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Pirkle-Chapter 19-Study Guide
Terms in this set (109)
the heart which acts a muscular pump that has a right pump and a left pump and two circuits which are the pulmonary and systemic circuits (tubes)
What does the cardiovascular system consist of?
the ___________ side supplies the systemic circuit
the ________________ side supplies the pulmonary circuit
This is the double walled sac that encloses the heart and allows for the heart to beat without friction
the pericardial sac just so happens to also be the...
visceral pericardium also known as the epicardium
this is the serous membrane that is actually covering the heart
What helps to lubricate the heart to also avoid friction between each heart beat?
it is continuous with the endothelium of the blood vessels
What is special about the endocardium?
This is the layer that covers the valve surfaces
Between the two other layers, the heart has a thick layer of cardiac muscle. What is this layer called?
the thickness is proportional to the workload of the heart
for example, the left ventricles are very thick because they must push all the blood up to leave the body
Why does the thickness of the myocardium range in thickness?
it is organized into bundles that spiral around the heart which forms a myocardial vortex so that when the ventricles contract they wring the blood out, which better enhances the ejection of blood
How is the myocardium organized?
because not all of the blood can get out with the wringing motion, it gets most but not all
Why is how much blood the heart pumps out known as the ejection fraction?
the coronary blood vessels run through here to supply the heart with oxygenated blood
What is the use of the epicardium?
Which chambers of the heart receive and which pump blood out?
it provides structural support for the heart
it anchors cardiomyocytes and gives them something to pull against
it serves as electrical insulation between the atria and the ventricles because the atria cannot stimulate the ventricles directly
the elastic recoil may air in the sucking and refilling of the heart with blood after each beat
What is the use of the fibrous skeleton of the heart?
they ensure one way flow of blood through the heart
Why are valves necessary?
atrioventricular valves control blood flow between the atria and ventricles
semilunar valves control blood flow into the great arteries
what are the two types of valves? Describe what they do.
they connect the valve cusps to papillary muscles on the floor of the ventricle and they prevent the AV valves from flipping inside out or bulging into the atria when the ventricles contract
What is the function of the chordae tendineae?
they surround the cusps and when the ventricles contract and put pressure up on the valve it closes the valve but to prevent the valve from bulging due to too much pressure, the papillary muscles contract and pull the chordae tendineae to keep the valve in its closed resting position
Describe in simple terms how chordae tendineae work:
the left AV valve is also known as the:
the right AV valve is also known as the:
gravity causes pressure to be placed on the valves and they fall open to let blood rush in, but once the ventricles contract they put pressure on the bottom of the valves; thus, closing them
Why do the valves open in the atrium in the first place?
when the ventricles contract it pushes blood flow through the valves and when the ventricle relaxes the change in pressure causes the blood to fall back towards to heart but the valves catch the blood and eventually they fill up with enough pressure and slam back shut
Describe how semilunar valves open and close:
Which valves do not have chordae tendineae?
between the right ventricle and the pulmonary trunk
between the left ventricle and the aorta
Where are semilunar valves found?
The pericardial sac is also known as:
inferior and superior vena cava empties blood into the right atrium and the blood flows through the right AV valve into the ventricles which pushes the blood through the pulmonary valve into the pulmonary trunk which travels into the pulmonary arteries that travels to the lungs for Oxygen then the pulmonary veins return the oxygenated blood to the left atrium then it travels through the left AV valve into the left ventricle then the left ventricle contracts which causes blood to travel through the aortic valve and then through the ascending aorta where it gets distributed throughout the body
Describe the flow of a single drop of blood:
any failure of a valve to prevent reflux or backward flow of blood
it is the regurgitation of blood through the incompetent valves (you are basically hearing the blood splashing back into the atrias when the valves don't close once the ventricle contracts)
What is a heart murmur referring to?
hypertrophy of the heart muscle because the heart is working extra hard to pump out the regurgitated blood
What can a heart murmur lead to?
the first heart sound is louder and longer (lubb) and the sound comes from the closure of the AV valves
the second heart sound is sharper and softer (dupp) and the sound comes from the closure of the semilunar valves
what is the first heart sound you hear and what is the second?
valvular stenosis which is when the valves stiffen and the opening of them is constricted by scar tissue
mitral valve prolapse which is when the valve cusps into the atria during ventricular contraction
What are some ways valves can be insufficient?
when the heart is relaxed because when the myocardium contracts it squeezes the coronary arteries closed and obstructs the blood flow and when the ventricles contract the aortic valve opens and blocks the opening to the coronary arteries but then when it relaxes, some of the blood that flows back towards the heart flows into the coronary arteries
When is coronary pressure the highest?
coronary artery disease
what are some disorders that occur when the blood flow is interrupted to the heart?
This is when a complete blockage blocks blood supply to the heart and begins causing death of cardiac cells in minutes
this is chest pain associated with a partial blockage that causes ischemia of the heart muscle
arterial anastomosis which is when the body makes extra blood vessels to give blood another route to supply the heart muscle with oxygen
What is the long term effect of long term blood clots?
it is a result of when macrophages eat fat and cholesterol deposits and become foam cells and they eventually settle and grow into plaque
What is an atheroma in coronary artery disease?
this is known as coronary artery disease
it happens when the lumen of the vessel walls are broken and macrophages get into the vessels and begin to eat themselves full of fat and then they turn into plaque themselves then platelets come in and start doing their thing because they have noticed a break in the vessel and this causes a bulging mass to grow
When the coronary arteries become obstructed by a blood clot or fatty deposit, what happens?
they admit calcium ions from the extracellular fluid to activate muscle contraction
During excitation of a cardiac cell, what do the T tubules do?
cardiomyocytes are joined end to end by what?
skeletal muscles have satellite cells so they can divide and replace damaged muscle cells but cardiac muscle lacks these cells so they rely solely on fibrosis to repair
What is the biggest difference between skeletal and cardiac muscle cells?
they have interdigitating folds, mechanical junctions, and electrical junctions (gap junctions)
The intercalated discs in cardiac muscle are different from anything skeletal muscles have because why?
it allows ions to flow from the cytoplasm of one cell directly into the next and allows the direct electrical stimulation of their neighbor
Why are gap junctions needed in the myocardiocytes?
is helps the to interlock with each other and increase the surface area of their intercellular contact
Why are interdigitating folds important in the myocardiocytes?
What mechanism does cardiac muscle use almost exclusively to make ATP?
it does not rely anaerobic fermentation of oxygen debt mechanisms like your skeletal muscles so it does not fatigue
your heart is also very oxygen sensitive over energy so it could be out of energy and still carry on because all it really wants is oxygen
Your heart is a unique muscle because it is fatigue resistance, what does this mean?
What is known as the pacemaker?
cells of the SA node does not have a stable resting membrane potential like skeletal muscles
What is the difference between skeletal cells and cells of the SA node?
every 0.8 seconds which sets the resting rate at 75 BPM
How often does the SA node fire?
SA node fires and the signal travels across the atriums and makes them contract simultaneously
the electrical signal travels from the SA node to the AV node by way of bundles
another bundle splits off into the right and left ventricles known as bundle branches
These then meet up with purkinje fibers that spreads the signal throughout the myocardium
Describe the cardiac conduction system:
the delay is to allow the ventricles time to fill before contracting (if there was no delay you blood would literally just be pushing against each other everyday)
There is a slight delay between the SA node and the AV node's action, why?
the vagal nerve sends more signals to the SA and AV nodes and tells them to slow down
The parasympathetic nervous system can ______________ heart rate by doing what?
The sympathetic nervous system can _____________ heart rate.
AV node can take over is SA node is damaged but it only fires about 40-50 BMP
the SA node should be the pacemaker of the heart, but sometimes it isn't. What is this called and what else can act as the pacemaker of the heart?
after atrial systole and atria contract
When is the EDV in each ventricle achieved?
you take the EDV (which is the milliliters once the ventricles are completely filled) and subtract the stroke volume (which is the amount ejected from the ventricles)
The amount left if known as the end-systolic volume
The ventricles do not expel all of their blood. How do you measure the ejection fraction or how much blood is actually getting expelled from the ventricles?
the amount of blood pumped by each ventricle of the heart in 1 minute
What is the equation for cardiac output?
the difference between the maximum and resting cardiac output is known as:
a persistent, resting adult heart rate above 100 BMP
Can be caused due to stress, anxiety, stimulants, heart disease, fever of low stroke volume (like when the body has lost a significant quantity of blood or when there is damage to the myocardium)
persistent, resting adult heart rate below 60 BMP
endurance training enlarges the heart an increase its stroke volume, enabling it to maintain the same output just with fewer beats.
What is a reason athletes might be bradycardic?
congestive heart failure
this results from the failure of either ventricle to eject blood effectively
the left ventricles are not pumping out enough blood to the body so it causes a backup of blood coming from the lungs and causes it to stay in the lungs and cause pulmonary edema
in congestive heart failure, what is the effect of left ventricular failure?
pulmonary edema due to pressure backing into the lungs
If the left ventricle pumps less blood than the right, what happens?
pressure builds up in the systemic circulation and causes systemic edema
If the right ventricle pumps less blood than the left, what happens?
heart muscle weakening due to mycardial infarction, valvular insufficiency, or congenital defects in heart structure
What typically causes congestive heart failure?
Oxygen cardiac carrying capacity
the bigger the cardiac reserve the more what?
a small cardiac reserve number indicates what?
positive chronotropic agents
These are factors that raise the heart rate
negative chronotropic agents
These are factors that lower heart rate
positive chronotropic agents
negative chronotropic agents
What are the two ways to change heart rate?
The amount of blood ejected from the heart in one contraction
it modulates the speed and the force
How does the autonomic nervous system play a role in altering heart rate?
some neurons of the cardiac center transmit signals to the heart by way of sympathetic pathways
explain cardiostimulatory effects of the autonomic nervous system:
some neurons of the cardiac center transmit parasympathetic signals by way of the vagus nerve
explain cardioinhibitory effects of the autonomic nervous system:
Norepinephrine binds to beta adrenergic receptors in the heart and activates the cAMP second messenger system which causes calcium channels in the plasma membrane to open and the inflow of calcium accelerate depolarization of the SA node so it fires more quickly and the heart gets faster
Sympathetic postganglionic fibers are adrenergic which means they release norepinephrine. Explain how this effect the heart:
it binds to muscarinic receptors and open potassium channels, potassium steadily floods out of the cells and they become hyperpolarized and fire less frequently
How does ACh from the vagal nerve stimulation effect the heart?
vagal tone which is the constant firing of the vagus nerves to keep the SA node from firing too quckily
Without any other influence, our intrinsic firing rate is 100 bmp. What helps stabilize this and keep this down?
they inform the medulla of changes in activity so that the HR can increase to meet muscle demands
How do proprioceptors have an effect on heart rate?
the aorta and internal carotid arteries
Where are baroreceptors found in the body?
because when you are laying down for a long time and then stand up the blood rushes down to your limbs but if all of the blood went to your limbs and not your brain you would pass out so the baroreceptors detect the change in pressure at the head changing and rushes blood back up to your brain
Why are the baroreceptors in our carotid arteries important?
this happens when the baroreceptors in your neck do not detect that you are sitting up and no blood rushes to your head and your body's reaction is to pass out and fall down so blood will rush to your head
they notice the drop in oxygen levels (hypoxemia) and slow down the heart rate so the heart does not compete with the brain for limited oxygen
In a victim who is strangled, how do the chemoreceptors respond?
pH of blood then CO2 levels then Oxygen levels
chemoreceptors are most sensitive to what?
thryoid hormone stimulates the up-regulation of adrenergic receptors which makes the heart more responsive to sympathetic stimulation
explain why people with hyperthyroidism typically have tachycardia:
it accelerates heart rate by stimulating catecholamine (epi and norepi) secretion
How does nicotine effect heartrate?
it inhibits the breakdown of cAMP so it prolongs adrenergic effect so the heart rate stays high
How does caffeine effect the heart rate?
decreases dramatically because the heart is unable to repolarize so the myocardiocytes are less excitable
Excess potassium causes the heartrate to do what?
it slows the heart rate down because stops the heart from reaching a threshold and exciting the other cells
Excess calcium does what to heart rate? How?
the heart rate increases
Too little of ions typically results in what reaction from the heart?
it slows the heart rate
Too much of ions typically results in what reaction from the heart?
CO=HR x (EDV-ESV)
what is the equation for stroke volume?
the amount of tension in ventricular myocardium immediately before it begins to contract
the sum of all forces a ventricle must overcome before it can eject blood
If there is an increase in EDV, there will be an increase in what?
preload, contractility, afterload
What are the three variables that govern stroke volume?
force of contraction
an increase in preload causes an increase in the what?
Frank-Starling Law of the Heart
stroke volume is proportional to end diastolic volume
when they are stretched because they have more area to make smaller
Cardiac muscle cells have the most forceful contraction when?
how hard the myocardium contracts for a given preload
make cardiomyocytes more responsive to stimulation
contractility does not describe an increase in tension produced by stretching the muscle, but rather an increase caused by factors that do what?
positive inotropic agents
negative inotropic agents
Factors that increase contractility are called ____________ _____________ _____________ and those that reduce it are ______________ ___________________ _______________
it reduces the strength of myocardial action potentials and thus reduces the release of calcium into the sarcoplasm so the muscles contract weakly
how does too much potassium effect contractility?
very little effect
Does hypokalemia have any effect on the heart's contractility?
the heart rate is lowered so the contractions are longer in between beats and the more calcium there is, the more forceful the contraction will be
Explain in detail how hypercalcemia effects contracility:
the blood pressure in the aorta and pulmonary trunk because it opposes the opening of the valves and limits stroke volume
What is the most significant contribution to afterload?
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