By and large, the features observed in animals, plants, fungi,and biological organisms, in particular, are representative oftheir function and shaped by natural selection in the context oftheir environment. When we, as scientists, observe forms in nature,such as differing limb structures in vertebrates, varying toothshapes in mammals, a diversity of leaf shapes in trees, or even thedifferent shapes and sizes of cell types, we see both the functionof the trait in question as well as the constraints, andpossibilities, of living in the physical world. In this lab, youwill take some moments to observe a variety of structuresrepresentative of the Animal kingdom that have been shaped bynatural selection, and whose function may be represented, andtherefore inferred, by their form.

During this lab, we will investigate anatomy (form) tounderstand the physiology (function). Our investigation will beginat the cellular level, comparing cellular shapes and structures ofvarious tissues, allowing us to understand their purpose. We willthen bring our focus to an organismal level, using clues ofmorphology to conclude habits and even behaviors of differentspecies of fish. We will also focus on a specific characteristic,dentition in mammals, to help us to determine their dietarytype.

In particular, we will be looking at the relationship betweenthe form and function of:

1) Cells - different cells and a virus

2) Tissues- representatives of animal tissue types,

3) Body Morphology- various fish species

3) Dentition - a variety of vertebrate skulls and the teeth thatthey possess.

Cells and Viruses

Observe and draw the following cells.  

Plant cell (slide) – Note cell wall,chloroplast

What does this tell you about the functions of this cell?

Pancreatic cell (slide) – Note large amounts ofendoplasmic reticulum and ribosomes.

What do these structures reveal about its function?

Virus (Electron micrograph) – Note the lack oforganelles. Why do viruses need to infect a host cell toreproduce?

  Table 1

	Drawing of Cell Include total magnification	Organelles observed	Summarize your relationship between the cell’s anatomy andfunction.
Plant Cell
Pancreatic Cell
Virus

Tissues

Tissues are groups of cells that have similar structure andfunction together. In this lab, we will investigate the anatomy ofvarious tissue types and investigate the relationship between theirstructure and function.

Types of tissues we will investigate in this lab include:

• Epithelial – squamous, cuboidal, and columnar
• Connective tissues – connective tissue proper and muscle

Future labs will investigate additional tissue types studydifferent organismal systems.

Epithelial Tissues

Epithelial tissues are comprised of tightly packed cellsenabling them to form barriers:

- between the body and the outside world

- to line organs

- to line cavities.

In this exercise, you will be observing three different types ofepithelial tissue squamous, cuboidal, and columnar, so namedbecause of their shape.

Squamous

The cells of squamous tissue are flat and thin to allow for thecritical diffusion of nutrients and gases in the alveoli of lungsand blood vessels.

(Think of the word squashed to remember the shape.)

Cuboidal

The cells of cuboidal tissue are, as the name implies, shapedlike cubes.

Cuboidal cells are found in tubules throughout the body.

Observe the individual cells surrounding the tubules. Noticethat when cuboidal cells form the circumference of the tube, theyhave a slightly trapezoidal shape, allowing the cells to form atight seal around the tube, and to distribute the force, furthersupporting its integrity. Think of the keystone of a free-standingarch.

Columnar cells

Columnar epithelial cells are long and often found where largeamounts of secretions or active absorption are essential.

Columnar tissue can be found in the intestines secretingenormous amounts of digestive enzymes and absorbing nutrients. Theyare also located in the trachea of the respiratory tract, wherelarge quantities of mucus are created to help trap particles beforethey enter the lung.

In the columnar epithelium of the respiratory tract, you can seegoblet cells that release mucus and cilia at the apical surface ofmany of the cells.

How do cilia and mucus in the respiratory tract protect provideprotection?

Many columnar epithelial cells produce mucus. These cells arecalled goblet cells. (To remember their name, think of gobletsfilled with white mucus.) Look for goblet cells in your intestinalslide.

Table 2 Summary of Epithelial TissueAnalysis

Tissue Type	Draw the tissue which represents the relevant structuralfeatures. Be sure to include total magnification!	Describe the structure or form of this tissue	Location in Animal Body (possibly indicated on the slide)?
Simple Squamous
Simple Cuboidal
Simple Columnar

Connective tissue

Connective tissue is so named because it connects tissues andorgans throughout the body together.

Connective tissue contains:

• Cells
• Matrix (may be solid or liquid)
• Sometimes fibers are present to enhance strength, resilience,or elasticity.

Examples of connective tissue include:

• Blood
• Bone
• Cartilage
• Adipose (fat)
• Connective tissue proper

Dense regular connective tissue

Ligaments and tendons – are composed of fibersthat attach muscle to bone (tendons) or bone to bone (tendons)

You can determine function from the types and placement of thefibers. Look at the two slides.

Slide 1 – Dense regular unilateral fibers

Slide 2 – Dense regular fibers swirl in more than onedirection.

Which do you think undergoes forces in many directions?

Which supports forces in predominantly one direction?

Examine the slide below.

     

  

Note the direction of the collagen fibers. Do you feel that thefibers reinforce strength laterally or vertically? Why?