Help
Options
Didn't know it?
click below
click below
Knew it?
click below
click below
Don't Know
Remaining cards (0)
Know
retry
shuffle
restart
0:00
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.
Normal Size Small Size show me how
Normal Size Small Size show me how
Chapter 18
The Cardiovascular System - Cardiac Cycle, ECG's, Intrinsic Conduction System
| Question | Answer |
|---|---|
| pacemaker cells set the pace, one special thing about them is: | they can spontaneously depolarize |
| this type of cell has an unstable resting potential. | pacemaker cells |
| ___ causes depolarization | calcium |
| what is the pacemaker of the heart? | SA node |
| 3 steps of the cardiac action potentials. | pacemaker potential -> depolarization -> repolarization |
| what happens in the pacemaker potential? | the K+ channels close because of the opening of Na+ channels |
| in the depolarization phase the pacemaker potential __ | reaches threshold - calcium causes depolarization |
| due to calcium channels and potassium channels opening the membrane potential goes back to negative voltage. this is because of __ | repolarization |
| what is the fastest depolarization rate? | SA node |
| this sets the rhythm via sinus rhythm & has the fastest depolarization rate | SA node |
| step 1 of the intrinsic conduction system | SA node generates impulses |
| after the SA node generates impulses. what happens? | the wave spreads through the atrium to AV node |
| why is there a delay when the wave spreads from the atrium to AV node? | because the muscle fibers are so small |
| step 3 of the intrinsic conduction system | the AV bundle connects the atria to the ventricle |
| after the AV bundle connects the atria to the ventricle, the ___ and lastly the __ | bundle branches conduct impulses to the inter-ventricular septum - the punkinje fibers connect |
| when the pukinje fibers network it: | spread impulses to both ventricles, depolarizing the cells |
| there are no gap junctions connecting the __ and __ | atria - ventricles |
| what is the purpose of the AV node/? | it slows down impulses so contraction can occur |
| depolarization | contracting |
| repolaruzation | relaxing |
| what is an electrocardiogram (ECG) | graphic record of the electrical activity of the heart |
| sequence of events when the atria & ventricles are contracting or relaxing is known as the: | cardiac cycle |
| diastole refers to __, while systole refers to __ | relaxation - contraction |
| heart murmur | abnormal heart sounds that results from valve problems |
| condition of rapid & irregular heart contractions | fibrillation |
| what are the 3 steps of the cardiac cycle? | ventricular filling (mid to late diastole) ventricular systole early diastole |
| in ventricular filling (mid-to-late diastole) what happens? | atrial contracts --> pumps blood to ventricle |
| during the ventricular filling the __ stays open allowing: | mitral valve - blood to move in |
| the ventricular systole is known as the ___ phase. during this phase no ___ . after this phase the ___ occurs | isovolumetric contraction - blood has left yet - ventricular ejection |
| in the early diastole ___ occurs. the ventricular filling then begins to open the __ and __ | relaxation - AV valve , pushes blood to large ventricles |
| the semilunar valve closes during which step of the cardiac cycle? | early diastole |
| the lub sound comes from the: | AV valves closing |
| the dub sounds come from the: | SV valves closing |
| arrythmias are __ | irregular heart rhythms |
| extrasystole is a __ contraction | premature |
| ectopic pacemakers with functional SA nodes can lead to: | extrasystole |
| in defective SA nodes when the pacemaker is abnormal, what happens? | the AV node becomes pacemaker |
| ___ can cause uncoordinated atrial & ventricular contractions | arrythmias |
| heart block occurs when __ | there is damage to intrinsic network |
| 5 distinct characteristics in cardiac muscle thats not in skeletal. | no muscle spasms. extracellular fluid involved -> triggers calcium release. self excitable. heart contracts as a unit. heart relies on aerobic respiration (lots of mitochondria - resistance to fatigue) |
| unlike skeletal muscles, cardiac cells can be__ | autorhythmic |
| in cardiac cells, the heart contracts as a unit due to : | gap junctions |
| muscle spasms cannot occur in cardiac muscles because... | the refractory period is the same as contraction |
| atrial diastole occurs at__ | QRS point |
| isovolumetric contraction & ejection are apart of: | systole |
| in isovolumetric contraction, what is happening? | no blood is leaving the heart - just pressure building up |
| in isovolumetric both valves are __ so the volume is ___ | closed - constant, just increasing pressure |
| continued contraction and increase in pressure forces aortic valve to open & cause: | ejection |
| isovolumetric relaxation and filling deals with: | diastole |
| what happens at the P point of an ECG? | atrial depolarization - systole starts |
| what happens at the QRS point of an ECG? | ventricular depolarization - beginning of ventricular contraction |
| at the T point of an ECG, ventricular ___ takes place | repolarization |
| ventricles are depolarized at the ___ segment | ST |
| at the PR segment, atrial __ and ___ takes place | depolarization & AV node conduction |
| condition of rapid & irregular heart contractions | fibrillation |
| in fibrillation, blood vessels ___ | aren't coordinated enough to deliver blood |
| aorta is the __ | major systemic artery - arises from left ventricle of heart |
| heart murmurs are common in: | children |
| the amount of blood pumped out of the ventricles to the body per minute is: | cardiac output |
| the heart rate is set by the__ | SA node |
| heart rate units: | beats/min |
| stroke volume units: | ml/beat |
| the normal stroke volume is__ | 70 ml/beat |
| maximum amount of blood AFTER contractions is known as: | End systolic volume (ESV) |
| End diastolic volume (EDV) | maximum amount of blood BEFORE contractions |
| cardiac output = | heart rate x stroke volume |
| the amount of blood pumped out of your heart with each heartbeat is known as__ | stroke volume |
| average adult CO | 75 beats/min (5.25L/min) |
| cardiac output has a direct relationship with __ | heart rate & stroke volume |
| the volume pumped by each ventricle is the same, however.... | the pressure is different |
| pressure is higher in which ventricle?" | left |
| how do you calculate stroke volume? | EDV-ESV |
| EDV is determined by __ | length of ventricular diastole & venous return |
| ESV is determined by ___ | arterial blood pressure & force of ventricular contraction |
| ESV is usually __ ml | 50 |
| EDV is usually __ ml | 120 |
| frank-starling law states: | the greater the stretch, the greater the SV |
| preload is the degree to which cardiac muscle has stretched __ contarction | before |
| preload means increase in __ which means increase in __ | EDV - SV |
| low venous return results from __ | blood loss of rapid heart rate - doesn't allow time for ventricular filling |
| excersise __ venous return through sympathetic activation & __ | increases - squeezing action of skeletal muscles on veins |
| more calcium that enters, __ the contractions | stronger |
| increase in contractility means ___ | more blood is ejected, ESV decreases while SV increases |
| afterload is normally __ mmHg in the aorta | 80 |
| the CAC and CIC are located where? | medulla |
| the cardioaccelatory system (CAC) is more global, therefore it talks to the __ while the cardioinhibitory system (CIC) talks to the __ | SA node, AV node and other parts of heart - SV & AV nodes |
| the CAC can effect ___, while the CIC effects the __ | contractility - heart rate |
| exercise acts through the __ nervous system | sympathetic |
| baroreceptors respons to : | blood pressure changes |
| blood pressure changes when __ changes | cardiac output |
| atrial reflex is initiated by: | increase in venous return |
| when one autonomic division is activated by sensory input, the other is ___ | temporarily inhibited |
| what is contractility? | muscle cells ability to move by shortening |
Created by:
Mariahj25
Popular Anatomy sets