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EX 111
Spring 2017
Chapter 9 Objectives:
 Know the 6 main functions of the cardiovascular system
o Deliver O2 and nutrients
o Remove CO2 and other waste
o Transports hormones and other substances
o Temperature balance and fluid regulation
o Acid-base balance
o Immune function
 Name the two main roles of the cardiovascular system during exercise
o increases cardiac output
o redistributes blood to muscles from inactive organs
 Why is the cardiovascular system described as a “closed loop” system?
o Ideally, there is nothing that enters or leaves the system, no way to get in
or out
o What is the relationship between arteries, veins, capillaries, arterioles and
venules within this system?
 Arteries: move blood away from the heart, arterioles are smaller
arteries that branch off
 Veins: move blood towards the heart, venules are smaller
branched-off veins
 Capillaries: small exchange tube for O2 that trades blood to get
oxygenated
 Heart→ arteries→ arterioles→ capillaries→ venules→
veins→heart
 HEART
o Know the 4 chambers of the heart and describe the two pumps within the
heart
 2 atria: right and left, receive blood
 2 ventricles: right and left, pump blood
 Basically 2 side by side pulps, separated by interventricular septum
o Know the direction of blood flow through the heart
 flows in 2 circuts: pulmonary circuit and systemic circuit
 Pulmonary circuit: right side of heart, receives O2 poor
blood and pumps to the lungs, low-pressure
 Systemic circuit: left side of heart, receives O2 rich blood
and pumps to body, high-pressure
 can only go in one direction, uses valves to make sure blood
follows the path
 AV (atrioventricular) valves: 2, between the atria and
ventricles, right side is tricuspid valve and left is bicuspid

Semilunar valves: 2, between ventricles and vessels leaving
the heart, pulmonary and aortic
 Path: O2-poor blood comes to the heart from the body (superior
and inferior vena cava), right atrium→ tricuspid valve→ right
ventricle, pumped out through the pulmonary valve to the right and
left pulmonary arteries (going to lungs)
 After oxygenation, comes from pulmonary arteries→ left atrium→
bicuspid valve→ left ventricle→ aortic valve→ aorta, then is
distributed to the body
o Know the three layers of the heart wall and the importance of the coronary
circulation
 Epicardium:
 qualities: lubrication of outside of the heart, slimy, has
vessels and nerve fibers
 layer with coronary blood supply, takes functional blood
supply to heart muscle through coronary arteries and veins
 crucial to maintaining constant blood supply, there is a high
demand for O2 and nutrients at rest and exercising
 disruption=permanent damage (coronary artery disease,
myocardial infarction, angina pectoris)
 Myocardium:
 qualities: heart muscle, contracts to pump blood
 cardiac muscle is very different from skeletal muscle:
striated, short, thick, branched interconnected cells,
uninucleated, uniform fiber type (high capillary density,
can only work aerobically, high number of mitochondria)
 Ca++ is stored outside of the cell, some in sarcoplasmic
reticulum, fibers are interconnected with intercalated discs
(desmosomes hold cells together, gap junctions conduct
action potentials), synchronized functions w/ continuous,
involuntary, rhythmic contractions
 Endocardium:
 qualities: inside lining of heart, lubricates and protects
inner workings
o Know the components of the cardiac conduction system and how they
control the intrinsic heart rate
 SA node: initiates contraction signal, located in the right atrial wall
 spreads from SA node via right atrium/left atrium
contraction to AV node
 stimulates RA/LA contraction
 AV node: delays, relays signal to ventricles, located in lower right
atrial wall (near center)
 delay allows the atria to contract fully
 spreads signal to AV bundle
 AV bundle: relays signal to ventricles
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 travels along the interventricular septum
 from right/left bundle branches to apex of the heart
 Purkinje fibers: sends contractions to ventricles
 terminal branch of right/left bundle branches
 spreads through ventricular wall
 stimulates RV/LV contraction
o Be able to explain the physiological role of the extrinsic heart controls:
 Parasympathetic nervous system: slows heart rate, relays blood to
digestive organs
 Sympathetic nervous system: speeds heart rate, relays blood to
active muscles (skeletal/cardiac)
o Know what each portion of a ECG represents within the cardiac cycle
 P wave: atrial depolarization
 QRS complex: depolarization of ventricles
 T wave: ventricular repolarization
o Be able to describe the cardiac cycle and the steps involved with:
 Ventricular systole: the contraction of the ventricles pushing the
blood through the systemic vessels
 Ventricular diastole: relaxation of the ventricles
 Pressure changes within the heart: pressure changes with heart
diastole and systole to move the blood through the chambers
Define
o Blood pressure
 Systolic pressure: max arterial pressure during contraction of left
ventricle
 Diastolic pressure: min pressure during dilation of the ventricles
 Mean arterial pressure: average pressure during cardiac cycle
(systole and diastole)
o Hypertension (high blood pressure)
Identify the factors that influence blood pressure
o amount of blood pumped (cardiac output)
o resistance to flow (total vascular resistance)
o mean blood pressure (MPB/MAP= CA*TVO
Explain how blood pressure is regulated both short term and long term
o Be able to explain the influence of resistance, pressure, and vessel
diameter in relation to hemodynamics within the vascular system
 resistance: increases blood pressure with more resistance (direct
relationship), since blood has a harder time moving through the
vessels, decreases flow
 pressure: as pressure rises, flow increases (but is dependent on
other factors as well)
 vessel diameter: as vessels constrict, BP increases and flow is
restricted
o Know the difference in blood distribution from rest to exercise

At rest: blood is distributed to the organs (digestive, etc
...
Aortic pressure: to move blood out of heart,
LV pressure must be higher than aortic pressure
(afterload), when afterload rises, stroke volume
decreases (inverse), during exercise, afterload
decreases due to vasodilation in working tissues
o Strength of ventricular contraction: sympathetic
nerve fibers in ventricle walls and catecholamines
(epi and norepinephrine as hormones) increase
contractions, more Ca++ allowed in myocardial cell
and more force produced
 Explain three ways to increase venous return:
o Venoconstriction: decreases diameter of most veins
in system, sympathetic system causes veins leaving
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capillary beds to constrict (veins tend to “store”
blood, constriction forces more blood to come back
to the heart and circulate)
o Muscle pump: use of paired skeletal muscles to
“move” blood, contractions and relaxations affect
venoconstriction (“milking” blood to the heart)
o Respiratory pump: use of pressure differences
during breathing to move blood, pressure changes
with breathing (inhale=lower chest pressure→
blood rushes in to the heart, opposite for exhalation)
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BLOOD
o Know the 3 main functions of blood
 support and transport O2
 Immune functions
 blood clotting
o Know the composition of blood
 Define and explain hematocrit: % of blood that is composed of
cells, blood is composed of cells and plasma (mostly water, ions,
proteins, and hormones), usually around 38-42% (reduced
hematocrit: reduced viscosity, flow increases, means anemia or
other disorders, increased hematocrit is opposite, means possible
dehydration)
o Explain the role of hemoglobin within red blood cells
 can bond with up to 4 O2 molecules, follows concentration
gradient of O2 when bringing it to cells and takes back CO2 when
given to cells
o Be able to explain the importance of blood viscosity
 impacts ability of heart and vessels to deliver O2, the more
difficult it is to flow, the more the heart needs to work to deliver
the blood
o Explain the relationship among the following: pressure, resistance, and
flow…what happens when these variables change in the system?
 When pressure increases, flow increases
 When resistance increases, flow decreases
OXYGEN DELIVERY DURING EXERCISE
o Explain the changes in cardiac output: CO increases directly proportionate
to metabolic demand, done by increasing HR and SV (HR increases with
intensity, max depends on age, but SV plateaus between 40 and 60% of
VO2 max but higher in trained subjects)
o Explain the changes in blood oxygen content: amount of O2 taken up by
tissues during one trip around the system is called AV-VO2 difference,
increases drastically with exercise (from 20ml at rest to 100ml)
o Explain the distribution of blood flow: only have around 5L of blood in
the body, distributed to the tissues that need the nutrients more (usually
taken from splanchnic region, aka stomach, intestines, kidneys)

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o Explain how blood flow in the tissue is regulated: alter arteriole diameter
with constriction
 Autoregulation: metabolic products cause vasoconstriction
(decrease in O2, increase in CO2, increase in pH/K+ and H+), as a
result resistance decreases and flow increases, more muscle
capillaries open, contractions are altered
RESPONSES TO EXERCISE
o How do emotions affect the CV response?
 Closely linked to sympathetic nervous system, submaximal
exercise in an emotionally charged state will give a higher HR and
BP
o Rest-to-Exercise transition: first second: BP increases, HR increases, CO
increases, after 2-3 min steady state- all plateau
o Recovery from exercise: with low intensity, rapid decrease in HR, BP, and
CO, takes longer with long-term exercise, less time with trained subjects
o Incremental exercise response (VO2 max test): HR and CO increase in
direct proportion to workload, SV increases at first but plateaus at around
40% VO2 max, increase in flow to muscles and systolic BP (not DPB)
 RPP (rate-pressure product)=HR*SBP
o Arm vs Leg exercise: HR and BP will increase more with arms than legs
(greater sympathetic response from heart), greater vasodilation in arms
o Intermittent exercise response: dependent on fitness level, also on
environment (temp, humidity)
o Prolonged exercise response: CO and SV decline, HR increases
REGULATION OF EXERCISE RESPONSES
o Explain the “central command” theory: initial signal to “drive” the CV
system at beginning of exercise comes from higher brain centers
 Be able to explain Figures 9
...
29
 9
...
29: cardiovascular control is prompted by higher brain
centers (central command), which goes through the
baroreceptors, heart, and blood vessels, and the chemo and
mechanoreceptors (which are also directly affected by the
central command)



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