Integument

Question 1

What are the layers of the skin?

Answer 1

From outside to inside:

Epidermis - epidermal barrier: stratified squamous epithelia -> multiple layers of flattened cells

Dermis: with nerve and blood vessels and tough connective tissue

Hypodermis: Subcatenouns fat and connective tissue

Question 2

What are the main functions of the integument?

Answer 2

Protection: Microorganisms, physical injury, temperature, UV (synthesis of vitamin D), immunologic barrier

Homoestasis: prevent water loss, Thermoregulation

Sensory reception (nerve endings)

Question 3

How is Vitamin D in the skin produced?

Answer 3

7-dehydrocholesterol stored in the skin -> under the direction of UV light and heat Vitamin D3 is formed

Question 4

What is the structure of the Epidermis look like?

Answer 4

Keratinocytes -> Keratinized (protein) + Lipid, stratified (mulit-layer), squamous (flatterned) epithelium

Question 5

What are the layers of the Epidermis? EXAM

Answer 5

From inside to outside -> they produce keratinocytes -> differentiate on their way outside

Basale (stratum germivativum)-youngest: single layer attached to Dermis -> dividing through mitosis -> pushed outwards

-Spinosum
-Granulosum
-Lucidum (thick - only on hands and soles)
-Corneum

Question 6

What are keratinocytes and how are they connected?

Answer 6

Produced by basal cells -> skin cells within the epidermis are connected through cellular junctions that connect to keratin (intermediate) filaments (Desmosomes)

Question 7

What are melanocytes?

Answer 7

-located in stratum basale and they produce melanin (Eumalin - brown/black or Pheomelanin: yellow/red (UV reactive)

Question 8

Where do melanocytes originate?

Answer 8

Like neuron cells, they migrate from the neural crest
(melanoma is a severe form of cancer because it migrates easily)

Question 9

Where exactly is Melanin produced?

Answer 9

In the Melanocytes (Golgi-Endosome -> Melanosome) and they are transferred through extension (microtubules) into keratinocytes to protect the nucleus from UV damage

Question 10

What is the function of the basal membrane?

Answer 10

-Adhesion between Epidermis and Dermis: Hemidesmosome
-Selective molecular filter

Question 11

What is the function of the Dermis?

Answer 11

-Provides nutrition to the Epidermis (contains blood vessels)

Question 12

What does the Dermis consist of?

Answer 12

Mostly collagen (strong structural protein), and ground substance (proteoglycan provide polar charge and attracts water -> turgor (maintains water in the skin)

Question 13

What are the two layers in the Dermis?

Answer 13

-Papillary: increases surface area for adhesion to Epidermis

-Reticular: “hide”, thicker layer with blood vessels

Question 14

What is the blister on the skin?

Answer 14

When the Epidermis separates from the Dermis -> can happen with strong robbing

Question 15

What is the difference between thick and thin skin?

Answer 15

The thick skin has stratum lucidum and a thicker stratum corneum

Question 16

Where are the nerve endings located to sense pain, temperature, vibration, etc. on the skin?

Answer 16

In the dermis

Question 17

How is temperature regulated in the skin?

Answer 17

-Arteriovenous anastomoses (no nutritional blood flow bc no capillaries) arteriole to venule

-Sweat glands
-Arrector pili muscles (Sympathetic NS: NE to alpha/ß receptor -> Piloerrection when scared or cold (goosebumps)
-Sebum (sebaceous glands, oily substance as barrier to reduce heat loss)

Question 18

Why is there decreased blood flow on the skin in cold environments?

Answer 18

Because blood is a source of heat, and we don’t want to loose heat -> kept in the center of the body in cold environments

Question 19

What are the sweat glands?

Answer 19

-Exocrine glands that secrete substances into a duct
-Innervated by sympathetic NS:
ACh -> muscarinic receptor (weird bc sympathetic usually secrete NE to alpha/ß receptor)

Question 20

What happens if an antimuscarinic drug is taken in the heat?

Answer 20

Risk for overheating b/c less ability to sweat

Question 21

What types of sweat glands are there?

Answer 21

Eccrine: most numerous, open through pores; 99% water and some waste and salts

Apocrine: in axillary, anal, and genital areas opens into hair follicle duct and lubricates hair follicle -> oily
-it mixes with bacteria

Question 22

What are modified apocrine glands

Answer 22

Ceruminous glands: secrete ear wax
Mammary glands: secrete milk

Question 23

What are sebaceous glands?

Answer 23

-exocrine glands located everywhere except palms, soles, sides of
feet
-secrete sebum: oily substance to prevent heat loss on the skin

Question 24

What does sebum consist of?

Answer 24

-Triglycerides, cholesterol, cellular debris -> make it oily
-Prevents evaporation of moisture: bc as an oil it doesn’t mix with water and prevents water loss
-Hormonally regulated: Androgen and estrogen increase production of sebum (puberty -> more sebum ->bacteria causes acne -> estrogen decrease sebum production (child control drug)

Question 25

What is the Pilosebaceous unit?

Answer 25

Hair follicle: Errectopilomuscle (cause the hair to stand) + sebum production (lubricates)

Question 26

What is the cyclical growth of the hair follicle?

Answer 26

Anagen: growth phase - hair is thickest and longest

Catagen: transitional

Telogen: resting phase -> hair falls out and will be replaced

Question 27

How can drugs interfere with cyclical growth?

Answer 27

Produce more hair in the anagen growth phase

Male hair baldness, growth of eyelashes

Question 28

How are nails structured?

Answer 28

On top, there is the nail plate, with the Lunula on the end - next to Eponychium (Cuticle)

Underneath: Nail bed: epidermis -> Pink bc lots of blood flow: nail matrix (Nail will grow normal unless Nail bed is damaged)