Blood Pressure: Facts and Measurement
March 26-27, 2014
Pulse Points
Areas where can easily
feel pulse
Also act as
pressure
points.
Compressing these
points will reduce
downstream blood
flow
useful when dealing
with major wounds.
Try to find several of these!
Blood Pressure
Blood pressure is the pressure the blood exerts against
the inner walls of the blood vessels.
Usually, we refer to the pressure of the arteries.
Blood Pressure
Blood pressure is the pressure the blood exerts against
the inner walls of the blood vessels.
Usually, we refer to the pressure of the arteries.
Why does blood
pressure drop so low
in the capillaries?
1)
Because there are so
many more capillaries
2)
So that the flow of
blood will slow to
facilitate exchange of
materials
Blood Pressure
Blood pressure is the pressure the blood exerts against
the inner walls of the blood vessels.
Usually, we refer to the pressure of the arteries.
Why do we record
blood pressure as two
numbers?
Blood pressure in the
arteries fluctuates with
the cardiac cycle.
Blood Pressure
Systolic pressure occurs due to ventricle contraction
Diastolic pressure occurs when ventricles relax
Measuring Blood Pressure
1.
A
sphymomanometer
is placed over the
brachial artery.
2.
The cuff is inflated to
~150 mmHg (above
systolic pressure)
3.
Air pressure is
slowly
released from cuff
while a stethoscope is
used to listen for
Korotkoff
sounds in
the artery.
Measuring Blood Pressure
Korotkoff sounds
•
Cuff pressure > systolic pressure
there is no blood flow through
artery
NO SOUNDS
•
Cuff pressure = systolic pressure
blood begins to flow turbulently
through artery
TAPPING
SOUND BEGINS
•
Cuff pressure = diastolic
pressure
blood begins to flow smoothly
SOUNDS DISAPPEAR
Test yourself! (Start at ~3:30)
Factors which affect BP
Increased cardiac output (heart rate & stroke volume) increases
blood pressure
Exercise
Stress / Sympathetic nervous system
Increased peripheral resistance (friction of blood traveling
through vessels) increases BP
Atherosclerosis
Constriction of blood vessels (due to sympathetic nervous system,
cold, chemicals such as nicotine)
Number of vessels (body size / fat / pregnancy)
Increased blood volume increases blood pressure
Kidney problems
Which factors will decrease BP?
Resting Blood Pressure
Hypotension
is low
blood pressure.
May cause dizzy
spells, especially
when rising
Not problematic
among young,
healthy people
Acute hypotension
may indicate shock
Resting Blood Pressure
Hypertension
is high
blood pressure.
Damages blood
vessels, which may
lead to clots and
atherosclerosis
Causes heart to work
harder, leading to
enlarged heart that
will eventually
weaken
Hypertension can be a
positive feedback
cycle – why?
Capillary Exchange
Capillary exchange is the movement of substances
(water, gases, nutrients, wastes, etc.) between capillaries
and the interstitial fluid of tissues
Capillaries have special features which increase their
permeability:
Intercellular clefts
:
spaces between cells
Fenestrations
:
very thin membrane-
covered spots, or pores
Capillary Exchange
Capillary exchange is the movement of substances
(water, gases, nutrients, wastes, etc.)
Capillaries have special features which increase their
permeability:
Intercellular clefts
:
spaces between cells
Fenestrations
:
very thin membrane
-covered spots, or
pores
Clefts and fenestrations are most
important for the diffusion of what
kinds of substances?
Water, and other lipid-insoluble substances
What can get through without their
help?
O
2
, CO
2
, fats
Capillary Exchange
Capillary exchange is the movement of substances
(water, gases, nutrients, wastes, etc.)
Capillaries have special features which increase their
permeability:
Intercellular clefts
:
spaces between cells
Fenestrations
:
very thin membrane
-covered spots, or
pores
What type of capillaries
don’t
have
fenestrations or intercellular clefts?
Capillaries in the brain – work with
astrocytes to form blood-brain barrier
Capillary Exchange
Differences in pressure in blood pressure and osmotic
pressure help fluids move
out
of capillaries at the
arterial end and
into
capillaries at venous end.
Watch
me!
Closure
What was our objectives, and what did we learn?
What was our learner profile trait and how did we
demonstrate it?
How does what we did today tie to our unit question?
Exit Ticket
Learn about pulse points, pressure points, and how to measure blood pressure accurately. Discover the reasons for blood pressure variations and the importance of systolic and diastolic pressures. Explore the process of measuring blood pressure using a sphygmomanometer and understanding Korotkoff sounds.
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Presentation Transcript
Pulse Points Areas where can easily feel pulse Also act as pressure points. Compressing these points will reduce downstream blood flow useful when dealing with major wounds. Try to find several of these!
Blood Pressure Blood pressure is the pressure the blood exerts against the inner walls of the blood vessels. Usually, we refer to the pressure of the arteries.
Blood Pressure Blood pressure is the pressure the blood exerts against the inner walls of the blood vessels. Usually, we refer to the pressure of the arteries. Why does blood pressure drop so low in the capillaries? 1) Because there are so many more capillaries 2) So that the flow of blood will slow to facilitate exchange of materials
Blood Pressure Blood pressure is the pressure the blood exerts against the inner walls of the blood vessels. Usually, we refer to the pressure of the arteries. Why do we record blood pressure as two numbers? Blood pressure in the arteries fluctuates with the cardiac cycle.
Blood Pressure Systolic pressure occurs due to ventricle contraction Diastolic pressure occurs when ventricles relax http://www2.estrellamountain.edu/faculty/farabee/BIOBK/cardiaccycle.gif
Measuring Blood Pressure 1. A sphymomanometer is placed over the brachial artery. 2. The cuff is inflated to ~150 mmHg (above systolic pressure) 3. Air pressure is slowly released from cuff while a stethoscope is used to listen for Korotkoff sounds in the artery.
Measuring Blood Pressure Test yourself! (Start at ~3:30) Korotkoff sounds Cuff pressure > systolic pressure there is no blood flow through artery NO SOUNDS Cuff pressure = systolic pressure blood begins to flow turbulently through artery TAPPING SOUND BEGINS Cuff pressure = diastolic pressure blood begins to flow smoothly SOUNDS DISAPPEAR
Factors which affect BP Increased cardiac output (heart rate & stroke volume) increases blood pressure Exercise Stress / Sympathetic nervous system Increased peripheral resistance (friction of blood traveling through vessels) increases BP Atherosclerosis Constriction of blood vessels (due to sympathetic nervous system, cold, chemicals such as nicotine) Number of vessels (body size / fat / pregnancy) Increased blood volume increases blood pressure Kidney problems Which factors will decrease BP?
Resting Blood Pressure Hypotension is low blood pressure. May cause dizzy spells, especially when rising Not problematic among young, healthy people Acute hypotension may indicate shock
Hypertension can be a positive feedback cycle why? Resting Blood Pressure Hypertension is high blood pressure. Damages blood vessels, which may lead to clots and atherosclerosis Causes heart to work harder, leading to enlarged heart that will eventually weaken
Capillary Exchange Capillary exchange is the movement of substances (water, gases, nutrients, wastes, etc.) between capillaries and the interstitial fluid of tissues Capillaries have special features which increase their permeability: Intercellular clefts: spaces between cells Fenestrations: very thin membrane- covered spots, or pores
Capillary Exchange Capillary exchange is the movement of substances (water, gases, nutrients, wastes, etc.) Capillaries have special features which increase their permeability: Clefts and fenestrations are most important for the diffusion of what kinds of substances? Intercellular clefts: spaces between cells Water, and other lipid-insoluble substances Fenestrations: very thin membrane -covered spots, or pores What can get through without their help? O2, CO2, fats
Capillary Exchange Capillary exchange is the movement of substances (water, gases, nutrients, wastes, etc.) Capillaries have special features which increase their permeability: What type of capillaries don t have fenestrations or intercellular clefts? Intercellular clefts: spaces between cells Capillaries in the brain work with astrocytes to form blood-brain barrier Fenestrations: very thin membrane -covered spots, or pores
Capillary Exchange Differences in pressure in blood pressure and osmotic pressure help fluids move out of capillaries at the arterial end and into capillaries at venous end. Watch me!
Closure What was our objectives, and what did we learn? What was our learner profile trait and how did we demonstrate it? How does what we did today tie to our unit question?
