Ex7: The Skin and 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 did not observe Meissner's Corpuscle and the sebaceous glands.
Part 3: Plotting the Distribution of sweat glands:
Which skin area tested had a greater density of sweat glands?
The palm had a greater density of sweat glands.
Labeled Pictures:

palm sweat glands


forearm sweat glands

Part 4: Classification of Membranes:
How do the roles of trachea mucosa and small intestine mucosa differ? How are they the same?
The trachea mucosa secrete mucous and move it up using cilia while small intestine mucosa absorb nutrients using villi.

Do you think that mucous membranes have a high regenerative capacity? Explain why or why not.
Yes, mucous membranes are subject to severe abrasion and wear and tear, thus it must be able to regenerate at a sufficient rate to replace lost cells.



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

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

1. What are the important functions of the skin/integumentary system? The functions of the skin are to protect the body from the environment, from both abrasion as well as bacterium. The integumentary system is also involved in secreting waste in the form of sweat, which also cools the body.
2. Can you recognize and name the following structures from a slide, model or diagram?
• epidermis (including strata), yes
  
• dermis (papillary & reticular layers, yes
  
• hair follicles & hair, yes
  
• sebaceous glands & sweat glands, yes
  
3. Compare the properties of the dermis & epidermis: The dermis contains blood as well as nerve endings, whereas the epidermis is composed of stratified squamous epithelium and keratin.
   
4. Describe the distribution and function of the sebaceous glands, sweat glands, and hair Sebaceous glands are are concentrated around the hair follicle, they are responsible for oil secretion. Sweat glands secrete sweat and are distributed around the skin; they are independent of the hair follicle. Also, their concentration varies around the body. Hair shafts are present all over the skin except in the palms and the soles of the feet. Evolution-wise, hair was meant to provide warmth; however, our hair on our skin has become too thin to provide warmth.
   
5. Differentiate between eccrine & apocrine sweat glands. Eccrine glands are on the palms, soles, and forehead, and virtually on all skin. Apocrine glands are in the axillae and genital areas.
6. Ennumerate the factors determining skin color. Skin color depends on, firstly, genetics. Genes determine how dark your skin is. However, light exposure also plays a role in skin color. The more the skin is exposed to light, the darker the skin becomes.
7. Describe the function of melanin. Melanin is a pigment that filters the ultra-violent radiation from the sun, protecting the tissues and organs underneath the skin.
8. Compare the structure and function of the major membrane types AND
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? It is more likely for us, at this point, to be able to recognize epidermal membranes with its stratified squamous epithelium cells, than mucous and serous membranes. Mucous and serous membranes are harder to identify because we have not seen many slides.