Lecture 7 Flashcards
What is the role of the circulatory system?
to provide O2 and nutrients to every cell in the body and remove CO2/waster products from every cell in the body
What two things does a circulatory system require and what things make up each of these two things?
- driving force ie. pump = heart
- conduit system = vascular bed made up of arteries, capillaries, veins
Arteries take blood to the heart or from the heart?
away from the heart
Veins take blood to the heart or from the heart?
take blood to the heart
What are the names of the two juxtaposed systems?
systemic and pulmonary
Describe the order of flow in the systemic circuit
- left ventricle (on the right on the slides)
- aorta
- arteries
- arterioles
- capillaries
- venules
- veins
- vena cava
- right atrium
- right ventricle (to then enter the pulmonary circuit)
Describe the order of flow in the pulmonary circuit
- right ventricle (on the left had side on the slides)
- pulmonary artery
- arterioles
- capillaries
- venules
- pulmonary vein
- left atrium
- left ventricle (to then enter the systemic circuit)
How does the size of the blood vessels change going from arteries, arterioles, capillaries, venules and veins?
it decreases in size from arteries to capillaries and then increases again from capillaries to veins so capillaries are the smallest
Which blood vessel has the thickest wall?
the aorta
Which three blood vessels are termed “microvasculature”?
terminal arterioles, capillaries, venules
Which blood vessels have an endothelium?
all of them
Which blood vessel is only made up of the single layer of endothelium?
Why is this?
Capillaries
this is so that there is as short a distance as possible so that the rate of diffusion is as fast as possible
The function of a blood vessel depends on the specific vascular _______
region
What is the purpose of microvasculature?
this is where the gas exchange control and regulation occurs
What two things does the flow depend on?
the driving force (cardiac output) and the resistance
What causes the driving force which leads to the flow of blood?
the pressure difference between the aorta and the veins
What is the equation for flow of blood around the body?
Q = (P1 - P2)/R
What happens to resistance if we reduce the radius?
it increases a lot
What is the Poiseuillie Relationship which relates radius and viscosity to blood flow?
Q = (P1-P2)πr^4/8ηl which means that resistance = 8lη/πr^4
Which factor in the Poiseuillie Relationship is most likely to change?
radius
Although it is resistance that is most likely to change, how can viscosity change?
if you are severely dehydrated, the viscosity could increase
The vessels branch as you go into the _________
capillaries
The cross sectional area of each vessel gets _________ as you get to the capillaries but the total vascular cross sectional area is ________ in the capillaries for both the systemic and pulmonary circuits
smaller
highest
As the cross sectional area gets smaller from arteries to veins, the resistance __________
increases
Where is most of the blood located?
in the veins
How can we calculate velocity?
flow/total CSA
If we increase the total CSA, what happens to the velocity?
it decreases
If we decrease the total CSA, what happens to the velocity?
it increases
There is the mean velocity the lowest? Why is this good?
in the capillaries
so that there can be exchange of gases and nutrients
Where is there the largest pressure drop? Why?
in the arterioles
because this is controlling the blood flow into the capillaries
The left ventricle generates pressure in the _____. This pressure is highest at the __________ and it decreases as we go through the systemic circuit. Because the heart is “turned on” during systole and “turned off” during diastole, what does this mean for the pressure?
aorta
aorta
it means that the pressure is pulsatile
Pulsatility decreases as we go further away from the heart. True or false?
true
The high pressure from the heart and the low pressure in the right atria is the gradient to drive blood around where?
the circulatory system
A large capillary network means what in terms of the cross sectional area?
the cross sectional area is increased
A low velocity in the capillaries means there is more time for ______
diffusion
The pressure progressively _________ across the venous system to ________ in the right atrium
decreases
lowest
Like the systemic circuit, the pressure is decreasing in pulsatility towards the capillaries and veins. How do they differ?
The blood pressure is much lower
Why does the systemic circuit have a greater pressure than the pulmonary circuit?
because the walls of the right atria are thinner than the left and so the pressure generated is lower
The resistance to blood flow through the arterioles is higher than in the aorta BECAUSE resistance is proportional to radius^4
True
False
