Lecture 25 - Hypertension I Flashcards
What does hypertension relate to?
Hypertension relates to high BP, specifically arterial blood presure.
What is pulse pressure?
Difference between systolic and diastolic pressure
How can we find MAP from SAP and DAP?
MAP= DAP +1/3(SAP-DAP)
What is SAP and DAP in normal arterial pressure?
SAP<120 and DAP<80
What is SAP and DAP in elevated arterial pressure?
SAP=120-129 and DAP<80
What is the SAP or DAP in Stage I Hypertension?
SAP=130-139 or DAP=80-89
Dont need both to have hypertension
What is the SAP or DAP in Stage II Hypertension?
SAP>140 or DAP>90
Dont need both to have hypertension
What happens to the physical factors of MAP during hypertension?
Arterial blood volume increase
Arterial compliance decrease
What regulates arterial blood volume long-term?
Kidney
What is arteriosclerosis?
Disease of media which alters stiffness
Media thickening in large or resistance arteries
Increasing stiffness of the arteries
What is atherosclerosis?
Disease of the intima which alters conduit
Changes of the intima
Blockage of the arteries
What does increases in blood volume measure?
Vessel compliance. Increase of volumes is a measure of compliance, as vessel compliance decreases, so does the increase/change in volume.
Why does vessel compliance decrease with age?
Structure remodelling of the arterial wall
What are the changes in the vessel wall due to age?
Less elastin, more collagen, different type and more crosslinking
Collagen 1000x stiffer than elastin
Why does peripheral vascular resistance increase with age?
Because there is a decrease in arterial compliance
What does the increased peripheral vascular resistance do to BP?
Increase SAP and DAP
What increases more, SAP or DAP, when there is an increase in peripheral vascular resistance and why?
An increase in peripheral vascular resistance will elevate systolic pressure more than diastolic pressure
At higher pressures (systole) the arteries are stiffer (less compliant) than at diastole (vessels are less stiff, more compliant).
Why does arteriosclerosis cause hypertension?
Because arteriosclerosis alters media stiffness, which makes the vessel less compliant, thus increasing BP
In systole, what is the flow wave generated by?
The heart
In diastole, what maintains capillary flow?
In diastole, recoil of aorta maintains capillary flow
What is flow wave?
Flow wave – blood flow caused by ejection of the heart which runs through the vasculature
What does the distensibility of the act aorta as?
Storage of stroke volume in conduit vessels
What is the flow of blood throughout the body?
Pulsatile flow into the aorta, but continuous/constant flow through the capillaries
What is essential for dampening the pulsatile flow wave of the heart?
Compliance of the aorta
What happens to flow waves as we age/in hypertension?
Stiff/rigid aorta – limited or almost no storage of stroke volume
During systole, aorta and capillary flow are high 24
During diastole, capillary flow decreases
Capillary flow is now pulsatile – less O2 nutrients exchange
During systemic hypertension, the compliance of the aorta:
A. decreases, which decreases the pulsatility of blood flow through the capillaries.
B. decreases, which increases the pulsatility of blood flow through the capillaries.
C. increases, which decreases the pulsatility of blood flow through the capillaries.
D. increases, which increases the pulsatility of blood flow through the capillaries.
B. decreases, which increases the pulsatility of blood flow through the capillaries.
What is pulse wave?
pressure wave caused by contraction of the heart which runs over the vasculature
What is flow wave?
blood flow caused by ejection of the heart which runs through the vasculature
What is the speed of pulse wave?
3-12 m/s
What is the speed of pulse wave?
200-0 cm/s
What is the observed pulse wave?
The observed pulse wave is created by a reflection of waves - forward, reflected
Reflection waves form at bifurcation
What has a bigger contribution of reflections of pulse wave and why?
Distal vessels
Distal vessels are stiffer (faster pulse wave) they have larger contribution of reflections compared to proximal vessels
Where does pulse wave travel faster?
Pulse wave travels faster in distal than proximal vessels
Aorta 3-5 m/s Radial artery 5-12 m/s
Why does pulse wave increase as we age?
Reduced compliance of conduit arteries increases pulse wave velocity
Where do reflection waves form?
At bifurcations
Why does pulse wave contribute to coronary perfusion when young?
Reflected wave reach heart after closure of aortic valves (contributing to coronary perfusion)
Why does pulse wave contribute to afterload when old?
Reflected waves reach heart before closure of aortic valves, increasing systolic blood pressure (afterload)
The pulse wave velocity of the aorta decreases with older age BECAUSE at older age remodelling of the arterial wall results in a faster reflected pulse wave.
A. Both statements are correct and causally related.
B. Both statements are correct and NOT causally related.
C. Only the first statement is correct and the second statement is incorrect.
D. Only the second statement is correct and the first statement is incorrect.
E. Both statements are incorrect.
D. Only the second statement is correct and the first statement is incorrect.
Where does peripheral resistance mostly reside?
Smaller arteries
