Physiology of the HeartPhysiology of the HeartPhysiology of the HeartPhysiology of the Heart

Physiology of the heartPhysiology of the heart

You should understand by now that the Physiology of the Heart refers to the function of the heart

You need to be familiar with the conduction system of the heart, the cardiac cycle, sounds of the heart, and cardiac out put

You should understand by now that the Physiology of the Heart refers to the function of the heart

You need to be familiar with the conduction system of the heart, the cardiac cycle, sounds of the heart, and cardiac out put

Conduction System of the HeartConduction System of the Heart

Cardiac muscle is unique because it can contract spontaneously and independently even if all nervous connections to the heart are severed

These contractions however, are not erratic but regular and steady in rhythm

Cardiac muscle is unique because it can contract spontaneously and independently even if all nervous connections to the heart are severed

These contractions however, are not erratic but regular and steady in rhythm

Beats per minuteBeats per minute

The atrial cells of the heart beat roughly 60 times per minute

The ventricular cells of the heart beat only 20-40 times per minute

Without some unifying system to control them the heart would be an uncoordinated and inefficient pump

The atrial cells of the heart beat roughly 60 times per minute

The ventricular cells of the heart beat only 20-40 times per minute

Without some unifying system to control them the heart would be an uncoordinated and inefficient pump

Intrinsic ConductionIntrinsic Conduction

The Intrinsic Conduction System (Nodal System) of the heart is made of very specialized cardiac tissue that is a cross between muscle and nervous tissue

The Intrinsic Conduction System (Nodal System) of the heart is made of very specialized cardiac tissue that is a cross between muscle and nervous tissue

Intrinsic ConductionIntrinsic ConductionWe see 2 large ovals

which are the nodes of

the system

•The sinoatrial node (SA

Node) acts as the pace

maker of the heart

•The atrioventricular

node (AV Node) slows the

impulse before sending it

to the ventricles

We see 2 large ovals

which are the nodes of

the system

•The sinoatrial node (SA

Node) acts as the pace

maker of the heart

•The atrioventricular

node (AV Node) slows the

impulse before sending it

to the ventricles

Cardiac Cycle Cardiac Cycle

Two most important terms in understanding cardiac cycle are Systole and Diastole

Systole is heart contraction

Diastole is heart relaxation

Two most important terms in understanding cardiac cycle are Systole and Diastole

Systole is heart contraction

Diastole is heart relaxation

5 Phases of Cardiac 5 Phases of Cardiac CycleCycle

5 Phases of Cardiac 5 Phases of Cardiac CycleCycle

Cardiac sounds Cardiac sounds

In a healthy heart you should be able to hear a steady “lub-dub” sound of contraction

We have to understand that there is a sequence to the sounds

lub-dub, pause, lub-dub, pause

In a healthy heart you should be able to hear a steady “lub-dub” sound of contraction

We have to understand that there is a sequence to the sounds

lub-dub, pause, lub-dub, pause

“Lub” and “Dub” sounds“Lub” and “Dub” sounds

The “lub” sound we hear is from the the closing of the AV valves

This is then followed by a pause

The “dub” sound we hear is from the closing of the semilunar valves

The “lub” sound we hear is from the the closing of the AV valves

This is then followed by a pause

The “dub” sound we hear is from the closing of the semilunar valves

Blood flowBlood flow

It is important to realize that blood flows silently as long as the flow is smooth and un-interupted

If the flow becomes irregular we can hear murmurs

It is important to realize that blood flows silently as long as the flow is smooth and un-interupted

If the flow becomes irregular we can hear murmurs