Test 4 - Integumentary

Question 1

What are the functions of the integumentary system (6)?

Answer 1

1. barrier
2. immunologic info (antigen processing)
3. homeostasis (temp/h20 loss)
4. sensory info
5. endocrine function (vit D)
6. excretion

Question 2

How are all 4 tissue types represented in the integument?

Answer 2

• epidermis: epithelium
• dermis: connective (loose & dense irr) + muscle (arrector pili)
• hypodermis: nervous + connective (adipose)

Question 3

List histological differences between thick and thin skin

Answer 3

thick: stratum corneum is wide/thick/dense/solid
thin: stratum corneum is thin/stringy

both have keratinization just one more than the other

Question 4

What are the layers within the epithelium of integument?

Answer 4

1. stratum corneum (keratinized cells)
2. stratum lucidium (only thick visible - subset of corneum)
3. stratum granulosum (keratohyaline granules)
4. stratum spinosum (spindle-shaped… cell-cell processes and desmosomes)
5. Stratum basale/germinativum (stem cells)

Question 5

What is meant by epidermal differentiation?

Answer 5

specialized from of apoptosis

Question 6

How does epidermal differentiation occur?

Answer 6

stratum granulosum nuclear morphology is apoptotic with DNA fragmentation, but cellular fragmentation doesn’t occur - cells fill with keratin instead

Question 7

What occurs at the epidermal-dermal junction?

Answer 7

dermal papillae are complemented by epidermal ridges (rete ridges - depth and spacing reflect mechanical stress)

Question 8

Why is the epidermal-dermal junction important for fingerprints?

Answer 8

development (dermal ridges - genetically based) of finger prints

Question 9

What is the difference between the epidermis, dermis, and hypodermis as far as tissue types found there?

Answer 9

epidermis - epithelium
dermis - CT, adipose, muscle
hypodermis - dense ir, CT, adipose, large blood vessels

Question 10

Describe keratinocytes

Answer 10

primary skin cell that produces keratin (have desmosomes and mainly in stratum spinosum)

Question 11

Function of keratinocytes:

Answer 11

1. produces keratin
2. forms epidermal water barrier

Question 12

Describe keratinization.

Answer 12

1. keratohyalin granules have filaggrin that triggers apoptosis ->
2. trichohyalin proteins aggregate keratin filament into tonofilaments ->
3. as they travel up acidity increases and activates proteases that degrade desmosomes ->
4. desquamation (sloughing off)

Question 13

Melanocytes function (3):

Answer 13

1. cytocrine secretion (secretion directly to another cell)
2. pigment (melanin) producing
3. variation of skin color

Question 14

Melanocyte location

Answer 14

stratum basale (send processes up into stratum spinosum)

Question 15

What is the epidermal to melanin ratio?

Answer 15

how many epidermal cells per melanocyte (1:4-dark; 1:10-light)

Question 16

Describe a Langerhans cell.

Answer 16

• located in stratum spinosum
• no desmosmal attachments
• APC (antigen presenting cell) - can present/phagocytose/process/display antigen on surface
• contact dermatitis aka “delayed-type hypersensitivity reaction”

Question 17

Describe a Merkels cell.

Answer 17

• located in stratum basale
• sensitive mechanoreceptor
• joined to keratinocytes with desmosomes
• has Merkel’s corpuscle (cell receives and send to here through basal lamina)

Question 18

What is the difference in free vs. encapsulated nerve endings?

Answer 18

encapsulated have a CT capsule whereas free do not have any CT or Schwann cell investments

Question 19

Structure of hair:

Answer 19

1. medulla
2. cortex
3. cuticle

Question 20

Structure of a hair follicle (5)

Answer 20

1. hair bulb (base)
2. dermal papilla (tuft of vascularized loose CT)
3. external root sheath (down growth of epi)
4. matrix cells (germinative region of follicle surrounding papilla)
5. internal root sheath

Question 21

Describe the histology of a nail (7).

Answer 21

1. nail plate (cornified plate - nail we touch)
2. nail bed (stratified squamous epi. - attaches nail to skin)
3. nail root (proximal, covers matrix)
4. matrix (germinative zone - grows into nail)
5. lunula (white moon)
6. eponychium (cuticle)
7. hyponychium (secures nail plate at fingertip)

Question 22

Sebaceous glands.

Answer 22

• outgrowth of external root sheath of hair follicle
• not in thick skin
• secretes sebum (holocrine) - coats hair and skin
• simple, branched alveolar glands

Question 23

Similarities between eccrine and apocrine.

Answer 23

• both secrete NaCl, H2O, and some urea
• simple coiled tubular glands

Question 24

Eccrine sweat glands.

Answer 24

1. secretions: salty, sweaty
2. fx: thermoregulation
3. location: everywhere
4. histo: decrease lumen size increase duct size
   - not assc. with hair follicle

Question 25

Apocrine sweat glands.

Answer 25

1. secretions: lipids/proteins (pheromones/hormones)
2. fx: responsible for body odor
3. location: mostly genitalia and armpits
4. histo: increase lumen size and decrease duct size
   - assc. with hair follicle