Apresenta

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Atenção Recomendamos o material a seguir apenas
com o objetivo de divulgar materiais de qualidade
e que estejam disponíveis gratuitamente. Profa.
Cristina Maria Henrique Pinto CFS/CCB/UFSC
O presente arquivo é uma coletânea de figuras e
textos extraídos da coleção em CD-ROM utilizada
em nossas aulas. Interactive Physiology, da
Benjamin Cummings.
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Você pode também dar baixa destes resumos dos
CD-ROMs, não apenas de Cardiovascular mas de
diversos outros assuntos de Fisiologia Humana
(arquivos em .pdf e/ou .doc), com textos e
ilustrações, diretamente do site Selecione
assignmentsem http//www.aw-bc.com/info/ip/ e
escolha entre os seguintes assuntos Muscular
Nervous I Nervous II CardiovascularRespiratory
Urinary Fluids ElectrolytesEndocrine e
Digestive (novos)     Veja também aulas online
(DEMO dos CD-ROMs) sobre Endocrine topics e
Digestive system (recém-lançados)
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Cardiovascular Physiology
parte 3 Factors that Affect Blood Pressure,
Cardiac Cycle, Cardiac Output
Profa. Cristina Maria Henrique Pinto -
CFS/CCB/UFSC monitores Vinicius Negri Dall'Inha
e Grace Keli Bonafim (graduandos de
Medicina) Este arquivo está disponível em
http//www.cristina.prof.ufsc.br/md_cardiovascular
.htm
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Factors that Affect Blood Pressure Graphics are
used with permission of Pearson Education Inc.,
publishing as Benjamin Cummings
(http//www.aw-bc.com)
Introduction Blood pressure is affected by
several factors peripheral resistance vessel
elasticity blood volume cardiac output As
you go through this topic, keep in mind this flow
chart, which outlines the factors affecting blood
pressure
Goals To understand the factors that affect
peripheral resistance, and therefore blood
pressure. To understand how vessel elasticity,
blood volume, and cardiac output affect blood
pressure.
Sources of Peripheral Resistance One of the
main factors that affects blood pressure is
peripheral resistance. Blood cells and plasma
encounter resistance when they contact blood
vessel walls. If resistance increases, then
more pressure is needed to keep blood moving.
Three main sources of peripheral resistance 1.
blood vessel diameter 2. blood viscosity 3. total
vessel length
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Vessel Diameter Analogy Vessel diameter affects
peripheral resistance. As a the diameter of a
tube gets smaller, a greater proportion of the
fluid is in contact with the wall of the tube.
Therefore resistance to flow is increased and
pressure rises. Larger diameter, same volume,
less pressure. Smaller diameter, same volume,
more pressure.
Vasomotor Fibers Constriction of blood vessels
raises blood pressure. Vessel diameter is
actively regulated by vasomotor fibers,
sympathetic nerve fibers that innervate the
vessel's smooth muscle layer. Vasomotor fibers
release norepinephrine, a powerful
vasoconstrictor. A vasoconstrictor is a
substance that causes blood vessels to constrict.
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Vasoconstrictors Blood vessel diameter is also
regulated by blood-borne vasoconstrictors.
Record the effect of each of these chemicals on
the blood vessel
Viscosity Demonstration Blood viscosity affects
peripheral resistance. Viscosity is related to
the thickness of a fluid.
The greater the viscosity, the less easily
molecules slide past one another and the more
difficult it is to get the fluid moving and keep
it moving. Because of this greater resistance
to flow, a greater pressure is required to pump
the same volume of viscous fluid.
 
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Blood Viscosity The hematocrit is the
percentage of red blood cells in the total blood
volume. The hematocrit affects blood viscosity
and therefore resistance to flow. The more
viscous the blood, the greater resistance it
encounters and the higher the blood pressure.
The hematocrit can increase when there are more
red blood cells or less plasma in the blood.
The hematocrit can decrease when there are fewer
red blood cells or more plasma.
Vessel Length Total vessel length affects
peripheral resistance. Increased fatty tissue
requires more blood vessels to service it and
adds to the total vessel length in the body.
The longer the total vessel length, the greater
the resistance encountered, and the greater the
blood pressure.
When an individual has arteriosclerosis,
arteries become calcified and rigid, so they
can't expand when the pulse wave of systolic
pressure passes through them. Thus the walls of
the artery experience higher pressures and become
weaker and weaker.    
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Vessel Elasticity Besides peripheral
resistance, blood vessel elasticity also affects
blood pressure. A healthy elastic artery
expands, absorbing the shock of systolic
pressure. The elastic recoil of the vessel then
maintains the continued flow of blood during
diastole. When an individual has
arteriosclerosis, arteries become calcified and
rigid, so they can't expand when the pulse wave
of systolic pressure passes through them. Thus
the walls of the artery experience higher
pressures and become weaker and weaker.    
Blood Volume Analogy Hoses Blood volume
affects blood pressure. When there is a greater
volume of fluid, more fluid presses against the
walls of the arteries resulting in a greater
pressure. When there is less volume there is
less pressure.
Blood Volume Examples Reduced blood volume (for
example due to excessive sweating) reduces blood
pressure short term. Long term homeostatic
mechanisms compensate, bringing blood volume and
blood pressure back up to normal levels.
Increased blood volume (for example due to water
retention from excessive salt intake) increases
blood pressure short term. Long term homeostatic
mechanisms compensate, bringing blood volume and
blood pressure back up to normal levels.
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Cardiac Output Heart Rate Anything that
decreases cardiac output, also decreases blood
pressure, because there is less pressure on the
vessel walls. An increase in cardiac output
results in increased blood pressure. Cardiac
Output Heart Rate X Stroke Volume Anything
that affects heart rate or stroke volume affects
cardiac output and thus blood pressure. What
happens to heart rate, cardiac output, and blood
pressure with parasympathetic stimulation (vagus
nerve)?
What happens to heart rate, cardiac output, and
blood pressure with sympathetic stimulation?
Cardiac Output Stroke Volume Affect of stroke
volume on blood pressure. If less blood is
ejected from the heart with each beat, then blood
pressure will be lower because there will be less
blood pressing against the vessel walls. Blood
volume affects end diastolic volume and therefore
stroke volume. With decreased stroke volume,
due to decreased venous return, volume there is a
decreased cardiac output and a decreased blood
pressure. With increased stroke volume, due to
increased venous return and/or increased
contractility, there is an increased cardiac
output and increased blood pressure.
Summary Increases in peripheral resistance,
blood volume, and cardiac output result in higher
blood pressure. Conversely decreases in any of
these factors lead to lower blood pressure.
Three main sources of peripheral resistance
Blood vessel diameter, blood viscosity, and total
vessel length. If arteries lose their
elasticity and become more rigid, blood pressure
increases.
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Study Questions on Factors that Affect Blood
Pressure 1. (Page 1.) What are the four main
factors affecting blood pressure?   2. (Page 3.)
Blood cells and plasma encounter resistance when
they contact blood vessel walls. What is this
resistance called?   3. (Page 3.) Is more or less
pressure needed to keep blood moving when
resistance increases?   4. (Page 3.) What are the
three main sources of peripheral resistance?   5.
(Page 4.) What is the relationship between the
diameter of a tube and the proportion of fluid
that is in contact with the wall of the
tube?   6. (Page 4.) What is the relationship
between the diameter of a tube and resistance to
flow? What effect does this have on
pressure?   7. (Page 5.) Does constriction of
blood vessels raise or lower blood pressure?   8.
(Page 5.) What actively regulates the diameter of
blood vessels?   9. (Page 5.) What chemical is
released by vasomotor fibers that acts as a
powerful vasoconstrictor?   10. (Page 6.) List
three blood-borne vasoconstrictors?
11. (Page 7.) Explain viscosity.   12. (Page 7.)
What is the relationship between viscosity and
pressure required to pump a fluid?   13. (Page
8.) Define hematocrit.   14. (Page 8.) What is
the effect of hematocrit on blood
viscosity?   15. (Page 8.) When does hematocrit
increase?   16. (Page 9.) What is the
relationship between the total vessel length,
resistance, and blood pressure?   17. (Page 10.)
Why is expansion and recoil of the elastic
arteries important?   18. (Page 10.) Why does
blood pressure often increase in individuals with
arteriosclerosis?   19 (Page 11.) What is the
relationship between blood volume and blood
pressure?     20. (Page 13.) What is the
relationship between blood pressure and cardiac
output?
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21. (Page 13.) What is the relationship between
heart rate, stroke volume and cardiac
output?   22. (Page 13.) What happens to heart
rate, cardiac output, and blood pressure with
both parasympathetic and sympathetic
stimulation?   23. (Page 14.) What is the
relationship between venous return and stroke
volume?
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Você pode ver a aula a seguir, diretamente do
site, online. Clique abaixo
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The Cardiac Cycle Graphics are used with
permission of adam.com (http//www.adam.com/) Ben
jamin Cummings Publishing Co (http//www.awl.com/b
c)
Introduction The cardiac cycle includes all the
events related to the flow of blood through the
heart during one complete heartbeat.
Goals To list the phases of the cardiac cycle
in consecutive order. To recognize that the
pressure changes determine valve action and
direction of blood flow through the heart. To
relate an ECG and heart sounds to events of the
cardiac cycle.
Heart Valves During the cardiac cycle, heart
valves open and close in response to differences
in blood pressure on their two sides. The Heart
Valves Pulmonary semilunar valve Aortic
Semilunar Valve Left AV valve or Bicuspid valve
or Mitral valve Right AV valve or Tricuspid
valve
Overview of Cardiac Cycle Phases of the Cardiac
Cycle 1. Ventricular Filling - Occurs during mid
to late diastole. 2. Ventricular Systole -
Includes isovolumetric contraction and
ventricular ejection. 3. Isovolumetric Relaxation
- Occurs during early diastole.
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Ventricular Filling Passive Occurs during mid
to late diastole, when the heart chambers are
relaxed. Blood flows passively into the atria,
through open AV valves, and into the ventricles,
where the pressure is lower.
Ventricular Filling Atrial Contraction Atria
contract, forcing the remaining blood into the
ventricles.  Blood flows through both sides of
the heart at the same time.
Ventricular Systole Contraction Isovolumetric
contraction Ventricles contract and
intraventricular pressure rises, closing the AV
valves. Briefly, ventricles are completely
closed chambers.
Ventricular Systole Ejection Ventricular
ejection Rising ventricular pressure forces
semilunar valves open. Blood is ejected from the
heart into the aorta and pulmonary trunk.
Isovolumetric Relaxation Ventricles relax and
ventricular pressure drops. Blood backflows,
closing semilunar valves. Ventricles are totally
closed off again.
Atrial Filling Meanwhile, the atria have been
filling with blood. When atrial pressure exceeds
ventricular pressure, AV valves open and
ventricular filling, phase 1 begins again.
Ventricular and Atrial Contraction Although we
have been highlighting the flow of blood on the
right side of the heart, remember that both atria
contract at the same time and both ventricles
contract at the same time.
Control of Blood Flow by Pressure Pressure
changes reflect the alternating contraction and
relaxation of the heart. Blood moves along a
pressure gradient (from higher to lower pressure)
through any available opening. Pressure
changes cause the heart valves to open and close,
which keeps the blood flowing in the forward
direction.
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Overview Graphs and Heart During ventricular
ejection phase, ventricular pressure rises higher
than aortic pressure. This is necessary to open
the semilunar valve. Only a little more than
half of the blood is ejected during ventricular
ejection.
Left Atrial Pressure
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Left Ventricular Pressure   Aortic
Pressure   Ventricular Volume   ECG
Notes on Quiz Questions Quiz Question 1 Blood
Flow through Heart This question asks you to
trace the blood through the right side of the
heart.   Quiz Question 2 Valves This question
asks you to predict when the valves are open or
closed during the various stages of the cardiac
cycle.   Quiz Questions 3a, 4a, 5a, 6a Cardiac
Cycle Phase These question asks you to view a
diagram of the heart and predict what stage of
the cell cycle it's in. You may take notes on
the diagrams below. The dye-labeled blood has
been colored light here to make it more
visible.   Quiz Question 3b, 4b, 5b, 6b Cardiac
Cycle Graphs These questions asks you to
predict the correct phase of the cardiac cycle by
viewing an ECG, graph of ventricular volume, and
a graph of pressures. You may want to take notes
on this diagram
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(No Transcript)
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Study Questions on the Cardiac Cycle   1. (Page
1.) What is a cardiac cycle?   2. (Page 3.) What
opens and closes the heart valves?   3. (Page 4.)
List the three phases of the Cardiac Cycle.   4.
(Pages 5-10.) Match the stages of the cardiac
cycle to their description.
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5. (Page 6.) True or false Blood passes through
the bicuspid valve at the same time blood is also
passing through the tricuspid valve.   6. (Page
7.) What closes the AV valves?   7. (Page 8.)
What opens the semilunar valves?   8. (Page 9.)
What closes the semilunar valves?   9. (Page 10.)
What opens the AV valves?   10. (Page 11.) True
or false The right side of the heart contracts,
then the left side of the heart contract.   11.
(Page 12.) What is the relationship between
pressure inside a chamber of the heart and the
state of the heart muscle (relaxed or
contracted)?   12. (Page 12.) Blood always moves
from ____ pressure to ____ pressure.   13. (Page
12.) What causes heart valves to open and close?
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14. (Page 12.) Predict if the AV and semilunar
valves are open or closed during the following
phases of the cardiac cycle by circling the
appropriate answer on this chart  
15. (Pages 14-19.) What is happening to the
volume of blood inside the ventricles during each
labeled part of the graph below?   16. (Pages
14-19.) What is happening to the pressure inside
the ventricles during each labeled part of the
graph below? Explain.   17. (Pages 14-19.) What
is happening to the depolarization,
repolarization and contraction of the atria and
ventricles during each labeled part of the graph
below?
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18. Pages 14-19.) On the graph below, which
number corresponds to ventricular ejection
isovolumetric relaxation ventricular filling
isovolumetric contraction
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Cardiac Output Graphics are used with permission
of Pearson Education Inc., publishing as
Benjamin Cummings (http//www.aw-bc.com)
Introduction Cardiac output is the amount of
blood pumped out by each ventricle in one minute.
Cardiac output can increase markedly to meet
the demands placed on our body, whether dashing
to catch a bus or riding a mountain bike,
Goals To recognize that cardiac output varies
directly with heart rate and stroke volume. To
identify factors that modify heart rate and
stroke volume, and to indicate how they change
cardiac output.
Cardiac Output Definition Cardiac Output (CO)
The volume of blood ejected from the left or
right ventricle into the aorta or pulmonary trunk
per minute. Cardiac output depends on 1. Heart
rate 2. Stroke volume   Cardiac Output
Heart Rate X Stroke Volume CO
HR X SV
Heart Rate Definition Heart rate (HR) is the
number of times the heart beats in one minute,
averaging 75 beats per minute (bpm) in the adult
at rest.
Stroke Volume Definition Stroke volume (SV) is
the amount of blood pumped by each ventricle with
each heartbeat, averaging 70 ml per beat in the
adult at rest.
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SV EDV - ESV Stroke volume represents the
difference between end diastolic volume (EDV) and
end systolic volume (ESV). By the time diastole
ends, each ventricle has filled up with blood.
This amount of blood is the end diastolic volume
or EDV. The amount of blood ejected during the
systole is the stroke volume. At the end of
systole the volume of blood remaining in each
ventricle is the end systolic volume or ESV.
Each ventricle normally contains about 120 ml of
blood by the end of diastole. At the end of
systole about 50 ml of blood are left in each
ventricle. This means that 70 ml of blood were
pumped out of each ventricle during
systole. Stroke Volume
End-Diastolic Volume - End-Systolic
Volume SV EDV - ESV  
70 ml/beat 120 ml/beat
- 50 ml/beat
Regulation of Cardiac Output The key factor
regulating stroke volume is the amount of
stretching that occurs to ventricular cardiac
muscle prior to ventricular contraction. The
more cardiac muscle stretches, the more
forcefully it contracts. These stronger
contractions increase stroke volume.
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Fill out this chart, making note of the reasons
for the increase or decrease
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Increased Sympathetic Stimulation - Increased
sympathetic stimulation (due to fright, anger,
etc.) increases the heart rate. It also
increases stroke volume by increasing
contractility, which results in more complete
ejection of blood from the heart (lower ESV).
Increased Parasympathetic Stimulation -
Parasympathetic activity increases after a crisis
has passed. This reduces heart rate and stroke
volume from their high levels, bringing cardiac
output back to normal. Increased Venous Return
- Cardiac muscle fibers are stretched by
increased blood volume returning to the heart
(increased venous return and EDV). Increased
stretch results in greater force of contraction,
which increases stroke volume. Slow Heart Rate
- Slow heart rate allows for more time for
ventricular filling, increasing EDV and therefore
stroke volume. Extremely Fast Heart Rate -
Extremely rapid heart rate results in low venous
return and therefore decreased stroke volume.
Exercise - Exercise activates the sympathetic
nervous system, increasing heart rate,
contractility, and stroke volume. Both the
higher heart rate and squeezing action of
skeletal muscles on veins increase venous return,
contributing to increased stroke volume. Sudden
Drop in Blood Pressure - A sudden drop in blood
pressure results in low venous return and
therefore decreased stroke volume. However heart
rate increased due to sympathetic activity, and
normal cardiac output is maintained. Rising
Blood Pressure - Rising blood pressure reduces
sympathetic activity, decreasing heart rate.
High blood pressure also increases arterial
pressure which ventricles must overcome before
semilunar valves open, increasing ESV and
decreasing stroke volume. Reduced cardiac output
helps bring blood pressure down to normal
levels. Sudden Drop in Blood Volume - A sudden
drop in blood volume (eg. due to severe blood
loss) results in low venous return and therefore
decreased stroke volume. Sympathetic activity
increases heart rate, maintaining cardiac output.
Excess Calcium - Excess calcium can lead to
spastic heart contractions, an undesirable
condition. Calcium also increases stroke volume
by enhancing contractility.
Heart Videos Effect of Epinephrine on a Frog's
Heart Epinephrine is normally released when
there is increased sympathetic activity. Effect
of Acetyl Choline on a Frog's Heart Acetyl
choline is a parasympathetic neurotransmitter.
Summary Cardiac Output Heart
Rate X Stroke Volume Heart rate is
increased by sympathetic nerve activity and
epinephrine. Heart rate is decreased by
parasympathetic nerve activity.
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Study Questions on Cardiac Output 1. (Page 3.)
Define cardiac output.   2. (Page 3.) What two
factors does cardiac output depend on?   3. (Page
3.) What is the mathematical relationship between
cardiac output, heart rate, and stroke
volume.   4. (Page 4.) Define heart rate.   5.
(Page 4.) What is the average heart rate in an
adult at rest?   6. (Page 5.) Define stroke
volume.   7. (Page 5.) What is the average stroke
volume in an adult at rest?   8. (Page 6.) Define
end diastolic volume.   9. (Page 6.) Define end
systolic volume.   10. (Page 10.) What is the
mathematical relationship between end diastolic
volume, end systolic volume, and stroke
volume?   11. (Page 6.) If the ESV is 50 ml and
the EDV is 120 ml, what is the stroke
volume?   12. Page 7.) If the heart rate is 75
beats per minute and the stroke volume is 70 ml
per beat, then what is the cardiac output?   13.
(Page 8.) What's the relationship between cardiac
muscle stretch and force of contraction? What
effect does this have on stroke volume?
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14. (Page 8.) What's the relationship between
venous return and stroke volume?   15. (Page 8.)
What is the effect of increased sympathetic
activity on heart rate and stroke volume? How
does this effect cardiac output?   16. (Page 8.)
What is the effect of increased parasympathetic
activity on heart rate and stroke volume?   17.
(Page 8.) What is the effect of increased venous
return on heart rate and stroke volume? How
does this effect cardiac output?   18. (Page 8.)
What effect does a slow heart rate have on stroke
volume?   19. (Page 8.) What effect does a fast
heart rate have on stroke volume?   20. (Page
8.) What is the effect of exercise on heart rate
and stroke volume? How does this effect cardiac
output?   21. (Page 8.) What is the relationship
between blood pressure and sympathetic activity?
What effect does this have on heart rate?   22.
(Page 8.) What is the effect of a sudden decrease
in blood pressure on heart rate and stroke
volume?   23. (Page 8.) What is the effect of a
sudden increase in blood pressure on heart rate?
  24. (Page 8.) What is the effect of a sudden
increase in blood pressure on stroke volume?
  25. (Page 8.) What is the effect of a sudden
drop in blood volume on heart rate and stroke
volume?   26. (Page 8.) What is the effect of
an increase in calcium on heart rate and stroke
volume?
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Cardiovascular Physiology
continua em parte 4 Blood Pressure Regulation
and Autoregulation and Capillary Dynamics parte
1 Anatomy review the heart, anatomy review
blood vessel and structure and function parte 2
Intrinsic Conduction System, Measuring Blood
Pressure and Cardiac Action Potential
Profa. Cristina Maria Henrique Pinto -
CFS/CCB/UFSC monitores Vinicius Negri Dall'Inha
e Grace Keli Bonafim (graduandos de
Medicina) Este arquivo está disponível em
http//www.cristina.prof.ufsc.br/md_cardiovascular
.htm