here is the lab

To submit, print this document, complete all lab activities and answer the review questions, scan the pages using the free phone app AdobeScan and upload the PDF to Canvas.

· You are only required to submit pages that require your drawings or answers. No need to submit other pages (such as pages 1, 9).

· Include your full name on the first page you submit.

Objectives

After completing this lab, you should be able to:

· Differentiate between different types of tissues

· Explain the function of tissues based on an analysis of their structure

· Determine facts about an organism’s lifestyle and habitat through an analysis of its morphology

· View and understand the differences between light and electron microscope pictures

The primary purpose of this lab is to investigate the relationship between form and function. The various adaptations seen in living organisms from the tiniest of cells to the largest of animals enable the organism to survive, thrive, and to carve out a niche in the ever-changing environment.

Introduction

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

During this lab, we will investigate anatomy (form) to understand the physiology (function). In the world of architecture and design, there is a similar tension between form and function of spaces and buildings. In the natural world, form has evolved for optimal (ie., efficient) function. Our investigation will begin at the cellular level, comparing the cellular shape and structure of various tissues, which will allow us to understand their purpose. We will then shift our focus to the organismal level, using clues of morphology to deduce habits and behaviors of different fish species. We will also focus on a specific characteristic: the dentition (ie., teeth) in mammals, to help us to determine their diet.

In particular, we will be looking at the relationship between the 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 that they possess. 

Cells and Viruses

Using an online picture search engine, find, observe, and draw the following cells (be sure to note the magnification of the picture you have found, do not use an image if the magnification has not been specified) Complete the drawings in the table below, answer questions in the space below: 

Plant cell (light microscope) – Note cell wall, chloroplasts

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

Pancreatic cell (light microscope) – Note large amounts of endoplasmic reticulum and ribosomes.

To review from Bio 101, what do these organelles do? What does the abundance of these structures reveal about the pancreas’ function?

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

  Table 1

Tissues 

Tissues are groups of cells that have similar structure, which work and function together. In this lab, we will investigate the anatomy of tissue types and determine the relationship between their structure 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 seen in different systems.

Epithelial Tissues

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

- between the body and the outside world

- to line organs

- to line cavities.

In this exercise, you will be observing 3 different types of epithelial tissue: squamous (think “squished”), cuboidal (think “cubes”), and columnar (think “column-like”), so named because of their shape.

Squamous (Think of the word “squashed” to remember the shape.)

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

Cuboidal

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

Cuboidal cells are found in tubules (tube-like structures that usually make chemicals) throughout the body.

Observe the individual cells surrounding the tubules. Notice that when cuboidal cells form the circumference of the tube, they have a slightly trapezoidal shape, allowing the cells to form a tight seal around the tube, and to distribute the force, further supporting its structural integrity. Think of the keystone (highest center stone) seen in a free-standing arch.

Columnar cells

Columnar epithelial cells are long and often found where large amounts of fluid secretion or active absorption are essential.

Columnar tissue can be found in the intestines secreting large amounts of digestive enzymes and also absorbing nutrients. They are also located in the lungs: specifically the long tube called the trachea, where large amounts of mucus are made to help trap particles before they enter the deep tissues of the lung.

In the columnar epithelium of the respiratory tract, you can see goblet cells that release mucus and cilia at the apical (ie., top) surface of many of the cells.

How do cilia and mucus in the respiratory tract protect provide protection?

Many columnar epithelial cells produce mucus. These cells are called goblet cells. (To remember their name, think of goblets filled with white mucus.) Look for goblet cells in a slide of the intestines found online. (you may need to look at 2-3 different photos, with different magnifications, to understand the arrangement of the cells, specifically which cells face the interior and which cells face the exterior).

   Table 2 Summary of Epithelial Tissue Analysis

Connective tissue

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

Connective tissue contains:

· Cells

· Matrix (may be solid or liquid)

· Sometimes fibers are seen (they enhance strength, resilience, or elasticity)

Examples of connective tissue include:

· Blood

· Bone

· Cartilage (a rubbery tissue found in your nose and covering the ends of bones)

· Adipose (fat)

· Connective tissue (which includes bone, ligaments, tendons)

Dense regular connective tissue

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

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

Slide 1 – Dense regular unilateral fibers

Slide 2 – Dense regular fibers swirl in more than one direction.

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 the fibers reinforce strength horizontally or vertically? Why?

Muscle

Muscle tissues can contract. Contractile proteins slide past one another, allowing for movement. During this section of the lab, you will investigate three different types of muscle tissue: Skeletal, Smooth, and Cardiac.

Skeletal Muscle – Voluntary control

Note the striations in the muscle cells, also known as muscle fibers. These are the areas where there is an overlap of the actin and myosin contractile proteins. Also, note that each cell has many nuclei located on the outside of the cell. The peripheral nuclear position allows for less interference during contraction. 

Draw a skeletal muscle cell:

Cardiac Muscle- Involuntary control of the heart

Cardiac muscle is found only in the heart. Cardiac cells branch out to form multiple connections with the cells adjacent to them, thus promoting coordination of the beating heart.

Find a microscopic picture of cardiac muscle cell(s). The darker lines you see between the cells are called intercalated discs. What you cannot observe is that these intercalated discs are studded with pores to allow for chemical communication between the cells.

Striations are also visible in cardiac muscle because the contractile proteins slide next to each other in a way that is similar to the skeletal muscle.

Find a slide of cardiac tissue at 400x

Draw a small area of cardiac tissue.

Outline an individual cell in red and show the intercalated discs in blue.

Smooth muscle- Involuntary control of your guts

Smooth muscle named because of its lack of striations and long smooth shape of each cell. Contractile fibers of smooth muscle are arranged in a fishnet pattern wrapped around the cell. (Imagine the mesh sacs containing fruit in the grocery store.) During contraction, the entire cell compresses.

Drawing of a cell relaxed ---a drawing of a cell contracted. 

Find a microscope slide online with 400x magnification.

Draw smooth muscle tissue and outline one cell in red.

Organismal Level

Now that we have examined the relationship between the form and function of tissues, we will now examine the structure of various animals to see if you can conclude something about their habitat or lifestyle. In this lab, we will see how much we can determine about the lifestyle of a particular fish through the investigation of its anatomy.

Fish

Through an examination of a fish's anatomy: its overall body shape, markings, the placement of its mouth, as well as the shape and placement of its fins, you may infer information of the fish's habitat and survival mechanisms.

Tuna

Catfish

Flounder

Butterfly Fish

Table 3: Observational Data for Fish Anatomy Analysis

Through an investigation of the physical characteristics of each fish, what can you conclude about the fish’s habitat or lifestyle?

Which fish do you believe to be the fastest swimmer? Explain why.

Which fish(es) or fishes do you believe to bottom dwellers? Explain why.

Which fish(es) do you believe lives in coral reefs? Explain why.

Note that the real eyes on the butterfly fish is obscured and yet there are black spots (which are false eyes) near the back of the fish. What purpose do you think these false eyes serve?

Mammals

Much can be determined about the diet of an animal through the observation of its dentition.

There are four different types of teeth that may be found in land mammals.

Tooth Types and the Dental Formula

By and large, mammals have what is called heterodont dentition. This means that the teeth have different shapes, and therefore, different functions. Specifically, there are four different tooth types: incisors, canines, premolars, and molars. 

Incisors - The anterior most teeth, always found in the premaxilla bone. Many mammals use these for nipping or biting off smaller pieces of a food item. In humans, there are four in the top jaw and four in the bottom jaw.

Canines - When present, the canines are found immediately posterior to the incisors. It is frequently pointed and conical in shape. These teeth are mostly used for holding onto prey items in carnivores, or for either aggressive display or combat. In humans, there are two in the top jaw and two in the bottom jaw.

Premolars - Premolars, or cheek teeth, are usually used for grinding or processing food items prior to swallowing. These teeth are posterior to the canines and are the posterior most teeth that are replaced in human development in adolescence. In humans, there are four in the top jaw and four in the bottom jaw. 

Molars - Molars are posterior to the premolars and are not replaced in development. They are defined as the teeth immediately posterior to the back-most tooth that is replaced in adolescence. Molars are generally larger than premolars and are used to grind food items prior to swallowing. In humans there are either two or three in the top and bottom of each side of the jaw. When a third molars, the posterior-most teeth, are present, they are referred to as “wisdom teeth” and are frequently removed as they develop in the jaw.  

Dental Formula of Humans

Exercise:

1) Familiarize yourself with the 4 different tooth types mentioned above. 

2) Identify the dentition of each of the 4 skulls

3) Fill in the chart below 

Table 4; Dentition Analysis

Review Questions

1) Answer with epithelial or connective tissue

a) Which type of tissue forms barriers, covers, and lines body surfaces, and hollow organs?

b) Which type of tissue acts to support, protect, and transport?

c) Which type of tissue’s major function is to contract?

d) Which type of tissue is composed primarily of densely packed cells?

e) Which type of tissue contains cells, a large matrix, and often supported by fibers?

2) What is the major function of squamous epithelial tissue?

 Where are these tissues found in the body?

3) Which type of epithelial tissue are shaped like cubes and often are found as the lining and supporting cells of tubules, such as those found in kidney tubules?

4) Which type of epithelial tissues has a height that is greater than its base, and a large internal area allowing for the production of proteins, and the processing of molecules?

5) Columnar cells lining the small intestines contain microvilli at the apical (free) surface. What purpose do these microvilli serve?

6) How can you determine the direction of force associated with a ligament or tendon?

7) Which type of muscle is under voluntary control and has multiple nuclei located on the surface of the cell?