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Histology > Skin > Flashcards

Skin Flashcards

1
Q

Skin fx

A

Enviro barrier
Temp reg (insulation, sweat, blood flow reg)
Immunological (via langerhans & dendritic cells)
Mech support
Neurosensory
Metabolic & endocrine
Glandular secretion

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2
Q

Epidermis comp

A

Stratified squamous keratinised epithelium.
No own blood supply, rely on dermis (avascular)
Most of epidermis made of keratinocytes which are divided further

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3
Q

Epidermis divisions

A 
Stratum basale
Stratum spinosum
Stratum granulosum
Stratum lucidum
Stratum corneum
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4
Q

Stratum basale

A

Basal layer
Cuboidal cells act as stem cells to produce new epidermal cells.
New cells continually migrate outwards & become more diff / keratinised
Adhered by hemidesmosomes to BM running between epidermis & dermis

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5
Q

Stratum spinosum aka prickle layer

A

Many layers of polygonal shaped cells which synth cytokeratin - forms tonifibrils that combine to form desmosomes which adhere cells together. Seen well after shrinkage during prep for slide
Varies in thickness
Targetted by some immune diseases

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6
Q

Stratum granulosum

A

Flattened cells containing dense dark keratohyalin & lamelar granules

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7
Q

Stratum lucidum

A

Only at some anatomical sites where skin is v thick of is hairless
Thin translucent layer of compacted cells w/ out nuclear detail

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8
Q

Stratum corneum

A

Variable no of layers of dead keratinised cells continuously replaced
Many diseases resulting in hyperkeratosis

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9
Q

Physiology of keratinisation

A

As keratinocytes mature incr size as they synth intracellular components (tonofibrils, keratihyalin granules, lamelar granules)
Nuclei slowly disintegrate, lamelar granules release lipid-like content into ECspaces. Meanwhile cells become flat dense structures and lose nuclei and cytoplasm eventually to be plates of keratin

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10
Q

Epidermal cells

A

Keratinocytes
Melanocytes
Merkel cells
Langerhans cells

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11
Q

Melanocytes

A

Contain pigmented granules called melanosomes which migrate to cell periphery to be phagocytosed by adjacent keratinocytes

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12
Q

Melanocytes found

A

Often epidermis basal layer
Glands
Hair follicles

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13
Q

Merkel sites

A

Present in basal region
Have vacuolated cyt on dermal side
Can act as mechanoreceptors by assoc with axons

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14
Q

Langerhans cells

A

Potent anitgen presenting cellsmainly found in stratum spinosum
Responsible for canine cutaneous histiocytoma

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15
Q

BM anchors

A

Attach to stratum basale cells via hemidesmosomes and anchoring filaments
Essential for maintaining structural integrity of skin

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16
Q

BM unusual features

A

Sometime dives down into dermis forming projections which help bind epid strongly to dermis aka rete ridges
Common where skin subject to much friction eg footpad

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17
Q

Dermis comp

A

Irregular bundles of coll fibres produce by fibroblasts
Elastic fibres embedded within acellular GS
Blood vessels nerves lymphatics
Fibrocytes and inflamm (dendritic) cells
Can be divided into layers

18
Q

Dermis divisions

A

Papillary dermis

Reticular dermis

19
Q

Papillary dermis

A

Adjacent to epid and follows contours of stratum basale (thin layer)
Delicate C bundles

20
Q

Reticular dermis

A

Deep layer of thicker denser C

21
Q

Subcutus/hypodermis

A

Anchors dermis to underlying muscle
Cont adipose tissue to act as cushion allow flex and insulation
Less C and more blood vessels than dermis

22
Q

Adnexal structures

A

Additional structures
All epithelial derivatives separated from dermis by a BM
Eg hair

23
Q

Equine bovine hair

A

Sigle follicle evenly distributed

24
Q

Pig hair

A

Single follicle grouped in clusters

25
Q

Dog hair

A

Compound follicles
Single primary hair with smaller secondary underhairs
Short coated breed have more primary hairs

26
Q

Cat hair

A

Single and compound

Single primary follicle with clusters 2-5 compound follicles surrounding

27
Q

Sheep hair

A

Single and compound
Face/legs single follicles
Wool areas mostly compound

28
Q

Special hair types

A

Sinus hairs

29
Q

Sinus hairs

A

Highly specialised
Surrounded bh blood filled sinus
Skeletal m attaches to outer sheath - degree of voluntary control. Outer sheath assoc with many nerve bundles

30
Q

Gland types

A

Sebaceous

Sweat: apocrine & merocrine

31
Q

Sebaceous glands

A

Antibac Sebum secretion
Into hair canal, sometimes direct onto skin (anus)
Simple cuboidal epithelium on a BM which diff into classic sebaceous cells w/ a foamy cyt and large & polygonal in shape
Cells disintegrate and release content

32
Q

Apocrine sweat glands

A

Coiled secretory portion & straight duct
Evenly distributed
Typically cuboidal epi on a BM but can become low columar
Possible tonsee myoepi cells between epi cells and BM
In horse produce recognisable sweat, others just scent or diff to detect sweat

33
Q

Merocrine sweat glands

A

In specialised areas eg footpads of dogs, frog if horse
Open directly onto skin
Simple cuboidal in nature
Assoc with myoepi cells

34
Q

Myoepithelial cells

A

Epi cells with muscle assoc to aid with secretion

35
Q

Footpad adaptations

A

Thickened stratum corneum for protection
Prominent hypodermis with many fat cells for cushioning
Abundant merocrine sweat glands

36
Q

Eyelid adaptations

A

Cont Specialised type of sebaceous gland aka tarsal or meibomian gland.
Specialised apocrine sweat glands open into eyelash follicles

37
Q

Meibomian gland

A

Multilobular
Open directly onto palperbral surface at margin of eyelid
Best dev in cat
Potential tumour source

38
Q

Nose adaptations

A

In dog and cat comp thick stratified squamous epit with deep grooves in an indiv pattern
Cattle similar but lack deep grooves
No hair follicles

39
Q

Claws

A

Modification of the skin
Continuous with epidermis
Comp much hard keratin to protect distal phalanges

40
Q

Claw anatomy

A

Hard wall
Softer underlying sole
V good blood supply to underlying dermis so bleed if nail cut too short

41
Q

Subdivisions of skin

A

Epidermis
Dermis
Subcutis(aka hypodermis)

Histology (10 decks)

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