Pressure and Flow in Arteries and Veins Flashcards
(41 cards)
How is arterial pressure measured
Auscultation of Korotkoff sounds using sphygmomanometer and stethoscope
Systolic pressure sound
Tapping
Diastolic pressure sound
Silence
Order of pressure sounds from high cuff pressure to lower
Silence, tapping, thumping, muffled, silence
Disadvantages of measuring by Korotkoff sounds
Low accuracy
Discontinuous
Needs care
Advantages of measuring by Korotkoff sounds
Non-invasive
Cheap
Energy changes in aorta during systole and diastole
Absorb energy during systole and release energy during diastole
Elastic arteries act as
Pressure reservoir
Pressure wave of arteries is affected by
Stroke volume and velocity of ejection - rising phase
Elasticity of arteries - both
Total peripheral resistance - falling phase
Normal arterial pressure
120/80mmHg
Effect of age on arterial pressure
Increases
Pressure from arteries to veins
Decreases
Pressure drop in arteries
Small = 95 to 90 mmHg
Pressure drop in arterioles
Large = 90 to 40 mmHg
Pressure drop in veins
Small = 20 to 5 mmHg
Velocity is related to
Total cross section
Velocity is greatest in
Aorta and vena cava
Velocity is lowest in
Capillaries
Veins are
Distensible and collapsible
External influences that affect flow in veins
Gravity Skeletal muscle pump Respiratory pump Venomotor tone Systemic filling pressure (main)
Pressure in body due to gravity
Low pressure at head and high pressure at feet
Gravity does not affect
Pressure from arteries to veins
Gravity causes
Venous distension in legs and neck
Effects of venous distension in legs
Decrease EDV, preload, stroke volume, cardiac output and main arterial pressure
Orthostatic (postural) hypotension
