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Biomed II Test 2
Cardiac cycle, Hemodynamics, EKG
| Question | Answer |
|---|---|
| what forms the conduction system of the heart? | autorhythmic fibers |
| which cardiac muscle fibers are self excitable? | autorhymic fibers |
| what are contractile fibers? | contracting atrial and ventricular muscle fibers |
| where are the sinoatrial (SA) node located? | cluster of cells in the wall of right Atrium |
| what are the sinoatrial (SA) nodes? | spontaneously and repeatedly depolarize to threshold which triggers an action potential each action potential spreads to both atria and two atrial contract at the same time |
| where is the atrioventricular (AV) node located? | interatrial spetum |
| what does the atrioventricular (AV) node do? | receives action potentials from atrial muscle fibers conducts action potential more slowly allowing atria to empty their blood into ventricles |
| how does the heart conduct? | SA node--> AV node--> atrioventricular bundle--> right and left bundle branches-->Purkinje Fibers |
| where are the atrioventricular (AV) bundle or bundle of His located | connection between atria and ventricles, divides into right and left bundle branches extend through the interventricular septum towards the apex of the heart |
| what are the Purkinje Fibers? | large diameter fibers that conduct the action potential from the apex of the heart upward to the remainder of the ventricular myocardium ventricles contract pushing blood upward towards the semilunar valves |
| what sets the rhythm of the conduction system? | SA node, it is the natural pacemaker |
| if the SA node is damaged what picks up the rhythm of conduction system? | slower AV node |
| if both SA and AV nodes are suppressed what picks up the rhythm of the conduction system | autorhythmic fibers in the ventricles will take the pacemaking task |
| what happens during depolarization? | due to Na+ inflow when voltage gated fast Na+ channels opening |
| what happens during plateau phase? | Ca2+ inflow when voltage gated slow Ca2+ Ca2+ binds troponin to allow for actin and myosin filaments to slide past one another channels open and K+ outflow when some K+ channels open |
| what happens during repolarization? | closure of Ca2+ channels and K+ outflow when additional voltage gated K+ channels open |
| what is an ECG | a recording of the electrical signals generated when action potentials spread through the heart |
| what is an electrocardiograph? | the instrument that records ECG |
| what is the P wave | represents atrial depolarization |
| what is the QRS complex? | represents ventricular depolarization |
| what is the T wave? | represents ventricular repolarization |
| what is the P-Q interval | extends from the beginning of the P wave to the beginning of the QRS complex represents the conduction time from beginning of the atrial excitation to the beginning of the ventricular excitation |
| what is the S-T interval? | extends from the end of the S wave to the beginning of the T wave represents the time when ventricular contractile fibers are depolarized during the plateau phase |
| What is the Q-T interval? | extends from the beginning of the QRS complex to the end of the T wave represents the time from the beginning of ventricular depolarization to the end of ventricular repolarization |
| what is a cardiac cycle? | includes all the events associated with one heartbeat |
| systole is... | contraction |
| diastole is... | relaxation |
| what is the end diastolic volume or EDV? | the blood volume in ventricle at the end of its diastole 130mL |
| what is the end systolic volume or ESV? | the blood volume in ventricle at the end of its systole 60mL |
| what is the stroke volume or SV? | the volume ejected per beat from each ventricle 70mL |
| how do you calculate stroke volume? | EDV minus ESV |
| what is isovolumetric contraction? | a brief period, AV vales close before SL valves open cardiac muscle fibers are contracting but are not yet shortening, ventricular blood volume does not change |
| what is ventricular ejection? | SL valves open and blood is ejected from the heart |
| what is isovolumetric relaxation? | occurs as ventricles relax, SL valves close before AV valves open, ventricular volume does not change |
| what is rapid ventricular filling | blood flows from full atria |
| what is diastasis? | blood flows from atria in smaller volume |
| what is auscultation? | act of listening to sounds within the body with a stethoscope |
| where does the sounds of a heartbeat come from? | turbulence in blood flow caused by the closing of the heart valves |
| which heart sounds only be heard through a stethoscope? | S1 and S2 |
| S1 or lubb sound is created when | first heart sound caused by blood turbulence associated with the closing of AV valves |
| S2 or dupp sound is created when | caued by blood turbulence associated with the closing of the SL valves |
| which sound is a little bit longer and louder than S2? | S1 |
| S3 is created when | blood turbulence during rapid ventricular filling |
| S4 is created when | blood turbulence during atrial systole |
| what is the cardiac output? (CO) | volume of blood ejected from the left ventricle (or right ventricle NOT BOTH) into the aorta (or pulmonary trunk) each minute |
| how do you calculate cardiac output? | stroke volume times heart rate |
| what is heart rate | the number of heartbeats each minute |
| what is cardiac reserve? | the difference between a person's maximum cardiac output and cardiac output at rest |
| what is a normal cardiac reserve for average person | 4-5 times 7-8 for an athelete |
| what are the factors that regulate stroke volume | preload, contractility, afterload |
| what is preload? | the degree of stretch on the heart before it contracts |
| what is the frank starling law of the heart? | the more the heart fills with blood during diastole, the greater the force of contraction during systole |
| the greater the EDV... | the more forceful the ventricle contraction |
| what is contractility? | strength of myocardial contraction |
| what increases contractility? | stimulation of the sympathetic autonomic nervous system, hormones epinephrine and norepinephrine and increased Ca2+ level in interstitial fluid |
| what decreases contractility? | inhibition of sympathetic autonomic nervous system, increased K+ level in interstitial fluid |
| what is afterload? | the pressure that must be exceeded before ejection of blood from the ventricles can occur |
| afterload increases as... | blood pressure increases |
| what regulates heart rate? | autonomic nervous system, hormones, cation ions, others |
| what do proprioceptors do? | monitor the position of limbs and muscles |
| what do chemoreceptors do? | monitor chemical changes in the blood |
| what do baroreceptors do? | located in the arch of the aorta and carotid arteries, detect changes in blood pressure |
| sympathetic nervous impulses via cardiac accelerator nerves release... | norepinephrine |
| parasympathetic nervous impulses via vagus nerves release | acetylcholine |
| sympathetic nervous impulses are via | cardiac accelerator nerves |
| parasympathetic nervous impulses are via | vagus nerves |
| norepinephrine release from sympathetic nervous system does what | increases heart rate, increases contractility, increases stroke volume |
| acetylcholine released from parasympathetic nervous system does what | decrease the heart rate |
| hormones epinephrine, norepinephrine and thyroid hormone do what? | increase heart rate and contractility |
| high blood levels of Na+ or K+.. | decrease heart rate and contractility as blood levels of Na+ or K+ increase |
| as interstitial Ca2+ levels increase | heart rate and contractility increase as the interstitial Ca2+ level increase |
| what happens in left side heart failure? | pump becomes less effective so more blood remains in ventricle, heart is overstretched, blood backs up in lungs as pulmonary edema, fluid accumulation in the lungs causes suffocation |
| what happens in right side heart failure | blood backs up in the systemic veins, fluid builds up in tissues as peripheral edema |
| % of blood in systemic veins and venules with blood reservoirs | 60% |
| % of blood in pulmonary vessels | 12% |
| % of blood in heart | 8% |
| % of blood systemic arteries and arterioles | 15% |
| % of blood in systemic capillaries | 5% |
| what is blood flow | the volume of blood that flows through any tissue in a given time period |
| what is hemodynamics? | the forces involved in circulating blood throughout the body |
| what does total volume of blood flow equal? | cardiac output or the volume of blood that circulates through systemic (or pulmonary blood vessels each minute |
| how do you calculate cardiac output? | stoke volume times heart rate |
| what is blood pressure? | pressure exerted by blood on the walls of a blood vessel caused by contraction of the ventricles |
| where is blood pressure highest? | aorta |
| what is the mean arterial pressure or MAP | the average blood pressure in arteries Cardiac output times systemic vascular resistance |
| what are the factors affecting blood pressure | Cardiac output, vascular resistance and blood volume |
| if cardiac output increases, what does that do to blood pressure? | blood pressure increases due to an increases in stroke volume or heart rate |
| what is vascular resistance? | opposition to blood flow due to friction between blood and the walls of blood vessels |
| what does vascular resistance rely on? | size of the blood vessel lumen, blood viscosity and total blood vessel length |
| blood viscosity depends on | ratio of red blood cells to plasma volume increases in blood viscosity increase resistance |
| what is systemic vascular resistance normally derived from? | arterioles, capillaries and venules |
| what is systemic vascular resistance? | all the vascular resistance offered by systemic blood vessels |
| what is the major function of arterioles | control systemic vascular resistance (blood pressure and blood flow) by changing their diameters |
| what is venous return? | the volume of blood flowing back to the heart through the systemic veins |
| what does the venous return depend on | the pressure difference from venues to right atrium |
| pressure increases in the right atrium or ventricle...what happens to venous return? | it will decrease |
| what are the mechanisms that drive venous return? | heart pump, skeletal muscle pump, respiratory pump |
| what drives the heart pump? | pressure generated by contractions of the heart's left ventricle |
| what drives the skeletal muscle pump? | contraction of muscles and presence of valves |
| what drives respiratory pump? | decreased thoracic pressure and increased abdominal pressuring during inhalation, moves blood into thoracic veins and the right atrium |
| where is velocity of blood flow slower | arterial branches |
| what is a normal pulse? | 70-80 |
| tachycardia is... | pulse rate over 100 beats per minute |
| bradycardia is... | pulse rate under 60 |
| what is a pulse? | alternate expansion and recoil of elastic artery after each systole of the left ventricle |
| systolic blood pressure comes from... | ventricular contraction |
| diastolic blood pressure comes from.... | ventricular relaxation |
| what is pulse pressure? | the difference between systolic and diastolic, usually 40 mmhg |
| where is the cardiovascular center located and what does it do? | medulla oblongata and help regulate heart rate and stroke volume |
| cardiac accelerator nerves are... | sympathetic nerves and increases heart rate and contractility |
| vagus X nerves are... | parasympathetic nerves and decrease heart rate |
| vasomotor nerves are... | sympathetic and vasoconstrict blood vessels |
| what are the baroreceptor reflexes? | carotid sinus reflex and aortic reflex |
| what is carotid sinus reflex? | baroreceptors in wall of carotid sinuses send nerve impulses to cardiovascular center in medulla via glossopharyngeal nerves regulate blood pressure in the brain |
| what is aortic reflex? | baroreceptors in the wall of ascending aorta send nerve impulses to cardiovascular center via vagus nerves that regulate general systemic blood pressure |
| what does a negative feedback regulation of blood pressure via baroreceptors look like? | blood pressure falls so baroreceptors are stretched less and send decreased nerve impulses to cardiovascular center that reduces parasympathetic and increases sympathetic stimulation of the heart so blood pressure increases to normal |
| what is a carotid sinus massage? | stimulation by careful neck massage over the carotid sine to slow heart rate |
| where are chemoreceptors located | carotid bodies and aortic bodies to detect the changes in blood levels of 02, CO2 and H+ |
| what does angiotensin II do? | raises blood pressure by vasoconstriction and secretion of aldosterone which increases reabsorption of sodium ions and water by the kidneys |
| what does epinephrine and norpeinephrine do to vasoconstric and vasodilate? | sympathetic stimulation causes adrenal medulla to releases and cause vasoconstriction of arterioles and veins in skin and abdominal organs but vasodilation of arterioles in cardiac and skeletal muscles |
| what does antidiuretic hormone do? | causes vasoconstriction |
| what does atrial natriuretic peptide do? | lowers blood pressure and causes vasodilation and loss of salt and water in the urine |
| systemic vessels dilate in response to low levels of... | O2 |
| pulmonary vessels constric in response to low levels of... | O2 |
| what is diffusion | substances move down their concentration gradients, move in and out of a capillary |
| what does not allow diffusion of water soluble materials? | blood brain barrier because it is non fenestrated epithelium with tight junctions |
| how do substances move in diffusion | through intercellular clefts or fenestrations, diffusing across lipid bilayers of endothelial cells |
| what is transcytosis | passage of materials across endothelium in tiny vesicles by endocytosis and exocytosis |
| what usually moves by transcytosis? | large lipid insoluble molecules such as insulin |
| what is bulk flow | movement of large amounts of dissolved or suspended materials in the same direction (area of high pressure to an area of low pressure) |
| how do O2, CO2 move? | lipid soluble substances pass through the endothelial cells |
| how do Na+, K+, glucose and amino acids move? | small water soluble substances pass through pores |
| what can generally not pass through the capillary wall? | plasma proteins |
| what is blood hydrostatic pressure or BHP? | due to the pressure that water in blood plasma exerts against blood vessel walls, pushes fluid out of capillaries into interstitial fluid |
| what is interstitial fluid hydrostatic pressure or IFHP? | opposing pressure of the interstitial fluid, pushes fluid from interstitial space back into capillaries |
| what is blood colloid osmotic pressure or BCOP? | force caused by the colloidal suspension of large proteins in plasma, pull fluid from interstitial spaces into capillaries |
| what is interstitial fluid osmotic pressure? (IFOP)? | pulls fluid out of capillaries into interstitial fluid |
| what is filtration? | movement of materials from blood into interstitial fluid promoted by blood hydrostatic pressure and interstitial fluid osmotic pressure |
| what is reabsorption? | movement of materials from interstitial fluid into capillaries promoted by blood colloid osmotic pressure |
| what is net filtration pressure? | balance of all pressures, determines whether fluids leave or enter capillaries |
Created by:
Chobchi
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