Skin Lab

Question 1

Nerve cells in skin

Answer 1

Merkel disks: epidermis, connect to nerve cells in dermis. Detect light touch.
Corpuscles: structures found in dermis, sense pressure & vibrations.
Free nerve endings: found in dermis- neurons with their dendrites spread out – sensitive to pain, warm, cold.
Nerves surround hair follicles.

Question 2

What cells are in the Epidermis Layer:

Answer 2

90% Keratinocytes: produce & store the protein Keratin. Keratin makes the cells very tough, scaly and water-resistant.
8% Melanocytes: produce the pigment melanin. Melanin protects the skin from ultraviolet (UV) radiation & sunburn. Uv can cause cells to mutate.
1% Langerhans cells: these cells detect & fight pathogens that attempt to enter the body through the skin.
1% Merkel cells: cells that sense touch.
Basal cells: Dividing keratinocyte cells
Keratinocytes: As the cells are pushed toward the surface they differentiate and form Keratin.
Eventually they become flattened and become squamous.
Outermost layer is composed of dead keratinocytes that cover and protect the living cells below.

Question 3

Accessory structures of the skin?

Answer 3

Sweat glands: produce a secretion of water and NaCl. used to lower the body’s temperature through evaporative cooling. Eliminate metabolic wastes and toxins (alcohol)
Nails: Made of sheets of hardened keratinocytes. Grow from a deep layer of epidermal tissue.
Teeth: derivative of the skin.

Question 4

Hair

Answer 4

Made of columns of tightly packed dead keratinocytes
Consists of follicle, shaft, sheath, and bulb.
Helps protect skin from UV radiation
Also insulates the body by trapping warm air around the skin.
Hair follicle and root originate in the dermis.

Question 5

Risks of tattoos

Answer 5

Tattoos:
Specific risks include:
Allergic reactions, Skin infections.Sometimes bumps called granulomas, keloids — raised areas caused by an overgrowth of scar tissue.
bloodborne diseases — including tetanus, hepatitis B and hepatitis C.
Medication or other treatment — including possible removal of the tattoo

Question 6

Hypodermis:

Answer 6

bottom layer of the skin
Layer of loose connective tissue.
Flexible connection between skin and underlying muscles and bones.
Fat storage area.
Cushion against injury.

Question 7

How do we prevent skin cancer?

Answer 7

Seek the shade, especially between 10 and 3pm.
Do not burn. Even a single sunburn can increase your risk of cancer.
Avoid tanning booths.
Cover up with clothing, including a wide brimmed hat and sunglasses.
Use sunscreen with a SPF of 15 or higher every day.
Apply enough sunscreen to coat your skin. Re-apply every 2-3 hours.
Know your skin and do skin examinations every month.
See your doctor if you suspect skin cancer.

Question 8

Fatty adipose tissue and where is it found?

Answer 8

Fatty adipose tissue – stores energy in the form of fats. Also helps to insulate the body. Hypodermis.

Question 9

Hair arrector pilli muscle:

Answer 9

attached to hair follicle and acts to lift the hair shaft upright. Goosebumps.

Question 10

What are the main functions of our skin?

Answer 10

Protection
Support and Elasticity
Nervous Sensation
Temperature regulation- Dilated blood vessels increase heatloss, while constricted vessels greatly reduce cutaneous blood flow and conserve heat.
Storage and synthesis: acts as a storage center for lipids and water, synthesis of vitamin D by action of UV on certain parts of the skin.
Elimination of Wastes: The skin excretes sweat which evaporates reducing body temp

Question 11

Malignant melanoma

Answer 11

Less common but highly aggressive and deadly
Starts in the Melanocytes.
Develop when unrepaired DNA damage to skin cells, triggers mutations (genetic defects) that lead the skin cells to multiply rapidly and form malignant tumors. These tumors originate in the pigment-producing melanocytes in the basal layer of the epidermis.
Can enter lymph and blood vessels and spread to other parts of the body. Produce secondary tumors (metastasis).

Question 12

Tooth anatomy

Answer 12

Crown: covered with enamel.
Root: Part embedded in the jaw, anchors the tooth.
Enamel: hard outer layer of the crown
(hardest substance in the body)
Dentine: forms the bulk of the tooth (not as hard)
Pulp: Soft tissue called the nerve containing the blood and nerve supply to the tooth.
Cementum: layer of bone-like tissue covering the root
Periodontal ligament: fibrous tissue that connects the tooth root and the jaw bone

Question 13

Dermal papillae:

Answer 13

finger-like extensions that protrude into epidermis. They increase the surface area and contain many nerves & blood vessels. Blood from here provides nutrients & oxygen for epidermal cells.

Question 14

Sebaceous glands:

Answer 14

produce an oily secretion called sebum. Acts to waterproof & increase elasticity of the skin.

Question 15

Basal Cell Carcinoma

Answer 15

Most common type. Local cancer.

Begins in the basal cells — a type of cell within the skin that produces new skin cells as old ones die off.

Question 16

Hypothermia?

Answer 16

dangerously low body temperature
skin is able to help raise body temperature
Contraction of arrector pilli muscles. Forms goosebumps when the hair follicles are lifted. Results in more air being trapped around skin surface. Insulates the body.
Vasoconstriction: smooth muscles in blood vessels constrict to reduce blood flow to skin. Permits skin to cool while blood stays warmer at body’s core.
Shivering generates heat

Question 17

Hyperthermia

Answer 17

Hyperthermia: extremely high body temperature
skin is able to reduce body temperature
Sweating
Vasodilation: when the smooth muscle lining the blood vessels in the dermis relax and allow more blood to enter the skin, pulling heat away from the core and depositing it in the skin where it can radiate out.

Question 18

What is the largest organ in the body?

Answer 18

Skin

Question 19

Epidermis:

Answer 19

most superficial layer
About a tenth of a millimeter thick.
Made up of 40-50 rows of stacked cells

Question 20

Actinic Keratosis

Answer 20

Is a rough, scaly patch on your skin that develops from years of exposure to the sun. It’s most commonly found on your face, lips, ears, back of your hands, forearms, scalp or neck.
Also known as solar keratosis, an actinic keratosis enlarges and causes no signs or symptoms other than a patch or small spot on your skin. These lesions take years to develop, usually first appearing in older adults.
A small percentage of actinic keratosis lesions can eventually become skin cancer.

Question 21

Epidermal layers

Answer 21

Made up of 4 (5) distinct layers
Stratum basale: deepest region
Contains stem cells that form all other cells in the epidermis.
Stratum spinosum:
Langerhaus cells and many rows of spiny keratinocytes.
Stratum granulosum:
Keratinocytes begin to produce waxy lamellar granules to waterproof the skin.
Keratinocytes here are so far removed from the dermis that they begin to die from lack of nutrients.
Stratum lucidum: only found on hands and feet
Several rows of clear, dead keratinocytes that protect lower layers.
Stratum corneum: outermost layer
Made of many rows of flatterned, dead keratinocytes.
Dead cells are constantly being shed & replaced.

Question 22

Dermis:

Answer 22

deep layer found under the epidermis.
Mostly made of dense irregular connective tissue along with nervous tissue, blood and blood vessels.
Much thicker than epidermis.
Gives the skin its strength and elasticity

Question 23

Squamous cell carcinoma

Answer 23

2nd most common type.
Develops in the thin, flat squamous cells that make up the outer layer of the skin.
Can be aggressive and if not treated can continue to grow.