Term
| As heart rate goes up, does stroke volume rise or fall? |
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Definition
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Term
| As stroke volume goes up, does heart rate increase or decrease? |
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Definition
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Term
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Definition
| Persistent resting heart rate in adults over 100bpm |
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Term
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Definition
| Persistent resting heart rate in adults below 60bpm |
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Term
| Positive chronotropic agents |
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Definition
| Factors that raise heart rate |
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Term
| Negative chronotropic agents |
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Definition
| Factors that lower heart rate |
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Term
| Where in the brain are the cardiac centers located? |
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Definition
| Reticular formation of the medulla oblongata |
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Term
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Definition
| A region in the brainstem that is involved in multiple tasks such as regulating the sleep-wake cycle and filtering incoming stimuli to discriminate irrelevant background stimuli |
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Term
| What does it mean if neurons in the reticular formation of the medulla oblongata have a cardiostimulatory effect? |
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Definition
| They transmit signals to the heart via sympathetic pathway |
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Term
| What type of pathway transmits signals from the medulla to the heart - sympathetic or parasympathetic? |
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Definition
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Term
| Are the sympathetic postganglionic fibers adrenergic or dopaminergic? |
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Definition
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Term
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Definition
| Having to do with adrenaline (epinephrine) and/or noradrenaline (norepinephrine) |
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Term
| What do the postganglionic sympathetic fibres release? |
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Definition
| Norepinephrine (noradrenaline) |
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Term
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Definition
| In the autonomic nervous system, fibers from the ganglion to the effector organ |
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Term
| What does noradrenaline bind to in the heart? |
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Definition
| ß-adrenergic fibers in the heart |
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Term
| What does the binding of ß-adrenergic fibers in the heart to noradrenaline activate? |
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Definition
| Cyclic adenosine monophosphate (cAMP) second messenger system in the cardiocytes and nodal cells |
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Term
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Definition
| Cyclic adenosine monophosphate (cAMP) - a second messenger system in the cardiocytes and nodal cells |
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Term
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Definition
An enzyme that phosphorylates and opens a calcium channel in the plasma membrane
And also ccelerates uptake of Ca2+ by sarcoplasmic reticulum |
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Term
| What is the effect of the inflow of calcium ions in the plasma membrane of cardiocytes? |
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Definition
| Accelerates depolarisation of the SA node and contraction of the cardiocytes - speeds up the heart |
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Term
| What is the effect of cAMP accelerating the uptake of Ca2+ by sarcoplasmic reticulum? |
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Definition
| Enables cardiocytes to relax more quickly |
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Term
| What is the effect of noradrenaline and cAMP accelerating both contraction and relaxation of the heart? |
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Definition
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Term
| Why does cardiac output peak at 160-180bpm? |
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Definition
| Any higher and the ventricles have too little time to fill between heart beats |
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Term
| What type of effects do parasympathetic vagus nerves have on the SA and AV nodes? |
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Definition
| Cholinergic, inhibitory effects |
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Term
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Definition
| Typically refers to acetylcholine in the neurological sense |
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Term
| What does acetylcholine (ACh) bind to in the SA and AV nodes? |
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Definition
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Term
| What is the effect of acetylcholine (ACh) binding to muscarinic receptos in nodal cells? |
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Definition
| Opens K+ gates and they become hyperpolarised, fire less frequently, the heart slows down |
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Term
| Do sympathetic or parasympathetic nerves act faster on the heart? |
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Definition
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Term
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Definition
| Steady background firing of the vagus nerves |
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Term
| What is the benefit of placing heart rate under influence of cardiac centers in medulla? |
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Definition
| Centers receive input from many other sources and integrate into reaction |
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Term
| Which chemical has the greatest chronotropic effect? |
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Definition
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Term
| What three variables govern stroke volume? |
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Definition
| Preload, contractility, and afterload |
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Term
| Do increased preload or contractility cause an increased or decreased stroke volume? |
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Definition
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Term
| Does an increase in afterload cause an increase or decrease in stroke volume? |
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Definition
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Term
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Definition
| The amount of tension in the ventricular myocardium immediately before it begins to contract |
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Term
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Definition
| How hard the myocardium contracts for a given preload |
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Term
| Positive ionotropic agents |
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Definition
| Factors that increase contractility |
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Term
| Negative ionotropic agents |
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Definition
| Factors that reduce contractility |
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Term
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Definition
| The blood pressure in the aorta and pulmonary trunk immediately distal to the semilunar valves - it opposes these valves and thus limits stroke volume |
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