First Semester: Microscopic Anatomy > Lecture 14: Integument > Flashcards

Lecture 14: Integument Flashcards

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1
Q

Integument includes

A

Skin and epidermal derivatives

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2
Q

Are antlers epidermal derivatives?

A

Nope

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3
Q

What is the largest organ of the body?

A

Skin

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4
Q

Functions of skin (9)

A
  • Protection
  • Prevents loss of water and electrolytes
  • Temperature regulation
  • Sensation
  • Elasticity permits movement
  • Immune function
  • Excretion
  • Calcium homeostasis
  • Energy storage
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5
Q

Functions of hair (5)

A
  • Insulation
  • Camouflage
  • Social display
  • Sense/protect
  • Sex recognition
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6
Q

What percent of body weight is skin

A

8-16%

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7
Q

Epidermis cells

A

Stratified squamous keratinized

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8
Q

Hypodermis binds

A

skin loosely to adjacent organs

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9
Q

Three regions of the skin

A
  • Epidermis
  • Dermis
  • Hypodermis
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10
Q

Epidermis origin

A

ectodermal

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11
Q

Is epidermis vascular?

A

Nope

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12
Q

Dermis origin

A

Mesodermal

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13
Q

What regions are CT

A

Dermis

Hypodermis

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14
Q

Is dermis vascular?

A

Yes and innervated

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15
Q

Thick epidermis

A
  • Digital pads, muzzle, ect
  • Hairless
  • Merocrine sweat glands
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16
Q

Thin epidermis

A
  • Hair follicles with arrector pili muscle

- Sebaceous and sweat glands

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17
Q

Epidermal pegs/ridges

A

-Downward projections of the epidermis into the underlying dermis

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18
Q

Dermal papillae

A
  • Upward projections of the superficial dermis
  • Increased area of contact between dermis and epidermis
  • Bring blood vessels near the epithelium
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19
Q

Sites of pegs and papillae

A
  • Footpads, nasal planum, and scrotum
  • Areas subject to traction stress
  • Not in normal hair bearing skin of cats and dogs
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20
Q

What is the principle component of the dermis?

A

Connective tissue

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21
Q

Two layers of the dermis?

A
  • Papillary layer

- Reticular layer

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22
Q

Papillary layer

A
  • Loose CT
  • Type 1 and 3 collagen
  • Mast cells, macrophages, vessels, and nerves
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23
Q

Reticular layer

A
  • Dense irregular connective tissue
  • Type 1 collagen
  • Network of elastic fibers
  • Blood vessels, nerves
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24
Q

Skin elasticity

A

Network of elastic fibers in reticular layer of dermis

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25
Cells of the epidermis
- Keratinocytes | - Non-keratinocytes
26
Keratinocytes
Most common cell in epidermis, accounts for 95% of the total number of cells in the epidermis
27
Non-keratinocytes in the epidermis
1. Langerhans cells 2. Merkel's cells 3. Melanocytes 4. Variable number of intraepithelial lymphocytes
28
Epidermal layers generate a
constant supply of cells
29
Adhere cells
Desmosomes | Hemidesmosomes
30
Desmosomes
Between cells
31
Hemidesmosomes
Attach basal cells to the basal lamina
32
Epidermal layers replace cytoplasm with
keratin - waterproofs, flattens cells and provides many layers of oily cellular barrier
33
5 layers of the epidermis
- Stratum basale - Stratum spinosum - Stratum granulosum - Stratum lucidum (not present at all sites) - Statum corneum
34
Stratum basale is considered the
epidermal-dermal junction
35
Stratum basale cell structure
Single layer of cuboidal to columnar cells
36
Stratum basale rests on
- Basal lamina | - Hemidesmosomes bind cells to basal lamina
37
Stratum basale is an area of ____ activity
mitotic
38
May see _______ in the stratum basale
melanocytes
39
Stem cells in the stratum basale proliferate by
mitotic division | cells move up and keratinize
40
Stratum spinosum cells
Cuboidal or slightly flattened - Thin: 1-2 cells thick - Thick: Many layers Cohesive and resist abrasion Retain some capacity for division if needed
41
Stratum spinosum appearance
- Desmosomes and increased number of tonofilaments give spiny appearance - Prickle cells layer
42
Stratum granulosum cells
- 3-5 layers of flattened cells - Can be difficult to see in thin skin - Basophilic
43
Two granules associated with the stratum granulosum
- Keratohyalin granules | - Lamellar granules
44
Keratohyalin granules
-Bind with keratin filaments
45
Lamellar granules
Secreted by cells to form waterproof lipid sheets (intercellular cement)
46
Does the stratum granulosum have mitotic activity
Nope Last living layer Nucleus and organelles soon to be lost
47
Stratum lucidum
- Translucent layer that is present only in thick skin - Many keratin filaments, desmosomes present - Cellular organelles are gone - Fully keratinized
48
Cytoplasm of the stratum lucidum contains
eleidin - protein that is chemically related to keratin
49
Stratum corneum thickness
15-20 layers | Varies by location
50
Cells of stratum corneum consist of
Keratin
51
Stratum corneum cells are known as
- Horny cells - Surrounded by a thicker plasma membrane coated by the exterior lipid matrix - "Bricks and morter"
52
Stratum corneum cells continuously
Shed at surface
53
Superficial stratum corneum is composed of
non-nucleated dead keratinized cells
54
Stratum lucidum cells have ___ nuclei
pyknotic
55
What are the last living cells with keratohyalin granules
stratum granulosum
56
Keratinization
- Process by which keratinocytes differentiate | - About 21 days in the dog
57
Cornification
Production of stratum corneum by terminal epidermal differentiation
58
Langerhans cells are found
In stratum basale and stratum spinosum
59
Langerhans cells make up what percentage of total cells
2-8%
60
Langerhans cells are derived from
``` Bone marrow (monocyttes) Intra-epidermal macrophages ```
61
Lanerhans cells role in immunological skin reactions
- Antigen presenting cells | - Internalize surface-bound antigen for processing and presenting at its cells surface to T lymphocytes
62
Merkel's cells are found
In thick skin near stratum basale
63
What are seen at the base of Merkel cells?
Free nerve endings
64
Merkel cells may be
- Mechanoreceptors for cutaneous sensation | - Diffuse neuroendocrine system
65
Melanocytes are present
in the stratum basale
66
Melanocytes orginate
in the neural crest
67
Melanocytes produce
Pigment melanin, which migrates within cytoplasmic extensions and is transferred to keratinocytes of stratum basale and spinosum
68
Melanocytes protect
cells from effects of UV radiation
69
Melanocytes must have
Tyrosinase for proper function
70
Melanin absorbs
- Harmful UV radiation - Transforms energy into harmless amounts of heat - Keeps free radicals at a minimum
71
Eumelanin
- Most common form of melanin | - Brown/black pigment
72
Pheomelanin
-A red/brown polymer responsible for red hair and freckles
73
What happens in a situation where there is no tyrosine
No melanin | Albino animal
74
Sensory nerves of dermis
- Free nerve endings to stratum granulosum * Nocioreceptors - Encapulated nerve endings * Meissners corpuscles * Pacinian corpuscles * Ruffini corpuscles (sense stretching)
75
Hair follicle
- Epidermal invagination | - Glassy membrane: a thick basement membrane
76
Hair parts
- Medulla: loose cuboidal cells; air filled in areas - Cortex: dense compact keratinized cells parallel to hair shaft - Cuticle: single layer of flat keratinized cells
77
The pattern of cuticle and medulla is
Characteristic for each species
78
Two layers of hair follicle
- Dermal papilla | - Root sheath
79
Dermal papilla
- Carries blood supply to the cells of the hair | - Hair matrix cells comparable to stratum basale
80
4 layers of the root sheath
- External glassy membrane - External root sheath - Internal root sheath - Cuticle
81
External glassy membrane
Basal lamina; external to external root sheath
82
External root sheath
Continuous with epidermis
83
Internal root sheath
A few layers of squamous cells
84
Cuticle
- Internal to internal root sheath - Formed by overlapping keratinized cells but with free edges oriented in the opposite direction from the hair cuticle, towards the hair bulb
85
Primary hair follicle
- Large diameter - Rooted deep in the dermis - Sebaceous gland, arrector pili muscle, sweat glands - Primary or guard hair
86
Secondary hair follicles
- Smaller diameter - Rooted near the surface - +/- sebaceous gland; no sweat glands; no arrector pili muscle - Secondary or under hairs
87
Compound hair follicles
Clusters of several hair follicles
88
Compound hair follicles merge where? | Emerge where?
Merge at the level of the sebaceous gland and emerge through one external orifice
89
Compound hair follicles usually have one ___ __ and several ___ ___
primary follicle | secondary follicles
90
Sinus (tactile) hair follicles =
whiskers
91
Sebaceous glands produce
Sebum | A mixture of lipid and disintegrated cells which acts as an antibacterial and waterproofing agent
92
Sebaceous gland ducts empty into
hair follicle or skin surface
93
Sebaceous gland cells accumulate
lipid droplets as they differentiate towards the center of the gland
94
Uropygial/preen gland
Strongly developed in many waterbirds such as ducks (but not in cormorants)
95
Apocrine sweat glands
-Simple saccular or tubular glands with coiled secretory portion and strait duct
96
What help express the product of the apocrine sweat glands
Contractile myoepithelial cells that surround secretory units
97
In domestic animals, where are apocrine sweat glands located
Throughout most of the skin
98
Function of apocrine (sweat) glands?
Mainly communication (attraction, marker)
99
Role of eccrine/merocrine sweat glands in domestic animals
minor
100
Eccrine/merocrine purpose
- Thermoregulation - Electrolyte balance - Excrete on surface of skin when body temperature rises
101
Horse thermoregulation
Produce a protein rich sweat. The major component is latherin, a non-glycosylated protein
102
Do dogs produce sweat for thermoregulation?
Nope
103
Merocrine glands in foot pads of dogs
Produce a watery secretion similar to human perspiration
104
Apocrine glands associated with every hair follicle on dog body has two functions
- Seal the outer layer of epidermis | - Secrete pheromones that give dogs a distinctive body odor
105
Hooves and claws are modifications of
skin | variations of stratum corneum
106
Hooves and claws are underlain by
Highly vascular dermis
107
Hooves and claws lack
Stratum granulosum and stratum lucidum
108
Hoof
Highly modified, specialized skin derivative that protects and encloses the ends of the digits of an ungulate mammal
109
Hoof is the equivalent of
a nail or claw
110
Hoof has two main layers:
``` Outer epidermis Underlying dermis (corium) ```
111
Three layers of the hoof wall
- Stratum tectorium/externum - Stratum medium - Stratum lamellatum/internum
112
Stratum tectorium
- Thin - External layer is known as the glaze - Continuation of the perioplic epidermis
113
Stratum medium
- The main supportive layer - Tubular and intertubular horn. produced by the stratum basale and stratum spinosum of the epidermis of the coronary groove
114
Stratum lamellatum
- Lamellar horn | - Insensitive lamellae
115
Laminar corium
Sensitive laminae
First Semester: Microscopic Anatomy
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