Pressure & Flow in Arteries Flashcards
Define Diastolic pressure
The pressure at which the muscles are dilated and in the filling phase
Define Systolic pressure
The pressure at which the muscles are contracted in the ejection phase
What is the difference in pressure between Systolic and Diastolic called ?
Pulse pressure
Explain the origin of the Korotkoff sounds and their use
These sounds are used to assess a individual’s blood pressure manually.
At which Korotkoff sound is the systolic pressure taken and why ?
The systolic pressure is taken when tapping is first heard. This is when blood begins to flow back through the Brachial artery after being occluded by the blood pressure cuff
At which Korotkoff sound is the diastolic pressure taken and why ?
The diastolic pressure is taken between the muffled sound and the silence at the end of the sound pattern.
This is the sound of blood flow returning to normal and filling the artery.
Velocity through a vessel in a certain vascular group is dependant on what factor ?
Total cross section
What is total cross section of a vessel group ?
Total cross section is the sum of area of cross section of all that vessel group within the body.
In what vessel is velocity greatest ?
The aorta
In what vessel is velocity smallest and why is this needed ?
The capillaries, time is needed for exchange.
Which vessel group has the largest cross sectional area ?
The capillaries, as they are large in number throughout the body.
What is resistance like within the arteries ?
Resistance is low within the arteries
In what vessel is resistance greatest ?
Arterioles
What is the pressure like within the veins ?
Veins are a low pressure system and are also able to distend and collapse which can affect flow.
What are the pressures within the pulmonary circulation when compared to the systemic circulation ?
The pressure of the pulmonary circulation is 1/5 of the systemic circulation
Explain how gravity affects pressure in the lower extremities
When standing blood pools in the veins within the lower extremities which causes an increase in pressure in the veins in the lower extremities.
Why does blood pool in veins ?
Veins are easily expanded therefore expand to hold blood
What can be seen on the neck that indicates a high CVP ?
Visible bulging JVP
What is the skeletal muscle pump ?
During exercise muscles will squeeze veins, forcing blood back to the heart.
What does the skeletal muscle pump also prevent ?
DVT
What is the respiratory pump ?
When we inhale this pressure draws blood back to the heart. -ve pressure in thorax and +ve pressure in abdomen
Define venomotor tone
How well the smooth muscle surrounding the venules contracts and mobilises capacitance
Define system filling pressure
The pressure created by the ventricles and transmitted through the vascular tree to the veins
