Anatomy And Physiology Of The Heart
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Systole
The rhythmic contraction of the heart muscle
Diastole
The period in the complete heart beat when the heart muscle releases and the chambers fill with blood
Stenosis
A narrowing canal or vessel
Physiology of the Heart: The Cardiac Cycle
All the events that occur in one heartbeat
Phases of the Cardiac Cycle: All Valves Closed (diastole)
Atria filling All valves closed Atrial pressure increasing Short phase
Phases of the Cardiac Cycle: A-V Valves Forced Open
Heart is still in diastole Atrial Pressure> Ventricular Pressure Atria approximately 95% full ventricular about 70% full
Phases of the Cardiac Cycle: Atria Contract
Ventricle still in diastole Atrial systole Right atrium starts before left atrium Remaining 30% forced into ventricles
Phases of the Cardiac Cycle: Atria Relaxed
Atria and Ventricle are both diastole Ventricular pressure> atrial pressure
Phases of the Cardiac Cycle: Ventricles Contract
Ventricle Systole AV valves close Aortic and Pulmonary valves forced open Ventricle contract, beginning at apex
Phases of the Cardiac Cycle: Relaxation of Ventricles
Arterial Pressure> Ventricular Pressure Blood flows back towards ventricles Pulmonary and Aortic valves are shut AV Valves still closed
Valves of the Heart: Function of AV valves
Permissive: open property Prohibitive: close property
Valves of the Heart: Valvular Damage
Valvular Insufficiency or Incompetence…valve not closing properly…allowing blood to return where it came from stenosis: narrowing of a canal or vessel Endocarditis: inflammation in the heart Erysipelas: scar tissue developing around the valve Rheumatic Fever: diagnosed with a heart murmur
Intrinsic
Belonging naturally to a part or individual
Extrinsic
Being outside of the nature of something
Brady-
The combining form of the word “slow”
Tachy-
The combining form of the word “fast”
Intrinsic Conduction System: Sino-Atrial Node
Between cranial vena cava and right atria wall Pacemaker of the heart Consists of cells with the fastest rate of firing Lowest threshold of depolarization
Intrinsic Conduction System: Inter Nodal Fiber Bundles
In wall of atria Spreads impulses throughout atria
Intrinsic Conduction System: Atrioventricular Node
Collects waves of depolarization In atrial septum near ventricles Gathers impulse to be sent to a AV bundle
AV Bundle
In ventricular septum Composed of small diameter cardiac muscle fibers Conducts impulse towards apex
Purkinje Fibers
Third form of cardiac muscle Mammals have in ventricle In ventricular walls Conducts Impulse from AV bundle to muscle fibers to ventricles Twists..blood is pushed upward and is forced out
Functions of the Ventricle Septum
Separates oxygen rich from oxygen poor Composed of myocardium…aids in contraction of heart Site of AV bundle…transmits wave of depolarization
Extrinsic Conduction System
Autonomic portion of the peripheral nervous system (ANS) Sympathetic…drift increases causes heart to speed up Parasympathetic…drift decreases caused heart to slow down Endocrine
ECG: P Wave
Spread of depolarization throughout the atrial muscle ( precedes atrial systole)