Transcript blood pressure

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Today: Notes on cardio: finished
Wed – Thurs: labs/study guides
Fri: Test on cardio. Then urinalysis
Mon: finish urinalysis if needed
Mon – Fri: finish all labs and written work
Thurs: Test on Urinary
Friday: All due or 0
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Heart Sounds
Lubb
Dupp
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Figure 18.5: The systemic and pulmonary circuits
Capillary beds
of lungs where
gas exchange
occurs
Pulmonary Circuit
Pulmonary
arteries
Venae
cavae
Pulmonary
veins
Aorta and
branches
Left
atrium
Left
Right
ventricle
atrium
Heart
Right
ventricle
Systemic Circuit
Key:
= Oxygen-rich,
CO2-poor blood
= Oxygen-poor,
CO2-rich blood
Capillary
beds of all
body tissues
where gas
exchange
occurs
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Pathways of Blood Flow
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Anastamoses
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F. Electrocardiogram
1.
An electrocardiogram is a recording
of the electrical changes that occur
during a cardiac cycle.
2.
The first wave, the P wave,
corresponds to the depolarization of
the atria.
3.
The QRS complex corresponds to
the depolarization of ventricles and
See Charts and
hides the repolarization of atria.
diagrams for this
information
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4.
The T waves end the ECG pattern
and corresponds to ventricular
repolarization.
See Charts and
diagrams for this
information
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Note How Exchange takes
place at capillary beds
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 Blood Pressure
A. Blood pressure is the force of blood
against the inner walls of blood
vessels anywhere in the
cardiovascular system, although
the term "blood pressure"
usually refers to arterial pressure.
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B. Arterial Blood Pressure
1.
Arterial blood pressure rises and
falls following a pattern established
by the cardiac cycle.
a.
During ventricular contraction,
arterial pressure is at its
highest (systolic pressure).
b.
When ventricles are relaxing,
arterial pressure is at its
lowest (diastolic pressure).
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2. The surge of blood that occurs with ventricular
contraction can be felt at certain points in the body as a
pulse.
• Cardiac Output: Amount of blood ejected from the heart
per minute. Consists of:
– Stroke Volume: Amount of blood ejected per
contraction
– Heart Rate per minute
CO = SV X PR
CO = 70 mL X 72 bpm
5,040 mL/min
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• The velocity of blood flow varies in the circulatory system
– And is slowest in the capillary beds as a result of the high
resistance and large total cross-sectional area
Systolic
pressure
Veins
Venules
Capillaries
Arterioles
Diastolic
pressure
Arteries
120
100
80
60
40
20
0
Aorta
50
40
30
20
10
0
Venae cavae
Figure 42.11
Area (cm2)
Systolic pressure
Is the pressure in the arteries during
ventricular systole
Is the highest pressure in the arteries
Diastolic pressure
Is the pressure in the arteries during
diastole
Is lower than systolic pressure
5,000
4,000
3,000
2,000
1,000
0
Velocity (cm/sec)
Blood pressure
– Is the hydrostatic pressure that blood exerts against the wall of a vessel
Pressure (mm Hg)
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Blood pressure
– Can be easily measured in humans
Blood pressure is determined partly by cardiac output
– And partly by peripheral resistance due to variable constriction of the
arterioles
1 A typical blood pressure reading for a 20-year-old
is 120/70. The units for these numbers are mm of
mercury (Hg); a blood pressure of 120 is a force that
can support a column of mercury 120 mm high.
4 The cuff is loosened further until the blood flows freely
through the artery and the sounds below the cuff
disappear. The pressure at this point is the diastolic
pressure remaining in the artery when the heart is relaxed.
Blood pressure
reading: 120/70
Pressure
in cuff
above 120
Rubber cuff
inflated
with air
120
Pressure
in cuff
below 120
Pressure
in cuff
below 70
120
70
Sounds
audible in
stethoscope
Artery
Artery
closed
2 A sphygmomanometer, an inflatable cuff attached to a
pressure gauge, measures blood pressure in an artery.
The cuff is wrapped around the upper arm and inflated
until the pressure closes the artery, so that no blood
flows past the cuff. When this occurs, the pressure
exerted by the cuff exceeds the pressure in the artery.
Figure 42.12
3 A stethoscope is used to listen for sounds of blood flow
below the cuff. If the artery is closed, there is no pulse
below the cuff. The cuff is gradually deflated until blood
begins to flow into the forearm, and sounds from blood
pulsing into the artery below the cuff can be heard with
the stethoscope. This occurs when the blood pressure
is greater than the pressure exerted by the cuff. The
pressure at this point is the systolic pressure.
Sounds
stop
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Veins have Valves
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Major Arteries
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Arteries where the pulse
is often taken: Brachial
and Radial.
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Vein where blood is taken
= Median cubital.
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