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How much blood is going to the pulmonary vs the systemic system?
Exact same amount.
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True/False: Pulmonary circulatory system is under lower pressure but has the same volume of blood as systemic circuit
True
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Where is the heart located?
In the mediastinum, between the lungs. Directly behind sternum
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Where is the heart’s apex?
Inferior end that tilts to the left and tapers.
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What are the three layers of heart wall composed of?
- Endocardium
- Myocardium
- Epicardium
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What type of cell is found in the endocardium?
Simple squamous epithelium
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What type of cell is found in the myocardium?
Thick cardiac muscle
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What type of cell is found in the epicardium?
Simple squamous serous epithelium
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Which one of the three heart wall layers is the same type of cell found inside walls of vessels?
Epicardium
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Coronary veins (veins of the heart) drains into the _________.
Right atria
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Where does the blood go when the right atria contracts?
Everywhere!
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How does the ventricle get filled with blood?
Ventricle expands and the pull down the blood from the atria
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What creates the “lub” sound?
When the ventricle pumps blood to the arteries (either pulmonary or aorta)
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What creates the “dub” sound?
When the ventricle relax and the semilunar valve close, preventing backflow from the arteries back to the ventricles
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What is another name for the semilunar valve going to the pulmonary circulatory system?
Pulmonary valve
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What is another name for the semilunar valve going to the systemic circuit?
Aortic valve
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True/False: Cardiac output is to feed ¼ of the capillary beds
True. Three fourths of the bodies capillaries are shut down at a given time
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_____ provides mechanical junction that tightly join myocytes
Desmosomes
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____ provides electrical junction to create wave-like motion and depolarize cell
Gap junctions
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How does the cardiac muscles contract without motor units?
Beats by electrical and Ca2+ signals given off by their neighbors
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True/False: nerves directly stimulate cardiac muscle to contract
False. No nerve stimulate the cardiac muscles directly, only to tell the SA node how fast to beat
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What do the cardiac muscle use as organic fuels for energy?
- Fatty acids
- Glucose
- Ketones
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What is cardiac output?
The amount of blood ejected by the ventricle in 1 minute
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What is the relationship between cardiac output, stroke volume and heart rate?
CO = SV x HR
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What is preload?
- The amount of stretch the ventricle is under, fills more blood when it is stretched.
- The amount of tension in ventricular myocardium before it contracts
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What is the outcome of a high preload?
More ejection output
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What is the relationship between increased preload and stroke volume?
Higher stroke volume
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What is afterload?
The amount of pressure in the arterial system, opposing the opening of semilunar valves
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How does afterload relate to stroke volume?
Increased afterload would case decreased stroke volume
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What does Frank-Starling law says about the relationship between SV and EDV?
They are proportional
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What is ejection fraction?
The percentage of blood leaving the ventricle vs percentage staying in
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What can cause increased ejection fraction?
During exercise because of increased inotropy (contractile strength)
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True/False: Exercise causes ventricular hypertrophy
True. Athletes have bigger ventricles, therefore greater SV and increased cardiac reserve
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What is the threshold potential for SA node?
-40 mV
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The _______ vagus nerve secretes acetylcholine stimulate the SA node to decrease heart rate
Right
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The ______ vagus nerve secrete acetylcholine stimulate the AV node to decrease HR
Left
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The _______ cardiac nerve secrete _______ to stimulate the SA node, AV node and myocardium to increase HR
Sympathetic ; norepinephrine
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What is the relationship of blood flow (Q) to resistance (R)?
Q= P/R. Inversely proportional , decrease in resistance would increase flow
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What is the relationship between resistance (R) and radius (r)?
R = (1/r^4), increase in radius would decrease in resistance.
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Ventricle filling is _______.
Diastole
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Ventricle pumping is ______.
Systole
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What happens to the pressure inside heart chamber during contraction?
Pressure increases, driving blood out of the chamber.
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What would happen to the cardiac output if left ventricle pressure decreases?
Cardiac output would decrease
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Pressure is highest in _____ and decreases progressively through the vascular system
Aorta
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The site of greatest resistance is in the ______ and it has the largest decrease in pressure.
Arterioles
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_____ pressure contributes more heavily to the mean arterial pressure.
Diastolic
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_______ pressure is necessary to drive blood flow
Arterial
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What are the conducting cells of the heart?
- SA node
- Atrial internodal tracts
- AV node
- Bundle of His
- Left and Right bundles
- Purkinje fibers
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The most distinct characteristic of ventricular and atrial cardiomyocyte action potential is that it has a_____ phase due to ___________.
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Upstroke in SA node action potential is driven by ______.
Calcium
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Upstroke in ventricular and atrial myocytes is driven by ______.
Sodium
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True/False: Atria needs to contract before ventricles
True
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How does AV node play a role in heart conduction?
It slows the conduction to ventricles to increasing filling time
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Sympathetic nervous system affects which aspects of the heart?
- SA node
- AV node
- Ventricular myocytes, contractile force
- Heart rate
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True/False: Only the sympathetic nervous system have innervations to the blood vessels
True! Parasympathetic does not innervate blood vessels
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