Cardiovascular phgy part 2 (starting from slide 54) Flashcards
What is transmural pressure?
What is the difference between a vein and an artery in terms of compliance, size/resistance.
transmural pressure, is pressure in the vessel
large artery- stiffer vessel due to more smooth muscle (lower compliance), low resistance
large vein-low resistance, has few layers of smooth muscle so it has higher compliance
What is compliance, and what is the equation?
equation: change in volume/change in pressure
definition-the ability of a vessel to respond to an increase in pressure by distending and increase the volume of blood it can hold, or with decreased pressure, a decrease in volume
Why does heart failure occur?
-it occurs when the ventricle has become stiff (low compliance), so the volume of contractions is less so there is a lower stroke volume (less blood release)
what are the 4 chambers of the heart?
-right atrium, right ventricle
-left atrium, left ventricle
What are the great vessels of the heart?
right pulmonary artery (feeds right lung), right pulmonary veins (comes from right lung)
-inferior vena cava (input to the right heart), superior vena cava
-aorta, left pulmonary artery (feeds left lung), left pulmonary veins (comes from left lung)
-pulmonary trunk- splits into 2 vessels
what is the difference between the right ventriclular free wall (RVFW) and the left ventricular free wall (LVFW)?
-What separates them?
LVFW has a much thicker wall than the RVFW, causing LVFW to be the higher pressure side of the heart (5-10x more pressure than RVFW)
-separated by inter ventricular septum
What separates the atria?
-inter atrial septum
What are the 4 cardiac valves?
-tricuspid valve (has 3 cusps)
-pulmonary (pulmonic) valve
-mitral valve (bicuspid valve)
-aortic valve
what are the 2 types of semilunar valves?
-aortic semilunar valve
-pulmonary semilunar valve
What does the choradae tendonae do vs the papillary muscle?
-chordae tendinae=doesnt stress much (tendon like)
-papillary muscle (comes out of left VFW) and electrical contraction also contracts this muscle within the walls
how many layers are there in the pericardium, what is its purpose?
-it has 2 layers of tissue, one is tough and there is pericaridal fluid between the layers to act as lubricant
-it is a sac that is there so the heart doesnt overfill (constrains the size of vessels
what is difference between epicardium and endocardium?
-epicardium- is connective tissue layer
-endocardium is a single layer of cells (endothelium)
what is the circulation of blood in the pulmonary section of the body?
-TAACVPC
T-pulmonary trunk
-A-pulmonary arteries
-A-pulmonary arterioles
-C-Capillaries of lung
-V-pulmonary Venules
PC-Pulmonary veins
What is flow of blood directly after of the pulmonary section of body?
AAVLAV
A-left atrium
AV-left AV valve
L-Left ventricle
AV-aortic valve
What is the flow of blood after the aortic valve opens?
Ao-Aorta
A-Arteries
A-arterioles
C-capillaries
V-venules
V-veins
Vc-Venae Cavae (brings blood back to atrium)
What is the flow of blood after the venae cavae?
AAVVPV
A-right atrium
AV-right AV valve
PV-pulmonary valve
What is the function of the atrial/ventricular cells in the heart?
-their function is to contract
What is the activation seqeuence used for?
What do sinoatrial (SA) nodes do?
What do SA nodes drive?
-activation seq. is used to analyze ECG
-every second, cells in the sa node have special heart cells that are being spontaneously activated to generate action potentials
-their cells drive the heart rate
Where does the action potential in the heart begin, where does it go?
-action potential begins in the SA node then moves from cell to cell ( in a wave like motion) in the right atrium, over the septum, then to the left atrium and stops
when does the action potential arrive in the purkinje fibers?
Where does the AP move (direction wise)?
how is ventricular muscle activated (direction wise)?
-AP arrives at all the purkinje fibers at the same time
-AP moves from endocardium to epidcardium, these fibers are located just under the pericardium
-ventricular muscle is activated from inside to outside of pericardium
in what direction does the septum activate?
-septum activates left to right and from top to bottom
What is the first wave on the ECG from?
What is special about the right bundle branch?
-first wave on ECG is from Septum
-right bundle branch is surrounded by CT so AP doesnt leak out of the right bundle branch (only leaks from left bundle branch)
-Thus ap moves from left to right
What is the internodal pathway connecting?
-specialized tissue connecting SA node and AV node
-these nodal pathways dont actually exist
How are cardiac cells connected and what is the shape?
-cardiac cells are connected together end to end (intercalated disk at junction) and are rod shaped, not many side to side connections
What will we see near a gap junction?
-membrane of cells in gap junction will see gathering of small particles for gap junction channels (heme channel–> connexon)
How many subunits compose gap junctional channels?
What does it connect, what is channel filled with?
what does the channel allow?
-channels made of 6 identical subunits
-channel connecting the inerior of 2 cells, and is filled with cytoplasm
-channels allow for communication between cells
what is the predominant intercellular ion in local circuit of currents?
How does action potential propagate in intracellular flow?
-K is the most predominat
=-90mV is due to lost of negative charge inside, by depolariazing and removing the -ve the AP potential propagtes
What do we need in order for the circuit current to occur?
-intracellular and extracellular flow is required (flow on both sides) in order for current to occur
what are the 5 leads that connect to the patient in and ECG set up?
what is the reference lead?
- chest lead
2.RA lead - LA lead
- LL lead
- RL lead
RL is the reference lead (lead is 0)
what is an ECG?
How do you calculate voltage
ECG is a voltmeter that measures very small voltages, there are 2 leads that come out of voltmeter (red and black which are positve and negative respectively)
-take voltage from red and substract from black (input - (-input)
Why do we add gel between the wire and skin connection in ECG leads?
What is standard man heartbeat at rest?
-wire doesnt make a great contact with skin due to resistance do the gel is added to allow for lower resistance
-60 BPM laying flat on back
How often does a cardian cycle occur for standard man at rest/
-1 cycle per second which is why BPM is around 60
What is the direction of the waves in the QRS complex?
What is its amplitude?
-q wave is negative
-r wave is positive
-S wave is negative
-amplitude is 1mV (vs 100mV for intracellular recording)
What happens when there are waves of depolarization vs waves of repolarization on the + or - electrodes in a circuit?
What is the action potential flow in the heart?
-SA node –> AV node–> purkinje system (bundle of his–> septum, AP comes out to left and right bundle branch, left has leak)–> ventricular activation (septum)
How is the P-wave formed?
-is the voltage detected by ECG?
AT what point in the P wave is the left atrium depolarized
-formed from SA node having spontaeous creation of action potential (right atrium activates first) which leads to atrial muscle being depolarized
-voltage is generated but not picked up by ECG since there is small amount of local circuit current
-Only after p wave peak is the second half of atrium depolarized (left atrium)
How is the Q wave formed?
-by activation of the septum
-Av node is activated then enters bundle of his in very short time, then goes into bundle branches, then purkinje fibers (marks the baseline since structures are very small)
How is the R-wave formed?
-AP going through free wall from right to left atrium
How is S wave formed?
How is T wave formed?
-formed by activation of ventricles
-T wave is formed by repolarization of the free wave (ventricles
What are the 3 bipolar limb leads?
How many unipolar leads are there?
-left arm, right arm and left leg
-thereare 9 unipolar leads
What does bipolar lead 1 measure/connect to?
what is the formula?
-lead 1 is recorded by taking left arm (cable) to the +ve terminal volt meter and the right arm to the -ve volt meter
-lead 1=VLA-VRA (left arm -right arm)
What does bipolar limb lead II connect/measure?
-lead 2 takes right arm lead to -ve terminal and left leg lead to +ve terminal
-lead II=left leg-right arm voltage
What does bipolar limb lead III measure/connect?
-connect left leg lead to +ve terminal and left arm lead to -ve
-lead III=VLL-VLA
What is the equation for unipolar lead?
How many unipolar chest leads are there?
What leg is alwasy attached to a lead?
VLA+VRA+VLL=0 (get flatline) (sum these 3 voltages to minus terminal=0)
-there are 6 unipolar chest leads (V1 to V6)
-right leg is always attached to a lead
How to read certain parts of 12 lead ECG?
Where are the different terminals of the voltmeter placed?
How long is the plateau vs repolarization phase of an AP?
How does the resting potential charge differ in cardiac cell than neuron?
+ve terminal inside the cell and -ve terminal outside of cell
-plateau phase is 200-300ms long, repolarization is 100ms long
-in neuron resting potential is -60mV and in cardiac muscle it is -90mV ( more hyperpolarized
How are ions transported in the cell?
What does the transport of ions cause?
-ions are transported in the cell through channels, ions cant go through lipid bilayer
-Na+ and K+ current produces an AP
What causes cells to depolarize from resting potential?
What happens when sodium channels close?
-sodium channels are voltage sensitive and opens up when the cell depolarizes
-when sodium channels close the potassium and calcium channels open up
(note add picture from slide 101)
What ion is in higher concentration at rest in the ventricular AP graph?
-at rest Pk»PNa,PCa
What is special about the SA node potential?
what creates the upstroke potential
-SA node does not have a resting potential but it has a pacemaker potential (no Na+ current)
-Ca2+ channels open up eventually creating the upstroke potential (caused by influx of Ca ions not Na+)
Which sections of the heart produce a fast or low AP?
-SA node, and AV node is slow AP
-Fast AP:
VAHBP
V-ventricular muscle
A-atrial muscle
H-bundle of His
B-bundle branches
P-purkinje fibers
Why does the SA node have a slow AP, why is there a delay?
-contraction of atria first and allow for a delay of the ventricles contraction
-AP invade the atria and move down atria contracts expelling more blood into ventricles
When does the atrial action potential occur?
-upstroke of atrial AP occurs at the P wave, as P wave is produced by activation wave, produced by AP spreading through atria
What happens between end of P wave and start of QRS complex, where is the propagation?
-the peak of the P wave and the start of the QRS complex between the AP is the propagation through the AV node and through the bundle of His, bundle branches, and purkinje fibers
