Human Anatomy

Cells & Tissues Observation Lab

BACKGROUND INFORMATION

In the 17^th century, the amateur Dutch scientist Anton van Leeuwenhoek used one of the first microscopes to discover a whole new world of living organisms.  Using a single lens, or simple microscope, he observed tiny organisms in pond water and other substances.  Robert Hooke, an English scientist, discovered larger organisms had small microscopic sub-units called cells.  He noticed these “tiny compartments” while viewing cork cells.  Ever since this early era of discovery, biological microscopy has been essential in the study of living things.

The microscopes used in this course are compound microscopes, made of a set of lenses.  They are more powerful, and more complex, than those used by van Leeuwenhoek and Hooke.  This lab will introduce you to the use and care of the standard compound microscope.

PARTS OF A MICROSCOPE

• The set of lenses closest to your eye is the OCULAR or EYEPIECE.  The ocular magnifies an image by the factor indicated on the ocular's barrel, usually 10x.  if the factor is 10x, the image is magnified 10 times.  If the factor is 5x, the image is magnified five times

• The BODY TUBE holds the ocular in place.  Although called a tube, it may be more like a box in some models.

• At the bottom of the body tube is the REVOLVING NOSEPIECE.  A turretlike circular mechanism rotates so that different lenses can be selected.  Always rotate the nosepiece by holding the outside of the revolving disk--never push on the lens barrels.

• Each lens set attached to the revolving nosepiece is an OBJECTIVE.  As with the ocular, each objective is marked with its magnification factor.  Microscopes may vary in the number of objectives.  Our microscopes have three objectives.

• The LOW POWER OBJECTIVE has a magnification factor of 4x.

• The MEDIUM POWER OBJECTIVE has a magnification factor of 10x.

• The HIGH-POWER OBJECTIVE has a magnification factor of 40x.

• The TOTAL MAGNIFICATION is determined by multiplying the power of the ocular by the power of the objective in use.  For example, if the ocular is 10x and the objective is 15x, the total magnification would be 150x.  The ocular power of our microscopes is 10x.

• The specimen is usually mounted on a glass or plastic slide that rests on the STAGE, a platform just below the objective.  The stage has a hole so that light can pass through the specimen from below.  If the stage has an adjustable bracket that moves the slide around mechanically, the stage is called a MECHANICAL STAGE.  If not, the slide is held in place by STAGE CLIPS and must be moved by hand.

• Below the stage is a high-intensity LAMP.  Light rays from the lamp travel through a hole in the stage, through the specimen mounted on a slide, then through the objective and ocular, to the eye.

• Sometimes the light from the lamp is too strong to see the specimen clearly.  The light level may be reduced by adjusting the lamp intensity (if possible).  Light intensity may be adjusted by adjusting the DIAPHRAGM just below the stage.  Our microscopes have DISK DIAPHRAGMS, which are just holes of different diameters on a rotating disk.  The roman numerals on the disk indicate the level of intensity.  I = most intense, V = least intense.

• The entire upper assembly of the microscope is held in an upright position by a bar called the ARM.  The scope is supported by a square or horseshoe-shaped BASE.  The arm may be connected to the base by a pivot, which allows the upper assembly to move into a more comfortable viewing position.

• The COARSE-ADJUSTMENT KNOB and the FINE ADJUSTMENT KNOB are on the arm.  These knobs adjust the distance between the stage and the objective, thus focusing an image of the specimen.  The fine-adjustment knob changes the distance very little, whereas the coarse adjustment knob changes the distance greatly.

USING THE MICROSCOPE

• Always carry the microscope with two hands; one under the base and the other one grasping the arm.  Carry it in an upright position.

• Unwind the lamp cord carefully.  Avoid damaging the parts around which it is coiled.  Plug the cord into an outlet in a safe manner.

• Make sure the stage and objective are at their farthest distance apart and that the lowest power objective is in position.  Start each new observation at low power.

PURPOSE: 

The purpose of this lab is to expose the student to a variety of different types of tissues and cells that are found in both humans and other animals.  The slides will show how the shape of the cells play and important part in the function of the cells and tissues.

MATERIALS NEEDED:

• Compound Light Microscope

• colored pencils

• Prepared Slides

• Giant multipolar neurons

• Hyaline cartilage

• Elastic cartilage

• Colon

• Jejunum

• Blood

• Spinal cord

• Cardiac muscle

• Striated muscle

• Smooth muscle

PROCEDURE:

   Part One:  Viewing Prepared Slides of Cells & Tissues

• Obtain a prepared slide and view the slide under low power, medium power or high power…this is your choice.  Which ever     objective gives you the best view of the material on the slide.

• On your observation sheet sketch the view of each slide that is listed.  Follow these guidelines:

  • sketch what you see, and use the correct colors

  • label the magnification that you used to view the slide (100x for medium power, 430x for high power)

  • make sure your sketches match the labels on your observation sheet

  • that means put the blood cells sketch in the area marked “BLOOD CELLS”!!

• Repeat these steps for all ten (10) of the prepared slides.  Each sketch will be worth 5 pts.

Part Two:  Conclusion Questions

• Complete the Conclusion Questions on JupiterEd.

To help you understand what you are to be looking at for each slide you are viewing, here are some micrographs of the items you are asked to find:

Giant Multipolar Neurons:

Spinal Cord:

Hyaline Cartilage:

Elastic Cartilage:

Colon:

Jejunum:

Blood:

Cardiac Muscle:

Striated Muscle:

Smooth Muscle: