Labs 33
Circulation
Lab Pressures in the
Systemic Circuit
• Systolic pressure:
– peak arterial pressure during ventricular
systole
• Diastolic pressure:
– minimum arterial pressure during diastole
• Pulse pressure:
– difference between systolic pressure and
diastolic pressure
• Mean arterial pressure (MAP):
– MAP = diastolic pressure + 1/3 pulse pressure
Measuring blood pressure
• Enclose arm in cuff
• Inflate to 160+ mmHg
• Slowly allow pressure out while watching needle
and listening to brachial artery with stethoscope
• Watch and listen for the point where blood starts
to flow through the cuff to the arm – this is the
max pressure or systolic
• Continue slowly letting pressure out until the
point where you no longer hear the sound of
turbulent blood flow (and needle stops bouncing)
this is the point at which blood can flow freely
meaning the pressure in cuff is just below
minimum pressure or diastolic
MAP
• MAP is considered to be the perfusion pressure
seen by organs in the body
• MAP of 60 is necessary to perfuse the tissues
• Formula is an estimate
• Diastole counts for 2/3 of MAP because 2/3 of
cardiac cycle is spent in diastole (and 1/3 in
systole)
• At high HR, this difference decreases and a
better estimate is actually just the average of
systole and diastolic
Lab #37
• Follow instructions on lab handout and
enter your data there
• Part 1 – auscultation
• Part 2 – blood pressure:
– At rest
– Lying down
– After exercise
• Part 3 – measure pulse at three different
locations
When done
• We’ll put up the values on the board and
look at the variation
Assignment
• Work in groups of 2 (3 max)
• Lab guide filled out with data for yourself
• Review Sheet Lab 33A- numbers
1 - 6, 11 - 28