The Heart

Learning Objective

By the end of the lesson, you should be able to:

• to state the function of the circulatory system
• to state the function of the heart
• to label the structures of the heart
• to describe cardiac cycle

Lesson Outline

1. The Circulatory System.
2. The Structures of the Heart and Their Functions.
3. The Cardiac Cycle.

1. The Circulatory System

The transport system in the human body is the circulatory system. The circulatory system consists of:

1. The heart
2. The blood vessels (artery, capillary, vein)
3. The blood

The functions of the circulatory system are:

1. to carry oxygen from the lungs to the rest of the body.
2. to carry digested food from the small intestine to all areas in the body which need it.
3. to fight diseases by using white blood cells.
4. to help in the removal of all wastes from the body.

The circulatory system in human is a closed double circulatory system. The blood is confined to the blood vessels and the blood flows through the heart twice on one complete journey around the body.

Double Circulation

Repeated circulation through the heart is necessary to maintain the blood pressure that is required to keep the circulation of blood around the body. 

Please login to Edmodo to complete and turn in 'Assignment 1: The Circulatory System'.

Other Resources:
Circulatory system vocabulary - A vocabulary game on circulatory system

2. The Structures of the Heart and Their Functions

The function of the heart is to pump blood around the body. It lies in the chest region between the 2 lungs. It is made of cardiac muscle. This muscle contracts and relaxes regularly, throughout life.

You may dissect a sheep's heart at your own time at home using the video above and this website as guideline. Now, please login to Edmodo to complete and turn in 'Assignment 2: The Structures of the Heart and Their Functions'.
Other Resources: Label the heart activity - Practice on labeling the heart. Label the heart activity #2 - More practice on labeling the heart. Structure of the human heart - More information on human heart.

3. The Cardiac Cycle

The cardiac cycle is the sequence of events that occurs when the heart beats. There are 2 phases of the cardiac cycle.

1. Diastolic phase
2. Systole phase

In diastolic phase, the heart ventricles are relaxed and the heart fills with blood.

In the systolic phase, the ventricles contract and pump blood to the arteries. 

One cardiac cycle is completed when the heart fills with blood and the blood is pumped out of the heart.

Flow of blood in the heart (Cardiac cycle)

Difficult to remember the sequence? Log-in to Edmodo to complete and turn in 'Assignment 3: The Cardiac Cycle' while you listen to this song...

Other Resources:

Video and quiz - Watch a video then answer the quiz on cardiac cycle.

Flashcard - Flashcard quiz on cardiac cycle.