Practical 2 - Blood Pressure + Pulse

cardiac cycle

cycle of contraction and relaxation of atria and ventricles

systole

contraction → blood pumped out of chamber

diastole

relaxation → blood filling a chamber

atria diastole

blood flows through veins into atria

80% of blood goes to ventricles

atria systole

20% of blood delivered by atrial systole

ventricular systole

shortly after atrial systole

contraction begins → pressure rises → closing the AV valves

ventricular ejection pjase

pressure rises in ventricles → blood is pumped into great arteries

ventricular diastole

filling → cycle repeats

ventricular filling passive

phase 1

atrial pressure > ventricular pressure

AV valves open → blood flows passively into atria and ventricles

• diastole of ventricles and atria

• AV valves open

• SL valves closed

atrial contraction & ventricular filling

phase 1

atria contracts → ventricles filled → EDV

• relaxed ventricle

• contracted atria

• open AV

• closed SL

isovolumetric contraction

phase 2

ventricular pressure increases → ventricular contraction → AV valves close

• ventricular systole

• atrial diastole

• closed AV

• closed SL

ventricular ejection

phase 3

ventricular pressure rises → exceeds pressure of great vessels → SL valves open → blood ejected

• ventricular systole

• atrial diastole

• closed AV

• open SL

isovolumetric relaxation phase

ventricles relax → pressure in ventricles decreases → SL valves close

dicrotic notch

• ventricle diastole

• atrial diastole

• closed AV

• closed SL

aortic valve

pressure fluctuation when aortic valve snaps shut

stethoscope

auscultates heart sounds

lub

1st heart sound → closure of AV valves

dub

2nd heart sound → closure of SL valves

heart murmur

abnormal heart sound → defect in one of the valves

2nd intercostal space at right sternal margin

aortic valve heard at

2nd intercostal space at left sternal margin

pulmonary valve heard at

heart apex in 5th intercostal space with middle of clavicle

mitral valve heard at

right sternal margin of 5th intercostal space

tricuspid valve heard at

pulse

surges of pressure in arteries as blood pushed out during cardiac cycle

• equivalent to heart rate

heart rate

number of beats per minute

60-100 bpm

normal resting range

70-76 bpm

average resting range

0.8 seconds

average heart beat lasts

heart rate

= 60 seconds/heart beat duration

avg heart rate = 60 seconds/0.8 seconds = 75 bpm

blood pressure

pressure exerted against arterial walls

systolic blood pressure (SBP)

pressure exerted against walls of arteries during ventricular systole

diastolic blood pressure (DBP)

pressure exerted against arterial wall during ventricular diastole

sphygmomanometer

measures blood pressure (mmHg)

SBP/DBP

normal bp

less than 120 and less than 80

elevated bp

120-129 and less than 80

high bp (hypertension) stage 1

130-139 or 80 - 89

high bp (hypertension) stage 2

140 or higher or 90 or higher

hypertensive crisis

higher than 180 and/or higher than 120

measuring bp

1. cuff on upper left arm

2. stethoscope on brachial artery

3. inflate cuff until circulation is off

4. slowly release ~2mmHg/second

160 mmHg

do not inflate higher than

sounds of Korotkoff

sounds heard during bp reading

• no sounds → artery is closed

• first sound → systolic pressure

• sounds heard → artery opening and closing

• last sound before it disappears → diastolic pressure

• no sounds → artery is open

Total peripheral resistance (TPR)

amount of force exerted on blood by vasculature

stroke volume (SV)

amount of blood pumped by left ventricle in one contraction

70 mL

average SV

cardiac output (CO)

amount of blood pumped by heart in one minute

CO =

SV x HR

BP =

CO x TPR

pulse pressure =

SBP - DBP

mean arterial pressure (MAP) =

DBP + (pulse pressure/3)

MAP

average pressure in a patient’s arteries during one cardiac cycle

• force generated by heart during contraction

• better indicator of perfusion to vital organs than SBP