Physiology 1
Human Skin: A Microscopic Study of an Organ and its Tissues
Background
Tissue types, which can mostly be recognized macroscopically, can be organized into sub-groups
based on cellular structure and function. Since cells are very small, these differences in cell structure
must be observed microscopically.
In this lab activity, we will use microscopes to make cellular observations and, ultimately, to
make the connection between organs and the microscopic tissues/cells of which they are composed.
This cellular level of organization is becoming increasingly well understood and is the main focus of most
current medical/physiological research. This lab will provide additional practice in microscopy and
microscopic observation/drawing. We will use these skills repeatedly throughout the year.
Some organs in the body are composed largely of one type of cell. For example, the brain is mostly
made up of neurons; muscles are mostly made up of muscles cells; glands are made up of epithelial
cells.
However, many organs are a composite of many different types of tissues. The skin is a good
example of this type of organ. Skin, the human body’s largest organ, is composed of three distinct
layers: epidermis, dermis and hypodermis (or subcutaneous). Each of these layers contains distinct
structures and distinct tissue types. In this lab, you will observe and identify the important layers,
structures and tissue types of human skin. You will also have the opportunity to observe, the same
phenomena of multiple tissue types found in the small intestine and the aorta, the major blood vessel
carrying blood away from the heart. You will also observe adipose tissue.
Focus Questions
• What are the major tissue types and sub-types?
• How can those tissue types be identified microscopically?
• What tissue/cell types compose skin, blood vessels and small intestine? What are the roles of
those tissues in the function of those organs?
Procedure
Part I: Human Skin
A. Pre-lab Preparation
1. Label the diagram of the skin given. Use Chapter 6, pages 112-123 and the diagrams in Chapter 6
(fig.6.1 - skin, 6.2 - epidermis, 6.3 - melanocyte, 6.4 - nails, 6.5 - hair follicle & 6.7 - sebaceous gland) are
especially helpful, as they show both photographs and diagrams of the important skin layers.
B. Microscopic Study of an Organ–Layers and Structures of Human Skin (The scalp)
1. Obtain a prepared slide of human scalp. Conduct a microscopic observation at 40X and 100X.
2. Make the following detailed microscopic drawings at the most useful magnification:
a) Identify, draw and label the epidermis.
b) Identify, draw and label the dermis and hypodermis. In addition, include a sweat gland in your field of
view and drawing.
c) Identify, draw and label the dermis and hypodermis. In addition, include a hair follicle in your field of
view and drawing.
3. You should also identify as many of the following structures as possible: blood vessels; sebaceous (oil)
gland; fat; muscle; sensory nerves.
Part II. Human Tissue Types
A. Pre-lab Preparation
1. Use the chart you completed for Tissues from Chapter 5, pages 94-109 and the diagrams in textbook
Chapter 5
2. You should be familiar with the four basic tissue groups – epithelial, connective, nervous and
muscle. We will focus on the sub-types within the epithelial and connective groups.
3. You should be familiar with the following epithelial tissues: simple squamous (5.1); simple cuboidal
(5.2); simple columnar (5.3); stratified squamous (5.5); stratified cuboidal (5.6); stratified columnar (5.7);
and pseudostratified columnar (5.4).
4. You should be familiar with the following connective tissues: loose connective – aerolar (5.13),
adipose (5.14); dense connective (5.15); cartilage – hyaline (5.16), elastic (5.17) and fibrocartilage (5.18)
bone –compact and cancellous (5.19); and blood (5.20).
5. Using the information from the sources listed above, complete your microscopic drawings below.
B. Epithelial Tissue- Small Intestines
1. Obtain a prepared slide of the small intestines-specifically the duodenum. Conduct a microscopic
observation at 100X and 400X.
2. Make a detailed microscopic drawing at the most useful magnification. Identify and label the epithelial
tissue found in Small intestines. Label the nucleus, the microvilli, the goblet cells (cells that secrete) and
the connective tissue.
C. Muscle Tissue-Aorta
1. Obtain a prepared slide of an aorta (the major vessel leaving your heart. Conduct a microscopic
observation at 100X and 400X.
2. Make a detailed microscopic drawing at the most useful magnification. Identify and label the nucleus,
the cell membrane, and the cytoplasm
D. Connective Tissue-Adipose Tissue
1. Obtain a prepared slide of adipose tissue. Conduct a microscopic observation at 100X and 400X.
2. Make a detailed microscopic drawing at the most useful magnification. Identify and label the fat
droplets, cell membranes, and the nucleus.
Analysis Questions
1. Define tissues.
2. In your study of the skin, what have you discovered? Explain how the skin is organized.
3. What are the major roles of the skin? Explain how the structure of the skin relates to each of the roles
it plays. What structures/tissues are present to carry out each of these roles.
4. What are the four types of tissue found in the human body and what are the main functions of each?
Which tissue type was not observed in this activity?
5. What role do the tissue types play in the small intestines and aorta? How does their structure relate
to their function?
Write a conclusion