Life Cycle - Human Biology (4B)
Pre Lab

   
OBJECTIVES:
  • Exploring how the circulatory system works.
  • Investigating the function of blood.
VOCABULARY:
  • arteries
  • atrium
  • capillaries
  • circulatory system
  • veins
  • ventricle
MATERIALS:

Students learn the parts of the heart.

 

BACKGROUND:

Digested food and other nutrients that are needed by our bodies are carried to the cells by the blood.  The blood also carries wastes away from the cells.  Blood must be kept moving through the body to accomplish these jobs.   This is made possible by the heart.  The heart acts as a pump.  Blood is carried through tubes called arteries, veins, and capillaries.  This entire network of blood is called the circulatory system. 

The human heart contains four chambers.  The upper two are the right and left atria.  The lower two are the right and left ventricles.  Arteries carry blood away from the heart and veins carry blood to the heart. 

Capillaries connect arteries and veins.  The heart is a mechanical device whose function is to pump blood through the body to replenish oxygen lacking blood cells with oxygen. The importance of constant circulation of blood throughout the body cannot be over emphasized, for without blood, life could not be.  If blood does not reach the brain for just five seconds an individual loses consciousness; after 15-20 seconds the body begins to convulse; and  if such a block lasts for nine minutes, irreparable damage to the brain results.  

The strong contraction of the heart muscle forces blood into the arteries in two ways:  the first expands the muscular walls of the arteries and the second pushes the blood through the arteries to regions of the body away from the heart.  This rhythm makes the arteries expand thereby producing a pulse.  In the wrist, the pulse is detected by a throbbing sensation near the surface.

PROCEDURE:
  1. The heart is composed of four chambers, two upper chambers, the right and left atria, and two lower ones, the right and left ventricles.  Using the worksheet go over the heart with the students, so that when they do the lab exercise they will be able to visualize the heart as it creates a pulse. Point out on the smaller diagram where the heart is located.
        
  2. Use the model of a  heart for students to see the different parts. 

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