Vascular chapter 21 Flashcards
systolic pressure
“Peak” arterial BP, during ventricular systole
diastolic pressure
“Minimum” arterial BP, at end of ventricular diastole
pulse pressure
difference between systolic and diastolic pressure
mean arterial pressure (MAP)
(mean arterial pressure) = diastolic pressure + (pulse pressure/3)
how to calculate pulse pressure
ex if BP = 120mmHG/ 80 mmHG then…
systolic BP- diastolic BP
120mmHG- 80 mmHG
=40 mmHG
how to calculate MAP
ex if BP = 120mmHG/ 80 mmHG then.. Diastolic BP + Pulse pressure/3 80mmHG + 40 mmHG/3 80mmHG + 13.3 mmHG = 93.3 mmHG
Describe how the following change from arteries through capillaries and veins:
-vessel diameter
- decreases from arteries to capillaries
- increases from capillaries to small vessels
Describe how the following change from arteries through capillaries and veins:
-total cross sectional area
- big vessels near the heart have a small cross sectional area
- capillaries have a large cross sectional area
- decreases again for small vessels
Describe how the following change from arteries through capillaries and veins:
-velocity (speed) of blood flow
- high velocity near aorta
- decreases in capillaries
- starts to increase slowly in veins
therefore blood flows slower through smaller vessels
Describe how the following change from arteries through capillaries and veins:
-blood pressure.
- blood pressure is highest near the heart (areteries)
- decreases in veins
therefore decrease in BP away from pump
its all about capillaries
each capillary is smaller in diameter to make it easier for diffusion to occur, we have huge numbers of them , BP is fairly low but higher at one end of the capillary bed, velocity and blood flow through capillaries are very slow making lots of time for efficient exchange
hydrostatic pressure
Fluid pressure
- Forces water out of a solution (“push”)
- Water is being “pushed” from an area of higher pressure to an area of lower pressure
ex: blood pressure, the force of hydrostatic pressure means that as blood moves along the capillary, fluid moves out through its pores.
Osmotic pressure
- Draws water into a solution (“pull”)
- Higher solute concentration = higher osmotic pressure
net hydrostatic pressure
CHP - IHP
net colloid osmotic pressure
BCOP - ICOP
Define/describe the following terms relating to capillary exchange: net filtration pressure.
(NFP) = net hydrostatic pressure – net colloid osmotic pressure -NFP = (CHP – IHP) - (BCOP - ICOP)
Describe how net filtration pressure is affected by net hydrostatic pressure and net colloid osmotic pressure, and how this adds up to filtration.
essentially asking you to describe “bulk flow” and exchange across the capillary wall, at the arteriole end
“Arteriole end” of capillary: blood pressure in capillary (CHP=35 mmHg out) is greater than osmotic pressure (BCOP=25 mmHg in)
-HP>OP so Net movement: out of capillary! (filtration)
Describe how net filtration pressure is affected by net hydrostatic pressure and net colloid osmotic pressure, and how this adds up to reabsorption.
essentially asking you to describe “bulk flow” and exchange across the capillary wall, at the venule end of a capillary.
“Venous end”: pressure in capillary (CHP=18 mmHg out) is less than osmotic pressure (BCOP=25 mmHg in)
-HP less than op therefore absorption and net movement in to the capillary
Describe how blood is moved through veins.
Valves in the veins prevent blood flow from moving backward
describe various factors that can help to increase venous return
-Pumping from skeletal muscles
-increasing sympathetic vasoconstrictor activity
-increasing blood volume
All increase venous pressure and venous gradient which increases venous return