Integumentary System Flashcards

1
Q

What is integument?

A

Skin and epidermal derivatives

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2
Q

T/F: The largest organ in the body is skin

A

True

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3
Q

What are skins functions?

A
  • protection; barrier against physical, chemical, and biological agents
  • prevents water and electrolyte loss
  • temperature regulation
  • sensation
  • calcium homeostasis
  • energy storage
  • immune function
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4
Q

What are the layers of skin? What are their characteristics?

A
  • epidermis (ectoderm derived, avascular, thick barrier, composed of stratified squamous keratinized epithelium)
  • dermis aka corium (mesoderm derived, vascular and nervous tissues, connective tissue composition, supports epidermis)
  • **hypodermis aka subcutis (mesoderm derived, loose connective tissue,rich in adipocytes (panniculus adiposus))

** not really a layer of skin -> superficial fascia

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5
Q

What are the characteristics of thick vs thin skin?

A

Thick
- thick epidermis, hairless, merocrine sweat glands (ex: paw pads)

Thin
- thin epidermis, hair follicles (often w arrector pili), sebaceous and sweat (apocrine) gland

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6
Q

What is the dermo-epidermal junction? What are some of its features?

A
  • interface between dermis and epidermis
  • epidermal pegs/ridges (downward projections of deep epidermis into the dermis)
  • dermal papillae (upward projections of the superficial dermis that increase surface area between the layers and bring blood supply closer to the epithelium)
  • ex: footpads, nasal planum, scrotum, areas subject to traction
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7
Q

What are the two layers of the dermis?

A

Papillary and reticular

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8
Q

What are features of the papillary layer?

A
  • LOOSE connective tissue
  • type i + iii collagen
  • mast cells + macrophages
  • vessels + nerves
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9
Q

What are features of the reticular layer?

A
  • DENSE IRREGULAR connective tissue
  • type i collagen
  • elastic fibers
  • blood vessels + nerves
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10
Q

What cell types are in skin?

A
  • keratinocytes (most common, 95 %of cells in epidermis)
  • non-keratinocytes
    • langerhams cells (immunity/tissue macrophage)
    • merkel’s cells (mechanoreception)
    • melanocytes
    • variable #s of intraepithelial lymphocytes
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11
Q

What are the layers of the epidermis, in order from deepest to most superficial?

A

Stratum basale, stratum spinosum, stratum granulsum, stratum lucidum, stratum corneum

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12
Q

What layer of the epidermis is this? What are its features?

A
  • stratum basale
  • deepest layer, at epidermal-dermal junction
  • single layer of cuboidal columnar epithelium
  • attached to basal lamina via hemidesmosomes
  • actively dividing via mitotic activity
  • basal keratinocytes (functionally heterogenous, some are stem cells, some anchor epidermis)
  • melanocytes sometimes
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13
Q

What layer of the epidermis is this? What are its features?

A
  • stratum spinosum
  • cuboidal/slightly flattened (thin skin 1-2 cells thick, thick skin many layers)
  • increased # of tonofilaments and desmosomes give “spiny” appearance
  • cells are cohesive and resist abrasion
  • cells retain some capacity for division
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14
Q

What do hemidesmosomes do?

A

Bind cells to basal lamina

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15
Q

What is shown in these structures? What do they do?

A

Desmosomes. Bind cells to cells

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16
Q

What do both desmosomes and hemidesmosomes do?

A

Connect intermediate filaments

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17
Q

What layer of the epidermis is this? What are its features?

A
  • stratum granulosum
  • 3-5 cells thick
  • somewhat flattened cells
  • contains basophilic keratohyalin granules (bind w keratin filaments)
  • lamellar granules (secreted by cells to form waterproof lipid sheets “intracellular cement”)
  • last living layer, no mitotic activity
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18
Q

What layer of the epidermis is this? What are its features?

A
  • stratum lucidum
  • translucent layer
  • thick skin only
  • many keratin filaments, desmosomes present
  • cell organelles gone, fully keratinized
  • cytoplasm contains eleidin (protein related to keratin)
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19
Q

What layer of the epidermis is this? What are its features?

A
  • stratum corneum
  • outermost layer
  • many (up to 20) layers thick, location dependent
  • cells consist entirely of keratin (water-resistant)
  • no nuclei or organelles
  • known as horny cells surrounded by a thicker plasma membrane coated by the exterior lipid matrix “bricks + mortar”
  • cells continually shed at surface
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20
Q

What is keratinization? Cornification?

A
  • process by which keratinocytes differentiate (~21 days)
  • production of stratum corneum by terminal epidermal differentiation
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21
Q

What is this structure? What are it’s characteristics?

A
  • langerhans cells
  • located in stratum basale and spinosum
  • intra-epidermal macrophages
  • derived from bone-marrow monocytes
  • role in immunity (antigen presenting to t-cells, mediators of tolerance)
  • not usually seen with H+E stain
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22
Q

What is this structure? What are it’s characteristics?

A
  • merkel’s cells
  • located in stratum basale of thick skin
  • connected to adjacent keratinocytes via desmosomes
  • can act as sensory mechanoreceptors for cutaneous sensation
  • can also function to attract nerve endings and stimulate growth
  • free nerve endings at the base of the cells
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23
Q

What is this structure? What are it’s characteristics?

A
  • melanocytes
  • present in stratum basale
  • neural crest origin
  • produce melanin pigment (migrates within cytoplasm extensions, transferred to keratinocytes of stratum basale/spinosum)
  • protects cells from effects of UV radiation
  • must have tyrosine for proper function
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24
Q

What is this pigment? What purposes does it serve?

A
  • melanin
  • absorbs harmful UV radiation
  • transforms radiation energy into harmless heat
  • keeps the generation of free radicals at a minimum
25
Q

What are the sensory nerves of the dermis?

A

Free nerve endings:
- nociceptors: detect pain, itch, temperature

Encapsulated nerve endings:
- meissner’s corpuscles: detect light pressure/touch
- pacinian corpuscle: detect deep pressure
- ruffini corpuscle: senses stretch

26
Q

What are some epidermal derivatives?

A
  • hair follicles
  • compound hair follicles
  • sinus (tactile) hairs
  • sebaceous glands
  • sweat glands (apocrine/merocrine)
  • udders/mammary glands
  • hooves/claws/nails
  • footpads
  • anal sac glands/anal sacs
  • circumanal glands
27
Q

Identify the following:
Epidermis, dermis, hair shaft, hair follicle, hair bulb, sebaceous gland, apocrine sweat gland

A
28
Q

What are functions of hair and feathers?

A
  • insulation
  • camouflage
  • social display
  • sense/protect
  • sex recognition
29
Q

What are the components of hair?

A
  • medulla: loose cuboidal cells w/ areas of air
  • cortex: dense compact keratinized cells
  • cuticle: single layer of flat keratinized cells
30
Q

What is the difference between the hair shaft and hair root?

A

Hair shaft - above the surface of the skin
Hair root - within the follicle and ends with the bulb

31
Q

What are features of the root sheath?

A
  • external glassy membrane = basal lamina
  • external root sheath: continuous with the epidermis
  • internal root sheath: few squamous layers
  • cuticle: internal to external root sheath formed by overlapping keratinized cells but in the opposite direction from the hair cuticle
32
Q

What carried blood supply to the cells of the hair?

A

Dermal papilla

33
Q

What are the phases of the hair cycle?

A

Anagen, catagen, telogen

34
Q

What happens during anagen?

A

Period when hair bulb cells are mitotically active

35
Q

Describe catagen

A

Regressive stage when metabolic activity slows down and the base of the follicle migrates towards the surface. Detachment of the dermal papilla occurs.

36
Q

What phase is the resting or quiescent phase when growth stops and the base of the bulb is at the level of the sebaceous canal?

A

Telogen

37
Q

What are the types of hair follicles? What are their features?

A

Primary hair follicle
- large diameter
- rooted deep in dermis
- sebaceous glands, arrector pili muscle, sweat glands
- primary or guard hair

Secondary hair follicle
- smaller diameter
- rooted nearer the surface
- +/- sebaceous glands, no arrector pili or sweat glands
- secondary or under hairs

**follicles can be arranged as individuals or clusters and can vary in the number of hairs per cluster

38
Q

What are features of compound follicles?

A
  • cluster of several hair follicles
  • follicles merge at the level of sebaceous gland and emerge through on external orifice
  • compound follicles usually have one primary follicle (hf) and several secondary hair follicles (s)
  • most common in carnivores
39
Q

What is smooth muscle attached to the follicle of primary hairs?

A

Arrector pili, contraction causes hair to stand up (role in insulation)

40
Q

What are tactile hairs composed of a single very large follicle, a blood filled sinus between the inner and outer dermal root sheet, and attachments to skeletal muscle that allow for voluntary movements called?

A

Sinus hairs aka whiskers

41
Q

What is this epidermal derivative? What are it features?

A
  • Sebaceous gland
  • located in dermis
  • produce sebum (mix of lipids and cell debris)
  • holocrene secretion
  • antibacterial and waterproofing
  • ducts empty in a folllicle
  • can be simple, branched, or compound glands
42
Q

What is this epidermal derivative? What are it features?

A
43
Q

What is this epidermal derivative? What are it features?

A
  • Apocrine sweat glands
  • secretion by apical budding
  • epithelial cells have apical secretory caps (a)
  • simple saccular or tubular glands with coiled secretory portion and straight duct that opens into distal hair follicle
  • contractile myoepithelial cells (m) help express product
  • in domestic animals, located throughout most of the skin
  • function is mainly communication (attraction, markers)
44
Q

What are the following examples of:
- supracaudal glands : dog
- mental glands : cat
- horn glands : buck goat
- preputial glands : smegma in horse
- tarsal (meibomian) glands : eyelids
- uropygial gland (preen gland) - birds

A

Specialized sebaceous glands

45
Q

What are the following examples of:
- mammary gland
- glands of mal : eyelid, tear film
- ceruminous glands : ear wax
- mental organ and planum rostiale

A

Specialized apocrine sweat glands

46
Q

What is this structure?

A

Mammary gland

47
Q

What are some features of merocrine/eccrine sweat glands

A
  • merocrine : excrete via exocytosis
  • open directly to skin surface via hair follicle
  • minor in domestic animals
  • thermoregulation and electrolyte balance; secrete fluid onto skin surface when body temperature rises
48
Q

What are some features of hooves and claws?

A
  • modification of skin
  • variation of stratum corneum
  • underlain by highly vascular dermis
  • lack stratum granulosum and stratum lucidum
49
Q

What is a highly modified, specialized skin derivative that protects and encloses the end of the digit of an ungulate animal?

A

the hoof

50
Q

What are the two main layers of the hoof?

A
  • outer epidermis
  • underlying dermis (aka CORIUM)
51
Q

What are the layers of the hoof wall superficial to deep?

A
  • stratum externum
  • stratum medium
  • stratum lamellatum/internum
  • laminar corium ** (not hoof wall)
52
Q

What hoof wall layer is called the “glaze” and is a continuation of the perioplic epidermis?

A

Stratum externum

53
Q

What is the main supportive layer of the hoof wall and its features?

A
  • Stratum medium
  • tubular and intertubular horn produced by the stratum basale and stratum spinosum of the epidermis of the coronary groove
54
Q

What layer of the hoof wall has insensitive lamellae (lamellar horn)?

A

Stratum lamellatum/internum

55
Q

What feature of the hoof is this?

A

Interlocking dermal and epidermal laminae

56
Q

What is the white line?

A
  • interdigitation of the non-pigmented wall laminae with the pigmented tubular and intertublar horn of the sole
57
Q

What is the laminar corium?

A
  • the sensitive laminae, the innermost portion of the hoof structure before bone
58
Q

What are features of the uropygial/preen gland?

A
  • strongly developed in many waterbirds
  • rest of bird skin is aglandular
  • function: involved in chemical protection, water-proofing, and maintenance of plumage brightness