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P1W1

Terms in this set (195)

blood pressure is
the measurement of force applied to the walls of a blood vessel
blood pressure is recorded using ______________ and ___________ pressures
systolic, diastolic
Average Normal Systolic pressure
120 mmHg
average normal diastolic pressure
80 mmHg
cardiac output is defined as
the amount of blood pumped per minute by each ventricle
Cardiac output is calculated by
stroke volume x heart rate`
Normal resting cardiac output
5-6 L/min
Stroke volume is defined as
the volume of blood pumped from the ventricle in one heart beat
heart rate
number of heart beats in one minute
Maximum cardiac output is ______ greater than resting output
4-7x
The difference between resting and maximum cardiac output is called
cardiac reserve
Cardiac index
cardiac output/body surface area
Is cardiac output or cardiac index a better indicator of the heart's pumping ability?
cardiac index because it takes body surface area into consideration
ejection fraction is defined as
the percentage of blood pumped in one contraction
Ejection fraction equation
Stroke volume/ end diastolic volume
Normal ejection fraction
50-60%
Benchmark for left ventricular systolic dysfunction
<40% ejection fraction
To increase cardiac output you need to:
increase stroke volume and/or increase heart rate
__________ is the most anterior portion of the heart
right ventricle
The heart is _______ to the sternum
posterior
The heart is ______________ to the trachea and esophagus
anterior
The heart is ___________ to the diaphragm
superior
Bottom of the heart where the right and left ventricles meet is known as the
apex
PMI
(point of maximal impulse) where the apex of the heart taps the chest wall
What is the significance of PMI?
a noninvasive way to approximate heart size
PMI shifted to the left suggests
cardiac enlargement or remodelling
Layer of heart wall in direct contact with blood pumped through the heart chambers
endocardium
innermost layer of the heart
endocardium
thickest layer of the heart wall
myocardium
the layer of the heart that contracts
myocardium
outer layer of heart wall that contains coronary arteries
epicardium
outermost wall of the heart
pericardium
pericardium definition
fibrous sac that encases, protects, and secures the heart
Pericardium has multiple layers that create the _________________
pericardial space
Pericardial space contains ___________ that acts as a _____________ for the heart
pericardial fluid; shock absorber
abnormal collection fo fluid in the pericardial sac
cardiac tamponade
The ___________ collects deoxygenated blood from the body
right atrium
The _________ pumps deoxygenated blood to the lungs
right ventricle
The ________________ receives oxygenated blood from the lungs
left atrium
The ____________ pumps oxygenated blood to the body
left ventricle
Groove that separates the atria from the ventricles and contains coronary arteries
AV groove; coronary sulcus
_______________ attach valve cusps to papillary muscles
chordae tendinae
Number of ___________________ corresponds to the number of valve cusps
papillary muscles
Walls of the ventricles differ for the walls of the atria in what way?
ventricular walls have porous trabeculae unlike smooth walled atria
The route blood takes as it travels out of the ventricle and to the semilunar valve
Right and left ventricular outflow tracts
This vascular structure moves blood through muscular contractions
arteries
This vascular structure contains valves to keep blood flowing unidirectionally
veins
Subclavian, axillary, and cephalic veins all drain into this great vessel
superior vena cava
deoxygenated blood from the lower portion of the body dumps into the right atrium via
inferior vena cava
carries deoxygenated blood from the right ventricle to the lungs
pulmonary artery
dumps oxygenated blood into the posterior wall of the left atrium
pulmonary veins
location of the aorta in the chest
rests on the bifurcation of the right and left pulmonary arteries
coronary arteries originate from the right and left _____________
aortic cusp
perfusion of the coronary arteries occurs during
diastole
Right coronary artery location
emerges from the right aortic cusp and travels along the coronary sulcus posteriorly
Right coronary artery perfuses:
Right atrium, sinus node (55% of hearts), AV node, parts of the right ventricle
coronary dominance
determined by the coronary artery that supplies the posterior descending artery
incidence (population) of right coronary dominance
85%
The left main coronary artery bifurcates (divides) into
Left anterior descending artery (LAD) and left circumflex (LCx)
the left main artery passes between
the pulmonary trunk and the left atrial appendage
Left anterior descending artery location
travels anteriorly along the inter-ventricular septum
left anterior descending artery perfuses:
-anterior, lateral and apical wall of the left ventricle
-part of the right ventricle
-most of the bundle branches
Left circumflex artery location
travels along the left coronary sulcus laterally to the posterior wall of the heart
left circumflex perfuses
left atrium, posterior and lateral wall of the the left ventricle, SA node in 40% of hearts
Main structural difference between semilunar and atrioventricular valves
atrioventricular valves are supported by papillary muscles and chordae tendinae to stay open and closed at appropriate times
Valvular disease is more likely to occur in which valves and why?
Mitral and aortic valves due to high pressure
S1
heart sound made by turbulent backward blood flow against closed atrioventricular valves
S2
heart sound made by turbulent blood flow against closed semilunar valves
fossa ovalis
oval shaped depression in the interatrial septum where a thin membrane protects blood from crossing between atria
Location of the coronary sinus
base of the right atria between the inferior vena cava and the tricuspid valve on the inferior aspect of the interatrial septum
coronary venous system dumps blood into the right atrium via
the coronary sinus
which valve separates the left atrium for the left ventricle
mitral valve
which valve separates the right atrium from the right ventricle
tricuspid
what is between the parietal and visceral pericardim
pericardial space
the coronary arteries arise form what great vessel?
aorta
What is atrial kick?
term used for atrial contraction to conclude ventricular diastole
atrial kick comprises for what percent of cardiac output?
20-30%
What is the amount of pressure the right ventricle must overcome to open the pulmonic valve?
12 mmHg
What is the pressure the left ventricle must overcome to push blood through the aortic valve?
120 mmHg
What vessel below carries deoxygenated blood?
a. Aorta
b. Pulmonary artery
c. Pulmonary vein
d. Coronary Artery
B. pulmonary artery
during left heart ejection, what valves are closed?
mitral and tricuspid
The cardiac cycle begins when
the atrium contract at the end of ventricular diastole
Atrial kick maximizes
end diastolic volume
isovolumetric contraction
contraction of the ventricles while all valves remain closed
__________ begins when ventricular pressure exceeds pulmonic and aortic arterial pressure
Ejection
amount of blood left after contraction
End systolic volume (ESV)
Stroke volume equation
SV = EDV - ESV
isovolumetric relaxation
early ventricular diastole when all valves are closed and atria are filling from venous return
diastasis
period of ventricular filling before atrial kick
Diastole takes up _____ of the cardiac cycle
2/3
As heart rate increases, cardiac cycle length __________. Diastole and systole __________________.
shortens; shorten proportionately
List intracardiac pressures from least to greatest
RA, LA, RV, LV
Preload
the pressure on the cardiac fibers created by the volume of blood at the end of diastole
Preload is also estimated as
EDV
Afterload
the pressure that must be exceeded by the ventricles to eject blood
afterload is also referred to as
systemic vascular resistance
Blood pressure is reflective of what two factors
the strength of the heart as a pump and the status of the vascular system
PCWP
pulmonary capillary wedge pressure; also known as pressure in the pulmonary artery ~12mmHg
Which affects cardiac output more, AV synchrony, SV, or HR?
HR
Normal stroke volume range
60-120 cc
Factors that affect stroke volume:
Preload, Afterload, contractility
Explain Starling's law
increased volume in the ventricles causes greater stretching of the muscle fiber and a more forceful contraction
_________ preload will __________ stroke volume.
Increasing; increase
Increased afterload, _______ myocardial oxygen consumption
increases
__________ afterload will _________ stroke volume.
Decreasing afterload will increase stroke volume.
The factors that directly or indirectly influence cardiac output are all of the following except:
a. HR
b. preload
c. afterload
d. automaticity
d. automaticity
contractility is the ability of muscle cells to
shorten
cardiac muscle is both
striated and involuntary
four unique properties of a cardiac cell
automaticity, excitability, conductivity, contractility
automaticity
the ability of a cardiac cell to depolarize spontaneously
excitability
the ability of a cell to respond to an electrical stimulus
conducitivty
the ability of a cardiac cell to propagate an electrical signal
contractility
ability of a cardiac cell to shorten and cause a contraction
Two types of cardiac cells
pacemaker cells and myocardial (working) cells
electrolytes
substance that dissociates into ions when in solution and has the ability to conduct electricity
The extracellular cation that is primarily responsible for the movement fo electrolytes in and out of the cell is ________
sodium
_____________ represents atrial polarization on the ECG
P wave
________________ represents ventricular depolarization on the ECG
QRS complex
________________ represents ventricular repolarization on the ECG
T wave
When does atrial repolarization occur in the ECG?
During the QRS, but it is overshadowed
What happens during phase 0 of the ventricular muscle action potential curve?
DEPOLARIZATION--> rapid influx of NA+ and outwards movement of K+ marked by a sharp rise to positive membrane potential
Whats phases of the AP curve correspond to the QRS complex of the ECG?
Phase 0 and 1
What happens during phase 1 of the ventricular muscle action potential curve?
Initial rapid repolarization--> Na+ channels close, still an outward movement of K+
What happens during phase 2 of the ventricular muscle action potential curve?
Plateau phase--> inward movement of calcium and outward movement of K+
What waveform on the ECG corresponds to phase 2 of the action potential curve?
ST segment
What happens during phase 3 of the action potential curve?
Repolarization--> potassium continues to build up outside of the cell
Phase 3 corresponds to what waveform of the ECG?
T wave
What happens during phase 4 of the action potential curve?
resting membrane potential--? polarized resting state cells will remain in until stimulated again
What phase of the action potential curve corresponds to systole?
phase 1
What phase of the AP curve is associated with the diastole portion of the heart cycle?
phase 4
Phase 4 represents what portion of the ECG?
the isoelectric line
What is a refractory period?
it is the period of time where a cell has been activated and will not respond to another stimulus until it returns back towards it resting state
When is the cardiac cells absolute refractory period?
From the onset of the QRS to the peak of the T wave
What is a relative refractory period?
Period in time after depolarization where a cell can be reactivated by a strong stimulus
When is the relative refractory period of a cardiac cell?
Peak of the T wave to midway through the downslope of the T wave
The relative refractory period corresponds to what phase of the action potential curve?
phase 3
What is the primary pacemaker of the heart and what is its intrinsic pacing rate?
SA node, 60-100 BPM
What is the location of the SA node?
upper portion posterior portion of the right atrium where the right atrial wall meets the superior vena cava
Where does the SA node blood supply come from?
SA node artery branches from either the RCA or left circumflex
Where does the electrical impulse travel after leaving the SA node
internodal tracts and the Bachman's bundle
What is the Bachman's bundle?
Bifurcation of the anterior internodal tract that reaches the left atrium ensuring the atria depolarize simultaneously
Where does the electrical impulse travel after the internodal tracts?
To the AV node
Where is the Av node located?
the floor fo the right atrium behind the tricuspid valve and very close o the os of the coronary sinus
How is blood supplied to the AV node?
via the right coronary artery
Conduction ____________ at the AV node
slows
What is the backup pacemaker of the heart and what is its intrinsic firing rate?
AV node, 40-60 BPM
What is the most proximal portion of the AV node?
Atrio-nodal junction
What is the middle portion of the AV node called?
Nodal region
What is the most distal portion of the AV node?
Nodal- His
What are the two reasons conduction is slowed at the AV node?
1. allows time for atria to contract and properly fill the ventricles
2. protects the ventricles from inappropriate rates and rhythms
Where does the electrical impulse travel after leaving the AV node?
Bundle of His
What makes the bundle of his particularly prone to injury?
Dual blood supply from the LAD and PDA
What is the location of the Bundle of His
upper portion of the interventricular septum
What is the function of the Bundle of His?
Acts as a tunnel from atria to ventricles through the electrically inert atrioventricular groove
Where does the electrical impulse travel after the Bundle of His?
Right and left bundle branches
what is significant of the left bundle branch?
divides into two fascicles (anterior and posterior) due to large left ventricular muscle mass
Where does the electrical impulse travel after the bundle branches?
The purkinje fibers
What is the third intrinsic pacemaker of the heart and what is its intrinsic rate?
Purkinje fibers, 20-40 BPM
Depolarization electrical wavefront has particular characteristics. Which of the following statements are true?
a. Spread though both atria towards the AV node
b. Conduction velocity slows through the aV node
c. The ventricular cells depolarize from the right side toward the left side
d. Depolarization of the cardiac muscle cell causes muscular contraction
A, B, and D
Ventricular cell depolarize from ___________ to ____________
left to right
What effects will sympathetic tone have on cardiac activity?
Increase HR, Increase conduction, increase contractility
What is the main chemical messenger of the sympathetic nervous system?
epinephrine
What effect will parasympathetic tone have on cardiac acitivity?
Slow HR, Slow Av node conduction, decrease contractility
What is the main chemical messenger of the parasympathetic nervous system?
acetylcholine
T or F. Ventricular repolarization does not propagate from cell to cell.
T
T or F. Ventricular repolarization begins in the epicardial layer first, moving towards the endocardium.
True.
Which of the following statements are true?
a. Ventricular depolarization starts in the ventricular septum and travels left to right
b. Ventricular depolarization starts in the apex and travels towards the bundle of HIS
c. Ventricular depolarization starts in the terminal purkinje fibers and travels towards the septum
d. Ventricular depolarization starts in the right bundle branches and travels right to left.
A
The cation __________ plays the largest role on contractility
calcium
How does the sympathetic nervous system increase contractility?
the release fo norepinephrine leads to an increased influx of calcium by the SR in the cell leading to shorter phase 2 with a stronger contraction and more rapid repolarization
Chronotropy refers to
Heart rate
ionotropy refers to
contractility
dromotropy refers to
conduction
Lusitropy refers to
relaxation of myocardium
Patients with weakly pumping left ventricles may need to take medication with a positive _________ effect to improve cardiac output
ionotropic
The middle cardiac vein runs along what structure?
the posterior surface of the interventricular septum
the coronary sinus separates
the left atrium from the left ventricle
the great cardiac veins runs along what structure?
the anterior surface of the heart along the interventricular septum
as the heart lies in the body, what is the most anterior structure?
the right ventricle
the inferior portion of the right atrium serves as the _______ to the coronary sinus
ostium
the vein that runs on the posterior surface of the heart along the interventricular septum is
the middle cardiac vein
the os of the coronary sinus is located in the inferior portion of the
right atrium (between the opening of the inferior vena cava and the tricuspid valve)
another name for the location of the coronary sulcus could be the
AV groove
the coronary sinus is venous structure that runs along the _______________ surface of the heart
posterior
Chordae tendinae joins what structures?
the tricuspid and mitral valves to papillary muscles
The crux of the heart is marked by the intersection of the coronary sinus and the
middle cardiac vein
the intersection of the middle cardiac vein and the coronary sinus is known as the
crux
the vein that turns along the inferior interventricular groove is known as the
great cardiac vein
the left ventricle must overcome pressure that is in the __________ during systole
aorta
aortic pressure must be overcome bu the ________ during systole
left ventricle
a furrow of groove separating parts of the heart is known as a
sulcus
the papillary muscles are connected to the atrioventricular valves using what structures?
chordae tendineae
left ventricular hypertrophy can occur due to a systemic increase in ______________
arterload
passive fixation with tines are more common in the ___________ because the tines will secure well to the _____________
ventricles; trabeculae
Which of the following components of the conduction system has the slowest inherent rate of automaticity?
purkinje fibers
The Pulmonary Veins are an important anatomical site for treating a very common arrhythmia, what chamber of the heart are they attached to, and what arrhythmia can originate around the pulmonary veins
left atrium, Afib
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