Pressure and Flow in Arteries and Veins Flashcards
How is arterial blood pressure measured?
Auscultation of korotkoff sounds using a sphygmomanometer and a stethoscope
When the pressure in the sphygmomanometer cuff is higher than systolic pressure what sound is heard on a stethoscope?
Silence
When the pressure in the sphygmomanometer cuff is just lower than systolic pressure what sound is heard on a stethoscope?
Tapping
When the pressure in the sphygmomanometer cuff is significantly lower than systolic pressure what sound is heard on a stethoscope?
Thumping
When the pressure in the sphygmomanometer cuff is slightly higher than diastolic pressure what sound is heard on a stethoscope?
Muffled sounds
When the pressure in the sphygmomanometer cuff is less than diastolic pressure what sound is heard on a stethoscope?
Silence
What should be heard normally when a stethoscope is on the arm?
Silence
Where should a stethoscope be placed on the arm to auscultate for Korotkoff sounds?
Over the brachial artery, in the antecubital fossa
What effect so elastic arteries have on blood pressure?
They act as a pressure reservoir and dampen down pressure variations
What is arterial pressure affected by?
Stroke volume
Velocity of ejection
Elasticity of arteries
Total peripheral resistance
What is normal arterial pressure?
120/80 mmHg
How does normal arterial pressure change?
It increases with age
How does pressure change through blood vessels?
Pressure falls throughout the vascular tree from arteries to arterioles to capillaries and finally the veins
What is the difference in blood pressure between the pulmonary and systemic circulation?
The pulmonary circulation has a pressure about 1/5th that of the systemic circulation
How does velocity change in blood vessels?
Velocity is related to total cross section so is highest in the aorta and vena cava and lowest in the capillaries
Which vessels have the highest total cross-sectional area?
Capillaries
How is flow affected in veins?
Veins are distensible and collapsible so external influences affect flow
What affect can gravity have on blood flow?
Doesn’t affect driving pressure from arteries to veins
Causes venous distension in legs
Causes venous collapse in the neck
What is venous distension?
Stretching of the veins because there is a greater volume of blood moving through them than there should be
What is jugular venous pressure?
The blood pressure in the veins at the neck and can be used to estimate the central venous pressure
What is jugular venous collapse?
When the veins in the neck close
What does jugular venous collapse show?
The height of the collapse can be used to estimate central venous output
How is blood brought back up to the heart in the venous system?
Skeletal muscle pump
Respiratory pump
Venomotor tone
Systemic filling pressure
What is venomotor tone?
Contraction of smooth muscle surrounding the venues and veins
