Week 12 Arterial Blood pressure

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Week 12 Arterial Blood pressure Heart sounds
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• Systole ventricle contraction
• Diastole ventricle relaxation
• Systole and diastole one cardio cycle

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BLOOD PRESSURE

• Blood pressure is defined as the pressure of the
  blood exerts against the blood vessel walls
  (arteries).
• The highest blood pressure that results from
  contraction of the ventricles of the heart is the
  systolic pressure
• the force of blood in your arteries as the heart
  contracts and pushes it out
• The lowest blood pressure that results from
  relaxation of the ventricles is the diastolic
  pressure
• the force of your blood between heartbeats
• A measurement of 130 / 85 reflects a systolic
  pressure of 130 and diastolic pressure of 85.

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MEASURING BLOOD PRESSURE

• To measure blood pressure, place the blood
  pressure cuff, sphygmomanometer, and stethoscope
  as shown in the diagram.
• measured as the brachial artery compressed by a
  blood pressure cuff
• A stethoscope is used to hear sounds that result
  from the compression and release of pressure on
  the blood vessel.
• Pronounced
• (sfig-mo-ma-nom-e-ter)

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Blood pressure reading

• Place the cuff so that it just fits the arm, and
  is neither too tight nor too loose.
• Inflate the cuff so that the sphygmomanometer
  reads at least 160. You should not hear any
  sounds at this point.
• Slowly deflate the cuff, and note the reading
  when you begin to hear thumping/sharp tapping
  sounds through the stethoscope. This reading is
  the systolic pressure (the first sound of
  Korotkoff).
• Continue deflating the cuff until the thumping
  sound stops/muffles, and note the reading. This
  is the diastolic pressure (the second sound of
  Korotkoff).
• Finish deflating the cuff, and remove it from the
  arm.
• Wait ten minutes before attempting to take a
  second blood pressure reading on the same person.

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Sounds of Korotkoff

• Sound is created by turbulent flow of blood
  through the compressed vessel
• Sound disappear when the vessel is no longer
  compressed by the pressure cuff and normal
  (non-turbulent) laminar flow resumes

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Factors that affect BP

• Genetics
• Age
• Body weight
• State of physical activity
• Level of salt, caffeine, or drugs

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Closed circulatory system

• Arterial system is connected to the venous system
  by means of capillaries
• Allows for gas exchange to occur
• Pulmonary circulation
• (Lungs) Pick up O2 and drop off CO2
• Systemic circulation
• (Tissues) Pick up CO2 and drop off O2

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Relationship between flow, pressure resistance

• F P/R
• F flow
• P pressure
• R resistance

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Average rate of blood flow (pressure)

• Mean Arterial Pressure
• pulse pressure diastolic pressure
• 3
• Pulse Pressure systolic pressure diastolic
  pressure
• OR
• (systolic pressure 2x diastolic pressure)
• 3

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MAP
120mmHg
75mmHg
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Heart sounds
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Pathway of blood flow

• (from tissues) dO2 blood enters R. atrium via
  superior inferior vena cava ? tricuspid valve ?
  R. ventricle ? pulmonary semilunar valve ?
  pulmonary (trunk) arteries ? lungs ? drop off dO2
  blood pick up O2 blood
• (from lungs) O2 blood enters L. atrium via
  pulmonary veins ? bicuspid valve ? L. ventricle ?
  aortic semilunar valve ? aorta ? rest of the body

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Auscultation areas using a stethoscope.

• SL valves
• Aortic valve
• Pulmonary valve
• AV valves
• Tricuspid valve
• Bicuspid valve

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Four major heart sounds

• Heart Sounds lub and dup
• First Sound (S1) occurs during ventricular
  systole. Under low pressure, closure of the
  atrioventricular (AV) valves and opening of the
  semilunar (SL) valves ? lup
• Second Sound (S2) occurs during ventricular
  diastole. Under high pressure, closure of the SL
  valves and opening of the AV valves ? dup
• Third Sound (S3) turbulence associated with
  rapid filling of the ventricles shortly after
  opening of the AV valves
• Forth Sound (S4) turbulence associated with the
  passage of blood from the atria into the
  ventricles during atrial systole

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Ventricles

• Diastole the period of ventricular filling
  (relaxation), the AV valve open SL valves are
  closed to prevent arterial blood from re-entering
  the heart
• Systole when the ventricles contract compress
  the blood in their chambers, closes the AV valves
  (prevents backflow into atria) SL valves are
  forced open as the ventricles discharge the blood
  into the large arteries

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Phases of the Cardiac Cycle
Fig. 12-18 on p 374
End-Diastolic Volume
Isovolumetric contraction
Isovolumetric relaxation
End-Systolic Volume
Stroke Volume
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Fig. 12-19

1. (a) Atrial contraction begins (S4)
2. Atria eject blood into ventricles
3. (b) Atrial systole ends AV valves close (S1)
4. (c) ventricular contraction
5. (d) Ventricular ejection occurs
6. Semilunar valves close (S2)
7. (e) relaxation occurs
8. (f) AV valves open passive ventricular filling
   occurs (S3)

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