced rate of ventricular relaxation (lusitropy) aids in filling
What mechanism is responsible for relaxation of ventricle ? What increases lusitrophy?
You have to resequester Calcium back into sarcoplasmic reticulum more quickly, in order to relax ventricle.
you can increase lusitrophy by enhancing phosphorylation of phospholamban and troponin I; which both enhance relaxation of cardiac myocytes. Important for high cardiac output and High HR.
What is Maximum Oxygen Consumption (VO2 max)?
Maximum Oxygen Consumption (VO2 max) - maximum amount of oxygen that the body can consume during intense whole body exercise (breathing air at sea level)
what variable limits VO2 max?
Oxygen DELIVERY LIMITS VO2 max. The limiting factor is Cardiovascular system (delivers O2 to tissue)
hence long-term endurance athletes can get great increase in muscle Oxygen capacity, but only small increase in VO2 max.
What has the greatest range in oxygen consumption?
MUSCLE
What is the equation for Vo2?
Vo2= Q (cardiac output; Hr X SV) x (a-V) O2 difference
what is the equation for cardiac output? Which factor normally contributes more to increase in cardiac output.
Cardiac output= HR (heart rate) x SV (stroke volume)
HEART RATE contributes more to increase in cardiac output
What are is Heart rate determined by?
Heart rate determined by response to exercise,
and regulation
untrained individuals- HR increases more than trained
with significant exercise training you can increase stroke volume .
Explain how you can regulate Heart rate through sympathetic and parasympatheitc innervation.?
You can regulate HR through sympathetic and parasympathetic innervation
sympathetic - causes increases in Heart rate
parasympathetic- decrease heart rate
intrinsic factor- SA node and Na+ leak channels and AV node (can be back up pacemakers . Purkinje fibers can be a pacemaker but its slower than Av node.
What are intrinsic and extrinsic factors that affect heart rate?
What is brain bridge reflex?
intrinsic factors:
SA node, AV node, Purknje fibers, Atrial stretch reflex (brain bridge reflex stimulated by increases in right atrial pressure)
Extrinsic factors:
Sympathetic and parasympathetic nervous system
circulating Catecholamines (adrenal medulla produces epinephrine) Epinephrine binds to beta receptors, which stimulates increase in heart rate.
beta 1 receptor- mediates increase in heart rate in cardiac muscle
How can individuals alter their heart rates before exercise?
depending on length of exercise event, individuals in training can learn to anticipate the start of hearing starting gun. You can do this by increasing heart rate (by many more beats per minute) before hearing starting gun. This occurs by removing parasympathetic tone (learned through training) and you can have significant increase in heart rate before the exercise starts. This is beneficial for great performance rate.
what factors determine stroke volume ? How does stroke volume change in untrained vs trained athletes?
Stroke volume based on:
1. response to exercise
2. regulation
in untrained individuals- change in stroke volume NOT very significant
in Trained individuals- stroke volume is HIGHER at REST but pumps more blood
resting heart rate lower than HR of untrained for those who consistently do aerobic exercise.
What are the intrinsic and extrinsic factors of stroke volume?
intrinsic:
1. stretching of myocardium (preload)- during exercise, you want to bring as much blood back to heart to support maximum preload
-Frank Starling Curve- stretch heart to optimal length
increasing venous return, important in maximizing cardiac output.
Extrinsic:
sympathetic and parasympathetic nervous system a
circulating catecholamines
What leads to increase in cardiac output during training?
training increases maximum stroke volume the most; Maximal heart rate does not increase at all with training
increased in cardiac output during training is primarily due to increase in stroke volume (from extrinsic hypertrophy)
What happens to peripheral resistance during exercise? What happens when you open valves, or dilate arterioles?
when exercising, peripheral resistance decreases because you produce a lot of vasodilators during exercise, allowing you to dilate arterioles (more blood flow into capillaries)
dilate arterioles, more blood flowing through and capillary pressure Rises, increasing filtration fluid from capillary to interstitial space.
When dilate arterioles, fluid is lost and you get increase in blood flow that has more blood leaving capillaries than energy in interstial space (reduce effect of circulating blood volume)
How do you maintain blood volume during exercise
During exercise- deplete circulate blood volume
to maintain blood volume, you venoconstrict, pool blood to bring more blood into circulation. Fluid balance is important during exercise.
volume lost during sweating is lost and needs to be replaced.
How does sweating during exercise affect our volume?
As one exercise, it leads to sweating which depletes circulating volume.
What happens to a person if you place them in a room and increase skin temperate by 10 degrees? how does Cardiac output change? Why do you have to double cardiac output to maintain blood pressure?
Person sitting in a room, turn up thermostat to increase temperature by 10 degrees. Over 40 minute period, temperature of skin increases and temperature of blood increases. Their cardiac output DOUBLES over the 40 min period (6.4 L to 13 L). due to increase in temperature, you have to double cardiac output to maintain blood pressure.
You have to double Cardiac Output b/c
-As temperature of blood goes up, temperature sensors (thermoreceptors) sense rise in temperature.
when temps goes up, sympathetic tone to skin arterioles decrease, cutaneous blood vessels dilate, allowing decrease peripheral resistance, and blood pressure drops
-when dilate all cutaneous blood vessels, you drop peripheral resistance and blood pressure drops and recovers (from 80 to 90) due to:
baroreceptor reflex sense drop in blood pressure, reduce inhibition to sympathetic activity, increase sympathetic tone to heart, increase heart rate and increase cardiac output get activated. Parasympathetic tone is also decreased.
What kind of environment is it harder to exercise in and why?
harder to sustain exercise in hot environment: since heat (increase in temperature) puts more strain on heart to increase cardiac output to sustain activity, dissipate heat.
Explain how exercise is affected with patient who has cardiac transplant. What would you expect basal heart rate and exercise tolerance in these individuals and why?
Exercise following cardiac transplant:
Donor and recipient hearts are removed via transection at the mid-atrial level; preserving pulmonary venous connections
cardiac transplant
PARASYMPATHETIC affects heart rate the most in normal individual.
normal individual: normal autonomic interventions
in cardiac transplant; you sever all autonomic connections so donor heart has no connections and heat rate will be determined by intrinsic rate of SA node.
heart rate will be higher since all parasympathetic nerves will be cut.
person with post-transplant- have heart rate about 100 beats per minute (since all autonomic parts severed)
heart rate will not increase much during exercise
patient with post-cardiac transplant has high basal HR due to release of Epinephrine.
No sympathetic connection due to transplant surgery, so no increase heart rate during exercise.
how do you calciulate mean arterial blood pressure?
Mean arterial blood pressure= diastolic + 1/3 pulse pressure
pulse pressure: systolic pressure - diastolic pressure
What causes pulse pressure to change during exercise?
The pulse pressure changes (increases) during exercise because of it reflects the increase in stroke volume.
Why does systolic pressure increase during exercise and diastolic pressure remain unchanged?
Systolic pressure increases during exercise because of Increase in stroke volume (causing systolic pressure and pulse pressure to increase)
Diastolic pressure remains unchanged-
diastolic pressure initially decreases, because peripheral resistance drops and dilating arterioles, which lowers diastolic (more blood run off toward capillaries between each heart beat) . Increased local productions of metabolites dilate arterioles and decrease pressure.
what happens to patient during exercise that took drugs blocking beta receptors.
normally with beta receptors; and exercises, heart rate will increase and stroke volume increasing. These are mediated by beta receptor stimulation. Taking a beta blocker, HR and Stroke volume would not increase as much, and exercise tolerance would be reduced.
WHY IS YOUR skin cooler to touch in beginning of exercise?
Skin is cooler to touch at beginning of exercise because skin vessels are initially constricted, and baroreceptor sense low bp and increase sympathetic tone.
CASE STUDY: What is the ultimate purpose of the cardiovascular response during exercise? How does this occur?
The purpose of Cardiovascular system is to
increase O2 delivery and nutrients to the muscles that are working harder during exercise (cardiac and skeletal). You can increase O2 delivery by having increased BLOOD FLOW to exercising muscle and myocardium.
To increase blood flow:
1) increase total blood flow (cardiac output)
2) redistribute blood flow so that the percentage of total blood flow is increased to some organs and decreased to other
CASE STUDY: How do you calculate mean arterial pressure and pulse pressure?
Mean arterial pressure: Diastolic BP + 1/3 pulse pressure
Pulse pressure: systolic BP - diastolic BP
CASE STUDY: How do you calculate cardiac output. Also does heart rate or stroke volume contribute most to increase cardiac output during exercise in this case study?
Cardiac output: Heart Rate x Stroke volume
HR (heart rate) contributes more to increasing cardiac output in case study?
CASE STUDY: What happens to pulse pressure during exercise and explain why
pulse pressure is related to STROKE VOLUME and compliance of arterial vasculature. Pulse pressure increases during exercise because stroke volume increases. Compliance most likely stayed constant, but may have decreased during exercise due to sympathetic activation
CASE STUDY: Explain why systolic pressure increases during exercise, but diastolic pressure remains largely unchanged or decrease?
The systolic aortic pressure increases during exercise because you are increasing your Stroke volume (which increases systolic BP and pulse pressure)
Diastolic pressure remains largely unchanged or decrease, because more blood flows from the arteries to peripheral tissues between heart beats due to DECREASE in total peripheral resistance
during exercise, there is a decrease in TPR and an increase in local metabolites which lead to arterioles dilating
CASE STUDY: What would happen to a patient who had been taking propranolol (beta-adrenergic antagonist); how would the response to exercise differ? Would her exercise tolerance decrease, increase or remain the same?
A patient who took propranolol (beta-adrenergic antagonist) would NOT be able to increase their HR and contractility via normal beta-aderenegic mechanisms.
-This would lead to them having significantly REDUCED exercise tolerance
CASE STUDY: early on in exercise a woman’s skin was cool to touch. however, at peak of exercise, her skin was flushed and very warm to touch. What mechanisms are responsible for changes in skin color and temperature as exercise progressed?
Cutaneous blood flow exhibits a biphasic response to exercise. Early in exercise, VASOCONSTRICTION occurs due to activation of sympathetics and alpha-1-adrenergic receptors.
As exercise progressed, body temperature rises and activates temperature receptors in anterior HYPOTHALAMUS to INHBIT sympathetic activity and produce VASODILATION in cutaneous arterioles. As a result, warm blood shunted from body core to venous plexuses (A-V shunt channels) to dissipate heat to the environment for thermoregulatory purposes.
CASE STUDY: Arterial and venous PO2 was measured before and after exercise. Explain why venous PO2 decreased but arterial PO2 did not?
The Oxygen Hb dissociation curve is shifted to RIGHT due to increased temperature.
Increased PCO2 and decreased pH all of which are consequences of increased metabolic rate. a right shift facilitates UNLOADING of O2. Therefore, in addition to increasing blood flow and O2 delivery to exercising muscles more O2 was extracted from blood?
What are the two phases of cardiac cycle?
2 phases of cardiac cycle:
- Diastole: resting, refiling phase. The tricuspid and mitral valve is open, and blood flow from atria and ventricles; pulmonic/aortic valves are closed
- Systole: contraction phase; mitral/tricuspid valve closed; aortic/pulmonic valve open and blood is pumped out of artery.
