Physiology 1 Name Redwood High School Class Period 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 these 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 also 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 in the small intestine and blood vessels. Focus Questions • What are the major tissue types and sub-types? • How can those tissue types be identified microscopically? • What tissue/cell types comprise human skin? What are the roles of those tissues in the function of those organs? Procedure Part I: Human Skin A. Pre-lab Preparation 1. Construct a reading log using your textbook (Chapter 6, pages 112-123) and coloring assignments to review the important layers and structures of the skin. The diagrams in your textbook 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/Structures of Human Skin 1. Obtain a prepared slide of human skin. 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. Measure the width of the epidermis. b) Identify, draw and label the dermis and hypodermis. In addition, include a sweat gland in your field of view and drawing. Measure the diameter of the sweat gland. c) Identify, draw and label the dermis and hypodermis. In addition, include a hair follicle in your field of view and drawing. Measure the diameter of the hair follicle. 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. Construct a reading log using your textbook (Chapter 5, pages 94-109) and coloring assignments to review the important tissue types and sub-types. The diagrams in textbook Chapter 5 (especially fig. 5.1 fig. 5.9 for epithelial tissue and fig. 5.13 fig. 5.20 for connective tissue) are especially helpful, as they show both photographs and diagrams of the important tissue groups. 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 most familiar with the following epithelial tissues that are important in the structure of human skin: simple squamous (5.1); simple cuboidal (5.2); stratified squamous (5.5); and stratified cuboidal (5.6). 4. You should be most familiar with the following connective tissues that are important in the structure of human skin: loose connective – aerolar (5.13), adipose (5.14); and dense connective (5.15). 5. Using the information from the sources listed above, complete the Human Tissues Outline Worksheet. B. Tissue Types of Human Skin 1. Obtain a prepared slide of human skin. Conduct a microscopic observation at 100X and 400X. 2. Make a detailed microscopic drawing at the most useful magnification. Identify and label at least (2) types of epithelial tissue. You do not need to conduct any microscopic measurements. 3. Make a detailed microscopic drawing at the most useful magnification. Identify and label at least (2) types of connective tissue. You do not need to conduct any microscopic measurements.