205 L12 Flashcards
Blood pressure
High blood pressure causes death by ——- —— disease or ——–
There is a —— relationship between your risk of death and your systolic pressure - the higher your systolic pressure the ——- the risk of coronary artery disease or stroke. So the lower the BP the better it is
High blood pressure causes death by coronary artery disease or stroke
There is a linear relationship between your risk of death and your systolic pressure - the higher your systolic pressure the greater the risk of coronary artery disease or stroke. So the lower the BP the better it is
Big arteries have a high —— component and are very ——-. Therefore the —– helps to buffer the big swings in —— when the heart is —— and ——-, allowing the flow in the rest of the body to be continuous.
Arterioles - all the blood vessels that are leading up to the ——- and end ——, controlling the blood flow to the particular organs depending on its ——. The high component of —– muscle allows this to happen by regulating the —— size and thus ——-. The high ——- means that you will see a big drop in ——– in that area.
Capillaries - ——— thin wall
Venules - connect ——- to bigger ——–.
Veins ——– of the blood is stored here. High —— tissue, floppy, —— wall to lumen ratio although the wall is —- compared to arterioles, ——– muscle - can control the —— in the veins but because of the large ——– and the pressure is —– that doesn’t change the ——– much. If you squeeze a vein it will push the blood back to the heart, increasing —— but not changing ———.
Big arteries have a high elastic component and are very stretchy. Therefore the aorta helps to buffer the big swings in pressure when the heart is ejecting and relaxing, allowing the flow in the rest of the body to be continuous.
Arterioles - all the blood vessels that are leading up to the capillaries and end organs, controlling the blood flow to the particular organs depending on its need. The high component of smooth muscle allows this to happen by regulating the lumen size and thus resistance. The high resistance means that you will see a big drop in pressure in that area.
Capillaries - endothelium thin wall
Venules - connect capillaries to bigger veins.
Veins - most of the blood is stored here. High elastic tissue, floppy, thin wall to lumen ratio although the wall is thick compared to arterioles, smooth muscle - can control the resistance in the veins but because of the large capacity and the pressure is low that doesn’t change the pressure much. If you squeeze a vein it will push the blood back to the heart, increasing preload but not changing pressure.
Capacitance
A measure of the —– to —— relationship over the entire P/V curve. Reflects the storage capacity of the vessels.
Capacitance = Change in ——/change in ——-
Veins = capacitance vessels - they can store large amounts of blood volume with little change in ——. When they —— large quantities of blood are transferred to the heart thereby increasing ——- —–.
About —- of your blood volume is held in the veins and — is held in the arteries. (ratio = 3:1)
Capacitance
A measure of the volume to pressure relationship over the entire P/V curve. Reflects the storage capacity of the vessels.
Capacitance = Change in volume/change in pressure
Veins = capacitance vessels - they can store large amounts of blood volume with little change in pressure. When the constrict large quantities of blood are transferred to the heart thereby increasing cardiac output.
About ⅔ of your blood volume is held in the veins and ⅓ is held in the arteries. (ratio = 3:1)
Compliance
The ability to hold —- at a certain —–.
Initially the relationship in veins is very —— so they are very compliant. When they are about 300 times their initial volume then the ——– starts to rise and the compliance starts to ——–.
Arteries are more linear across the whole range of pressures. They are ——-, dont have the —— and don’t ——– the same as the veins.
As a result they have ——— compliance, so their ability to —- their volume is not as good as a vein at their working pressure
Compliance doesn’t effect the MAP
The ability to hold volume at a certain pressure.
Initially the relationship in veins is very steep so they are very compliant. When they are about 300 times their initial volume then the pressure starts to rise and the compliance starts to decrease.
Arteries are more linear across the whole range of pressures. They are stiffer, dont have the elastin and don’t collapse the same as the veins.
As a result they have decreased compliance, so their ability to increase their volume is not as good as a vein at their working pressure
Compliance doesn’t effect the MAP
What are the values of normal mean arterial BP, systolic BP (max) and diastolic BP (minimum)?
MAP = 100 mmHg systolic = 120 mmHG diastolic = 90 mmHg
MAP=__+ __(__-__)
MAP= Pd+ 1/3 (Ps - Pd)
Pulse pressure = (__-__)
PP= Ps-Pd
Aortic compliance and pulse pressure.
During —— the aorta stretches to absorb the blood.
Blood will continue to flow in ——- due to the aorta being —— out in ——-. Therefore the ——– pressure is going to be relatively ——.
The more compliant large blood vessels are the —- the pulse pressure.
If the aorta is compliant it stretches and absorbs the volume of blood then the pressure isn’t going to be too high.
If the aorta can’t stretch and absorb the volume of blood the pressure is going to be high.
Someone with a stretchy aorta (healthy) will have a not too high systolic and diastolic pressure. Therefore will have a —- pulse pressure
Someone who doesn’t have a stretchy aorta (not healthy) will not be able to —— the volume of blood, so the —— pressure is going to be high, but because the blood is not absorbed the —— pressure is going to be lower. This means that this person will have a —– pulse pressure
During systole the aorta stretches to absorb the blood.
Blood will continue to flow in diastole due to the aorta being stretched out in systole. Therefore the diastolic pressure is going to be relatively high.
The more compliant large blood vessels are the smaller the pulse pressure.
If the aorta is compliant it stretches and absorbs the volume of blood then the pressure isn’t going to be too high.
If the aorta can’t stretch and absorb the volume of blood the pressure is going to be high.
Someone with a stretchy aorta (healthy) will have a not too high systolic and diastolic pressure. Therefore will have a small pulse pressure
Someone who doesn’t have a stretchy aorta (not healthy) will not be able to absorb the volume of blood, so the systolic pressure is going to be high, but because the blood is not absorbed the diastolic pressure is going to be lower. This means that this person will have a high pulse pressure
Pulse pressure —— with age due to ——- compliance.
As a result of a decrease in compliance systolic pressure ——— and diastolic pressure may ——–.
A less compliant aorta will result in a —– pulse pressure.
Pulse pressure increases with age due to decreased compliance.
As a result of a decrease in compliance systolic pressure increases and diastolic pressure may decrease.
A less compliant aorta will result in a larger pulse pressure.
Increasing stroke volume delivered to the aorta increases arterial pulse pressure.
Systolic pressure increases in exercise because the stroke volume has increased.
The more volume that comes out the higher the pressure will be.
Has the compliance changed?
No
Diastolic pressure is determind by the ability of blood to flow ——–. This in turn is dependent on —— —- —— and — ——.
Slow heart rate = ——- diastole = blood pressure continues to —- for longer = diastolic pressure ——-
High resistance downstream = ——– for blood to flow forward = ——- diastolic pressure
During exercise the ——– pressure increases due to increased ——- ——-. The —– pressure decreases because the ——– decreases to allow more blood flow to the organs. This is why sometimes the mean pressure doesn’t change much during exercise.
If its cold then the diastolic pressure goes up during exercise
Diastolic pressure is determind by the ability of blood to flow forward. This in turn is dependent on total peripheral resistance and heart rate.
Slow heart rate = longer diastole = blood pressure continues to decrease for longer = diastolic pressure decreases
High resistance downstream = harder for blood to flow forward = increased diastolic pressure
During exercise the systolic pressure increases due to increased stroke volume. The diastolic pressure decreases because the resistance decreases to allow more blood flow to the organs. This is why sometimes the mean pressure doesn’t change much during exercise.
If its cold then the diastolic pressure goes up during exercise
Arterial pressure regulation
Different mechanisms dominate in blood pressure control over different time scales.
Short term - nerual reflexes such as baroreceptors, chemoreceptors and the CNS ischemic response.
Minutes to hours - hormonal (Angi ll) and fluid shifts
Hours to days - blood volume regulation via renal mechanisms.
Can you control blood pressure without baroreceptors?
Yes
Arterial pressure regulation
Different mechanisms dominate in blood pressure control over different time scales.
Short term - nerual reflexes such as baroreceptors, chemoreceptors and the CNS ischemic response.
Minutes to hours - hormonal (Angi ll) and fluid shifts
Hours to days - blood volume regulation via renal mechanisms.
Can you control blood pressure without baroreceptors?
Yes
Arterial baroreceptor reflex
The carotid baroreceptors are in the ——– ——- with their nerve endings locating in the ———–. They sense ——– in the arteries. The —– ——- nerve goes into the ———— nerve up to the—— in the brain
The receptors respond to ——– changes not ——— changes. ———– changes can result in the baroreceptors moving to the new mean pressure.
If the arteries can’t —— then even if the pressure increases the baroreceptors can’t fire.
Increase in arterial pressure results in an ——– in baroreceptor firing due to increased ———. This causes an ——– in PNS which decreases —— —–, therefore decreases —- —-and a ——— in SNS due to the —— inhibiting the —— which results in decreased —- and ——–. There is decreased —– —— and decreased vascular ——— resulting in a ——– arterial pressure.
Arterial baroreceptor reflex
The carotid baroreceptors are in the carotid sinus with their nerve endings locating in the adventitia. They sense stretch in the arteries. The carotid sinus nerve goes into the glossopharyngeal nerve up to the NTS (nucleus tractus soltarius) in the brain
The receptors respond to sudden changes not gradual changes. Gradual changes can result in the baroreceptors moving to the new mean pressure.
If the arteries can’t stretch then even if the pressure increases the baroreceptors can’t fire.
Increase in arterial pressure results in an increase in baroreceptor firing due to increased stretch. This causes an increase in PNS which decreases HR, therefore decrease CO and a decrease in SNS due to the CVLM inhibiting the RVLM which results in decreased HR and vasodilation. There is decreased cardiac output and decreased vascular resistance resulting in a decreased arterial pressure.
