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75 Cards in this Set
- Front
- Back
how does increasing sympathetic stimulation increase SV?
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NE binds to B1 receptors which release more Ca^2+
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since we cannot recruit more cells to produce a stronger contraction, how do we do it? what are the 3 things?
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we need to have greater
1- increase contractility 2- increaes preload 3- decrease afterload |
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what is preload?
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it is the stretch of myocardium. and this is caused by venous return.
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what is afterload?
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it is the pressure in the aorta that RESISTS the opening of the aortic valve.
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what is afterload represented by?
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DBP
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what would happen if we had an increase in afterload?
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the aortic valve would open later and close sooner, resulting in a decrease in SV and Q
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what is venous return?
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the amount of blood returning to the right atrium from the systemic circulation.
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what are the 4 things that cause an increase in venous return (or a decrease in venous pooling)?
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1- venoconstriction
2- muscle pump 3- cardiac output 4- thoracic pump |
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what is the main concern for diastolic hypertension?
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reduced cardiac output.
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cardiac output=
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HR * SV
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EF (ejection fraction)=
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SV/ EDV *100
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what is a good EF number?
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50-60%. So when about 1/2 of the volume is being ejected, that is pretty good.
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what does a low EF mean?
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low contractility, thus low cardiac performance.
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______ is a good diagnostic and prognostic tool. What does prognostic mean?
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EF
predicted value of health (death or survival) |
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what are some things we might want to consider before deciding how to give the heart transplant to?
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age
accept/reject heart? measure EF (if < 20%, heart transplant needed) |
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do smooth muscles have the property of conductivity?
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yes--not all cells are innervated. They have Gap junctions.
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what type of innervation does smooth muscle have?
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Symp. only.(so has TONIC control)
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myosin filaments in SM are _____ and have ______ myosin heads.
is there a central bear zone? why is all this important? |
longer
more NO it gives a longer range of contraction (vasoconstriction and vasodilation) |
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ARTERIES
are arteries high/low compliance? |
LOW
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why low compliance?
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we don't want arterial pooling
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what are the different levels of arteries?
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Aorta
artery arterioles capillary |
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why does the aorta have an elastic membrane?
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because it needs to withstand CHANGES in BP.
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how many layers of tissue in the aorta?
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3
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why doesn't DBP just drop to 0? Why still pressure?
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because that elastic membrane rebounds and helps maintain pressure.
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what is pulse pressure =
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SBP-DBP
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what is blood flow like up in the aorta and arteries?
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pulsatile
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what is the blood flow like down in the capillaries?
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non-pulsatile (smooth continuous blood flow)
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arterioles are known as _______ vessels
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resistance.
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are arterioles innervated by symp?
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Highly. This helps to vasoconstrict and vasodilate which helps regulate blood flow which in turn determines BP.
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what is an example when we need to change BP?
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all the time. Even when changing posture.
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if we faint a lot when standing up or changing posture, what is this called?
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orthostatic hypotension.
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capillaries are also known as _______ vessels
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exchange.
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do capillaries have smooth muscle?
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NO. just have endothelial cells (this allows for better exchange)
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T/F Can capillaries vasoconstrict/vasodilate?
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NO
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the precapillary spincters are wrapped around the beginning of each capillary.
How do they constrict/open to the bed of capillaries? |
through LOCAL CONTROL.
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what are the 4 factors that define local control?
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1- pH
2- pCO2 3- p)2 4- Temp |
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what will these 4 things do that will cause the spincters to open?
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low pH
high pCo2 low pO2 high temp |
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so...Local control is controlled by ________ _______ of the organ tissue
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metabolic demand.
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so local control helps prioritize blood flow where?
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to more metabolically active tissues.
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what do we have to prioritize?
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because we don't have enough blood. (we only have 5L of blood in us)
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Veins are _____ compliant
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highly
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what does compliant mean?
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refers to extensibility (means that they can expand easier).
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what causes the veins to extend?
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Blood pressure.
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at rest, how much of our blood volume is in veins?
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2/3 (pooling)
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so we have that graph showing the blood pressure from the aorta to the capillaries. If we draw a line down the center of the graph, what does that line represent?
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MAP (Mean Arterial Pressure)
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where is SBP measured?
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it is the BP in the arterial side during ventricular systole.
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where is DBP measured?
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it is the BP in the arterial side during ventricular diastole.
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what does blood flow?
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due to pressure gradients.
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MAP=
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DBP+ 1/3(PP)
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so mean arterial pressure is the mean...
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driving force of blood through circulation.
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what is the normal MAP at rest?
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93
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where is MAP measured?
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between the aorta and the large arteries.
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when blood is coming BACK to the heart, what is MAP?
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pretty close to 0
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why does MAP go up during exercise?
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because cardiac output goes up.
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so how can we say that cardiac output goes up? What happens to SBP and DBP during exercise?
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SBP goes up
DBP goes down. |
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why does DBP go down?
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because TPR (Total Peripheral Resistance) decreases.
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why does TPR decrease during exercise?
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because of vasodilation to sk. mm.
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so the normal Q at rest is 5L/min, and normal MAP is 93. What is TPR?
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18.6
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why else does TPR decrease during exercise?
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because within active sk. mm , capillary beds open due to LOCAL CONTROL.
So total cross sectional area of arteries increases. This causes a decrease in blood flow. |
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TPR=
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MAP/Q
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now so during exercise, what is going to happen to TPR?
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it is going to decrease (for example, it will go from 18.6 (rest) to 4 (during exercise)
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and why again do we get this decrease in TPR?
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because of opening of capillary beds in active sk. mm and total increase in cross sectional area.
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be able to do these calculations!
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and be able to explain why it's happening too.
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Where does h2O come from when we sweat?
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from the blood plasma.
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what happens if we don't replenish this water?
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cardiac output goes down. (and the ability to perform goes down)
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how much water can we loose before performance goes down?
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2%.
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how long does it take to loose 2% of body water?
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can happen in less than an hour.
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what percentage of the blood is RBC? (hematocrit)
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45%
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what is the O2 carrying part of blood?
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hemoglobin.
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how many oxygens can a hemoglobin carry?
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4.
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on what part of the hemoglobin carries the oxygens?
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the irons. (not the globin part)
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how much Hb per dL of blood?
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15g
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when hemoglobin saturated with oxygen, how much O2 can be carried?
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1.34 mL O2/g Hb
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so what is the oxygen carrying capacity of blood?
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20.1 ml O2/dL
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normally, Hb is only 97% saturated, so what does this number come to?
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19.5 mL O2/dL
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