Ex7: The Skin & Other Body Membranes

Ex7: The Skin & Other Body Membranes

I. Introduction/Background Information
Refer to the Lab worksheet : https://sites.google.com/site/physiolablist/
There are several sections to this lab, generally designed to assist students in understanding the structures & functions of skin & other body membranes. The objectives of this lab are:

1. to recount important functions of the skin/integumentary system
2. to recognize and name the following structures from a slide, model or diagram
* epidermis (including strata),
* dermis (papillary & reticular layers
* hair follicles & hair
* sebaceous glands & sweat glands
3. to compare the properties of the dermis & epidermis
4. to describe the distribution and function of the sebaceous glands, sweat glands, and hair
5. to differentiate between eccrine & apocrine sweat glands
6. to ennumerate the factors determining skin color
7. to describe the function of melanin
8. to compare the structure and function of the major membrane types
9. to list the general functions of each membrane type and note its location in the body
10. to recognize by microscopic examination epidermal, mucous, and serous membranes

II. Hypothesis
Part 1: Basic structure of the skin: If students read about structures as they locate them on a skin model then they will be able to write out a response to each objective
Part 2: Appendages of the Skin: If students examine a prepared slide of human skin then they will be able to identify skin structures on a drawing.
Part 3: Plotting the Distribution of sweat glands: If bond paper is taped to skin coated with iodine and left for 20 minutes, then a distribution of sweat glands will be mapped out because the sweat glands will dissolve the iodine, which will then be absorbed by the paper. As it reacts with the starch in the bond paper each sweat gland will produce a blue/black dot.
Part 4: Classification of Membranes: If students examine slides from trachea and small intestine, heart, as well as a freshly cut joint, then they can compare mucous, serous and synovial membranes.

III. Materials
Model of Skin, prepared slides/pictures, iodine, 1cm x 1 cm bond paper squares, tape.

IV. Procedure
“See Lab Instructions” (you may include pictures of procedure)
Part 1: Basic structure of the skin: Compare the following structures identified in the pictures with the model in the classroom.
Skin slide
Human Skin Slide
Part 2: Appendages of the Skin:
Part 3: Plotting the Distribution of sweat glands: Insert a photo of each of your sweat distribution patches. Label them "palm" and "forearm".
Part 4: Classification of Membranes:
pseudostratified ciliated columnar epithelium
mucosa of trachea


mucosa of small intestine


drawing of one villus
pericardium (around the heart)

V. Results/Observation/Data

List answers to questions from each section of the lab
Part 1: Basic structure of the skin: (No questions in this section)
Part 2: Appendages of the Skin:
What additional features did you observe in the two photos of skin (above) that you didn't see in the slides of stratified squamous epithelium that you studied for Chapter 3?
We didn't see Meissner's corpuscle, hair follicles, dermis, keratin, and the sebaceous glands.
Part 3: Plotting the Distribution of sweat glands:
Which skin area tested had a greater density of sweat glands?
The skin area from the palm contained a greater distribution of sweat glands.Labeled Pictures:
Part 4: Classification of Membranes:
How do the roles of trachea mucosa and small intestine mucosa differ? How are they the same?
The small intestine mucosa absorbs nutrients. It has simple columnar epithelium that contains absorptive cells and goblet cells. The mucosa has villi to increase its surface area. Trachea mucosa has pseudostratified ciliated columnar epithelium that contains goblet cells. Warms, moistens, and removes foreign particles from the air as it flows through the trachea. Produces mucus. Both contain goblet cells (look for more similarities)

We think that mucous membranes have a high regenerative capacity because they line all of the body cavities that open to the exterior. The mucosa epithelium are responsible for absorption and secretion; in other words, they are very important to the body. They must have a high regenerative capacity because of their large role in the body's functions.

The pericardium is an example of a serous membrane. It's too tiny to see, but the endothelium is composed of simple squamous epithelium. List the specific names of the following serous membranes:

Lining of the cavity in which the heart resides: visceral pericardium
Covering of the lungs: Visceral pleura
Lining of the thoracic cavity: parietal peritoneum
Covering on the viscera: Visceral pericardium
Lining of the visceral cavity: Visceral peritoneum

VI. Conclusion: Respond to each objective. What did you learn?

1. What are the important functions of the skin/integumentary system?
The important functions of the integumentary system are to protect the body from mechanical, chemical, and thermal damange, UV radiation, and bacteria, insulate and cushion body organs, absorption, secretion, and makes proteins.
2. Can you recognize and name the following structures from a slide, model or diagram?
* epidermis (including strata),
* dermis (papillary & reticular layers
* hair follicles & hair
* sebaceous glands & sweat glands
YES!
3. Compare the properties of the dermis & epidermis
The epidermis is the outer layer of skin and is made up of stratified squamous epithelium that can become hard and tough. Composed of five layers (stratum basale, spinosum, granulosum, lucidum, and corneum). It is avascular. Most of the epidermis's cells are keratinocytes ( produce keratin). The dermis is the inner layer which is made up of dense connective tissue. Dermis has two regions: papillary and reticular areas. Dermis is supplied with blood vessels that help maintain body temperature.

4. Describe the distribution and function of the sebaceous glands, sweat glands, and hair
Sebaceous glands secrete sebum by a holocrine process it prevents too much water loss. There are between 2 and 4 million sweat glands all across the body and they control body teperature. Hair is everywhere even when it is inconspicuous and it protects, regulates body temp., facilitates evaporation of perspiration.

5. Differentiate between eccrine & apocrine sweat glands
. Eccrine glands are all over your body and function throughout your life. Apocrine glands develop during puberty and are most active during adulthood.

6. Ennumerate the factors determining skin color
Your skin color is determined by the amount of melanin that you produce.

7. Describe the function of melanin
The main function is to act as a sunscreen to protect us from ultraviolet (UV) radiation in sunlight

8. Compare the structure and function of the major membrane types
The major membrane include epithelial membranes, which include the cutaneous, mucous, and serous membranes, and connective tissue membranes, represented by synovial membranes. The cutaneous membrane, generally called the skin or integumentary system.

9. List the general functions of each membrane type and note its location in the body
Membranes cover body surfaces, line cavities and protect organs. The mucous membrane is epithelial tissue that is open to the exterior environment (such as the lungs and trachea). Its function is secretion and absorption. Serous membranes is also epithelial tissue that lines closed organs (such as the heart). Its function is lubrication. Cutaneous membrane is epithelial tissue that forms the outer layer of the skin, protecting the tissues and organs underneath. Synovial membranes are connective tissue that provide a frictionless surface to movable joints.

10. Can you recognize by microscopic examination epidermal, mucous, and serous membranes?
YES