Arterial circulation Flashcards
What is the Relationship between flow and pressure in tissues (vessels)?
Increasing pressure difference
-> The flow increases (follow Ohm’s law)
What is the difference between these 2 lines?
The slopes are difference
-> because they depend on the resistance (the left line has smaller resistance)
Is this graph applied to real life?
No
Make a schematic diagram (flow vs pressure) for lung type vessel and kidney type vessel
How to initiate the flow?
Increase pressure to achieve interstitial pressure
What is transneural pressure?
The difference between the pressure in vessel and pressure in the interstitial
We can observe ___ (linear/continuous) increase in flow with increase in pressure (exponential increase)
continuous
When the pressure increases a lot we will reach a point -> What will we find?
where we get a straight line
Make a graph (flow vs. pressure) in lung vessels
Why does the resistance related to the slope get smaller?
The resistance is not constant, and it depends on pressure
How can the lung vessels affect the resistances?
The wall is elastic
-> increasing pressure
-> increasing radius
-> decreasing resistance
How to calculate the resistance of the vessels? (based on hagens poissule law)
Resistance =
The pressure needed to generate a flow is called critical pressure
=> Why does it exist?
for example the RBCs being larger than capillaries so we need more pressure to squeeze them into the capillaries.
What is interstitial pressure?
a pressure outside the vessel
Lung type vessel
-> What type of increase does this graph show? Why?
it shows a logarithmic increase and that is because the resistance of the vessel is continuously changing.
Lung type vessel
-> Is this an active or a passive response of the vessels? Why?
This is a passive response of the vessels due to their elasticity.
Make a graph (flow vs. pressure) of kidney type vessels
Why does increasing pressure lead to increasing resistance? (in case of kidney type vessels)
Increasing pressure
-> increasing wall tension
-> induce a mechanical stimulus on mechanosensitive channels (on membranes of smooth muscle cells)
-> cause depolarization
-> activate voltage-gated calcium channels
-> make Ca2+ signal
-> cause vasoconstriction
-> decreasing radius
-> INCREASING RESISTANCE
In case of kidney type vessels
-> Is this an active or passive response?
This is an active response of the smooth muscles.
In case of kidney type vessels,
What happen to the graph if there is no more depolarization and there is a high pressure
Now after the slope being constant for a while there will be a linear increase in the flow with pressure.
In case of kidney type vessels,
How does the vessels act after reaching 150mmHg in pressure?
It acts as a rigid wall tube to show a linear relationship
In case of kidney type pressure,
In which range does the flow is constant?
Between 50mmHg and 150 mmHg
In case of kidney type vessels,
This regulation is called autoregulation
-> Why?
The vessels regulation itself
-> the flow becomes independent from pressure
According to The Hagen–Poiseuille Law, what can affect the resistance of blood (EXCEPT pressure)?
Viscosity of blood
What is the viscosity value of water?
1
What is the viscosity of blood plasma?
1.2
What is the normal hematocrit value?
50%
Make a graph to describe the viscosity of blood? (Relative viscosity vs relative hematocrit)
What happen to the viscosity if we increase hematocrit?
The resistance will increase
What happen to the viscosity if we increase hematocrit from 50% to 70%?
The viscosity will double