Heart & Circulation
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The Right side of the Heart is also known as what?
The Left side of the heart is known as what?
What type of tissue is the heart made of?
Cardiac Muscle tissue
Describe cardiac muscle.
striated, uninucleate with intercalated discs (cell to cell junction)
Give an example of two functional syncytia.
the two ventricles act like a unit (syncytia) as well as the 2 atriums.
Why does the heart have a long refactory period?
- Na+ leaks in which opens Ca2+ channels to open and Ca2+ therefore slowly leaks in keeping a depolarized state (refactory period).
- No temporal stimulation = no tetany.
What is the heart able to do because there are slow and fast calcium channels
Exhibits rhythmicity. (Tissue beats together instead of when ever they want)
True or False. The heart conduction system has its own electrical conduction system to speed conduction.
What's the pacemaker of the heart?
Sino atrial node (SA node)
Why is the SA node the pacemaker of the heart?
Because it sends out impulses faster than other place in the heart.
Occurs in the upper right atrium - 72 beats/min.
Where does the impulse go after the SA node sends out an impulse?
- AV node (atrial ventricular node).
- Junction of atria and ventricles.
- AV sends impulses at 60 b/m.
In order, list the steps of the pacemaker system.
- SA node in upper right atrium send impulse (at ~72 b/m)
- that spread out through the L & R atria.
- Impulse comes to AV node.
- AV node sends out impulse. ~ 60b/m.
- Impulses travels to the AV Bundle (Bundle of His) below the AV node.
- Carries impulse down toward the septum.
- At septum bundles brach to L & R bundle branches down the interventricular septum.
- Impulse continues down myocardium out to the wall of the heart to Purkinje Fibers.
- From Purkinje Fibers to the myocardial cells.
TRUE or FALSE.
Nerves send out the impulses in the heart.
False. They are modified myocardial cells.
How fast does the myocardium impulse?
Does the heart pause during contraction?
Yes. Atria contracts first. There is a 0.1 sec. pause in AV node, then ventricles contract.
What happens if there's an SA node block?
The Av node takes over sending out 60 b/m.
What is it called when an impulse originates anywhere other than the SA node?
What happens when there are AV blocks?
Myocardial cells take over (ventricles) beat 20-30 b/m.
These are more common.
What is a Flutter?
Tissue is coordinating, but tissue is enlarged in atrium or ventricle so that by the impulse goes around and comes back the tissue is already repolarized and impulses again.
Continuous Impulses: ~200-300 b/m
What is Fibrillation?
- No coordination. Impulses everywhere in cardiac tissue.
- Atrial Fib. : Can still walk around, just not much energy. Need a carido conversion.
: no regular rythm. Not pumping any blood. death in 4-6 min. Need an AED.
What is an AED?
Automated External Defibrillator. Re-coordinates the heart by sending out 2,000-4,000 volts to the heart.
What is an ECG?
Electrocardiogram. Used to monitor the heart's depolarization and repolarization by placing electrodes on the body.
How many ways are there to hook up the body for an ECG and what are they?
- 12 Universal Leads
- 3 Bipolar Leads, 3 Unipolar Leads, 6 Chest Leads.
What does the P wave represent?
Depolarization of the atria.
What wave represents the depolarization of the ventricles?
The QRS wave.
What does the T wave represents?
Repolarization of the ventricles.
What wave represents the repolarization of the artia?
None. It can not be seen in this graph because it is overshadowed by the QRS complex.
When there is an elevation of an ST segmant, what does that mean?
- A mild cardio infarction. (Heart Attack)
- If there is a depression can indicated mild cardial iscemia. (Low blood flow)
How can you see if there is AV blockage?
- If the P-R interval is elongated its a 1st degree AV block.
- If P-R interval elongated, but also has occasional impulse drop (impulse doesn't get through) 2nd degree block.
- If P-R interval elongated, no impulse pass through is 3rd degree block.
What do the heart valves do?
They insure one-way flow and prevent back flow of blood.
Which valves prevent back flow to atria? what sound does this produce?
The AV valves. They produce a Lub sound.
Which valves prevent back flow to the ventricles? What sound does it produce?
Semilunar valves. Make a Dup sound.
What could happen is the valves are damaged?
cause regurgitation (not close all the way) or stenosis (not open all the way)
If the valves are damaged, what can one do to fix it?
Replace the valves with artificial valves.
Whats a heart murrmur?
the sound the heart makes a sound due to valve irregularity.
What is systole?
The contraction of the heart muscle
What is diastole?
The heart muscle is relaxing
What is ausculation?
the practice of hearing. (ex: ausculating the heart)
What are the ventricles doing is the atria are contracting?
Ventricles are relaxing.
How do you calculate cardiac output?
heart rate x stroke volume = cardiac output
Q=HR X SV
What is stroke volume?
Blood that gets pumped out. (The "size of the can.")
When does the T wave start?
at the end of systole
What is Frank-Staling Law?
the heart will punp all the blood that comes to it
Describe what is happening in early diastole
- Mitrol valve open to fill up ventricles.
- volume of blood goes up in left ventricle.
- Pressure of atria is greater than the ventricles.
Describe what happens in late diastole.
- P wave occurs.
- Atria contracts tops off venticles 20%.
- QRS complex occurs- which means depolarization of ventricles.
- (repolarization of ventricles is coming)
Describe what is happeningSystole
- Ventricles begin to contract (ventricular pressure begins to exceed atrial pressure)
- Mitrol valve closes.
- Semilunar valves open. (pressure increased)
- Blood flows out of ventricles to aorta. (volume drops in ventricles)
- Ventricles start to stop contraction, aorta semilunar valves close.
- Pressure starts to drop...start early diastole.
The blood left in the ventricles after contraction is called...
End systolic volume
The blood volume at the end of diastole is called..
end diastolic volume
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