Term
| Besides the heart, where else can you find cardiac muscle? |
|
Definition
|
|
Term
| Cardiac muscle combines properties of both _ and _ muscles. |
|
Definition
|
|
Term
| 2 things that are present in thin filaments? |
|
Definition
|
|
Term
| Cardiac muscle has a striated appearance, this is repeated sarcomeres composed of what 2 things? |
|
Definition
| Thick (myosin) and Thin (actin) filaments |
|
|
Term
| Name 6 properties that cardiac muscle has. |
|
Definition
1. Striated appearance
2. T-Tubule system with SR
3. Relatively small with a single nucleus
4. Arranged into myofibrils
5. Arranged in layers and surround hollow cavities
6. Attach to intercalated discs which join adjacent muscle cells |
|
|
Term
| Cardiac muscle cells are attached to intercalated discs which join adjacent cells. What holds the cells together? |
|
Definition
|
|
Term
| Cardiac muscle cells are attached to intercalated discs which join adjacent cells. What connects the cells? |
|
Definition
|
|
Term
| Where are desmosomes and gap junctions located? |
|
Definition
|
|
Term
| In a cardiac muscle, contraction starts from the __ and moves __ |
|
Definition
|
|
Term
| Arranged in layers and surrounds hollow cavities |
|
Definition
|
|
Term
| Cardiac muscle is arranged in layers and surround hollow cavities. This allows the contraction to start from the inside and move outward. What is significant about this? |
|
Definition
| This will show up on an ECG as either positive or negative |
|
|
Term
| Action potentials begin as an initial spike in the membrane potential from about __ mV to __ mV |
|
Definition
|
|
Term
| After the initial AP spike, the membrane remains depolarized for about __ seconds. This is called what? |
|
Definition
|
|
Term
| Followed at the end by an abrupt repolarization. |
|
Definition
|
|
Term
| The presence of the plateau of the AP causes the duration of __ contraction to be much longer than in skeletal muscle. |
|
Definition
|
|
Term
| Skeletal muscle AP is initiated by the opening of voltage gated __ channels which very quickly depolarize the cell membrane. |
|
Definition
|
|
Term
| Cardiac muscle AP is initiated by the opening of what 2 membrane channels? |
|
Definition
Fast voltage gated Na+ channels
Slow Ca++ channels (L-Type) |
|
|
Term
| Slower to open and remain open for LONGER periods. Allows a great influx of both calcium and sodium maintaining a long period of depolarization known as the plateau. |
|
Definition
| L-Type (slow ca++ channels) |
|
|
Term
| Immediately following an AP, membrane permeability in cardiac ms for K+ __ 5-fold |
|
Definition
|
|
Term
| In skeletal muscle, permeability for K+ does not decrease following an AP. This results in quick what? |
|
Definition
|
|
Term
| Immediately following an AP, cardiac muscle decreases its permeability to K+. This greatly decreases the outflux of K+ ions during the AP plateau and prevents what? |
|
Definition
|
|
Term
| After an AP, when L-type channels do close what does this do to the permeability to K+? |
|
Definition
| increases and helps return to RMP |
|
|
Term
| Can cardiac muscle cells undergo tetanic contractions like skeletal muscle? |
|
Definition
|
|
Term
| The period of time during which a normal cardiac impulse cannot re-excite an already excited area of cardiac muscle. |
|
Definition
|
|
Term
| How long does the cardiac muscle refractory period last? |
|
Definition
| 250 ms (much longer than skeletal ms) |
|
|
Term
| AP propogates to the interior of the cardiac muscle fiber along the membranes of the ___ |
|
Definition
|
|
Term
| AP triggers the release of some __ from the SR into the sarcoplasm |
|
Definition
|
|
Term
| Ca++ triggers the activation of what? |
|
Definition
| Troponin/Tropomyosin complex |
|
|
Term
| What is much smaller in cardiac muscle than skeletal? It has less Ca++ |
|
Definition
|
|
Term
| AP in the T-tubules opens voltage gated __ channels that are located within the membrane |
|
Definition
|
|
Term
| Ca++ enters the cell through __ receptors and increases cystolic Ca++ |
|
Definition
|
|
Term
| Cystolic Ca++ does what to the membrane? |
|
Definition
|
|
Term
| Ca++ binds to __ receptors on the SR and triggers the release of much more Ca++ |
|
Definition
|
|
Term
| High levels of Ca++ lead to what 3 things? |
|
Definition
1. Thin filament activation
2. Cross bridge cycling
3. Force generation |
|
|
Term
| Cardiac muscle contraction is graded and dependent on __ concentration in the ECF |
|
Definition
|
|
Term
| Ca++ in the t-tubules comes from where? |
|
Definition
|
|
Term
| A small amount of extracellular calcium enters the cell thru __ Ca++ channels during the plateau of the AP. |
|
Definition
|
|
Term
| At the end of the plateau, influx of Ca++ into the cell is __ and calcium ions are rapidly pumped where? |
|
Definition
Cut off
Back out into the ECF via t-tubules and into SR |
|
|
Term
| Buildup of Na+ is pumped out of the cell via what? |
|
Definition
|
|
Term
| Comprises all the events that occur between the beginning of a heartbeat and the beginning of the next. |
|
Definition
|
|
Term
| Does skeletal muscle have gap junctions? |
|
Definition
|
|
Term
| Initiated by the spontaneous generation of an AP in the Sinus Node which spreads rapidly thru the heart in a specialized manner. |
|
Definition
|
|
Term
| Name the 2 types of events of the cardiac cycle |
|
Definition
1. Mechanical (contraction of ms, closure of valves, etc.)
2. Electrical (depolarization, etc) |
|
|
Term
| Specialized cardiac tissue that does not have contractile filaments, but is directly connected to the surrounding cardiac tissue. |
|
Definition
|
|
Term
| How is the SA Node generated? |
|
Definition
|
|
Term
| Where are autorhythmic cells found? |
|
Definition
|
|
Term
| What is the RMP of autorhythmic cells? |
|
Definition
|
|
Term
| Can autorhythmic cells self-excite? |
|
Definition
|
|
Term
| Autorhythmic cells have a RMP of -55mV. At this level, inactivation sodium gates are __ and remain that way. Only the slow __ channels can __ and cause an AP |
|
Definition
|
|
Term
| As a result of the RMP of autorhythmic cells, the nodal AP is __ to develop than a ventricular AP. Recovery of the AP is also __. |
|
Definition
|
|
Term
| Have "leaky" membranes that constantly move positively charged Na and Ca into the cell after each AP. |
|
Definition
|
|
Term
| The membrane potential oscillates and is capable of generating what? |
|
Definition
| Its own AP b/c of the leaky membranes that let Na and Ca in |
|
|
Term
| After the AP, there is recovery of the AP, followed by __, followed by "drift" of the resting potential to ___. It then fires another AP, and the cycle continues. |
|
Definition
Hyperpolarization
Threshold |
|
|
Term
| What makes the rhythmical sounds of heart beat? |
|
Definition
|
|
Term
| Ends of the nodal fibers connect directly to the surrounding __ fibers, AP travel thru the entire __ muscle mass and, eventually, to the __node. |
|
Definition
|
|
Term
| The AP travels thru specialized bands of tissue called |
|
Definition
|
|
Term
| Name the 3 internodal pathways |
|
Definition
|
|
Term
| Where do the internodal pathways terminate? |
|
Definition
|
|
Term
| On the AP has reached the AV node, there is a delay in the spread of AP from the atria to the ventricles so that the atria may do what? |
|
Definition
|
|
Term
| After the AP has traveled thru the internodal pathways, there is a delay in what node? |
|
Definition
|
|
Term
| Impulse travels thru the _ __ __ to pass into the ventricles? |
|
Definition
|
|
Term
| There is a delay of impulse from the sinus node to the ventricles. What is the total delay in seconds? |
|
Definition
|
|
Term
| Why is there a 0.16 sec delay from the sinus node to the ventricles? |
|
Definition
| Diminished number of gap junctions between successive cells in the conducting systems |
|
|
Term
| How many AV bundles (bundle of His) do we have? |
|
Definition
|
|
Term
| Special fibers that travel thru the AV bundles to the ventricles |
|
Definition
|
|
Term
| Very large fibers that trasmit AP at great speeds |
|
Definition
|
|
Term
| Allow for the almost instantaneous transmission of cardiac impulse thru the entire remainder of the ventricular muscles. |
|
Definition
|
|
Term
| Why are purkinje fibers to fast? |
|
Definition
| very high permeability to gap junctions, which enhance the velocity of transmission |
|
|
Term
| What part of the heart forms the base? |
|
Definition
|
|
Term
| Prevents re-entry of cardiac impulses from the ventricles to the atria |
|
Definition
| One-way conduction thru AV bundles |
|
|
Term
| The fibrous bundles of tissue separate the atria and ventricles and acts as an __ to prevent passage of impulses except thru the AV bundle. |
|
Definition
|
|
Term
| Bundles divide into right and left bundle branches that course down the ___ __ and wrap around the base of the heart. |
|
Definition
|
|
Term
| The spread into both ventricles becomes continuous with the what? |
|
Definition
|
|
Term
| Can impulses pass between atria and ventricles? |
|
Definition
| Only thru the AV bundle, there are fibrous bundles that act as insulators to prevent them from going anywhere else |
|
|
Term
| Once the impulse reaches the end of the purkinje system, it is transmitted thru the mass by the what? |
|
Definition
| Ventricular muscle fibers |
|
|
Term
| Ventricular muscle fibers are arranged in spirals from the __ to __, so transmission angulates toward the surface along the direction of the spirals. |
|
Definition
|
|
Term
| What is important in understanding electrocardiography? |
|
Definition
| The way ventricular muscle fibers are arranged in spirals from the endo to epi cardium to angulate transmission |
|
|
Term
| Which node fires APs at a faster rate? |
|
Definition
|
|
Term
| Both the cells of the _ node and the _ node are capable of generating intrinsic AP. |
|
Definition
|
|
Term
| Which node predominates the other and determines the heart "rate". |
|
Definition
|
|
Term
| In abnormal conditions, other regions of the heart can develop faster AP generating velocities. |
|
Definition
|
|
Term
| Abnormal pacemakers can overcome the sinuse node and are called what? |
|
Definition
|
|
Term
| Causes an abnormal sequence of contraction of different parts of the heart. Can be debilitating for the heart to pump. |
|
Definition
|
|
Term
| Can be caused by a blockage of transmission of the cardiac impulses from the sinus node to other regions. The AV node most frequently becomes the new pacemaker. |
|
Definition
|
|
Term
| Occurs when the impulse fails to pass from the SA node to the ventricles via the AV system. |
|
Definition
|
|
Term
| When there is an AV block, the atria continues to beat at a normal rate, but what do the ventricles do? |
|
Definition
| They beat according to the rate of the AV system (15-40 bpm) |
|
|
Term
| Important to have rapid transmission to ensure a synchronous contraction of the ventricle. Otherwise, certain portions of the ventricles would contract sooner than others and lead to insufficient pumping. |
|
Definition
|
|
Term
| What part of the heart do the parasympathetics (vagal) mainly direct? |
|
Definition
SA and AV nodes
A bit of atrial muscle and very little ventricular muscle |
|
|
Term
| What parts of the heart do the sympathetics mainly direct? |
|
Definition
| all parts of the heart with strong supply to the ventricular muscle |
|
|
Term
| What do the vagal branches of the parasympathetic system release? |
|
Definition
|
|
Term
| Decreases the rate of rhythm of the sinus node. |
|
Definition
| Vagal branches of parsympathetic |
|
|
Term
| Decreases excitability of the AV junctional fibers between the atrial musculature and the AV node: slows transmission |
|
Definition
| Vagal branches of parsympathetic |
|
|
Term
| Weak to moderate stimulation slows the heart pumping. |
|
Definition
| Parasympathetic cardiac nerves |
|
|
Term
| Can a strong parasympathetic stimulation stop the heart? |
|
Definition
|
|
Term
| When the parasympathetics provide a strong stimulation and stop the heart, the ventricles will stop for __ seconds, then purkinje fibers will develop a rhythm of its own and cause contraction at a slowed pace. What is this called? |
|
Definition
5-20 seconds
Ventricular Escape |
|
|
Term
| ACh __ permeability to K+ |
|
Definition
|
|
Term
| ACh increases permeability to K+, which allows rapid leakage of K+ out of the cells and __ the membrane. |
|
Definition
|
|
Term
| Sympathetic stimulation will increasse the rate of what 2 things? |
|
Definition
1. sinus nodal discharges
2. conduction and level of excitability |
|
|
Term
| Sympathetic stimulation will increase the force of what? |
|
Definition
|
|
Term
| Sympathetic stimulation releases what at the nerve endings? |
|
Definition
|
|
Term
| The release of norepinephrine at the nerve endings stimulates what? |
|
Definition
| B-1 (beta) adrenergic receptors |
|
|
Term
| What does B-1 do in relation to K+? |
|
Definition
| Decreases the permeability to K+ causing depolarization |
|
|
Term
| Does B-1 lead to more or less APs? |
|
Definition
|
|
Term
| Low Serum K+ __ excitability of myocytes |
|
Definition
|
|
Term
| Where does epinephrine come from? |
|
Definition
|
|
Term
| High serum K+ __ the excitability of myocyttes |
|
Definition
|
|
Term
| Sympathetic stimulation releases norepinephrine, which releases B-1. This is thought to increase permeability to what ions? |
|
Definition
|
|
Term
| When Na and Ca are more permeable, what does this do to RMP and self excitation? |
|
Definition
| Causes a more positive RMP and accelerates self-excitation |
|
|
Term
| The spread of AP goes from the __ of the heart to the __ of the heart. |
|
Definition
|
|
Term
| If you are depolarizing your heart, it starts in the base (right) and then moves toward the apex which is where? |
|
Definition
|
|
Term
| When recording ECGs you record from _ to _ |
|
Definition
|
|
Term
| Represents the entire depolarization wave of the atrium. |
|
Definition
|
|
Term
| This is generated when the atria depolarize before atrial contraction begins. |
|
Definition
|
|
Term
| Does the atria contract during the p wave? |
|
Definition
| towards the end and on closer to Q |
|
|
Term
| The time between the beginning of atrial excitation and the beginning of ventricular contraction. |
|
Definition
|
|
Term
| The segment in which the atria is contracting |
|
Definition
|
|
Term
| Generated when the ventricles depolarize before contraction ( as the deopolarization wave spreads thru the ventricle) |
|
Definition
|
|
Term
| The segment in which the ventricles are contracting |
|
Definition
|
|
Term
| Generated as the ventricles recover from the state of depolarization known as the repolarization wave. |
|
Definition
|
|
Term
| beginning of Q to the end of T |
|
Definition
|
|
Term
| The time of ventricular contraction (.35 sec) |
|
Definition
|
|
Term
| After the membrane repolarizes, what is the muscle doing at the end of T wave? |
|
Definition
|
|
Term
| The relaxation period of the cardiac cycle. |
|
Definition
|
|
Term
| The contraction period of the cardiac cycle |
|
Definition
|
|
Term
| The period of the cardiac cycle in which the heart fills with blood |
|
Definition
|
|
Term
| An electrical representation of the mechanical events of the heart. |
|
Definition
|
|
Term
| The total duration of the cardiac cycle is the reciprocal of the what? |
|
Definition
|
|
Term
|
Definition
| 1/72 = duration of 1 cardiac cycle |
|
|
Term
| No change in the voltage is called what? |
|
Definition
|
|
Term
| As HR increases, what happens to the duration of hte cardiac cycle? |
|
Definition
|
|
Term
| As HR increases, the cardiac cycle duration decreases. Does diastole or systole decrease more? |
|
Definition
|
|
Term
| What percentage of the cardiac cycle is diastole? |
|
Definition
|
|
Term
| What percentage of the cardiac cycle is systole? |
|
Definition
|
|
Term
| At 210 bpm, diastole is what percentage, then systole is what? |
|
Definition
|
|
Term
| A heart beating very rapidly does not __ enough to allow complete filling before the next contraction. |
|
Definition
|
|
Term
| How many stages of diastole are there? |
|
Definition
|
|
Term
| How many stages of systole are there? |
|
Definition
|
|
Term
| Serves as a primer pump to increase ventricular effectiveness |
|
Definition
| Atrial Filling and emptying |
|
|
Term
| What stage of diastole is atrial filling? |
|
Definition
|
|
Term
| During mid diastole, is the atria relaxed or contracted? |
|
Definition
| Relaxes, b/c it is atrial filling |
|
|
Term
| During mid diastole (atria filling), blood normally flows continually from the __ veins into the atria |
|
Definition
|
|
Term
| What stage of diastole is atrial emptying? |
|
Definition
|
|
Term
| During late diastole, is the atria relaxed or contracted? |
|
Definition
| Contracted b/c it is atial emptying |
|
|
Term
| During late diastole, before the atria actually contracts to push blood out, about what percentage of blood flows directly into the ventricle? |
|
Definition
|
|
Term
| Atrial contracting forces the remaining __% into the ventricles |
|
Definition
|
|
Term
| The heart can function at rest without the aid of what? |
|
Definition
|
|
Term
| If a person has atrial dysfunction, what kinds of problems might they notice? |
|
Definition
| None really because the heart can function without the aid of the atria at rest. They might notice problems with exercising |
|
|
Term
| What phase of diastole is ventricular filling? |
|
Definition
| Mid diastole and Late diastole both |
|
|
Term
| What phase of diastole is rapid ventricular filling? |
|
Definition
|
|
Term
| What phase of diastole is slow ventricular filling? |
|
Definition
|
|
Term
| During ventricular systole, large amounts of blood accumulates in the __ because of the closed __ valves. |
|
Definition
|
|
Term
| During ventricular filling, what is the pressure and volume doing in the atria? |
|
Definition
|
|
Term
| As soon as ventricular systole is complete, pressure and volume in the ventricle fall to __ values. |
|
Definition
|
|
Term
| During rapid ventricular filling, increased pressure and volume in the atria force the AV valves open and allow blood to flow rapidly into the ventricles. Period of rapid ventricular filling lasts about the first __ of diastole. |
|
Definition
|
|
Term
| During the last 1/3 of diastole, the atria contract and thrust the final 20% of blood into the ventricles. |
|
Definition
| Slow Filling (or Atrial Emptying) |
|
|
Term
| This occurs immediately after the ventricles begin to contract, the pressure in the ventricles rises sharply and forces the AV valve closed. |
|
Definition
|
|
Term
| During which phase of systole is the isovolumetric contraction? |
|
Definition
|
|
Term
| During which phase of systole is the period of ejection? |
|
Definition
|
|
Term
| Isovolumetric contraction occurs for the first __ of contraction. |
|
Definition
|
|
Term
| This occurs when the ventricular pressure continues to rise in order to thrust the semilunar valves open against the pressure of the aorta or pulmonary artery. |
|
Definition
| Isovolumetric Contraction (early systole) |
|
|
Term
| During isovolumetric contraction, the ventricles are contracting and that is going on with blood flow? |
|
Definition
| No flow of blood or emptying yet |
|
|
Term
| During this phase, the ventricles are contracting and pressure is rising but it has not yet overcome aortic pressure. |
|
Definition
| Isovolumetric Contraction |
|
|
Term
| What causes valves in the heart to open or close? |
|
Definition
|
|
Term
| Occurs when the left ventricular pressure rises slightly above 80mmHg (8mmHg on right) |
|
Definition
| Period of ejection (late systole) |
|
|
Term
| Period of ejection causes the pressures to open which valve? |
|
Definition
|
|
Term
| During this phase, the blood immediately flows from the ventricles and into the aorta or pulmonary artery. |
|
Definition
| Period of ejection (late systole) |
|
|
Term
| What is another term for early diastole? |
|
Definition
|
|
Term
| When does isovolumetric relaxation occur? |
|
Definition
|
|
Term
| This phase occurs when ventricular relaxation begins abruptly allowing intraventricular pressures to decrease rapidly. |
|
Definition
|
|
Term
| The large volume and pressure in the aorta and pulmonary arteries force what valve to close during isovolumetric relaxation? |
|
Definition
|
|
Term
| How long does isovolumetric relaxation occur? |
|
Definition
|
|
Term
| During this phase, all valves are closed. |
|
Definition
| isovolumetric relaxation (early diastole) |
|
|
Term
| When ventricular pressure falls to low diastolic levels, what valves are forced open by the volume and pressure that has accumulated in the atria? |
|
Definition
|
|
Term
| The amount of blood in the ventricles following diastole |
|
Definition
|
|
Term
| The total amount of blood that was able to fill the ventricles (110-120ml) |
|
Definition
|
|
Term
| The degree of tensio on the muscle when it begins to contract. Usually this is considered to be the EDV. |
|
Definition
|
|
Term
| The amount of blood in the ventricles following systole (40-50ml) |
|
Definition
|
|
Term
| The total amount of blood left in the ventricles after contraction/emptying |
|
Definition
|
|
Term
| The amount of blood that was ejected from the ventricles. |
|
Definition
|
|
Term
| What is the equation for SV? |
|
Definition
|
|
Term
| The amount of blood ejected from the ventricles during systole (70ml) |
|
Definition
|
|
Term
| The normal SV for a resting adult |
|
Definition
|
|
Term
| SV is roughly what percentage of EDV? |
|
Definition
|
|
Term
| Pressure in the aorta or pulmonary arteries at the level of the heart. |
|
Definition
|
|
Term
| Is pressure in the feet higher or lower than pressure in the aorta at the level of the heart? |
|
Definition
|
|
Term
| When can you have an isoelectric line? |
|
Definition
| When entire thing is depolarized or polarized |
|
|
Term
| EDV can increase up to __ ml in a healthy person. |
|
Definition
|
|
Term
| Strength of contraction; tension a muscle fiber can produce; can increase by myosin/actin being at optimal length |
|
Definition
|
|
Term
| Changes in ventricular contractility (SNS input) is composed of very strong ventricular contractions that can decrease ESV to as little as what? |
|
Definition
|
|
Term
| Changes in afterload can help to control SV how? |
|
Definition
| Arterial pressures against which the ventricles must contract |
|
|
Term
|
Definition
Change EDV (preload)
Change ventricular contractility
Change afterload |
|
|
Term
|
Definition
|
|
Term
| The load on the heart; the amount of work the heart has to do or the amount of tension on the muscle at the beginning of contraction. |
|
Definition
|
|
Term
| The force against which the ventricles are going to have to overcome in order to contract. |
|
Definition
|
|
Term
| Equal to the pressure in the aorta or pulmonary arteries at the level of the heart. |
|
Definition
|
|
Term
| CO (cardiac output) is directly dependent upon what? |
|
Definition
|
|
Term
| The volume of blood that each ventricle pumps per minute |
|
Definition
|
|
Term
| What is the average CO for a normal adult? |
|
Definition
|
|
Term
| This is considered an indication of how well the heart is oxygenating the body |
|
Definition
|
|
Term
| What is the formula for CO? |
|
Definition
|
|
Term
|
Definition
|
|
Term
| Primarily controls pumping in response to changes in the volume of blood flowing through the heart |
|
Definition
|
|
Term
| An intrinsic ability of the heart to adapt to changes in volume of blood flowing through the heart. It tries to increase SV. |
|
Definition
|
|
Term
| If you raise EDV what also raises? |
|
Definition
|
|
Term
| Says that in order to increase the strength of the ventricle, you need to fill it more fully with blood |
|
Definition
|
|
Term
-Within physiological limits, the heart pumps all the blood that returns to it by way of the veins
- The increased stretch of the ventricle will align its actin and myosin in a more optimal pattern of overlap for force generation (length-tension relationship)
- To increase the heart's SV: fill it more fully with blood |
|
Definition
|
|
Term
| Primarily controls rate and strength of pumping |
|
Definition
|
|
Term
| What is the biological inherent heart rhythm? |
|
Definition
|
|
Term
| The biological inherent heart rhythm is approx. 100 bpm. What is this due to? |
|
Definition
| The pacemaker activity of the SA node. |
|
|
Term
| During rest, the PSNS is more or less active than the SNS? |
|
Definition
|
|
Term
| A combined stimulus of both the PSNS and SNS keeps the resting heart rate at what value? |
|
Definition
|
|
Term
| If you alleviated all sympathetic activity on the heart at rest what would the heart be like? |
|
Definition
|
|
Term
| Can increase CO by more than 100% per minute |
|
Definition
|
|
Term
| Under normal conditions, sympathetic fibers discharge continuously at a slow rate that maintains pumping at about __% above that with no sympathetic stimulation. |
|
Definition
|
|
Term
| Name 3 things sympathetic stimulation can do for the heart. |
|
Definition
1. Increase HR
2. Increase Force
3. Increase SV further |
|
|
Term
| Sympathetic stimulation can increase heart rate up to how many bpm? |
|
Definition
|
|
Term
| A resting heart rate of more than 100bpm is called what? |
|
Definition
|
|
Term
| Can double the force of contraction |
|
Definition
|
|
Term
| Name the 2 sympathetic signals |
|
Definition
|
|
Term
| How does the sympathetics increase SV further? |
|
Definition
| Deliver sympathetic signals (norepi, epi); also relaxes more rapidly which allows more time to refill. Sympathetic signals cause a stronger and more rapid contraction and a more rapid relaxation |
|
|
Term
| What will inhibition of sympatheti innervation do? |
|
Definition
| Slow HR and decrease force to 30% below normal |
|
|
Term
| Can decrease CO to as low as zero |
|
Definition
|
|
Term
| These fibers are distributed mainly to the atria and not much to the ventricles to help with PSNS regulation. |
|
Definition
|
|
Term
| Name 2 things that strong stimulation by the PSNS can do. |
|
Definition
1. Stop heart for a few seconds, followed by slow HR
2. Decrease strength of heart muscle contraction by 20-30% |
|
|
Term
| If you have a strong PSNS stimulation, this can stop the heart for a few seconds, then be followed by a slow HR of about ___bpm for the duration of the stimulation. |
|
Definition
|
|
Term
| A resting heart rate of less than 60 bpm |
|
Definition
|
|
Term
| At what bpm will bradycardia become symptomatic? |
|
Definition
|
|
Term
| A high K+ concentration in ECF __ RMP in cardiac muscle, therefore __ to threshold. |
|
Definition
|
|
Term
| If there is decrease in RMP, then the membrane is partially depolarized and __ negative. |
|
Definition
|
|
Term
| Results in very quick, easily generated AP. However the intensity of the AP is decreased and eventually blocked due to closed Na+ channels |
|
Definition
|
|
Term
| Excess ECF K+ causes causes the heart to become what? |
|
Definition
| Dilated and flaccid and slows heart rate |
|
|
Term
| Leads to progressively weaker heart contractions and can block conduction of the cardiac impulse from the atria to the ventricles. |
|
Definition
|
|
Term
| Has a direct effect in cardiac muscle to initiate contraction |
|
Definition
|
|
Term
| What will excess Ca++ cause? |
|
Definition
| The heart to go into spastic contraction |
|
|
Term
| What will Ca++ deficiency cause? |
|
Definition
|
|
Term
| These levels are very highly regulated and issues due to these levels are rarely seen clinically. |
|
Definition
|
|
Term
| Heat __ the permeability of cardiac muscles to __ ions |
|
Definition
|
|
Term
| How does excess heat (fever) effect the heart? |
|
Definition
-Accelerates the self-excitation process
-Increases HR
-Can enhance contractile strength temporarily
-Eventually, prolonged elevation will exhaust the metabolic systems of the heart and cause weakness |
|
|
Term
| Decreased temperature causes __ HR |
|
Definition
|
|
