Part 1: The Systemic Circulation Flashcards
What happens to pulse pressure as you move further from the heart?
It widens (increases - larger difference between systolic and diastolic in vessels further from the body)
Do capillaries and veins have a pulse pressure?
No
Where is the greatest decrease in arterial pressure?
across the arterioles
What plays a larger role in sculpting the mean arterial pressure?
diastolic
What happens to the mean arterial pressure as you move throughout the circulatory system?
it decreases
Which pressure increases further from the heart, systolic or diastolic?
Systolic
DIastolic DEcreases
What are the three components of the vascular wall (both artery and vein)?
1) Tunica Intima
2) Tunica Media
3) Tunica Adventitia
What cells line blood vessels and lymphatics?
endothelial cells
How does arterial tunica intima differ from venous tunica intima?
It has an internal elastic lamina (IEL)
What is the tunica intima?
subendothelial connective tissue
How does venous tunica media differ from arterial?
It has fewer smooth muscle cells and NO external elastic lamina
What is the tunica adventitia?
mostly connective tissue with some smooth muscle cells and vasa vasorum
What do arteries have that veins do not?
1) elastic lamina
2) more smooth muscle
3) less connective tissue
What layer of the vascular wall is more pronounced in veins?
tunica adventitia
Rank these in order of increasing compliance:
elastic lamina, smooth muscle, collagen
collagen < smooth muscle < elastic lamina (highest compliance)
Name the 3 types of capillaries
1) Continuous (tight junctions between cells; no holes)
2) Fenestrated (holes)
3) Discontinuous (sinusoidal) (endothelial cells are separated by wide spaces)
Where are continuous capillaries found?
muscle, connective tissue
Where are fenestrated capillaries found?
kidney, intestine
Where are discontinuous capillaries found?
liver, bone marrow, spleen
According to the LaPlace relationship, what ratio should be high to achieve the greatest control of vessel diameter and blood flow?
Wall thickness/lumen diameter
thick walls with thin diameter aka arteries
What has the highest wall thickness/lumen diameter ratio?
pre-capillary sphincters
Why do veins regulate volume more than flow or pressure?
because they have relatively small wall thickness/lumen diameter ratio
Do lower or higher compliant aortas generate larger pulse pressures (greater difference between systolic and diastolic?)
lower compliant aortas do!
Why? stiffer walls create a higher afterload generating a larger systolic pressure. Diastolic pressure decreases creating larger pulse pressure
How do highly compliant vessels generate pressure?
recoil (stiffer, low compliant vessels have less recoil)
What is an increase in pulse pressure bad?
it changes afterload in the heart (usually causing more oxygen utilization)
What is more dangerous, low or high compliant aorta?
low! creates larger afterload causing the heart to consume more O2
What happens to compliance of a blood vessel as blood volume increases?
it decreases because load on the vascular wall is first borne by elastin and smooth muscle (high compliance) at lower volumes and lastly by collagen (low compliance) at huger volumes.
What clinical danger do you need to look out for with blood volume expansion?
hypertension
What is the importance of an highly compliant aorta?
the recoil that occurs after the aortic valve closes acts as a sort of second pump after systole that maintains constant flow during diastole.
NEED TO HAVE HIGH COMPLIANCE
What happens to aortic compliance as we age?
it decreases (less elastin (highly compliant) and more collagen (low compliance)
What does a decrease in compliance of the aorta result in?
more cardiac work and a larger pulse pressure
afterload likely went up too causing an increase in O2 consumption
Younger people get _________ (systolic or diastolic) hypertension
diastolic (D is earlier than S in the alphabet)
Older people get __________ (systolic or diastolic) hypertension
systolic because aortic compliance has likely decreased
What can an increased pulse pressure lead to?
1) congestive heart failure
2) can contribute to systolic hypertension, cardiac hypertrophy, aortic distention, low exercise tolerance
Because arteries maintain relatively low compliance, they are known as __________ vessels
resistance
Conversely, because veins feature high compliance, they are known as __________ vessels
capacitance (meaning they can hold a lot of blood)
What happens to the compliance of veins as arterial pressure dramatically increases?
venous compliance decreases
why saphenous vein can be used for coronary artery grafts even though they are morphologically different
Where is the pressure pulse going to be the highest?
furthest from the heart (ex: femoral)
As compliance decreases, what happens to the pressure pulse?
It INCREASES because it is easier for the energy wave to run quickly down a stiff tube
