Heart Flashcards
What side of the heart is the pulmonary circuit?
Right
What side of the heart is the systemic circuit?
Left
What is the middle of the heart called?
Septum
Why are the two circuits kept separate?
To prevent dilution of blood
What type of blood enters the left side of the heart?
Oxygenated
What type of blood enters the right side of the heart?
Deoxygenated
Where does the left side of the heart send the blood?
The organs
Where does the right side of the heart send the blood?
The lungs
Where is the heart located?
In the mediastinum between the lungs
What two parts make the heart?
Base & Apex
What direction does the heart tilt?
To the left
What is the divot the heart makes on the lung called?
Cardiac impression
What type of membrane is the pericardium?
Serous
What is the function of the pericardium?
Allows muscle movement & prevents friction
What are the two parts of the pericardium?
Parietal & visceral
What is another name for the visceral pericardium?
epicardium
What is the pericardial cavity?
Space inside the pericardial sac filled with fluid
What is pericarditis?
inflammation of the pericardium (painful)
What are the three layers of the heart wall?
epicardium, myocardium, and endocardium
What is the endocardium?
Smooth inner lining of heart
What is the myocardium?
the middle layer, 95% of heart
What is the myocardium’s function?
provide structural support and attachment and electrical insulation
What are the 4 heart chambers?
right atrium, left atrium, right ventricle, left ventricle
What are the atria separated by?
interatrial septum
What are the ventricles separated by?
interventricular septum
What is the function of the atria?
receive blood returning to the heart
Where are the auricles located?
Surface of atria
What is the function of the ventricles?
Pump blood into arteries
What is systole?
contraction
What is diastole?
relaxation
What are the pectinate muscles?
grooves in heart
What is the pulmonary trunk?
blood vessel to the lungs
What is the aorta?
blood vessel to the system
What side is the myocardium thicker on? Why?
The left side, more force to pump out to the rest of the body
What are trabeculae carnae?
internal ridges that prevent ventricles from sticking together
What is the coronary sulcus?
groove that separates the atria and ventricles
What is the interventricular sulcus?
Divides right and left ventricles
What is the right AV valve?
Tricuspid
What is the left AV valve?
Mitral/bicuspid
What are the chordae tendinae?
cords that connect AV valves to papillary muscle
What do the papillary attachments do?
Distribute stress, coordinate timing of electrical conduction, and provide redundancy
What do the semilunar valves control?
blood flow into arteries
Where is the pulmonary semilunar valve?
between right ventricle and pulmonary trunk
Where is the aortic semilunar valve?
Between left ventricle and aorta
What happens to the valve pockets in diastole?
They fill with blood due to gravity
What happens to the valve pockets in systole?
blood pushes pocket shut and creates an opening
What happens to the valves in ventricular diastole?
semilunars close and AV open
What happens to the valves in ventricular systole?
semilunars open and AVs close
What direction does an artery take blood?
away from heart
What direction does a vein take blood?
toward heart
What are the only arteries with deoxygenated blood?
the 2 from the pulmonary trunk
Where does the left coronary artery branch off of?
the ascending aorta
What does the LCA supply blood to?
both ventricles and anterior interventricular septum
Where does the circumflex branch of the LCA go?
around the left side of the heart in the coronary sulcus
What does the circumflex branch give off?
the left marginal branch
What does the circumflex branch supply?
the left atrium and posterior wall of left ventricle
What does the right coronary artery branch off of?
the ascending aorta
What does the RCA supply?
right atrium and SA node
What does the right marginal branch supply?
the lateral aspect of right atrium and ventricle
What does the posterior interventricular branch supply?
posterior walls of ventricles
What is coronary artery disease?
constriction of the coronary arteries
What are some causes of coronary artery disease?
hypertension, diabetes, atherosclerosis
How do the arteries get obstructed?
bulging mass grows from atheromas and fatty plaques
What is a myocardial infarction?
heart attack- interruption of blood supply to the heart
What is angina pectoris?
Chest pain from ischemia (lactic acid buildup)
Why does lactic acid get produced?
the myocardium switches to anaerobic fermentation
What are the 3 main inputs of the coronary sinus?
great cardiac vein, posterior interventricular vein, and left marginal vein
Where does the great cardiac vein collect blood from?
Anterior portion of the heart
Where does the posterior interventricular vein collect blood from?
posterior portion of heart
Where does the coronary sinus empty into?
Right atrium
What are the nuclei of cardiocytes surrounded by?
glycogen
What allows electrical signals to be passed between cells?
gap junctions
What does myoglobin store?
oxygen
What is the limiting factor in what cardiac muscle cells can use as a fuel?
amount of oxygen
Do cardiomyocytes fatigue?
No
What is a contractile cell?
A cell that physically does the contracting
What is a conductile cell?
a cell that sends the signal
Where does the electrical signal start?
the SA node
Where is the SA node?
right atrium
Where does the signal travel after the SA node?
the AV node
Where does the signal travel after the AV node?
the AV bundle brances
Where does the signal travel after the AV bundle branches?
the Purkinje fibers
Where does the signal go after the Purkinje fibers?
through gap junctions and from cell to cell
What does the system need to initiate contraction?
Calcium
Where is calcium stored?
the sarcoplasmic reticulum
What needs to happen in order to release Ca?
An action potential
What do sympathetic nerves do to HR?
increase
What do parasympathetic nerves do to HR?
lower-vagus
What is normal heart rhythm called?
sinus rhythm
What is ectopic focus?
A region of spontaneous firing other than the SA node
Does the SA node have a stable resting potential?
No
What voltage does the SA node potential start? What happens to it?
Starts at -60 mV, drifts upwards due to slow Na influx
When do the voltage gated fast calcium and sodium channels open?
at -40 mV
When do K channels open (pacemaker)?
At 0 mV
What does the SA node firing cause?
Heartbeat
What does the Na/K pump require?
ATP
How much Na + K does the pump pump?
3 Na outside the cell and 2 K in the cell
What is the cardiocyte resting potential?
-90 mV
What are the 3 phases of cardiocyte action potential?
Depolarization, plateau, and repolarization
Where does the depolarization phase peak? (contractile)
+30 mV
What channels open at +30 mV?
Slow calcium
What channels open to cause repolarization?
K
What cells are in the cardiocyte action potential?
contractile
What are the 3 components of an ECG graph?
P wave, QRS complex, T wave
What happens during the P wave?
SA node fires, atria depolarize
What happens during the QRS complex?
Ventricles depolarize, atria repolarize (unseen)
What happens during the ST segment?
ventricular systole
What happens during the PR interval?
atrial systole
What happens during the T wave?
ventricles repolarize and relax
What causes Vfib?
electrical signals traveling randomly
What condition is marked by Vfib?
Heart attack
When ventricle pressure is low, what happens to the AV valves?
they are open
When ventricle pressure is high, what happens to the AV valves?
they close and blood goes to the aortic valve (semilunar)
What is valvular insufficiency?
failure of a valve to prevent regurgitation
What is valvular stenosis?
Cusps are stiffened by scar tissue
What is a mitral valve prolapse? Symptoms?
When the cusps bulge into atria during ventricular contraction; chest pain and shortness of breath
What does S1 sound like?
lubb
What causes S1?
Closure of AV valves
What does S2 sound like?
dubb
What causes S2?
closure of semilunar valves
What are the phases of the cardiac cycle?
ventricular filling, isovolumetric contraction, ventricular ejection, isovolumetric relaxation
What happens in ventricular filling?
Ventricles expand, AV valves open, EDV is achieved (130 m/l)
What happens in isovolumetric contraction?
Atria relax, ventricles begin to contract, AVs close, S1 occurs
What happens in ventricular ejection?
SL valves open, stroke volume (54% of EDV), remaining blood is ESV
What happens in isovolumetric relaxation?
T wave ends, ventricles expand, SL close, S2 occurs, no blood taken in
About how long is the cardiac cycle?
less than a second, ~70 bpm
What must both ventricles eject?
the same amount of blood
What is congestive heart failure?
failure of either ventricle to eject blood effeciently
What does left ventricular failure cause?
pulmonary edema
What does right ventricular failure cause?
systemic edema
What is cardiac output?
amount ejected in 1 minute
What is the formula for cardiac output?
HR x SV
What is a normal volume of blood?
~5 L
What is the cardiac reserve?
Difference between maximum and resting CO
What is tachycardia?
resting HR above 100
What is bradycardia?
resting HR below 60
What are positive chronotropic agents?
factors that raise HR, symp. nerves
What are negative chronotropic agents?
factors that lower HR, parasymp. nerves
What is vagal tone?
steady background firing rate, 70-80 bpm
What part of the brain receives cardiac input?
medulla oblongata
What is a baroreceptor? Where are they?
signal cardiac center, located in aorta and internal carotid arteries
What 3 variables govern stroke volume?
preload, contractility, afterload
What do preload and contractility do?
increase stroke volume
What does afterload do?
decreases stroke volume
What is preload?
amount of tension in ventricular myocardium before contraction
What does exercise do to preload?
stretches myocardium and increases contraction (more stretch = harder contraction)
What is the Frank-starling law?
SV is proportional to EDV
What is contractility?
how hard the myocardium contracts
What do positive inotropic agents do?
increase contractility
What can hypercalcemia cause?
strong, prolonged contractions
What does digitalis do?
raise calcium levels and contraction strength
What do negative inotropic agents do?
reduce contractility
What can hyocalcemia cause?
weak, irregular heartbeat
What can hyperkalemia cause?
reduced strength of myocardial action potentials
What is afterload?
sum of all forces opposing ejection of blood from ventricle
What is the largest part of afterload?
blood pressure in aorta and pulmonary trunk
What does hypertension do (afterload)?
increase afterload and oppose ventricular ejection
What can also increase afterload?
anything that impedes arterial circulation
What is Cor pulmonale?
right ventricular failure due to obstructed pulmonary circulation
What effect does exercise have on cardiac output? Why?
increases, bc increase in HR and SV, ventricular hypertrophy
