APII Notes Home Page

Anatomy of The Heart

http://www.holomatix.com/assets/heart/index.html

II). Coverings & Layers of the Heart Wall

http://science.tjc.edu/images/preserved_heart/Index.htm

A). Pericardium

Double walled sac that surrounds the heart.

The space between the linings is called the pericardial cavity

B). Epicardium

Layer of the pericardium that is closely aligned to the heart wall

(Also called the visceral layer of the serous pericardium)

C). Myocardium

Muscles are arranged in spiral and circular bundles.

 muscle contracts the chambers constrict and blood is expelled out of the chamber.

 

D). Endocardium

Thin, slick sheet of connective tissue located on the inner surface of the myocardium

It is continuous with the blood vessels

Purkinje fibers: carry electrical impulse from bundle of His

III). Histology Of Cardiac Muscle

http://starklab.slu.edu/Physio/Circulation.htm	http://w3.ouhsc.edu/histology/Text Sections/Cardiovascular.html

A).  Striated, single nucleated.

B).  Intercellular space contains connective tissue and fibers which function as an insertion point.

C).  Dark-staining junctions called intercalated discs.

These prevent the cells from separating

IV). Heart Exterior

A).  2 atria

 auricles: extends the atrium

B).  2 ventricles make

C). Anterior interventricular sulcus:

D). Posterior interventricular sulcus 

E).  Apex:

V). Chambers of the Heart

http://www.sunyniagara.cc.ny.us/val/sheep-heart-3.html	http://science.nhmccd.edu/biol/cardio/heartdis.htm

A). Atria

1).  Function: Receive blood returning to the heart and push it into the ventricles

2).  Fossa Ovalis is a small depression on the medial wall is where the foramen ovalis existed

3).  Right Atrium

• inferior vena cava
• superior vena cava
• coronary sinus

4).  Left Atrium

• pulmonary veins

 

The SA (sinoatrial) node on the right atrial wall initiates the signal causing atrial contraction.

 

The signal reaches the AV (atrioventricular) node on the atrial septal wall.

B). Ventricles

Septum

The walls of the ventricle are made up of muscle bundles called trabeculeae carnae

 

1.  Left ventricle is anterior and pumps blood into the systemic circuit.

It is the larger ventricle

Longer distance means

 higher resistance so it needs to create

 higher pressure

2.  Right ventricle is posterior and pumps blood into the pulmonary trunk and the pulmonary circuit

Shorter distance means

 lower resistance means

 lower pressure.

 (high pressure would damage the lungs)

 

The left ventricle must be able to create a force that will result in a pressure strong enough to overcome the systemic resistance.

To retain that initial pressure the aorta has to have a thick wall.

The right ventricle muscle is not as large as the left so it cannot create as high of a pressure as the left ventricle can.

 

VI). Valves

A). Atrioventricular (AV) Valves

Located between the atria and the ventricles

Flaps consist of connective tissue & endocardium.

They are attached  to collagen cords called chordae tendinae.

1). Tricuspid:

2). Bicuspid or Mitral Valve:

When the heart is relaxed the flaps hang open.

 When the ventricles contract they are pressed closed from the ventricular side.

B). Semilunar (SL) Valves

Lead into the large arteries

Formed from 3 moon-shaped cusps

1). Aortic Semilunar Valve

2). Pulmonary Semilunar Valve

When the ventricle contracts

 blood is pushed against the AV valve which closes

and expelled through the SL valve.

When the ventricle relaxes blood pressure is higher in the vessels, which closes the valve

A-V Valves
	When the heart is relaxed the flaps hang open.
	When the ventricles contract they are pressed closed from the ventricular side.
Semilunar Valves
	When the ventricle contracts blood is pushed against the AV valve and blood is expelled through the SL valve.
	When the ventricle relaxes blood pressure is higher in the vessels, which closes the valve.

 

 Circulation

blood supply from the outside through the epicardium to the inside the endocardium.

1). Left coronary artery

a). anterior interventicular artery

b). circumflex artery

2). Right coronary artery

a). marginal artery

b). posterior interventricular artery

 

B). Coronary Veins

1). Great Cardiac Vein

2). Middle Cardiac Vein

3). Small Cardiac Vein

4). Coronary Sinus