Block III - Integument

Question 1

What are the three layers of skin?

Answer 1

1) Epidermis
2) Dermis
3) Hypodermis

Question 2

What are the characteristics of the epidermis?

Answer 2

Features keratinized cells; derived from the ectoderm

Question 3

What are the characteristics of the dermis?

Answer 3

Features papillary (loose CT, vascularized) and reticular (deep layer; dense CT) layers

Question 4

What are the characteristics of the hypodermis?

Answer 4

Features loose CT and adipocytes

Question 5

Stratum Basale

Answer 5

Connects to the basal laminae;
single layer of cells;

features hemidesmosomes (attach epidermal cells to the extracellular matrix)

ALIVE and ACTIVE (mitotic activity)

Question 6

Stratum Spinosum

Answer 6

“Spiny” layer due to increased tonofilaments and desmosomes

ALIVE and LESS ACTIVE

Question 7

Stratum Granulosum

Answer 7

Features keratihyalin (gives rise to eleidin molecules in the Lucidum layer) and lamellar (waterproof) granules

ALIVE and INactive

Question 8

Stratum Lucidum

Answer 8

Keratinized layer with no organelles (thick skin ONLY!)

DEAD and INACTIVE

Question 9

Stratum Corneum

Answer 9

“Cornified” - Thick layer of entirely keratinized cells

VERY DEAD

Question 10

Langerhan’s Cells

Answer 10

Intra-epidermal macrophages;

These cells are antigen presenting in T-cells and mediators of tolerance against viruses

Question 11

Merkel’s Cells

Answer 11

Located in the stratum basale;

act as sensory mechanoreceptors for cutaneous sensations and contain free nerve endings at the base of the cell

Question 12

Melanocytes

Answer 12

Located in the stratum basale;

Produces melanin pigment which protects the nucleus from UV radiation;

melanin is transferred to keratinocytes of stratums basale and spinosum;

require tyrosinase for proper function

Question 13

Thick skin

Answer 13

Hairless with merocine sweat glands (i.e. paw and nose pads)

Question 14

Thin skin

Answer 14

Features hair follicles with arrector pili muscle; has sebaceous glands and aprocrine sweat glands

Question 15

Epidermal pegs

Answer 15

downward projections visible in the Dermo-epidermal layer

Question 16

Dermal papillae

Answer 16

Upward projections visible in the Dermo-epidermal layer; present at the bottom of hair follicles

vascularized - carries blood supply to surrounding region

Question 17

Hair shaft

Answer 17

rises above the skin surface

Question 18

Hair root

Answer 18

Present within the hair follicle and contains a bulb ending

Question 19

Medulla

Answer 19

loose cuboidal cells with air pockets located within the hair follicle

Question 20

Cortex

Answer 20

Dense, keratinized cells located between the hair cuticle and medulla

Question 21

Cuticle

Answer 21

single layer of keratinized cells;

forms the outermost layer of the hair shaft

Question 22

Glassy membrane

Answer 22

Thick basement membrane located within the root shaft

Question 23

External root sheath

Answer 23

continuous with the epidermis;

adjacent to the glassy membrane

Question 24

Internal root sheath

Answer 24

layer of squamous cells;

features another cuticle that runs opposite to the hair cuticle

Question 25

Primary Follicle

Answer 25

Large diameter;

features sebaceous glands, arrector pili muscles, and sweat glands

Question 26

Secondary Follicle

Answer 26

Smaller diameter; may contain sebaceous glands

Question 27

Arrector Pili Muscle

Answer 27

Smooth muscle responsible for goosebumps (contraction) and insulation

Question 28

Sebaceous glands

Answer 28

Produces sebum (lipids and cell debris) through holocrine secretion;

used for antibacterial and waterproof coating

Question 29

Apocrine sweat glands

Answer 29

Apical budding via apical secretory caps;

Myoepthelial cells responsible for product expression;

Question 30

Merocrine/Eccrine sweat glands

Answer 30

Secretion via exocytosis;

responsible for thermoregulation and electrolyte balance

Question 31

Stratum Externum

Answer 31

Outermost layer of the hoof (the “glaze”);

continuous with the perioplic epidermis

Question 32

Stratum Medium

Answer 32

Supportive layer of the hoof;

features the tubular and intertubular groove

Question 33

Stratum Lamellatum/Internum

Answer 33

Features the Lamellar horn (insensitive laminae)

Question 34

Laminar corium

Answer 34

Sensitive laminae (derived from dermis)

Question 35

Nociceptors

Answer 35

Free nerve endings responsible for detecting pain, itch, and temperature

Question 36

Meissner’s corpuscles

Answer 36

Encapsulated nerve ending responsible for detecting light pressure/touch

Question 37

Pacinian’s corpuscle

Answer 37

Encapsulated nerve ending responsible for detecting deep pressure

Question 38

Ruffini’s corpuscle

Answer 38

Encapsulated nerve ending responsible for detecting stretch

Question 39

Which layer is the sensitive laminar derived from?

Answer 39

Dermis

Question 40

Which layer is the insensitive laminae derived from?

Answer 40

Epidermis

Question 41

What is the function of Ceruminous glands and what kind of secretion does it use?

Answer 41

Ear wax; apocrine secretion

Question 42

What the function of Uropygial glands and what kind of secretion method does it use?

Answer 42

The preen gland in birds;

Type of sebaceous gland (holocrine secretion)

Question 43

What the function of Meibomian glands and what kind of secretion method does it use?

Answer 43

Help to keep eyes moist (located in the eyelid);

Type of sebaceous gland (holocrine secretion)