The integument

Question 1

What are the four-five layers of the skin?

Answer 1

Stratum corneum, lucidum(only in thick skin), granulosum, spinosum, and basale

Question 2

What cells make up the epidermis?

Answer 2

keratinocytes, melanocytes, merkel cells, and langerhans cells

Question 3

What is different between thick and thin skin?

Answer 3

Thick skin is found on palms (fingerprints) and soles of feet, and has 5 layers of skin instead of 4, the extra layer is the stratum lucidum

Question 4

Stratum Basale is the deepest layer of epidermis, what does it consist of and how is it bound?

Answer 4

(cuboidal) Consists of a single layer of mitotically active keratinocytes, which will migrate up and replace keratin.

Contains melanin

Bound apically by desmosomes and basally by hemidesmosomes

Question 5

Stratum Spinosum is the second deepest layer of epidermis, what consists of this layer?

Answer 5

Several cell layers thick, has polyhedral keratinocytes (cuboidal) w spiny processes

Layers thicken with corns and calluses

Question 6

Stratum Granulosum?

Answer 6

thickest layer of non-keratinized portion of epi, keratinocytes contain keratohyalin granules, stains basophilically

Precursor to filaggrin (assembles keratin into bundles) irregularly shaped

Question 7

Stratum corneum?

Answer 7

lose nucleus and organelles (filled with mature keratin), plas membrane coated with lipids=water barrier, always shedding

Question 8

Stratum lucidum (in between corneum and granulosum)?

Answer 8

Only in thick skin, translucent/ clear color, no organelles or nuclei (full of keratin)

Question 9

What is the most predominant cells type of the epidermis and what does it do?

Answer 9

Keratinocytes produce keratin, 85% of cells, participate in the epidermal water barrier

Question 10

What does the basal cell do?

Answer 10

synthesize intermediate (keratin) filaments, grouped into bundles called tonofibrils, sends to spinous cell

Question 11

What does the spinous cell do?

Answer 11

keratin synthesis continues, begins synthesis of keratohyalin granules and glycolipid-containing lamellar bodies (lipids for water barrier), sends to granular cell

Question 12

What does the granular cell do?

Answer 12

discharge the lamellar bodies to form water barrier, keratohyalin granules with filaggrin present, which further promotes aggregation of keratin filaments, keratinized!(no nucleus just keratin) sends to top

Question 13

What happens when the pH of epidermis starts to change?

Answer 13

The cell will get rid of the nucelus and organelles to adapt to the change in pH

Question 14

What are melanocytes and what do they produce?

Answer 14

Derived from neural crest, located in stratum basale, they produce melanin and transfer to keratinocytes.

Question 15

What is melanin?

Answer 15

Pigment protein that protects nuceli from UV radiation

Question 16

What is the epidermal-melanin unit?

Answer 16

one melanocyte maintains an association with a specific number of keratinocytes (1:36)

Question 17

How is melanin produced?

Answer 17

Tyrosine is oxidized by tyrosinase into DOPA, which is polymerized to form melanin which is UV sensitive

Question 18

What function do langerhans cells have and where are they located?

Answer 18

antigen-presenting cells (APCs) that provide defense against pathogens, developed from monocytes, located in the stratum spinosum

Question 19

What function do merkel cells have and where are they located?

Answer 19

cells that function as cutaneous sensation/ acute sensory perception. In stratum basale, can become Merkel cell carcinoma

Question 20

What is unique of the dermal-epidermal junction?

Answer 20

It has finger like dermal papillae (dermis), epidermal ridge which creates a wavy junction, more waves=more mechanical stress. Hemidesmosomes and focal adhesion present

Question 21

What are the layers of the dermis?

Answer 21

papillary layer (superficial)
reticular layer (deep)

Question 22

What is in the papillary layer of dermis?

Answer 22

loose CT with collagen and elastin fibers, has dermal papilla and ridges, vasculature and nerve endings

Question 23

What is in the reticular layer of dermis?

Answer 23

Thicker and less cellular, irregular bundles of type I collagen and elastic fibers, Forms langers lines! skin lines!

Question 24

What is characteristic of the hypodermis? (subcutaneous fascia)

Answer 24

has adipose tissue, energy storage site and insulation, has hair follicles

Question 25

What are meissner corpuscles, what do they do and where are they?

Answer 25

they are touch receptors, located at the dermal-epidermis junction, tappered cylinders

Question 26

What are pacinian corpuscles, what do they do and where are they?

Answer 26

onion looking ovoid structures found in deeper dermis and hypodermis, detects vibrations and have myelinated nerve in middle

Question 27

What do free nerve endings do?

Answer 27

they lack CT in the stratum granulosum, help with fine touch, heat, cold, and pain

Question 28

What are sebaceous glands and what do they produce?

Answer 28

type of holocrine secretion gland, produces sebum, lipid mixture, lubricates and soften skin, abundant on face and scalp.

Question 29

when sebum is discharged into the infundibulum (hair follicle), what does it form

Answer 29

pilosebaceous canal

Question 30

What are types of sweat/sudoriferous glands?

Answer 30

merocrine/eccrine & apocrine:

Question 31

Merocrine/eccrine sweat glands

Answer 31

(exocytosis by myoepithelial cells): coiled glands all over body except lips and penis, temperature regulation, duct is stratified cuboidal

Question 32

Apocrine sweat glands

Answer 32

large duct of stratified cuboidal, use merocrine secretion, myoepithelial cells squeeze to release content, activated when hot or nervous…. axilla, areola, nipple, anus, gently secretes