Pulmonary Circulation

Conus arteriosus Superior end of the right ventricle

Leads to the Pulmonary Trunk

Pulmonary Trunk Divides into Left and Right Pulmonary

Arteries

Blood flow:

Right Ventricle -> Pulmonary Trunk through the Pulmonary Semilunar Valve (PSL Valve)

Pulmonary valve has 3 Semilunar cusps

Systemic Circulation

Blood leaves Left Ventricle through …

• Aortic Semilunar Valve (ASL Valve) into Ascending Aorta

Ascending Aorta turns to the left into the … Aortic arch and becomes the

…. Descending Aorta

Systemic Circulation

Structural Differences between the Left & the Right Ventricle:

1. Left Ventricle Round

Thicker myocardium wall -> more pressure

2. Right Ventricle Pouch shaped

Thinner myocardium wall -> less pressure

Coronary Sinus Cardiac veins return blood to coronary

sinus Cardiac sinus opens into Right Atrium

Writing Activity (10 points)

You are a Erythrocyte (RBC) traveling through the human body. Describe the journey!

Condition in lungs for O2 pick up

Heart: atria, ventricles, 4 valves

Systemic pathway

Pulmonary pathway

Conditions of tissue for O2 dispersal & CO2 pick up

2 Bonus points: if all possible names for valves are given

Example: Atrioventricular valve, Mitral valve, …

Foramen Ovale Before Birth; an opening through

the Interatrial Septum Connects the two Atria Eliminates blood being sent to the

lungs in a Fetus!!

Seals off at birth -> Fossa Ovalis

Blue Baby Foramen ovale does not deal off

after birth Requires surgery

Heart Valves

Left AV valve:Bicuspid valveMitral valve

Aortic Semilunar Valve

Right AV Valve:Tricuspid

Pulmonary Semilunar Valve

Tricuspid Valve Bicuspid ValveMitral Valve

Aortic Semilunar Valve

Pulmonary Semilunar Valve

Cardiac Conduction

Heart Beat• A single contraction of the heart

The entire heart contracts in sequence1. Atria

2. Ventricles

Cardiac Conduction Structures of the Conducting

System Sinoatrial (SA) nodes

In the wall of the Right Atrium

Atrioventricular (AV) node Between Atrium & Ventricle

Conducting Cells Throughout myocardium

The Cardiac Cycle

Begins at the Sinoatrial ( SA) Node with an Action Potential

The Action Potential is transmitted through the conducting System:

1. SA node

2. AV node

Produces an Action Potential in the Cardiac muscle cells

• Contractile cells

5 Steps to the Cardiac Cycle:

1.Ventricular diastole

2.Atrial systole begins

3.Atrial diastole

4.Ventricular systole 1st phase

5.Ventricular systole 2nd phase

Diastole = RelaxationSystole = Contraction

5 Steps to the Cardiac Cycle:

1.Ventricular diastole All chambers are relaxed

Diastole = RelaxationSystole = Contraction

5 Steps to the Cardiac Cycle:

2. Atrial systole begins Atria contract & force

blood into ventricles

Diastole = RelaxationSystole = Contraction

5 Steps to the Cardiac Cycle:

3. Atrial diastole Atrium contraction ends Atrium relaxes Ventricle contractions begin

Diastole = RelaxationSystole = Contraction

5 Steps to the Cardiac Cycle:

4. Ventricular systole 1st phase

Contraction pushes AV valves close

Diastole = RelaxationSystole = Contraction

5 Steps to the Cardiac Cycle:

5. Ventricular systole 2nd phase

Increase in pressure forces SL valves to open

Blood is ejected

Diastole = RelaxationSystole = Contraction

5 Steps to the Cardiac Cycle:

1.Ventricular diastole

2.Atrial systole begins

3.Atrial diastole

4.Ventricular systole 1st phase

5.Ventricular systole 2nd phase

Diastole = RelaxationSystole = Contraction

Sinoatrial (SA) Node

Pacemaker of the heart Initiates heart beak Sends excitatory impulses every 0.85

seconds

Contracts: Atrium

Impulse is send to AV node

Atrioventricular (AV) Node

Sends impulses to AV bundles Bundles branch into Purkinje

fibers Cause ventricle to contract

Cardiac Cycle

Cardiac Cycle - Review

Is the period between the start of one heartbeat and the beginning of the next

Includes contraction & relaxation with the Atria & Ventricle Systole

Contraction

Diastole relaxation

Phases of the Cardiac CycleAtrial systole

Ventricular systole phase 1

Atrial diastole

Ventricular systole

phase 2

Ventricular diastole

Cardio dynamics

Cardiac center is in the Medulla Oblongata

Cardio acceleration is controlled by the sympathetic neurons

Cardio inhibition is controlled by the parasympathetic neurons

Vagus Nerve (Cranial Nerve X) carries fibers to the heart