SKIN APPENDAGES & SKIN CANCERSeptember 28-29 2015

Skin Appendages

The skin appendages include cutaneous glands, hair, and nails.

Cutaneous Glands

What is cutaneous?

What is an exocrine gland?

Cutaneous Glands

What is cutaneous? Relating to the skin

What is an exocrine gland? A gland that releases its product to a particular site, rather than into the blood stream. (Endocrine glands release their products to the blood).

Cutaneous Glands

1) Sebaceous (oil) glands• Found everywhere except palms of hands and soles of

feet

• The ducts mostly empty into hair follicles

• Produce oily product called sebum

• Functions:• Keep hair and skin from drying out• Kill bacteria• Become much more active in adolescence

You’ll be able to

identify

sebaceous glands on slides by

looking for la

rge, roundish glands

with a LARGE duct that e

mpties

into the hair f

ollicle.

Cutaneous Glands

1) Sebaceous (oil) glands• Found everywhere except palms of hands and soles of

feet

• The ducts mostly empty into hair follicles

• Produce oily product called sebum

• Functions:• Keep hair and skin from drying out• Kill bacteria• Become much more active in adolescence

Fun fact: the ‘pores’ on our faces are actually hair follicles

Acne occurs when the hair follicle is clogged with sebum.

Cutaneous Glands

2) Sweat (sudoriferous) glands

• Eccrine glands produce sweat (water, salt, urea, lactic acid)

• Duct lead to pores in skin

• Functions

• Thermoregulation

• Excretion

• Bacterial inhibition (sweat is acidic)

• Apocrine glands produce a milky secretion fully of fatty acids and proteins.

• Small duct leads to hair follicle

• Function: Pheromone!

Cutaneous Glands

2) Sweat (sudoriferous) glands

• Eccrine glands produce sweat (water, salt, urea, lactic acid)

• Duct lead to pores in skin

• Functions

• Thermoregulation

• Excretion

• Bacterial inhibition (sweat is acidic)

• Apocrine glands produce a milky secretion full of fatty acids and proteins.

• Duct leads to hair follicle

• Function: Pheromone!

Fun fact: Randy Thornhill’s work

Notice that sweat glands, since they empty into the skin, are often farther and deeper than sebaceous glands

Cutaneous Glands – Quick Review

Make a Venn Diagram comparing the three types of cutaneous glands. You may work with a partner.

5 min

Hair follicle• The hair follicle is surrounded by a thin layer of epidermal

tissue.

• The follicle

is slanted

unless the

arrector pili

muscles

are

contracted Dermal

epidermal

hair bulb

Why/when do the arrector pili muscles contract? The arrector pili muscles contract when we are cold, to raise the hairs and reduce heat loss

Change the words on the diagram of your guided notes

Hair• Hair can be divided into the shaft (part outside of body)

and root (inside body)

• Hair is produced by epithelial cells in the hair bulb, but as the cells are pushed away from the bulb they begin to die.

• Like the outer layer of the skin, the

hair shaft is composed of dead,

keratinized cells.

Fun fact: Round shaft = straight, coarse hairOval shaft = silky, wavy hairFlat shaft = curly hair

Nails • Produced by epithelial cells• The nail root, closest to the nail matrix, is living• The outer part, like the hair and skin, consists of dead

keratinized cells.

Fun fact: Fingernails are a derived trait in primates

Quick Review

Turn & Talk. Be prepared to share with the class.

Are the skin appendages (cutaneous glands, hair, hair follicles, and nails) found in the dermis or epidermis? Justify your answer.

Quick Review

Turn & Talk. Be prepared to share with the class.

Are the skin appendages (cutaneous glands, hair, hair follicles, and nails) found in the dermis or epidermis? Justify your answer.

They are in the epidermis, because the epidermis surrounds and gives rise to these structures. However, these structures usually sit deeper than the most of the epidermal tissue.

Label the diagram

Label the diagram• A: epidermis• B: dermis• C: hypodermis• 1: hair shaft• 2: pores• 3: Eccrine gland• 4: sebaceous gland• 5: capillary

What did we talk about today that you don’t see on this diagram?

Label the diagram• A: epidermis• B: dermis• C: hypodermis• 1: hair shaft• 2: pores• 3: Eccrine gland• 4: sebaceous gland• 5: capillary

What did we talk about today that you don’t see on this diagram? Apocrine glands.

Identify the parts of the skin

1

2

3

4

5

6

7

8

Common Types of Skin CancerThere a three main types of skin cancers, defined by the type of cell from which they arise.

Basal cell carcinoma – arise from the basal edge of the epithelial tissue.

Squamous cell carcinoma –arise from the keratin-producing cells in the middle of the epithelial tissue.

Melanoma – arise from the melanin-producing cells at the basal edge of the epithelial tissue

Excess sun

exposure

increases the

risk of each of

these cancers

Basal Cell Carcinoma

• Most common form of skin cancer

• Affects ~2.8 million people in the US each year

• Slow-growing and rarely fatal

Squamous Cell Carcinoma

• Second most common form of skin cancer

• Affects ~700,000 people in the US each year

• Grow and invade surrounding tissue quickly

• <5% are fatal

Melanoma

• Third most common skin cancer

• Affects ~76,000 people in the US each year

• Quickly metastasizes (spreads) to blood vessels and lymph nodes – which allows it to spread to other locations in the body

• Fatal in more than 10% of cases

Melanoma may be the least common type of skin cancer, but it is by far the most deadly.

Moreover, while rates of most other cancers are declining in the US (due to a reduction of smoking) melanoma rates are increasing.

• What were our objectives today?

How did we meet them?

• What was our learner profile trait and how did we use it?

• How does what we did today address our unit objective?

Closure