Human Anatomy and Physiology



Human Anatomy and Physiology

Integumentary System Lab

Identification

- Practice Identifying the following structures:

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Basic Structure and function of the Skin

- In your lab report, create a section titled: “Background Information” Answer the following questions and perform the activities pertaining to the structures and functions of the skin:

1. Epidermal layer

- Are the cells taller in the basal or superficial layer of the epidermis? Explain.

- Can blood vessels be found in the epidermis? Why or why not?

Activity:

• Microscopic examination of squamous epithelial cells from the oral cavity

- Put a drop of methylene blue on a glass slide. Caution: methylene blue will stain clothes and skin.

- Gently scrape the inside of your cheek with the flat side of a toothpick.

- Stir the end of the toothpick in the stain and throw the toothpick away.

- Place a cover slip onto the slide and be sure there are no air bubbles.

- Use the lowest objective lens to observe the cells. Once the cells have been located, switch to a higher power objective lens and refocus.

- Observe and record the appearance of the cells. Draw a few of the cells observed in your lab report.

2. Dermal layer

- The wavy junction (dermal papillae) between the epidermis and dermis is

responsible for increasing ____________ and the presence of ______________ .

- The papillary dermis has mostly ________ connective tissue and the ____________ has mostly dense connective tissue.

- The dermis has network of __________ and elastic fibers, contains many _________ vessels, and has a rich ________ supply.

- Glands and hair follicles are found in the dermis, but are composed of __________ tissue.

Activity:

• Dermal Blood Supply (need glass slide)

- Press the heel of you hand firmly against a flat portion of a glass slide

for a few seconds. Observe and record the color of your skin in the

compressed area by looking through the glass, record the following in your lab report:

- What is the color of compressed skin?

- Infer the reason for the color change?

3. Hair

- The bulk of the hair shaft is composed of _____________.

Activity:

• Microscopic examination of hair shaft with a compound microscope

- Pull out one strand of scalp hair (lighter colored hair only) and lay the hair

horizontally on a glass slide.

- Add a drop or two of tap water and top it all off with a cover slip.

- Observe the dark cuticle and lighter medulla of the hair shaft with the 4X

objective lens.

- Switch to a higher power lens to view and draw a few overlapping

squamous epithelial cells.

- If someone is willing to donate hair with “split ends,” then compare the cuticle of hair with split ends with undamaged hair. Describe the differences observed.

4. Sebaceous glands

- Are they exocrine or endocrine glands? Why?

- What substance is secreted from a sebaceous gland and what is its purpose?

- Which areas of the skin are devoid of sebaceous glands?

5. Sudoriferous glands

- Are they exocrine or endocrine? Why?

- What substances are secreted from sudoriferous glands and what is the purpose for these secretions?

- Compare and contrast the two types of sudoriferous glands.

- Which of the areas have the greatest density of sweat glands? Why?

6. Nails

- The body of the nail is composed of which material? __________

- Identify the following nail structures on yourself or your lab partner. Draw them in your lab report.

- Nail root

- Cuticle

- Lunula

- Body of nail

- Nail fold

- Free edge of nail

Activity:

• Microscopic examination of the nail with a compound microscope.

- Obtain a pair of nail clippers and clip a small sliver of fingernail.

- Observe the nail first with a magnifying glass. Describe how it looks in your lab report.

- Place the nail on a glass slide with tweezers or forceps.

- Add a drop of two of tap water and cover with a cover slip.

- Examine the slide under a microscope using the 4X objective lens.

- Switch to a higher power objective lens to get a closer look at the cells and draw a picture in your lab report.

7. Sensitivity

- Hypothesize which body areas have the greatest density of touch receptors? Why?

- What is the anatomical name for these receptors? In which layer of the skin do these receptors reside?

Name:_______________________________ Date:___________Block:__________

Anatomy and Physiology: Skin

Lab: Testing Tactile Localization

Background

The density of touch receptors varies significantly in different areas of the body. In general, areas that have the greatest density of tactile receptors have a heightened ability to “feel.” These areas correspond to areas that receive the greatest motor innervation; thus they are also typically areas of fine motor control.

Tactile localization is the ability to determine which portion of the skin has been touched. The tactile receptor field of the body periphery has a corresponding “touch” field in the brain. Some body areas are well represented with touch receptors, and tactile stimuli can be localized with great accuracy, but density of touch receptors in other body areas allows only crude discrimination.

Title: Complete in your lab report

Problem/Purpose: Complete in your lab report

Hypothesis: Complete in your lab report

Materials:

• Rulers

• Washable Markers

• Pennies

Procedure:

1. The subject’s eyes should be closed during the testing. The experimenter touches the palm of the subject’s hand with a felt-tipped marker. The subject should then try to touch the exact point with his or her own marker, which should be a different color. Measure the distance between the two dots (from the center) in millimeters to determine to error of localization.

2. Repeat the test in the same spot two more times. Record the “error of localization” for each trial. Average the results of the three trials and record it in your data table.

|Testing Tactile Localization – Record Table in your lab report |

|Body area tested |Trial 1 error of |Trial 2 error of |Trial 3 error of |Average error of |

| |localization (millimeters)|localization (millimeters)|localization (millimeters)|localization (millimeters)|

|Palm of hand | | | | |

|Fingertip | | | | |

|Ventral forearm | | | | |

|Back of hand | | | | |

|Dorsal forearm | | | | |

|Experimenter’s Choice | | | | |

|Experimenter’s Choice | | | | |

Analysis Questions (Answer in your lab report)

Does the ability to localize the stimulus improve the second time? The third time? Explain.

Which area has the smallest error of localization (is most sensitive to touch)? Why?

Demonstrating Adaptation of Touch Receptors

Background

In many cases when a stimulus is applied for a prolonged period, the rate of receptor response slows and our conscious awareness of the stimulus declines or is lost until some type of stimulus change occurs. This phenomenon is referred to as adaptation. The touch receptors adapt particularly rapidly, which is highly desirable. Who, for instance, would want to be continually aware of the pressure of clothing on their skin? The simple experiment conducted next allows you to investigate the phenomenon of adaptation

Procedure

1. The subject’s eyes should be closed. Place a coin on the anterior surface of the subject’s forearm, and determine how long the sensation persists for the subject.

Duration of the sensation: ________ seconds

2. Repeat the test, placing the coin at a different forearm location. How long does the sensation persist at the second location?

Duration of the sensation: ________ seconds

3. After awareness of the sensation has been lost at the second site, stack three more coins on top of the first one.

Does the pressure sensation return?

Duration of the sensation:________ seconds

Are the same receptors being stimulated when the four coins, rather than the one coin, are used? Explain.

Data & Calculations: Complete in your lab report

Conclusion: Complete in your lab report (restate purpose, use data to support or refute hypothesis, explain scientific principle being investigated, explain what was learned, give possible reasons for error (i.e. How could this lab investigation be improved?)

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