Cardiac Physiology Flashcards

Flashcards on Cardiac Physiology

Intercalated Discs

Structures connecting cardiac myocytes.

Cardiac Myocyte Gap Junctions

Required for coordinated electrical activity and contraction.

Cardiac Muscle Pacemaker Activity

Unique properties allow it to generate its own electrical impulses.

Refractory Period of Cardiac Muscle

Longer than skeletal muscle to prevent tetanus.

Origin of Cardiac Pacemaker

SA node.

Average Heart Rate

Dictated by the SA node firing rate.

AV Node

Slows down cardiac conduction.

Parasympathetic Stimulus on the Heart

Decreases heart rate.

Cardiac Centers Regulating Heart Rate

Located in the medulla oblongata.

ECG Clinical Importance

Assesses the electrical activity of the heart.

ECG Measurement

Measures the sum of electrical activity, not a single action potential.

ECG P Wave

Represents atrial depolarization.

Abnormal ECG QRS Complex

Indicates abnormality in the ventricles.

PR Interval

Time for atrial depolarization and AV node delay. Increased interval may indicate AV block.

Cardiac Cycle Phases

Systole and Diastole.

Atrial Contraction Absence

Decreased ventricular filling.

Diastole

Relaxation and filling of the heart.

Systole

Contraction and ejection of blood from the heart.

Isovolumetric Contraction

Increases ventricular pressure before ejection.

Blood Ejection from the Heart

Caused by ventricular pressure exceeding aortic/pulmonary pressure.

EDV

End-diastolic volume.

ESV

End-systolic volume.

Determinants of Blood Pressure

Cardiac output and total peripheral resistance.

Q (Cardiac Output)

Determined by heart rate and stroke volume.

Chronotropic Effect

Affects heart rate.

Inotropic Effect

Affects contractility.

Preload

Volume of blood in ventricles at end of diastole (EDV).

Afterload

Resistance the left ventricle must overcome to circulate blood

Normal Blood Volume

Approximately 5 liters.

Frank-Starling Mechanism

Increased preload leads to increased stroke volume.

Increase in Afterload Effect

Decreases cardiac output.

SV

Stroke volume.

Tachycardia

Fast heart rate.

Bradycardia

Slow heart rate.

Exchange Vessels

Capillaries.

Capillary Exchange Driving Forces

Hydrostatic and osmotic pressures.

Endothelium Function

Lines blood vessels and regulates permeability.

Blood Flow Calculation

Pressure difference divided by resistance.

Blood Flow Regulation

Primarily regulated by vessel radius.

Vasomotion Control

Controlled by local factors and autonomic nervous system.