Cardiac Physiology Yr1FA23 Flashcards
Each cycle of cardiac contraction and relaxation is initiated by
depolarization of the sinus node.
True/false: The cycle of cardiac contraction and relaxation being initiated by the sinus node is seen on the EKG?
FALSE
The P wave records
atrial depolarization and contraction.
The first part of the P wave reflects
right atrial activity; the second part reflects left atrial activity.
(the PR segment)
There is a brief pause when the electrical current reaches the AV node and the EKG falls silent
ventricular conducting system
(bundle of His, bundle branches, and Purkinje fibers)
The first part of the ventricles to be depolarized
the interventricular septum.
Ventricular depolarization generates what on the EKG
the QRS complex.
The wave of depolarization then spreads along the ventricular conducting system (bundle of His, bundle branches, and Purkinje fibers) and out into the
Ventricular Myocardium
The T wave records
repolarization of the ventricular myocardium
Is Atrial Repolarization seen on the EKG?
NO
the time from the start of atrial depolarization to the start of ventricular depolarization.
The PR interval
the time from the end of atrial depolarization to
the start of ventricular depolarization.
The PR segment
the time from the end of ventricular
depolarization to the start of ventricular repolarization.
The ST segment
the time from the start of ventricular
depolarization to the end of ventricular repolarization.
The QT interval
measures the time of ventricular depolarization.
The QRS interval
Alpha 1 Receptor Site
Vascular Smooth Muscle
Heart
Alpha 1 Receptor Action
Arterial Vasoconstriction
Alpha 2 Receptor Site
Vascular Smith Muscle
Presynaptic Nerve terminal
Alpha 2 Receptor Action
Vasoconstriction of venous capacitance vessels
Local feedback, inhibition of norepi release
Beta 1 Receptor Site
Heart
Beta 1 Receptor Action
Increased inotropic and chronotropic activity
Increased Av node conduction velocity
Beta 2 Receptor Site
Vascular smooth muscle
Bronchial smooth muscle
Beta 2 Receptor Action
Vasodilation of peripheral vasculature
Bronchodilation
D1 Receptor Site
post-synaptic
Vascular smooth muscle
(renal, Splanchnic, cerebral)
Renal Tubules
D2 Receptor Action
Decreased norepi release
D2 Receptor Site
Presynaptic sympathetic nerve terminals
D2 Receptor Action
Decreased norepi release
V1 Receptor Site
Vascular smooth muscle
platelets
Hepatocytes
myometrium
V1 Receptor Action
Vasoconstriction
Platelet aggregation
Glycogenolysis
Myometrial contraction
V2 Receptor Site
Basolateral membrane of collecting duct
Vascular endothelium
Vascular smooth muscle
V2 Receptor Action
INsertion of AQP-2 H2O channels in the apical membrane
induce AQP-2 synthesis
release of vwf and factor VII
vasodilation
V3/V1B Receptor Site
Anterior Pituitary gland
V3/ V1B Receptor Action
Release of ACTH
Prolactin
Endorphins
Norepinephrine Dose
0.02-.2 mg/kg/min
Norepinephrine Receptors
A1>B1& B2
Norepinephrine Inotropy
+
Norepinephrine Chronotropy
+
Norepinephrine SVR effects
+
Norepinephrine PVR Effects
+
Phenylephrine Dose
0.02-0.3 mcg/kg/min
Phenylephrine Receptors
Alpha1
Phenylephrine Inotropy Effects
<->
Phenylephrine Chronotropy effects
-
Phenylephrine SVR Effects
+
Phenylephrine PVR Effects
+
Vasopressin Dose
0.02-0.5 units/kg/hr
Vasopressin Receptors
V1 V2
Vasopressin Inotropy
<->
Vasopressin Chronotropy effects
<->
Vasopressin SVR Effects
+
Vasopressin PVR Effects
+
Nitroprusside Dose
0.2-5 mcg/kg/min
Nitroprusside Receptors
Increase cGMP in vascular myocytes
Nitroprusside Inotropy
<->
Nitroprusside Chronotropy
<->
+
Nitroprusside SVR
-
Nitroprusside PVR
-
Nicardipine Dose
0.5-5 mcg/kg/mni
Nicardipine Receptors
Calcium Channel Blocker
Nicardipine Inotropy
<->
Nicardipine Chronotropy
<->
Nicardipine SVR
-
Nicardipine PVR
-
Nitroglycerin Dose
0.2-10 mcg/kg/min
Nitroglycerin Receptors
Nitroglycerin Inotropy
Nitroglycerin Chronotropy
Nitroglycerin SVR
Nitroglycerin PVR
Epinephrine Dose
0.02-0.2 mcg/kg/min
Epinephrine Receptors
A1A2B1B2
Epinephrine Inotropy
+
Epinephrine Chronotropy
+
Epinephrine SVR
+
Epinephrine PVR
+
Epinephrine high-dose Inotropy
+
Epinephrine high-dose Chronotropy
+
Epinephrine high-dose SVR
<->
Epinephrine High-dose PVR
<->
Dopamine low dose
2-5 mcg/kg/min
Dopamine mid dose
5-10 mcg/kg/min
Dopamine high dose
> 10 mcg/kg/min
Dopamine low dose Receptors
D1, D2
Dopamine mid dose receptors
B1, B2> A1
Dopamine high dose receptors
A1>B1, B2
Dopamine low dose inotropy
same
Dopamine low dose chronotropy
same
Dopamine low dose SVR
same
Reduces
Dopamine low dose PVR
Same,
Reduces
Dopamine mid dose Inotropy
+