Lecture 23, The Integumentary System (part 2)

Question 1

Lines of Cleavage

Answer 1

cleavage lines are topological lines, or linear clefts, in the skin that indicate the direction of orientation of underlying collagen and elastin fibers
- collagen and elastin fibers within the dermis, arranged in parallel bundles
- also called tension lines of Langer lines
the arrangement of these fibers in parallel bundles create resistance to forces normally applied to the skin
clinical significance in healing following an incision
- an incision made parallel to the cleavage line will usually remain closed and heal with minimal scaring
- an incision made perpendicular, or at an angle, to a cleavage line will be pulled open due to the recoil of elastic fibers that have been severed
◦ results in a longer healing time and greater
scarring
- surgeons often choose to make neat incisions parallel to the lines of cleavage, when possible

Question 2

Clinical Case: Albinism and Vitiligo

Answer 2

albinism is a genetic disorder that partially or completely affects the colouring of the skin, hair and eyes
- primary results from abnormal melanocyte function, leading to very light-coloured hair, skin and eyes
- individuals with albinism generally need to use more sun protection to prevent sunburns and reduce the risk of skin cancer (very prone to getting sun burnt)
- melanin is also normally present in the retinal wall, and a lack of this pigment may lead to the light sensitivity and vision problems
vitiligo is similar to albinism, except it only in some areas of the skin
- some areas of the skin may not be completely unaffected, while some patches may contain little to no melanin
- proposed to be the result of an autoimmune condition
neither albinism nor vitiligo directly affects the lifespan of an individual (only affecting melanocytes)

Question 3

Clinical Case: Skin Cancer

Answer 3

skin cancer is a condition that involves uncontrolled, abnormal growth of skin cells, that is usually caused by UV exposure
- there are three main types: basal cell carcinoma, squamous cell carcinoma and melanoma

Question 4

Metastasis

Answer 4

the spread of cancer cells from the place of origin to another location in the body

Question 5

1. Basal Cell Carcinoma

Answer 5

the most common form of skin cancer
- excessive exposure to UV radiation causes DNA mutations in cells in the stratum germinativum
- metastasis very rarely occurs, allows this cancer to be a very high survival rate - because of the location in the epidermis

Question 6

2. Squamous Cell Carcinoma

Answer 6

second most common form
- excessive exposure to UV radiation causes DNA mutations in cells in the stratum spinosum
- usually not life-threatening, but can cause serious complications if left untreated

Question 7

3. Melanoma

Answer 7

the least common but most dangerous
- cancerous melanocytes grow rapidly and metastasize through the lymphatic system
- survival rate is highly dependent on how early the cancer is caught is cause and treated

Question 8

Melanoma Diagnosis

Answer 8

physician assess moles but using the following acronym:
- A = asymmetry: whether the two sides are symmetrical
- B = border: if the edges are irregular in shape
- C = colour: if the colour is vary shades of black and brown
- D = diameter: is it larger than 6 mm (0.24 in)
- E = evolving: has the shape changed over time
a suspected melanoma is confirmed by taking a sample of the tissue to test for cancerous cells
- excisional (can repair cells) or punch biopsy (can leave dimple in skin)

Question 9

Melanoma Treatment

Answer 9

treatment for melanoma often involves:
- surgery to remove the affected tissue and some of the healthy tissue surrounding it
- surgery to remove lymph nodes in the case of metastasis
- targeted drug therapy, radiation therapy and/or chemotherapy to kill any remaining cancer cells

Question 10

Clinical Cases: Burns

Answer 10

burn: tissue damage caused by intense heat, electricity, chemicals, or radiation (example: UV radiation)
the stages of burn severity: first-fourth degree burn

Question 11

First Degree Burn

Answer 11

a superficial burn where tissue damage only occurs in the epidermis
◦ skin is swollen, red, and will heal on its own within
days

Question 12

Second Degree Burn

Answer 12

tissue damage occurs in both the epidermis and dermis
◦ more swelling and painful blistering
◦ if kept clean and sterile, will heal within weeks

Question 13

Third Degree Burn

Answer 13

tissue damage occurs in the epidermis, dermis and hypodermis
◦ damages accessory structures such as nerves and
sensory receptors
◦ requires medical intervention for proper healing

Question 14

Fourth (“full-thickness”) Degree Burn

Answer 14

burn is so severe that deeper structures are also damaged (muscle, skin, etc.)
◦ skin is unable to repair itself, and requires more
intense medical intervention (debridement,
grafts, amputation)
burns that affect 15-20% of an adult’s body is considered a major injury and requires hospitalization

Question 15

The Integumentary System - Changes with Age (8)

Answer 15

1. fewer melanocytes – hair and skin become paler, and increased risk for sunburn and DNA damage
2. decreased sebaceous gland function – skin produces less oil and sweat, and becomes more dry
3. decreased germinative cell division – the epidermis begins to thin, and becomes more prone to injury or infection, is slower to repair, and less able to synthesize vitamin D
   A. decreased Vitamin D may contribute to the
   development of more brittle bones
4. fewer elastic fibers and thinner dermis – leads to a loss of elasticity (skin sagging) and wrinkles
5. merocrine sweat glands become less active – greater risk of overheating
6. reduced cutaneous blood supply – contributes to impaired thermoregulation (cold sensitivity and heat intolerance)
7. less active hair follicles – less hair produced, and hair is thinner and more fine
8. reduced sex hormones – influences fat and hair distribution