INTEGUMENT

Question 1

hair structure:

Answer 1

• medulla = innermost region composed of longitudinal rows of cuboidal cells
• cortex = middle layer, cornified spindle shaped cells that contain pigment
• cuticle = outer most layer = flat, cornified, anuclear cells

Question 2

hair follicle structure:

Answer 2

• dermal papilla -> stem cells located
• hair matrix
• hair shaft (hair)
• inner root sheath and outer root sheath (downward extension of epidermis)
• outer root sheath surrounded by glassy basement membrane zone (BMZ) -> downward reflection of epidermal basement membrane
• fibrous sheath

Question 3

types of hair

Answer 3

1. PRIMARY/guard hair -> long, coarse hairs in outer coat (also have medulla but thicker)
   - each primary hair has a sebaceous and sweat gland and an arrector pili muscle
2. SECONDARY -> undercoats, down, soft, short, cotton-like (narrow medulla, and more prominent cuticle)
   each primary hair has a sebaceous and sweat gland and an arrector pili muscle
   - secondary hairs ONLY HAVE SEBACEOUS GLAND

Question 4

compound hair follicles

Answer 4

• two to five large primary hairs surrounded by a group of smaller secondary hairs

Question 5

hair Cycle

Answer 5

1. ANAGEN = active phase (anagen follicle has a really well-developed spindle shaped dermal papilla, capped by hair matrix)
2. CATAGEN = regression phase
3. TELOGEN = resting phase
4. EXOGEN = shedding phase
5. KENOGEN = empty follicle after exogen

Question 6

What are sebaceous glands

Answer 6

• simple or branched alveolar glands
• develop from follicular epidermis
• open into pilosebaceous canal
• HOLOCRINE = entire cell forms secretory product, sebum (lipid)
• function of sebum = surface emulsification, maintaining hydration, chemical barrier
• cells appear foamy and pale

Question 7

Sweat glands

Answer 7

• loosely coiled, saccular or tubular apocrine glands
• distributed in haired skin
• not footpads or nasal planum
• open into pilary canal above the sebaceous gland duct
• Apocrine = portion of cytoplasm forms secretory product -> oily proteinaceous secretion
• function = thermoregulation
  can be apocrine or eccrine

Question 8

apocrine sweat glands

Answer 8

• Loosely coiled, saccular or tubular apocrine glands
• Distributed in haired skin
• Not footpads or nasal planum
• Open into Hilary canal above the sebaceous gland duct
• Apocrine: portion of cytoplasm forms secretory product
• Produce oily proteinaceous secretion
• Function: thermoregulation (domestic animals)

Question 9

eccrine sweat glands

Answer 9

• Small and tightly coiled eccrine (merocrine) glands
• Distributed in deep dermis of footpads or nasolabial plate of cattle
• Open onto epidermal surface
• Function: thermoregulation (humans) scent (domestic animals): marking, tracking

Question 10

footpad structure

Answer 10

• Pigmented epidermis: extensive keratinised, thickened stratum corneum
• Dermis: exaggerated dermal papillae and ridges
• Fibrous/fatty subcutaneous cushion
• Epidermis is smooth in cats but papillated and irregular in dogs
• Devoid of hair follicles
• Sweat glands are present for scent and trail marking

Question 11

What is plantigrade?

Answer 11

• Foot makes contact all the way along (effectively makes contact at 3 points)
• 3 Pads
• Hindfoot: 3 pads fused to 1

Question 12

what is digitigrade?

Answer 12

• 2 points of contact
• Metacarpal and digital pads
• Carpal pad still there but no longer in contact with the ground (vestigial) ‘stopper pad’ (not actually the function
• Dew claw also risen off ground as well
• Hindfoot = no tarsal pad

Question 13

what is Unguligrade

Answer 13

• Only contact at distal phalanx (en cased in a hoof)
• Even though horses have no function for other foot pads, they still have the ‘remnants’ of them
• Chestnut: thickened scab
• Ergot: soft bit of horn (protects area)
• Frog and bulbs and bulbs (cushions the area)

Question 14

nail structure

Answer 14

• eponychium = cuticle
• epidermis folds in on itself deeply to form nail
• hyponychium - skin under free edge of nail
• coronary region -> dermis and epidermis that produces nail material (on top)
• ungual crest = continual bony rim that hides coronary region (protects)
• sole and top of nails grow from either side of nail and meet at tip
• bulb under nail = fingerpad/tip (digital pad)

Question 15

wing topography

Answer 15

• Primary flight feathers (remixes) are attached to the manus
• Secondary regimes are attached to the ante brachium
• Tertials (aka humerals) are arched to the brachium
• The alula is attached to the ‘thumb’
• The patagium forms the leading edge of the wing