Cardiovascular System

The Heart

Lesson 8 Cardiovascular System Study Guide
Kids health site - Description of cardiovascular system
Interactive heart Anatomy - neat site!
Watch a video demonstration of dissection of a sheep heart.
Kid style video of how the heart works
More detailed video of how the heart works
Listen to various kinds of heart beats
Label the heart online quiz
Heart puzzles and games to do online

Identify parts of the heart by clues provided. - A little challenging because you will have to be able to spell the parts of the heart.
Online Heart anatomy quiz - a little challenging
heart anatomy information - lots of neat info but may be beyond the scope of the class.
Another neat interactive site for the heart
Crash Course Video on the Heart part 1
Crash Course Video on Heart, part 2















Below are pictures taken when our High School Anatomy class dissected a sheep heart.

External Anatomy of a sheep heart.

The heart is enclosed in a double membrane sac called the pericardium.  The pericardium protects the heart and reduces the amount of friction created when the heart beats.  In the picture to the right, the pericardium has been removed.  The bulk of the tissue making up the heart is cardiac muscle which has a special name: the myocardium.  These muscle cells contract and relax constantly to pump blood throughout your body.

The heart also needs blood supply to keep it healthy.  The coronary blood vessels run along the outside of the heart to deliver oxygen and nutrients. They also remove waste and carbon dioxide.

Internal anatomy of a sheep heart.

Inside the heart there are four chambers. The upper two chambers are called atria. The lower two chambers are called ventricles.  The heart is also divided in half so there is a right atrium and a right ventricle and a left atrium and a left ventricle.

Deoxygenated blood enters the right atrium.  Next, the blood passes through the right atrioventricular valve (also known as the tricuspid valve) in order to enter the right ventricle.  The right ventricle is smaller than the left ventricle as this side of the heart pumps the deoxygenated blood to the lungs in order to get rid of carbon dioxide and pick up oxygen.

Internal anatomy of a sheep heart. 4 Chambers.

In the picture to the left, the four chambers of the heart are visible. Also, note how thick the myocardium is on the left side compared to the right side.

Oxygenated blood is carried through the pulmonary veins back to the left atrium.  Next, the oxygenated blood passes through the left atrioventricular valve (also known as the mitral valve or bicuspid valve).  This valve is readily visible in the picture on the left. Note also the "string" like cords attached to the left atrioventricular valve.  These string like structures are called chordae tendineae, meaning tendinous chords or affectionately heart strings.  These chords are also associated with the right atrioventricular valve.