01 - Structure and Function of the Skin

Question 1

(General Function of the Skin)

(Barrier)

(physical)

1. prevention of water, electrolyte and macromolecule loss
2. prevent invasion by external agents (chemical, physical, microbial)
3. what constitutues the physical barrier?

Answer 1

3. stratum corneum

Question 2

(General Function of the Skin)

(Barrier)

(Physiologic)

1. Turnover rate: what is the turnover time for a keratinocyte to pass from basal layer to surface? Injuries affect mitotic rate how?
2. sebum: the fatty acids perform what two functions?

Answer 2

1. 30 to 45 days; increase (shorter time for keratinocytes to reach surface)
2. bacteriostatic and fungistatic

Question 3

(General Function of the Skin)

(Barrier)

(Immunologic)

1. Keratinocytes, langerhan’s cells, and lymphocytes provide immunosurveillance capacity that effectively protects againt development of what?

Answer 3

1. cutaneous neoplasms and persistent infections

Question 4

(General Function of the Skin)

(Barrier)

(Microbial Flora)

1. normal bacteria flora do what?
2. fungal and viral phyla also participate also serve same function

Answer 4

1. inhibit growth of pathogens

Question 5

(General Function of the Skin)

(communcation)

1. sensory: primary sense organ for touch, pressure, pain, itch, heat, and cold
2. immunologic: langerhan’s cells present antigen to what where?

Answer 5

2. lymphocytes in regional lymph nodes

Question 6

(General Function of the Skin)

(Temperature Regulation)

1. hair coat
2. cutaneous blood supply
3. subcutaneous fat
4. sweat gland function
   horses. .. what kind of sweat?

dogs and cat… what kind of sweat where?

Answer 6

4. apocrine sweat

eccrine sweat in footpads only

Question 7

(General Function of the Skin)

(secretion)

1. what three gland types?

Answer 7

1.apocrine, eccrine, and sebaceous

Question 8

(General Function of the Skin)

(Storage)

1. reservoir of electrolytes, water, vitamins, fat, carbohydrates, proteins, and other materials

Question 9

(General Function of the Skin)

(Pigmentation)

1. what three things determine the color of skin and coat?
2. pigmentation of skin helps protect from what?
3. what is produced in skin by stimulation by solar radiation?

Answer 9

1. melanin formation, vascularization, keratinization
2. solar radiation damage
3. vitamin D

Question 10

(General Function of the Skin)

(Adnexa Production)

1. skin produces keratinized structures such as hairs, nails, claws, hooves, and the horny layer of the epidermis

Question 11

(General Function of the Skin)

(indicator)

1. of general health and disesase

Question 12

(General Function of the Skin)

(Motion and Shape)

1. flexibiilty, elasticity, and toughness of the skin allow motion and provide shape and form
2. many species differences

Question 13

(Overview of the Skin Structure)

(Regions of the Skin)

1-5. name the five regions

Answer 13

1. epidermis
2. dermal-epidermal junction
3. dermis
4. hypodermis (subcutaneous tissue)
5. epidermally derived appendages (hair follicles, sebaceous glands, apocrine sweat glands, eccrine sweat glands, nails/claws/hooves)

Question 14

(Structure of the Epidermis)

1-5. What are the five layers of the epidermis?

Answer 14

1. basal layer (stratum basale or stratum granulosum)
2. spinous layer (stratrum spinosum)
3. granular layer (stratum granulosum)
4. clear layer (stratum lucidum)
5. horny layer (stratum corneum)

Question 15

(layers of the epidermis)

(basal layer: stratum basale or stratum germinativum)

1. one layer of cubodal to columnar cells called what and what?
2. keratinocytes account for what percent of cells? melanocytes? merkel cells?
3. basal layer is the site of what?
4. cell-to-cell attachments are characterized mainly by what (between keratinocytes)?

Answer 15

1. keratinocytes and melanocytes
2. 90%; 10%; < 1%
3. cell division (mitosis)
4. desmosomes
   (dynamic. .. allow movement between and movement of cells upward)

Question 16

(layers of the epidermis)

(basal layer: stratum basale or stratum germinativum)

(cont)

1. basal cells attached to basement membrane by what?
2. tight juctions, adherens junctions and gap junctions are also present…. why are desmosomes important to us?

Answer 16

1. hemidesmosomes
2. target antigen of most common autoimmune skin disease (pemphigus foliaceus)

Question 17

(layers of the epidermis)

(spinous layer - stratum spinosum, prickle cell layer)

1. composed of daughter cells of what?
2. layers depend on species, location, whether skin is hairy or glabrous… how thick with hair? how thick at footpads, masal planum, mucocutaneous junctions?
3. polyhedral, flatten at surface
4. what prominent junction?

Answer 17

1. of stratum basale
2. 1-3, 20 cell layers
3. desmosomes

Question 18

(layers of the epidermis)

(spinous layer - stratum spinosum, prickle cell layer)

(cont)

1. cells start differentiaton to become what?
2. synthesize proteins that become part of what? these produce lipids that will form what?

Answer 18

1. completely keratinized
2. cornified cell envelope and membrane coating granule; intercellular lipid lamellae

Question 19

(layers of the epidermis)

(spinous layer - stratum spinosum, prickle cell layer)

(cont)

1. what is the histiologic term used to describe and increased thickness of this layer?

Answer 19

1. acanthosis (chronic inflammation will result in this)

Question 20

(Layers of the epidermis)

(granular layer: stratum granulosum)

1. variably present in haired skin… how thick where it occurs? how thick in non-haired (glabrous)
2. keratinocytes are flattened in this region… contain what? which are rich in what? particpate in what?
3. Cells contain what other type of granule… that do what?

Answer 20

1. 1-2 cells thick; 4 to 8
2. keratohyalin granules; histidine and cytidine components; keratinization process and barrier function
3. membrane coating granules; produce lipid in intercellular spaces of stratum corneum

Question 21

(layers of the epidermis)

(clear layer (stratum lucidum)

1. consists of fully cornified flat cells compacted into a thin layer
2. staining?
3. present only in what areas?

Answer 21

2. no (hyaline like)
3. areas of friction and where epidermis is thick (eg footpads… less in planum nasale)

Question 22

(layers of the epidermis)

(Horny Layer: Stratum corneum)

1. flattened, anuclear cells in vertical columns
2. keratinocytes of this layer aka?
3. intercellular spaces filled with what?

Answer 22

2. corenocytes
3. lamellar lipids

Question 23

(layers of the epidermis)

(Horny Layer: Stratum corneum)

(cont)

1. terminally differentiated keratinocyte has a highly specialized structure in cell periphery (the cell envelope) which assumes protective funcitons - the cornified cell envelope is composed of what? provides what?
2. Constitues major barrier layer of epidermis…
3. brick = ?, mortar = ?
4. increase in thickness of this layer = ?

Answer 23

1. cross linked proteins; provides structural support and protections from outside invaders
2. keratinized keratinocyte + cell envelope, intercellular lemellar lipid
3. hyperkeratosis