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heart part 2
| Question | Answer |
|---|---|
| describe a single cardiac cycle | the period between the start of one hb and the beginning of the next |
| in systole contraction the chamber contracts, pushes blood into an adjacent chamber or into an _____. During diastole, the ___ | arterial trunk, chamber fills with blood and prepares for the next contraction |
| when heart rate increases, all phases of the cardiac cycle are shortened. The greatest reduction occurs in the length of time spent in __ | diastole |
| what is the 1st phase in ventricular systole ? | 1. ventricular contraction pushes AV valves closed, but "does NOT" create enough pressure to open semilunar valves. |
| what is the 2nd phase in ventricular systole ? | 2. ventricular pressure RISES, exceeds pressure in arteries, semilunar valves open and blood is forced out of ventricle |
| what is isovolumetric contraction? | when ventricle contraction pushes AV valves closed but does not produce enough pressure to open the semilunar valves |
| what is ventricular ejection? | when blood is forced out of the ventricle when semi lunar valves open due to ventricular pressure |
| what happens during "early" ventricular diastole? | ventricles relax and pressure drops, cusps of semi lunar valves close |
| blood flows into the relaxed atria but the AV valves remain closed, this is known as? | isovolumetric relaxation |
| what happens during "late" ventricular diastole? | ALL chambers are relaxed, ventricles fill 70% of their final volume |
| a sequence of systole and diastole last about ___ msec, and the ventricular diastole last ____ msec | 800, 530 |
| when semi lunar valves close, pressure rises as the elastic arterial walls recoil. This small RISE produces a valley in the pressure tracking called a ___ | dicrotic notch (dikrotos, double beating) |
| the best indicator of peripheral blood flow is ____, which is the amount of _____ | CO"cardiac output", blood pumped by the left ventricle in 1 min |
| cardiac output depends on two factors, what are they? How do u calculate cardiac output? | heart rate and stroke volume, HR x average stroke volume (SV) |
| ____ the amount of blood pumped out of the ventricle during a single heartbeat | stroke volume |
| cardiac muscle contracts on its own, in the absence of neural or hormonal stimulation. this property is called | automaticity |
| the ____ is a network of specialized cardiac muscle cells responsible for initiating and distributing the stimulus to contract | conducting system |
| each heart beat begins with an action potential generated at the ___ node. The SA node is embedded in the posterior wall of the _____ | SA, right atrium |
| in the atria, conducting cells are found in ____, which distribute the contractile stim. to atrial muscle cells as impulse travels toward ventricles | internodal pathways |
| the AV node contains ____, they do not ordinarily affect the hr. If the SA node or internodal pathways are damaged, the heart will___ | pacemaker cells, continue to beat |
| _____ propagate action potentials very rapidly-as fast as small myelinated axons. They are large-diameter conducting cells. | purkinje fibers |
| ___ are responsible for the depolarization of the ventricular myocardial cells that trigger ventricular systole. They are also the final link in the distribution network | purkinje cells |
| the AV node delivers the stimulus to the ____, located within the inter ventricular septum. And it is the only electrical connection between the atria and ventricles | AV bundle |
| the av bundle leads to the right and left ___ | bundle branches |
| clinicians can use an ECG to assess the performance of specific ___, ____, and ____ components | nodal, conducting, contractile |
| the small ___ wave accompanies the depolarization of the atria. | P |
| The atria begin contracting about 25 msec after the start of the ___ | P wave |
| the ___ complex appears as the ventricles depolarize. This is a relatively strong signal because the ventricular muscle is much more massive than that of the atria | QRS |
| The ventricles begin contracting shortly after the peak of the ___ | R wave |
| The ____ wave coincides with ventricular depolarization | T |
| A deflection corresponding to atrial repolarization is not apparent because | occurs while the ventricles are depolarizing, the electrical events are masked by the QRS complex |
| the ___ extends from the start of the atrial depolarization to the start of the QRS complex (ventricular depolarization) | P-R interval |
| the ___ indicates the time required for the ventricles to undergo a single cycle of depolarization and repolarization | Q-T |
| the Q-T interval is usually measured from the ____ rather than the ____ | end of the P-R interval, the bottom of the Q wave |
| filtration predominates at the arterial end of a capillary, where _____ is highest | capillary hydrostatic pressure |
| As filtration occurs, the plasma osmolarity, or _____ increases | blood colloid osmotic pressure( BCOP) |
| blood colloid osmotic pressure rises because ____ is departing but the larger solutes, especially soluble plasma proteins, are remaining behind | water |
| the difference between CHP _____ and BCOP ____ is known as the ____ | pushes water out, draws water in, net filtration pressure |
| central regulation involves__ | neural and endocrine mechanisms |
| autoregulation involves ___ | changes in the pattern of blood flow within capillary beds |
| hormones important in long term response to decline in blood pressure | ADH, angiotensin 2, EPO and aldosterone |
| neurotransmitters involved in decline of blood pressure (immediate response) | E and NE rom the adrenal medullae |
| (decline in bp)" endocrine response of kidneys" ____ is released when renal blood pressure and blood volume decrease | renin |
| renin release activates ____, which is converted in the lung capillaries to angiotensin 2 by _______ | angiotensin 1, angiotensin converting enzyme (ACE) |
| effects of angiotensin 2 ___ | vasoconstriction, ADH released, aldosterone secreted, thirst stimulated, increase RBC formation |
| excessive bood volume triggers a response though its effects on the walls of the heart. When the heart walls are abnormally stretched during diastole, cardiac muscle cells release _____ | natriuretic peptides |
| ANP atrial natriuretic peptide is produced by ___ in the wall of the right atrium, a related hormone called BNP brain natriuretic peptide is produced by _____ | cardiac muscle cells, ventricular muscle cells |
| Responses to ANP and BNP | increase NA loss in urine , increase H2O loss in urine, reduced thirst, inhibition of ADH, peripheral vasodilatation |
| chemoreceptor reflexes respond to changes in ___, ___, or ___ levels in blood | carbon dioxide, oxygen, pH |
| the chemoreceptors involved are sensory neurons located in the _____ and _____ bodies | carotid, aortic |
| chemoreceptors are stimulated in response to elevated co2 and decreased ph and o2 in blood and csf, what are the effects on the cardiovascular centers? | 1. cardoacceleratory centers stimulated 2. cardoinhibitory centers inhibited 3. vasomotor centers stimulated |
| as u begin a light exercise three interrelated changes take place: | 1. vasodilation occurs 2. respiratory pump (pulls blood into the venae cavae) 3. cardiac output rises |
| during heavy exercise, massive sympathetic stimulation may occur. The vasomotor centers restrict blood to the nonessential organs such as the digestive viscera. Only the blood supply to the ____ remains unchanged | brain |
| at rest cardiac output=____, light exercise cardiac output=_____, heavy exercise cardiac output=___ | 5800ml per min, 9500ml per min, 17500ml per min |
| trained athletes have ____ and ____ than do non athletes. | bigger hearts, larger stroke volumes |
| an athlete at rest can maintain normal blood flow to peripheral tissues at a heart rate as low as ___ bpm, and cardiac output of an athlete in peak condition can increase to levels ____ % higher than those of non athletes | 32, 50 |
| short-term responses to blood loss | 1. carotid and aortic reflexes increase cardiac output and cause vasoconstriction. 2. stimulation of sympathetic nervous system. 3. secretion of E and NE |
| long-term responses to blood loss | 1. recall of fluids from interstitial spaces 2. aldosterone and ADH promote fluid retention by kidneys 3. thirst increase 4. EPO stimulates maturation of RBCS |
| _____ involves a series of interlocking positive feedback loops that begin when blood losses exceed ___ percent of total blood volume | circulatory shock, 35 |
| ____ is an initial stage characterized by positive feedback loops that accelerate tissue damage | progressive shock |
| "progressive shock" reduced cardiac output accelerates oxygen starvation in peripheral tissues, and the resulting chemical changes promote ____ that further restricts peripheral blood flow | intravascular clotting |
| local pH changes increase capillary permeability, and this further reduces blood volume, this occurs in ____ shock | progressive shock |
| ____ occurs when arteriolar smooth muscles and pre capillary sphincters become unable to contract, despite the commands of the vasomotor centers | circulatory collapse |
| the result of circulatory collapse is ___, ___ and ____ | peripheral vasodilation, fatal decline in blood pressure, cessation of blood flow |
Created by:
btuehara
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