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SP 10RG: The Cardiac Cycle
SP 10RG: The Cardiac Cycle Notecards
104
Physiology
Undergraduate 3
11/16/2012

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Term
What are the five mechanical events of the cardiac cycle?
Definition
1) Late diastole
2) Artial systole
3) Isovolumic ventricular contraction
4) Ventricular ejection
5) Isovolumic ventricular relaxation
Term
__________ __________ occurs when both sets of chambers are relaxed and ventricles fill passively.
Definition
1) Late diastole
Term
What is late diastole?
Definition
1) When both sets of chambers are relaxed and ventricles fill passively
Term
__________ __________ is when atrial contraction forces a small amount of additional blood into ventricles.
Definition
1) Atrial systole
Term
What is atrial systole?
Definition
1) When a small amount of additional blood is forced into the ventricles by atrial contraction
Term
__________ __________ __________ is the first phase of ventricular contraction pushes AV valves closed but does not create enough pressure to open semilunar valves.
Definition
1) Isovolumic ventricular contraction
Term
What is isolvolumic ventricular contraction?
Definition
1) First phase of ventricular contraction which pushes AV valves closed by does not create enough pressure to open semilunar valves
Term
__________ __________ is when the semilunar valves open and blood is ejected due to ventricular pressure rises and exceeding the pressure in the arteries.
Definition
1) Ventricular ejection
Term
What is ventricular ejection?
Definition
1) When the ventricular pressure rises and exceeds the pressure in the arteries, forcing the semilunar valves to open and blood to be ejected
Term
__________ __________ __________ is when the pressure in ventricles falls and blood flows back into the cusps of the semilunar valves and snaps them closed due to ventricles relaxing.
Definition
1) Isovolumic ventricular relaxation
Term
What is isolvolumic ventricular relax
Definition
1) As the ventricles relax, pressure in ventricles fall allowing blood to flow back into the cusps of semilunar valves and snaps them closed
Term
__________ __________ is calculated from multiplying the heart rate by the stroke volume.
Definition
1) Cardiac output
Term
__________ __________ is controlled by the ANS.
Definition
1) Heart rate
Term
What is cardiac output?
Definition
1) The result of heart rate being multiplied by stroke volume
Term
Without the ANS, the SA node fires at what rate?
Definition
1) 90-100x a minute
Term
What does the cardiac output depends on?
Definition
1) Heart rate
2) Stroke volume
Term
The __________ __________ consists of the beats of the heart per minute.
Definition
1) Heart rate
Term
The __________ __________ consists of the output of each ventricle per minute.
Definition
1) Cardiac output
Term
The __________ __________ is the output of each ventricle per beat.
Definition
1) Stroke volume
Term
What is the average cardiac output?
Definition
1) 5-6 L/min
Term
What is the average heart rate?
Definition
1) 60-80 beats/min
Term
What is the average stroke volume?
Definition
1) 70-80 mL/beat
Term
Changing __________ __________ is the most common way to change cardiac output; __________ __________ often remains relatively constant.
Definition
1) Heart rate
2) Stroke volume
Term
What is the most common way to change cardiac output?
Definition
1) Heart rate
Term
__________ __________ is varied by altering the balance of parasympathetic and sympathetic influence on SA node?
Definition
1) Heart rate
Term
__________ stimulation slows heart rate; __________ stimulation speeds it up.
Definition
1) Parasympathetic
2) Sympathetic
Term
What is the effect of the parasympathetic stimulation on the SA node?
Definition
1) Decreases the rate of depolarization to threshold; decreases the heart rate.
Term
What is the effect of sympathetic stimulation on the SA node?
Definition
1) Increases the rate of depolarization to the threshold; increases the heart rate
Term
What is the effect of the parasympathetic stimulation on the AV node?
Definition
1) Decreases excitability; increases the AV nodal delay
Term
What is the effect of the sympathetic stimulation on the AV node?
Definition
1) Increases excitability; decreases the AV nodal delay
Term
What is the effect of the parasympathetic stimulation on the ventricular conduction pathway?
Definition
1) No effect
Term
What is the effect of the sympathetic stimulation on the ventricular conduction pathway?
Definition
1) Increases excitability; hastens conduction through the bundle of His and Purkinje cells
Term
What is the effect of the parasympathetic stimulation on the atrial muscle?
Definition
1) Decreases contractility; weakens contraction
Term
What is the effect of the sympathetic stimulation on the atrial muscle?
Definition
1) Increases contractility; strengthens contraction
Term
What is the effect of the parasympathetic stimulation on ventricular muscle?
Definition
1) No effect
Term
What is the effect of the sympathetic stimulation on ventricular muscle?
Definition
1) Increases contractility; strengthens contraction
Term
What is the effect of the parasympathetic stimulation on the adrenal medulla?
Definition
1) No effect
Term
What is the effect of the sympathetic stimulation on the adrenal medulla?
Definition
1) Promotes adernomedullary secretion of epinephrine, a hormone that augments the sympathetic nervous system's actions on the heart
Term
What is the effect of the parasympathetic stimulation on the veins?
Definition
1) No effect
Term
What is the effect of the sympathetic stimulation on the veins?
Definition
1) Increases venous return, which increases the strength of cardiac contraction through the Frank-Starling mechanism
Term
What are the effects on the heart rate by norepinephrine and epinephrine?
Definition
1) Increases inward movement of Na+ and Ca2+ through the If and T-type Ca2+ channels
2) Reduces AV delay by increasing conduction velocity enhancing the slow, inward Ca2+ current
3) Speeds the spread of action potentials throughout the specialized conduction system
4) Increases the contractile strength of contractile cells effect produced by increased inward of Ca2+ movement through prolonged opening of L-type Ca2+ channels, which ehance the slow Ca2+ influx and intensifies Ca2+ participation in Excitation-Contraction coupling
5) Not only increase the speeds of contraction by allowing great influx of Ca2+ into the cell but it also speeds up relaxation by enhancing the active Ca2+ pump in sacroplasmic reticulum, and removes Ca2+ from the cytosol.
Term
What are the effects on the heart rate by acetylcholine?
Definition
1) Increased flow through K+ channels and decreased flow through Ca2+ channels
2) Enhances K+ permeability and hyperpolarizes the SA node membrane
3) By enhancing K+ permeability, vagal stimulation also opposes the automatic reduction on K+ permeability that contributes to the development of pacemaker potential
4) Acetylcholine by inhibiting cAMP pathway also depresses both inward movement of Na+ and Ca+
Term
__________ stimulation is a positive chronotrope on the regulation of heart rate.
Definition
1) Sympathetic
Term
__________ stimulation is a negative chronotrope on the regulation of heart rate.
Definition
1) Parasympathetic
Term
Sympathetic stimulation of __________ __________ __________ __________ increases the rate of spontaneous depolarization; this increases __________ __________.
Definition
1) SA nodal beta receptors
2) Heart rate
Term
Sympathetic stimulation increases conduction velocity through the __________ __________ and other parts of the conduction system, decreasing the duration of __________.
Definition
1) AV node
2) Systole
Term
Parasympathetic stimulation of __________ __________ __________ __________ decrease the rate of spontaneous depolarization, decreasing __________ __________.
Definition
1) SA nodal muscarinic receptors
2) Heart rate
Term
Parasympathetic stimulation decreases conduction velocity through the __________ __________ and other parts of the conduction system, resulting in the increased duration of __________.
Definition
1) AV node
2) Systole
Term
Epinephrine is a __________ chronotrope secreted by the __________ __________ in response to sympathhetic activity.
Definition
1) Positive
2) Adrenal medulla
Term
Epinephrine reinforces the effects of __________ stimulation on heart rate.
Definition
1) Sympathetic
Term
Stimulation of SA nodal beta receptors by epinephrine increases the rate of spontaneous __________ and increases __________ __________.
Definition
1) Depolarization
2) Heart rate
Term
Epinephrine increases the conduction velocity through the __________ __________ and other parts of the conduction system resulting in the decreased duration of __________.
Definition
1) AV node
2) Systole
Term
What are three examples of positive inotropics?
Definition
1) Adrenocortical steroids
2) Insulin
3) Pituitary hormones
Term
__________ __________ increase rate and contractility of the heart, with effects that are both direct and indirect via sympathetics.
Definition
1) Thyroid hormones
Term
Purpose of thyroid hormones?
Definition
1) Increase the rate and contractility of heart rate
Term
Heart rate is regulated by the ANS through __________ __________ __________ in the medulla oblongata in the brain stem.
Definition
1) Cardiac control centers
Term
Where are cardiac control centers which regulate heart rate located in the body?
Definition
1) Within the medulla oblongata in the brain stem
Term
What are the two cardiac control centers?
Definition
1) Cardiacaccelerator center (V.M.C.)
2) Cardiacinhibitory center (C.I.C.)
Term
What is the cardiacaccelerator center responsible for regulating? The cardiacinhibitory center?
Definition
1) Sympathetic fibers
2) Parasympathetic fibers
Term
What factors affect the two control centers in the brain?
Definition
1) Higher brain areas
2) Sensory feedback from press receptors (baroreceptors) in the aorta and carotid arteries
Term
What type of feedback do baroreceptor afferents provide to the medulla? What are the types of afferents?
Definition
1) Negative
2) Arterial (pressure)
3) Cardiopulmonary (volume)
Term
What type of feedback do chemoreceptor afferents provide to the medulla? What are the types of afferents?
Definition
1) Positive
2) Arterial
Term
What type of feedback do other afferents provide to the medulla?
Definition
1) Positive or negative
Term
What is the pathway from sympathetic neurons (NE) to increasing heart rate?
Definition
1) Sympathetic neurons (NE)
2) B1 receptors of autorhythmic cells
3) Na+ and Ca2+ influx increase
4) Increases the rate of depolarization
5) Heart rate increases
Term
What is the pathway from parasympathetic neurons (acetylcholine) to decreasing heart rate?
Definition
1) Parasympathetic neurons (acetylcholine)
2) Muscarinic receptors of autorhythmic cells
3) Increases K+ efflux and decreases Ca2+ influx
4) Hyperpolarizes cell and decreases the rate of depolarization
5) Decreases the heart rate
Term
What are the three variables which regulate stroke volume?
Definition
1) EDV (preload)
2) Contractility (strength of contraction)
3) Total peripheral resistance (afterload)
Term
__________ __________ is determined by the extent of venous return and by sympathetic activity.
Definition
1) Stroke volume
Term
What is stroke volume determined by?
Definition
1) The extent of venous return and by sympathetic activity
Term
What are the two types of controls that effect stroke volume? How do they effect stroke volume?
Definition
1) Intrinsic control (preload and afterload)
2) Extrinsic control
3) Increase stroke volume by increasing the strength of heart contractions
Term
What are five factors that affect venous pressure?
Definition
1) Venoconstriction
2) Skeletal ms pump
3) Pressure differential
4) Arterial pulsation
5) Venous tone and capacity
Term
What are two factors that affect blood volume?
Definition
1) Urine volume
2) Tissue-filed volume
Term
What is responsible for regulating urine volume?
Definition
1) The kidneys
Term
__________ is tissue-fluid volume.
Definition
1) Oedema
Term
What two factors affect contractility?
Definition
1) Starling's law of the heart (intrinsic control)
2) SNS (extrinsic control)
Term
Normally, the strength of contraction is sufficient to eject __________-__________ mL/beat out of total EDV of __________-__________ mL.
Definition
1) 70-80
2) 110-120
Term
__________ are extrinsic chronotropic factors.
Definition
1) Chronotropes
Term
What are chronotropes?
Definition
1) Extrinsic chronotropic factors
Term
__________ have an effect on heart rate such as pacemaker potential and conduction velocity.
Definition
1) Chronotropes
Term
__________ are extrinsic and intrinsic inotropic factors that have an effect on stroke volume such as contractility and force of ventricular contraction.
Definition
1) Inotropes
Term
What are inotropes?
Definition
1) Extrinsic and intrinsic inotropic factors that have an effect on stroke volume stoke volume
Term
What do chronotropes affect? Inotropes?
Definition
1) Heart rate
2) Inotropes
Term
What is EDV? ESV?
Definition
1) End-diastolic volume
2) End-systolic volume
Term
What does the Frank-Starling Law of the Heart state?
Definition
1) That the heart normally pumps out during systole the volume of blood returned to it during diastole
Term
What describes the relationship between the EDV and stroke volume?
Definition
1) Frank-Starling Law of the Heart
Term
What are two factors that affect stroke volume?
Definition
1) Ventricular contractility
2) End diastolic volume (EDV)
Term
What are two factors that affect ventricular contractility?
Definition
1) Sympathetic activity
2) Epinephrine
Term
As EDV increases, the __________ __________ force also increases.
Definition
1) Ventricular contraction
Term
As afterload increases, the __________ __________ __________ also increases.
Definition
1) End systolic volume (EVS)
Term
What occurs as contractility increases?
Definition
1) Ejection fraction increases
Term
What occurs as EDV increases?
Definition
1) Ventricular contraction force increases
Term
What occurs as afterload increases?
Definition
1) End systolic volume (ESV) increases
Term
__________ refers to end diastolic volume.
Definition
1) Preload
Term
What is preload?
Definition
1) Refers to end diastolic volume
Term
What occurs due to an increase in filling pressure of the heart?
Definition
1) Increased preload
Term
__________ can be described as the pressure that the chamber of the heart has to generate in order to eject blood out of the chamber, and thus is a consequence of the aortic pressure, since the pressure in order to open the aortic valve.
Definition
1) Afterload
Term
What is afterload?
Definition
1) The pressure that the chamber of the heart has to generate in order to eject blood out of the chamber, and thus is a consequence of the aortic pressure, since the pressure in order to open the aortic valve.
Term
What factors can cause end diastolic volume (EDV) increase?
Definition
1) Heart rate decreases -> filling time increases -> venous return increases -> atrial pressure increases
2) Central venous pressure increases -> venous return increases -> atrial pressure increases
3) Atrial contraction causes atrial pressure to increase
Term
What is the EDV, stroke volume, and ESV for a normal stroke volume?
Definition
1) EDV: 135 mL
2) Stroke volume: 70 mL
3) ESV: 65 mL
Term
What is the EDV, stroke volume, and ESV for a stroke volume during sympathetic stimulation?
Definition
1) EDV: 135 mL
2) Stroke volume: 100 mL
3) ESV: 35 mL
Term
What is the EDV, stroke volume, and ESV for a stroke volume with combination of sympathetic stimulation and increased end-diastolic volume
Definition
1) EDV: 175 mL
2) Stroke volume 140 mL
3) ESV 35 mL
Term
The more the __________ muscle is stretched, the stronger the __________.
Definition
1) Cardiac
2) Contraction
Term
__________ __________ is a vasodynamic parameter that relates the cardiac output to the body surface area, thus relating heart performance to the size of the individual.
Definition
1) Cardiac output
Term
The normal range of the cardiac index is __________-__________ L/min per square meter.
Definition
1) 2.6-4.2
Term
Cardiac output is a function of what two factors?
Heart rate is determined by what factor? Stroke volume?
The rate of depolarization in autorhythmic cells decreases because of what? What increases it?
The force of contraction in ventricular myocardium is influenced by what factors?
EDV varies with what? What is this aided by?
Definition
1) Heart rate and stroke volume
2) Heart rate: Rate of depolarization in autorhythmic cells
Stroke volume: Force of contraction in ventricular myocardium
3) Decrease: Parasympathetic intervention
Increase: Sympathetic innervation and epinephrine
4) Contractility and EDV
5) Venous return
6) Skeletal muscle pump and a respiratory pump
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