Exam 2 Study

• Atrial repolarization


  Obscured on an ECG
• QRS complex


  Represents ventricular depolarization
• Intercalated discs are visible structures joining cardiac muscle cells
• P wave on an EKG

  Represents atrial cell depolarization
• HCN channels


  Unique to pacemaker cells
• AV node delay


  Allows atria and ventricles to depolarize and contract separately
• Contractile cells do not spontaneously generate the cardiac conduction system
• SA node


  Serves as the pacemaker of the heart
• Autorhythmicity in the heart

  A function of cardiac pacemaker cells
• AV bundle or AV node


  Primarily affects the length of the P-P interval
• Ventricular cells


  Undergo action potentials during the QRS interval on an EKG
• P wave


  Corresponds to the atrial depolarization phase
• Left ventricle


  Generates the highest pressure during systole
• Ventricular ejection


  Approximately 70 ml of blood is pumped from each ventricle
• Closing of AV valves

  Can be heard most easily in a stethoscope
• Blood flow from the ventricles

  Into the pulmonary trunk during the ventricular ejection phase
• End systolic phase


  Follows the phase in the cardiac cycle
• The right side of the heart pumps oxygenated blood
• Left ventricle


  Has the thickest wall to generate enough pressure
• Right atrium


  Receives blood from the superior and inferior vena cavae
• Tricuspid valve


  Located between the right atrium and right ventricle
• Left ventricle


  Is the chamber with the thickest wall
• Left atrium


  Delivers oxygenated blood to the pulmonary veins
• Arteries


  Carry blood away from the heart
• Veins


  Carry blood toward the heart
• Pulmonary arteries


  Have lower blood pressure compared to systemic arteries
• Systemic arteries


  Handle the highest blood pressure
• Arteries


  Have a much thicker tunica media compared to veins
• Metarteries


  Have the smallest diameter among arteries
• Vasodilation


  Increases the diameter of a blood vessel
• Baroreceptor reflex response to high blood pressure

  Vasodilation and decreased cardiac output
• Arterial baroreceptors


  Located in the carotid sinus and aortic arch
• Stimulation of the adrenal medulla

  Could result in an increase in heart rate and contractility
• Decreased activity of the sympathetic nervous system

  Causes vasodilation of arterioles
• Increased parasympathetic nervous system activity or decreased sympathetic nervous system activity

  Occurs with increased blood pressure at arterial baroreceptors
• Hematocrit


  The percentage of blood composed of erythrocytes
• Albumin


  The most important plasma protein for maintaining colloid osmotic pressure
• Erythropoiesis


  Results in the production of reticulocytes
• Erythrocytes have a biconcave shape
• Normal blood pH


  Falls between 7.35 and 7.45