Lecture 40 4/23/24

Question 1

What is integument?

Answer 1

something that covers; especially an enveloping layer such as skin/membrane/cuticle

Question 2

What are the functions of skin?

Answer 2

-protection
-situational awareness
-temp. regulation
-secretion/excretion
-metabolic

Question 3

What are the components of the skin?

Answer 3

-epidermis
-dermis
-adnexa
-subcutis

Question 4

What are the characteristics of the epidermis?

Answer 4

-most superficial layer
-keratinized stratified squamous epithelium
-produces basement membrane
-sits on top of dermis

Question 5

How does epidermis differ from epithelium?

Answer 5

epidermis is only used to refer to the epithelium of skin; epithelium is more of an umbrella term

Question 6

What are the five layers of the epidermis?

Answer 6

-stratum corneum
-stratum lucidum
-stratum granulosum
-stratum spinosum
-stratum basale

Question 7

What are the characteristics of the stratum corneum?

Answer 7

-cornified/keratinized cells
-dead, flattened, and eosinophilic
-can have nuclei in cells
-continually shed and replaced
-thickness varies by location and in response to injury and disease

Question 8

What are the characteristics of the stratum lucidum?

Answer 8

-prominent only in the footpads
-may be seen in nasal planum
-located between stratum corneum and granulosum

Question 9

What are the characteristics of the stratum granulosum?

Answer 9

-intracellular keratohyalin granules
-thickness varies by location
-absent in areas of “hard” keratin
-trichohyalin granules in the hair follicles

Question 10

What are the characteristics of the stratum spinosum layer?

Answer 10

-spinous cell layer
-desmosomes hold adjacent cells together; causes prickly appearance
-often the thickest layer

Question 11

What are the characteristics of the stratum basale?

Answer 11

-single layer of cuboidal cells attached to underlying basement membrane
-hemidesmosome attachment
-continually divide; supply cells for the other layers

Question 12

Which non-epithelial cells ARE found in the epidermis?

Answer 12

-melanocytes
-Langerhans cells
-Merkel cells

Question 13

Which non-epithelial cell structures are NOT found in the epidermis?

Answer 13

-blood vessels
-lymphatics

Question 14

What are the characteristics of melanocytes?

Answer 14

-in the stratum basale
-produce and share melanin with adjacent keratinocytes
-melanin product protects against UV radiation

Question 15

What are the characteristics of Langerhans cells?

Answer 15

-in the stratum basale and spinosum
-similar to macrophages

Question 16

What are the characteristics of Merkel cells?

Answer 16

-clear cells found in the stratum basale
-function somewhat unknown
-thought to act as mechanoreceptors as well as regulate hair cycle

Question 17

What are the characteristics of reptile scales?

Answer 17

-epidermal in origin
-overlapping projections of stratum corneum
-extensions of the epidermis

Question 18

What are the characteristics of fish scales?

Answer 18

-dermal origin
-covered with epidermis

Question 19

What are the characteristics of the epidermal-dermal junction?

Answer 19

-smooth in most locations
-epidermal rete pegs interdigitate with dermal papillae in high friction areas

Question 20

What are the functions of the dermis?

Answer 20

-supports epidermis
-provides tensile strength

Question 21

What are the components of the dermis?

Answer 21

-collagen, reticular, and elastic fibers
-ground/interstitial substance
-blood vessels
-lymphatics
-nerves
-mixed cells

Question 22

What is adnexa?

Answer 22

“appendages” of an organ

Question 23

What are the adnexa of the skin?

Answer 23

-hair follicles
-glands

Question 24

What are the components of a hair follicle?

Answer 24

-hair shaft
-adventitial sheath
-outer root sheath
-inner root sheath
-matrix
-dermal papilla

Question 25

What are the layers of the hair shaft, from out to in?

Answer 25

-cuticle
-cortex
-medulla

Question 26

What are the segments of the hair follicle?

Answer 26

-infundibulum: granular layer w/ flaky keratin
-isthmus: glassy cells and homogenous keratin
-suprabulbar and bulbar: small dark cells

Question 27

What are the characteristics of primary hair follicles?

Answer 27

-large diameter
-deeply rooted in dermis
-have sebaceous glands
-have apocrine glands
-have arrector pili muscle

Question 28

What are the characteristics of secondary hair follicles?

Answer 28

-smaller diameter
-rooted more superficially
-may have a sebaceous gland
-lack apocrine glands
-lack arrector pili muscle

Question 29

What is a simple follicle?

Answer 29

-individual follicles clearly separated by connective tissue

Question 30

What are the two types of compound follicles?

Answer 30

-clustering of follicles within minimal intervening connective tissue
OR
-multiple hair shafts in a single follicular infundibulum

Question 31

Which types of follicles are seen in different species?

Answer 31

simple:
-horses
-pigs
-cows
simple and compound:
-sheep (hair-growing vs. wool growing)
primary and secondary follicles:
-goats
primary simple and secondary compound:
-dogs
-cats

Question 32

What are the steps of the hair cycle?

Answer 32

-anagen: growth phase
-catagen: transitional/involuting phase
-telogen: resting phase

Question 33

Which sections of the hair follicle are lost during catagen and telogen, and which are permanent?

Answer 33

-deeper suprabulbar and bulbar, are lost
-infundibulum and isthmus are permanent

Question 34

What are the characteristics of sinus hairs/whiskers?

Answer 34

-adventitial sheath is thickened by connective tissue trabeculae
-trabeculae are filled with blood
-well-innervated to provide sensation

Question 35

What are the characteristics of arrector pili muscles?

Answer 35

-smooth muscle
-lifts the hair
-sympathetic innervation leads tocontraction when stressed, which causes elevated hairs
-traps heat and warns off predators