Studied by 8 people
Where is the heart positioned in the thoracic cavity?
Heart is located slightly to the left
There’s a concavity in the left lung to accommodate the heart
What is the heart’s own blood supply?
Coronary arteries
The right coronary artery is also known as
posterior descending artery (PDA)
The left coronary artery is also known as
left anterior descending (LAD) circumflex artery
What are the coronary veins draining from the posterior surface of the heart?
great cardiac vein
small cardiac vein
posterior cardiac vein
middle cardiac vein
What are the coronary veins draining from the anterior surface of the heart?
great cardiac vein
small cardiac vein
anterior cardiac vein
Where do coronary veins go?
All drain into the coronary sinus
What is the function and location of epicardial fat?
Location:
between the heart wall and pericardial sac
Function:
insulate and cushion heart and coronary vessels
provide energy to myocardium
What is excess epicardial fat associated with?
heart disease
obesity
How is fat distributed?
Visceral - apple shaped = more epicardial fat
Subcutaneous - pear shape = less epicardial fat
What is ischemia?
INADEQUATE BLOOD SUPPLY TO AN ORGAN
decreased blood flow to tissue
decreased oxygen and nutrient to tissue
builds up metabolic waste
leads to cell death
What is myocardial infarction?
a heart attack = cardiac ischemia
cardiac muscle and cells die from lack of oxygen and nutrients
What is known as the widow-maker?
left anterior descending artery blockage
deadliest coronary occlusion
caused by left anterior descending artery blockage
What does the left anterior descending artery of the heart supply?
Most of the left ventricle and interventricular septum
What is the blood flow of deoxygenated blood?
right ventricle → pulmonary arteries → lungs
What is the blood flow of oxygenated blood?
left ventricle → aorta → rest of the body
How does a myocardial infarction affect heart function?
Scar tissue develops
What is the most leading cause of death in the US?
heart disease
What is ventricular remodeling?
loss of cardiomyocytes (heart muscle cells)
remaining cardiomyocytes thicken
fibroblast secrete collagen (fibrosis) that can’t contract
myocardial infarction symptoms
chest pain
dizziness, nausea, vomiting
jaw/neck/back pain
arm/shoulders pain
shortness of breath
What is referred pain?
pain at a site different from where it is actually happening
common in myocardial infarctions
Which sex has a higher risk of getting a MI?
Males have higher lifetime risks and develop earlier
What are the myocardial infarction disparities?
females die more often from MIs
males are more likely to develop MIs at 65/yo
females develop at 75 y/o
Different MI symptoms between male and female
females are more likely to experience shortness of breath, nausea, vomiting, and jaw/back pain
How can a MI be diagnosed?
MIs can be diagnosed using tests like electrocardiograms or echocardiograms
What are treatments for MI?
drugs and medications
anticoagulants (beta blockers)
agioplasty and stent
coronary bypass
What is percutaneous coronary intervention (PCI)?
used to unfold wire/metal meshes (stent) to hold vessels open
What is angioplasty?
Inflatable balloons that are used to widen blocked areas for blood to flow
What are risk factors for MI?
age
genetic and family history
male (2x the risk)
lifestyle factors: tobacco, hypertension, inactivity, obesity
What are symptoms of a stroke?
drooping face
asymmetry or weakness in arm
slurred speech
trouble seeing/walking/understanding
What is a coronary artery bypass graft? (CABG)
uses blood vessels from elsewhere to deliver around blockages
routes oxygenated blood from aorta or major arteries
delivers blood downstream of blockage
What are types of strokes?
brain attack
cerebrovascular accident (CVA)
ischemia
blockage of arteries causing ischemia
What is systole?
squeeze
contract
ejecting blood
What is diastole?
dilate
relaxation
fills with blood
What happens during systole?
contraction → relaxation → fills with blood
What happens during diastole?
relaxation → pressure decreasing → filling
What are the phases of the cardiac cycle?
atrial systole
isovolumetric ventricle contraction
ventricle ejection
isovolumetric ventricle relaxation
ventricle filling
What happens during atrial systole?
atria: systole (squeeze) blood is forced into the ventricles
ventricle: diastole
tricuspid and mitral valve: open
pulmonary and aortic valve: close
BLOOD FLOWS FROM HIGH TO LOW
What happens during isovolumetric ventricular contraction?
first heart sound is beat
ALL VALVES SHUT
atria: diastole
ventricle: systole
tricuspid and mitral valve: close
pulmonary and aortic valve: close
What happens during ventricular ejection?
PRESSURE BUILDS UP IN VENTRICLES
atria: diastole
ventricle: systole
tricuspid and mitral valve: close
pulmonary and aortic valve: open
What happens during isovolumetric ventricular relaxation?
VENTRICLES ARE RELAXING AND ALL VALVES ARE SHUT
CAUSE SECOND HEART SOUND
atria: diastole
ventricle: diastole
tricuspid and mitral valve: open
pulmonary and aortic valve: close
What happens during ventricular filling?
pressure in ventricles drop
ATRIA HAS GREATER PRESSURE
BLOOD FLOWS INTO ATRIA THEN VENTRICLES
mitral & tricuspid valves: open
atria & ventricles: diastole
What is the blood flow through the heart?
blood enters the body via the posterior and anterior vena cava into the right atrium
right atrium contracts, pushing the blood through the right atrial ventricular valve (tricuspid) into ventricle
ventricle contracts then pushes blood via the semilunar valve to the pulmonary arteries
goes to lungs and picks up oxygen
comes back oxygenated via the pulmonary veins to the left atrium
left atrium contracts then pushes blood into left ventricle
left ventricle contracts then pushes the blood via the aortic valve to the aorta
aorta to rest of the body
What does the cardiac conduction system do?
coordinates and drives cardiac muscle contraction
What are conducting cells?
specialized cardiac muscle cells
not nerves
generate electrical action potentials and spread them throughout the heart
control the cardiac conduction system
What is electrical potential?
work needed to move a charge in an electric field
potential energy per unit charge
What is membrane potential?
electrical charge inside a cell based on [+] & [-] ion concentrations
difference in electrical potential between cytosol inside a cell and extracellular fluid outside of the cell
What is autorhythmicity?
pacemaker cells triggering their own action potentials
What makes up the cardiac conduction system?
specialized cardiomyocytes
What are different anti-arrhythmic medications?
class 1: Na+ channel block
class 2: Beta blocker
class 3: K+ channel blocker
class 4: Beta blocker
What are different types of class 1 Na+ channel blocks?
weak: lidocaine & phenytoin
moderate: quinine & procainamide
strong: flecainide & propaferone
What are examples of class 2 Beta blockers?
proparnolol
metoprolol
What are different types of class 4 Ca+ channel blockers?
verapamil
diltiazem
What are different types of class 3 K+ channel blockers?
amiodaron
solatol
What makes up the conducting system of the heart and pacemaker potential?
sinoatrial (SA) node
atrioventricular (AV) node
bundle branches
purkinje fibers (subendocardial branches)
What happens when the action potential is at the SA node?
slow influx of Na+ pre potential
rapid influx of Ca 2+ depolarization
outflow of K+ repolarization
threshold
What is prepotential?
gradual slow increases in membrane potential toward threshold
What are contractile cell potentials?
pacemaker cell action potentials (SA and AV node)
purkinje action potential
atrial action potentials
ventricular action potentials
Intracellular fluid
has more K+ inside
Extracellular fluid
has more Na+, Cl-, and Ca2+
What is polarization?
unequal balance of ions and shared molecules on either side of a membrane
What happens when a resting cell’s membrane potential reaches a certain voltage?
ion channels open and close
ions move in and out of the cell
big change in action potentials occur
What is an action potential?
a set of sequence of ion movement and membrane potential change in excitable cells
do not occur until a certain voltage is reached
What is a cardiac action potential?
different with neuronal action potential
pacemaker cell
ventricular
What is a threshold?
membrane potential voltage needed for a cell to start an action potential
slightly positive
What is a prepotential?
gradual slow increase in membrane potential toward threshold
can be used by the pacemaker cells to reach their threshold
What are calcium channel blockers?
block Ca2+ channels
can be used to treat arrythmias (lower blood pressure)
verapamil
What are different types of cardiomyocyte action potentials?
pacemaker cell action potentials
SA node potential
AV node potential
His-purkinjie action potentials
contractile cell action potentials
atrial action potential
ventricular action potential
What is the normal adult heart rate?
60 - 100 bpm
Heart rate (HR)
changes with age and health
newborns and children have faster heart rate
max HR decreases with age
What is chronotropy?
refers to heart rate (changes)
What is tachycardia?
heart rate that is greater than 100 bpm
What is bradycardia?
heart rate that is less than 60 bpm
Big box of ECG length
0.2 sec
Little box of ECG length
0.04 sec
Fast (L-type) Ca2+ channel
can cause a huge peak in the action potential
What is the sinus rhythm?
normal depolarization of the sinus node (SA) and atria
What is the normal sinus rhythm?
normal human heart rhythm with normal ECG tracings
What is an ECG?
gives a lot of information on how conduction and heart system is working
changes in wave shapes or timing could indicate abnormalities or disease
What is autorhymicity?
the ability of pacemaker cells to trigger their own action potentials
What is cardiac muscle excitation?
Na+ and Ca+ flow from conducting cell to contractile cell through gap junctions
What is the process of action potentials in cardiac contractile cells?
sodium channels open with more sodium outside
sodium flows in which makes cell more positive
depolarization occurs and sodium channels close
calcium channels plateau and repolarize
K+ channel closes
What happens during skeletal muscle contraction?
calcium binds to myosin and actin
What does ECG stand for?
electrocardiogram
What is superventricular tachycardia (SVT) also known as?
paroxysmal atrial tachycardia
What is superventricular tachycardia?
SVT occurs when the electrical system that controls the heart rhythm is not working properly
What is ventricular fibrillation? (V-Fib)
ventricle depolarization becomes erratic which usually leads to cardiac arrest
heart doesn’t pump blood to rest of the body
What is a cardiac arrest?
sudden stop in heart function that is deadly
What is an automated external defibrillator? (AED)
delivers about 3000 volt charge
depolarizes the entire heart
stops arrhythmia
allows SA node to restore rhythm
ineffective on hearts that have stopped beating completely
What is the cardiac output equation?
CO = HR (heart rate) x SV (stroke volume)
What is cardiac output? (CO)
amount of blood pumped by each ventricle in one minute
unit of volume (L or mL/min)
What is stroke volume? (SV)
volume of blood pumped from the left ventricle in one beat
What is the sympathetic effect on heart rate?
increases the sympathetic cardiac nerve heart rate
What is the parasympathetic effect on heart rate?
decreases the vagus nerve heart rate
What is the stroke volume equation?
SV = EDV (end-diastolic volume) - ESV (end systolic volume)
What is end-diastolic volume (EDV)?
amount of blood in ventricles at the end of atrial systole
“preload”
volume when fully relaxed
What is the ejection fraction equation?
SV (stroke volume) / EDV (end-diastolic volume) x 100
What is cardiac reserve?
difference between maximum and resting CO
measures the residual capacity of the heart to pump blood
What is a venous return?
amount of blood returning from the vena cava to the right atrium
What is a preload?
amount of blood or stretch in the ventricles just before systole
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