CIRCULATORY SYSTEM: THE HEART

I.   INTRODUCTION

A.  Size & Shape

-- placement: left-hand side of body in thoracic cavity
-- located behind sternum and left ribs
–  enclosed in pericardium

B.  Layers

1.  Endocardium: endothelium covering a CT layer
* lines the inside of the heart & covers its valves

2.  Myocardium: cardiac muscle
* thickest layer
*  review structure of cardiac muscle from your tissues lecture!

3.  Epicardium (Visceral layer of the Serous Pericardium): thin serous membrane and some fat

II.  PERICARDIUM

1.  Fibrous Pericardium:
* outermost layer
* dense CT
* functions:

2.  Serous Pericardium:

a) Parietal Layer: adheres to fibrous pericardium

b) Visceral Layer: adheres to heart wall

- pericardial cavity

III. BASIC HEART ANATOMY

1.  Right Atrium: receives venous blood from superior and inferior vena cavae

* blood will flow from right atrium to right ventricle through the Right Atrioventricular (Tricuspid) Valve:

2.  Right Ventricle:

* 3 papillary muscles
** chordae tendineae: from the papillary muscles to the 3 flaps of the right AV valve

functions of chordae tendineae:

* blood runs from right ventricle through the Pulmonary Semilunar Valve and into the pulmonary trunk
** 3 semilunar cusps

** blood will now travel in the pulmonary arteries to lungs

3.  Left Atrium: receives oxygenated blood from the lungs via 3 or 4 pulmonary veins
* blood will flow from left atrium to left ventricle via the Left Atrioventricular (Mitral) Valve:

4.  Left Ventricle: pumps oxygenated blood into the aorta

*  papillary muscles and chordae tendineae

* blood is pushed from the left ventricle through the Aortic Semilunar Valve

IV.  REVIEW OF HEART BLOOD FLOW

1.  blood LOW in oxygen enters right atrium

2.  blood from right atrium goes to right ventricle

3.  blood from the right ventricle goes through pulmonary trunk

4.  pulmonary trunk branches into pulmonary arteries, which carry blood to lungs
5.  exchange of gases occurs in the lungs

6.  oxygenated blood travels through pulmonary veins to left atrium

7.  blood from left atrium goes to left ventricle

8.  blood from left ventricle is pumped through the aorta

9.  body travels through the blood vessels, will return to right atrium of the heart, and the cycle repeats!

V.   BLOOD SUPPLY TO THE HEART

A.  Arterial Circulation:

1.  Right Coronary artery:

2.  Left Coronary artery:

B.  Venous Circulation: returns blood low in oxygen back to the right atrium
–  most of these veins unite/drain into the Coronary sinus

VI. CONDUCTION SYSTEM OF THE HEART

-- the heart exhibits autorhythmicity, which means the heart itself (and not external nerves) are responsible for initiating the heartbeat

-- the heart’s conduction system consists of:

1. Sinoatrial (SA) node:

2. Atrioventricular (AV) node:

 

 

 

3. Atrioventricular bundle:

 

 

 

4. Left and right bundle branches:

 

 

 

5. Purkinje fibers:

 

-- sympathetic innervation effects on heart rate:

-- parasympathetic innervation effects on heart rate:

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