Abstract:
A kit for fabricating various visual models is used to teach students about blood, blood pathology, and the quantitative concepts associated with blood pathology. The kit includes various sized containers that hold colored beads that resemble red blood cells and the various types of white blood cells.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of the U.S. Provisional Patent Application No. 60/945,222 filed on Jun. 20, 2007. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to teaching aids; and in particular to visual aids for teaching scientific biological concepts. 
     2. Brief Description of the Prior Art 
     The processes of hemopoiesis, hematocrit analyses, and identification of blood cells for white blood cell differentiation are difficult concepts for students to understand without an advanced education in biology or physiology. The ability to visually identify the presence of white blood cells in a cubic millimeter of blood and classify the white blood cells based on their appearance and population when scattered among staggering numbers (˜5 million) of very minute transparent red blood cells requires an understanding of quantitative statistics. 
     White blood cells defend the body against both infectious disease and foreign materials and the number of white blood cells in a sample of blood can change if a person is afflicted with a particular blood disorder. White blood cells only make up approximately 1% of blood in a healthy adult and the total number of white blood cells is further divided into several categories. The types of white blood cells include neutrophils (60-70%), eosinophils (2-4%), basophils (0.5-1%), lymphocytes (20-25%), and monocytes (3-8%). Because white blood cells are greatly outnumbered by red blood cells, it is difficult for a student, for example, to examine a blood smear under a microscope to identify a white blood cell, and even more difficult for the student to identify the type of white blood cell. If the sample is taken from a person afflicted with a blood disorder, determination of the blood disorder is impossible without first determining the type and number of blood cells present in the sample. 
     There is a need, therefore, for a teaching aid to assist students in understanding blood cell pathology and the quantitative concepts related to this subject. 
     SUMMARY OF THE INVENTION 
     The present invention provides a kit for producing a blood cell visual model that can be used to teach students scientific concepts, including, for example, the types of blood cells, quantitative concepts relating to the blood, and blood cell pathology. The kit includes two sets of beads, the first resembling red blood cells and second set resembling white cells. Preferably, the beads resemble, in one or more aspects, the respective blood cells that they are intended to signify. Preferably, the beads resembling white blood cells include beads resembling one or more specific types of white blood cells, including neutrophils, monocytes, lymphocytes, eosinophils, and basophils. The kit optionally includes coarse, granular material that resembles platelets. The kit also optionally includes various sized containers for the beads. The containers preferably have a transparent area such as a transparent side through which the contents in the containers can be viewed to provide a macroscopic model of a blood smear viewed under a microscope, a model blood vessel, or a model of centrifuged blood cell sample from which packed cell volume is determined. The physical characteristics of the beads, such as the proportion, shape, and color of the beads, can be selected to permit a group of beads to represent normal blood or blood afflicted with a specific disorder. The beads and containers may be made of any suitable material such as plastic or glass. 
     The term “bead” is defined as any body that resembles the shape of a blood cell, including, but not limited to, a sphere, spheroid, ellipsoid, torus, and disk. 
     In one aspect, the present invention provides a blood cell visual model that makes it easier for students to analyze and readily identify the various white blood cell types based on their size, shape, color, and number. 
     In another aspect, the present invention provides a blood cell visual model that enables a student to better understand the significance of high and low blood cell counts during infections, allergic reactions, and other pathological conditions. 
     In a further aspect, the present invention can be used to improve the ability of a student to obtain information from a blood sample when viewed under a microscope. 
     In another aspect the present invention provides a blood cell visual model that can make it easier for students to understand differential counts of blood cells under a variety of pathological conditions. 
     In yet another aspect, the present invention can be used to enable students to better understand the physiology of blood circulation and the effects of a blood disorder on circulation. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The following drawings form part of the present specification and are intended to further demonstrate certain aspects of the present invention. The invention may be better understood by referring to the drawings while reviewing the specific embodiments described in the detailed description below. 
         FIG. 1  is a plan view of a first embodiment of the kit of the present invention shown simulating the visual appearance of normal human blood under a microscope. 
         FIG. 2  is a side elevational view of a second embodiment of the kit of the present invention shown simulating normal human blood flow through a vessel. 
         FIG. 3  is a plan view of third embodiment of the kit of the present invention shown simulating the visual appearance of human blood afflicted with sickle cell anemia under a microscope. 
         FIG. 4  is a side elevational view of the fourth embodiment of the kit of the present invention shown simulating human blood afflicted with sickle cell anemia in a blood vessel. 
         FIG. 5  is a plan view of a fifth embodiment of the kit of the present invention shown simulating the visual appearance of human blood afflicted with polycythemia under a microscope. 
         FIG. 6   a  is a perspective view of a sixth embodiment of the kit of the present invention shown simulating a centrifuged normal blood cell sample from which packed cell volume is determined. 
         FIG. 6   b  is a perspective view of a seventh embodiment of the kit of the present invention shown simulating a centrifuged blood cell sample from which packed cell volume is determined, the sample having an abnormally high packed cell volume. 
         FIG. 7  is a plan view of an eighth embodiment of the kit of the present invention shown simulating the visual appearance of human blood afflicted with hairy cell leukemia under a microscope; 
         FIG. 8  is a plan view of a ninth embodiment of the kit of the present invention shown simulating the visual appearance of human blood afflicted with acute lymphocytic leukemia under a microscope; 
         FIG. 9  is a plan view of a tenth embodiment of the kit of the present invention shown simulating the visual appearance of human blood afflicted with acute monocytic leukemia under a microscope; and 
         FIG. 10  is a plan view of an eleventh embodiment of the kit of the present invention shown simulating the visual appearance of human blood during an allergic reaction under a microscope. 
     
    
    
     DETAILED DESCRIPTION 
     The present invention provides a kit for producing a blood cell visual model. The blood cell visual model provides a macroscopic view of the various blood cells that would only be possible by viewing a sample of blood under extreme magnification. By providing a macroscopic view of blood, an instructor can easily present and demonstrate the distinguishing characteristics of the cells simultaneously to multiple students, as well as their typical population size. The macroscopic view of the blood provides a tool to enable a student to recognize and comprehend the relative number of red and white blood cells that are expected within a sample of normal human blood and how the population and appearance of blood cells change due to particular blood pathology. 
     The kit includes at least two sets of beads and a container. The first set of beads represents red blood cells. The second set of beads represents white blood cells. Preferably, the beads resemble, in one or more aspects, the respective blood cells that they are intended to signify; therefore, the first set and second sets of beads are preferably round with the first set being transparent and a light red color while the second set is preferably white, such that the beads can be colored to resemble nucleated white blood cells by staining them deep purple to blue. The shade of deep purple to blue varies depending on the type of white blood cell that the bead represents. For example a bead representing a basophil or lymphocyte would be stained a darker color than a neutrophil or eosinophil. Also, the shape of the stain on the surface of the second set of beads preferably resembles the nucleus of a white blood cell. For example, a bead representing a neutrophil would have a multi-lobed nucleus painted on its surface, an eosinophil would have a bi-lobed nucleus, and a monocyte would have a U-shaped nucleus. The beads and containers may be made of any suitable material such as plastic or glass. The kit optionally includes coarse, granular material that when mixed with the first and second set of beads resembles platelets. 
     The diameter of the second set of beads is slightly larger than the first set. Preferably, the diameter of the first and second set of beads is proportional to the red and white blood cells that they represent. The average diameter of a human red blood cell is 6-8 microns and white blood cells have an average diameter of 7-14 microns depending on the type of white blood cell. Preferably, the number of beads present in the mixture of the first and second set is also dependent on the type of blood cell that the bead represents and proportional to the average number of red and white blood cells present in human blood. 
     The kit also optionally includes various sized containers filled with a mixture of the beads. The containers preferably have a side through which the contents can be viewed. The side can either be open or transparent. For example, the kit can include a large circular Petri dish. The top surface of the Petri dish can be open or covered with a transparent lid, so that when viewed from above the macroscopic model resembles the circular field of view of a microscope and the beads resemble a blood smear. The kit can also include a long, flexible cylindrical tube having transparent walls filled with the first and second set of beads to provide a model of a blood vessel to demonstrate blood circulation and the impact of blood pathology on circulation. Another container optionally included in the kit is a test tube having transparent walls, such that the tube can be filled with the first and second set of beads to produce a model of centrifuged blood from which packed cell volume can be determined. The containers, like the beads, can be made of any suitable material such as plastic or glass. 
     Referring now to the drawings, in which like reference numerals refer to like elements in each of the several views, there is shown in  FIG. 1  a first embodiment of the invention which provides a visual macroscopic model  32  of blood, wherein a container  34 , preferably a large, transparent, and circular Petri dish, is filled with red blood cell replicas  30  to simulate the millions of red blood cells typically seen when viewing a blood smear under a microscope. Also mixed with the red blood cell replicas  30  in the container  34  are various replicas of white blood cells, including a neutrophil replica  20 , a lymphocyte replica  22 , a monocyte replica  24 , an eosinophil replica  26 , and a basophil replica  28 . Optionally, the mixture of white and red blood cell replicas can include small pieces of coarse material that represent platelets  54 . The coarse material  54  which is mixed with the beads is preferably made of crushed sea shells due to their resemblance to cell fragments. 
     Referring now to  FIG. 2 , which is a second embodiment of the present invention, the mixture of beads and crushed sea shells that was used to fill the container  34  in  FIG. 1  is transferred to a long, flexible transparent tube  38 . The tube preferably has at least one open end having a removable stopper  40 , such that when removed, the contents can flow out of the open end. The diameter of the tube  38  is sufficiently large, so that the mixture of red and white blood cell replicas and coarse material can flow within the walls of the tube  38 . 
     In order to demonstrate the effects of various pathologies on blood, the mixture of red and white blood cell replicas is manipulated by changing the shape or number of the beads. For example, in  FIGS. 3 and 4 , the mixture of beads that was in the first and second embodiments of the present invention shown in  FIGS. 1 and 2 , respectively, has been changed by removing some of the red blood cell replicas  30  with elongated, oval shaped beads  42  that are red in color to resemble blood afflicted with sickle cell anemia. The size of the sickle cell replicas  42  is selected, such that the length of the oval shaped beads is longer than the diameter of the transparent tube  38  in  FIG. 4 . Because the sickle cell replicas  42  are larger than the normal red blood cell replicas  30 , the sickle cell replicas  42  may become wedged between the inner walls of the tubing  38  impeding the flow of beads. This provides a better understanding of the effect of sickle cell anemia on circulation. Various other obstructions can be incorporated into the flexible tubing in order to demonstrate the effects of conditions, such as tumors, on blood circulation. 
     Referring to  FIG. 5 , the proportion of red blood cells and white blood cells has been changed by increasing the number of red blood cell replicas  30  in the transparent container  34 . The increased number of red blood cell replicas  30  resembles the excessive accumulation of red blood cells typical of a person afflicted with polycythemia. The excessive accumulation of red blood cells is also demonstrated using a sixth and seventh embodiment of the present invention shown in  FIGS. 6   a  and  6   b , respectively. The sixth embodiment of the present invention provides a visual model  44  to determine packed cell volume (PCV) which is the proportion of blood volume that is occupied by red blood cells. It is normally about 46% for men and 38% for women. A PCV is obtained by placing a sample of blood in a tube and separating the red blood cells from the rest of the fluid with a centrifuge. The resulting layers are then measured to calculate the PCV. In  FIG. 6   a  a container  46 , preferably a test tube that optionally has a removable lid  48 , is filled with red blood cell replicas  30  to a level which is normal for human blood. For a person afflicted by polycythemia, the level of red blood cells in a PCV would be elevated which is reproduced in the model  44  shown in  FIG. 6   b . The models demonstrated in  FIGS. 5 ,  6   a , and  6   b  allow a student to comprehend the quantitative aspects of blood pathology by identifying the presence of red blood cells which are statistically excessive. 
     By increasing the proportion of white blood cell replicas in the mixture of beads to an amount which would be statistically excessive, various models are produced that will familiarize a student with other blood pathologies.  FIGS. 7-10  show the eighth, ninth, tenth, and eleventh embodiments of the present invention, respectively, demonstrating the various blood pathologies that can be demonstrated using the blood cell visual model. In  FIG. 7 , an increased number of lymphocyte replicas  50  are present in the container  32 . Preferably, the additional lymphocyte replicas  50  are colored to have a cloudy surface to impart an overall cloudy appearance to the model to resemble the view under a microscope of blood afflicted with hairy cell leukemia. In  FIG. 8 , the hairy cell lymphocyte replicas  50  are replaced with immature lymphocyte replicas  52  having a dark shade of blue. The resulting visual model resembles the view under a microscope of blood afflicted with acute lymphocytic leukemia. In  FIG. 9 , an increased number of monocyte replicas  24  are present in the container  32  to resemble a blood smear exhibiting acute monocytic leukemia. Finally, in  FIG. 10 , the original mixture of beads is manipulated by increasing the number of basophil and eosinophil replicas  28 ,  26  to create a visual model to demonstrate how the level of these particular white blood cells increase due to an allergic reaction. 
     Various modifications can be made in the details of the various embodiments of the visual models of the present invention, all within the scope and spirit of the invention and defined by the appended claims.