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RUSVM Microanatomy Orange 2016 > Integument (Exam II) > Flashcards

Integument (Exam II) Flashcards

1
Q

List some important functions of skin.

A

Protection (barrier against invasion of physical, chemical and biological agents)
Prevents loss of H2O and electrolytes
Temperature regulation (arterio-venous anastomoses, hair elevation and sweating all help in this)
Sensation
Elasticity permits movement
Immune function
Excretion (sweating to help maintain ion and water balance)
Calcium homeostasis (UV light absorbed through skin has a role in production of vitamin D)
Energy storage (lipids in adipose tissue within subcutaneous CT)

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2
Q

List some important functions of hair.

A 
Insulation (thermal regulation)
Camouflage
Social Display
Sense/Protect
Sex recognition (role in reproduction)
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3
Q

What is the hypodermis (subcutis)?

A

Loose connective tissue, may be rich in adipocytes, panniculus adiposus
Binds skin loosely to subjacent organs (muscle, bone, etc)

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4
Q

List the important characteristics of epidermis (including germ layer origin, vascularity and function)

A

Ectodermal origin
Avascular
Thick barrier

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5
Q

List the important characteristics of dermis (including germ layer origin, vascularity and function)

A

Mesodermal origin
Connective Tissue
Vascular and Nervous
Supports epidermis (reason behind vascularity)

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6
Q

Describe the characteristics of thin skin vs. thick skin

A

Thick Skin: Thick epidermis, hairless, merocrine sweat glands are present (eg foot pads, muzzle)
Thin Skin: Thin epidermis, has hair follicles and arrector pili muscles, sebaceous and sweat glands are present.

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7
Q

What is the function of the dermal papillae? Where are they found?

A

Upward projections of the superficial dermis into the epidermis. Increase SA of contact between epidermis and dermis. Bring blood vessels near the epidermis.
Not found in normal hair bearing skin (Thin skin) - typically only in thick skin where skin needs to be tough (areas subject to traction stress)

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8
Q

What are the 2 layers of the dermis and what are they made up of?

A

Papillary Layer: Loose CT (principal component), Type I and III collagen. Mast cells, macrophages, vessels, nerves.
Reticular Layer: Dense irregular CT, Type I collagen. Network of elastic fibers. Blood vessels, nerves.

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9
Q

What are the 2 types of cells in the epidermis? Give examples of each if possible.

A

Keratinocytes - most common cell - 95% of epidermis

Non-keratinocytes (Langerhans cells, Merkel’s Cells, Melanocytes, Intraepithelial lymphocytes)

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10
Q

What it’s the function of the epidermal layer?

A

Generate constant supply of cells.
Adhere cells: Desmosomes - between cells, Hemidesmosomes - adhere cells to basement membrane.
Replace cytoplasm with keratin, waterproof, flatten cells, provide many layers of this “oily” cellular barrier.

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11
Q

What are the layers of the epidermis from most mitotically active to least (most alive to least alive)…

A 
Stratum basale
Stratum spinosum
Stratum granulosum 
Stratum lucidum 
Stratum corneum
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12
Q

List the important characteristics of the stratum basale.

A

Epidermal-dermal junction.
Rests on basal lamina - hemidesmosomes bind to basal lamina, desmosomes bind neighboring cells together.
Single layer of cuboidal/columnar cells.
Area of mitotic activity.
May be melanocytes in this layer.

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13
Q

List the important characteristics of the Stratum Spinosum.

A

Cuboidal or slightly flattened cells.
In thin skin - 1-2 cells thick, in thick skin - many layers thick
Desmosomes and increased number of tonofilaments give spiny appearance
Cells are cohesive and resist abrasion
Cells have some capacity for division

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14
Q

List the important characteristics of Stratum Granulosum

A

Never divides
3-5 layers - cells are flattened
Keratohyalin granules - bind with keratin filaments
Stains basophilic
Lamellar granules - secreted by cells to form waterprood lipid sheets, intercellular cement
No mitotic activity, last living layer

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15
Q

List the important characteristics of Straum Lucidum

A

Translucent layer
In thick skin only
Many keratin filaments, desmosomes are present
Cellular organelles are gone - cells are fully keratinized
Cytoplasm contains Eleidin - protein chemically related to keratin

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16
Q

List the important characteristics of Stratum Corneum.

A

15-20 layers thick (depending on location)
Cells consist of keratin (water resistant protein- forms barrier against destructive forces)
Known as Horny Cells - surrounded by thicker plasma membrane coated by the exterior lipid matrix. Bricks & mortar.
Cells continually shed at surface (as individuals or groups)

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17
Q

Describe the difference between keratinization and cornification.

A

Keratinization - entire process by which keratinocytes differentiate
Cornification - production of stratum corneum by terminal epidermal differentiation

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18
Q

List the characteristics of the epidermis of thick skin.

A

Keratinized stratified squamous epithelium
Contains stratum lucidum with pyknotic nuclei
Has superficial stratum corneum
Stratum granulosum - last living cells, keratohyalin granules

19
Q

List the 3 most important epidermal non-keratinocytes and give their functions.

A

Langerhans Cells - immune system
Merkel’s Cells - sensory cells
Melanocytes - protective function

20
Q

Where are Langerhans cells found? What is their function? Why do they have finger-like extensions?

A

Found in stratum basale and stratum spinosum.
Function in immunological skin reactions: antigen presenting cells, internalize surface bound antigen for processing and presenting at its cell surface to T lymphocytes.
Fingers give high SA to take stuff up from the environment (eg antigens)

21
Q

Where are Merkel’s Cells found? What is their function? Can they be see in light microscopy?

A

Present in thick skin near Stratum basale.
Many be sensory mechanoreceptors for cutaneous sensation or diffuse neuroendocrine system
Free nerve ending seen at the base of these cells.
Can’t see in LM

22
Q

Where are melanocytes found? What is their origin? What do they do?

A

Found in stratum basale.
Neural crest origin.
Stable cells, live for years.
Produce melanin.

23
Q

Where is melanin found? What does melanin do?

A

Melanin migrates from melanocytes (where it is produced) through cytoplasmic extensions to the keratinocytes.
Within the keratinocytes melanin tends to be around the nuclei - protects the DNA,
Protects cells from effects of UV radiation - dark pigment. Does this by transforming the energy into harmless amounts of heat. Reduces the amount of free radicals generated.

24
Q

Where are keratinocytes found?

A

Stratum basale and stratum spinosum

25
Q

What happens if an animal does not have tyrosinase?

A

Animal cannot produce melanin = Albino

26
Q

What is eumelanin and pheomelanin?

A

Eumelanin - most common form of melanin, brown-black pigment
Pheomelanin - red-brown polymer - responsible for red hair and freckles.

27
Q

List the 2 types of sensory nerves in the dermis and give examples of each.

A

Free nerve endings to stratum granulosum (Nociceptors - pain, itch, temperature)
Encapsulated nerve endings (Meissner’s corpuscles, pacinian corpuscle, ruffini corpuscle (sense stretching))

28
Q

What layer of the hair follicle is continuous with the epidermis?

A

Outer root sheath

29
Q

What is the function of the dermal papilla in a hair follicle?

A

Carries blood supply to cells of hair.

30
Q

What are the layers of the root sheath?

A

Dermal Sheath, External Glassy membrane (basal lamina), external root sheath, internal root sheath (a few layers of squamous cells), cuticle (toward hair bulb, formed by overlapping keratinized cells),

31
Q

Describe the differences between a primary and secondary hair follicle.

A

Primary Hair Follicle (primary or guard hair): large diameter, rooted deep in dermis, sebaceous glands, arrector pili muscles, sweat glands
Secondary Hair Follicle (secondary or under hair): smaller diameter, rooted nearer surface, with or without sebaceous gland, no sweat glands, no arrector pili muscles.

32
Q

What is a compound hair follicle?

A

Cluster of several hair follicles. The follicles merge at the level of the sebaceous glands and emerge through one external orifice.

33
Q

What are arrector pili muscles?

A

Smooth muscle attached to follicle of primary hairs. Courses obliquely through dermis. Contract when you get goosebumps. Causes hair to stand up.

34
Q

List important characteristics of sinus hair/tactile hair/Whisker

A

Sinus is filled with blood (red blood cells)
Big dermal papillae
Sinus tends to be ~ heart shaped

35
Q

What do sebaceous glands secrete? What does their secretion do? What type of gland (apocrine, holocrine, merocrine) is a sebaceous gland? Where do the ducts empty?

A

Sebum (oily) mixture of lipid and disintegrated cells.
Sebum acts as an antibacterial and waterproofing agent.
Holocrine gland - glad disintegrates
Ducts empty into hair follicle or on skin surface.
Cells accumulate lipid droplets as they differentiate towards the center of the gland.

36
Q

What is the Uropygial/Preen Gland?

A

Strongly developed gland in many water birds. Aids in waterproofing - sebaceous gland.

37
Q

Explain the structure of an aprocrine sweat gland.

A

Epithelial cells have apical secretory cap.
They are simple saccular or tubular glands with coiled secretory portion and strait duct.
Contractile myoepithelial cells surround secretory units and help express the product.

38
Q

Where are aprocrine sweat glands located? What is their main function?

A

In domestic animals they are located throughout most of the skin (wherever there is hair). In humans - only armpits.
Function mainly in communication (attraction, making) - smelly (eg anal glands)>

39
Q

A mammary gland is an example of what type of gland?

A

Apocrine sweat gland

40
Q

What is the function or Eccrine/Merocrine Sweat Glands?

A

Thermoregulation and electrolyte balance - secrete fluid onto skin surface when body temperature rises
Minor in domestic animals.

41
Q

What type of glands supply the anal sacs?

A

Supplied by the perinatal glands (sebaceous and apocrine sweat glands)

42
Q

What layer of epidermis is varied in hooves and claws?

A

Stratum Corneum. Lack Stratum granulosum and stratum lucidum.

43
Q

What are the layers of the hoof and briefly describe them.

A

Insensitive Laminae (epidermis) - avascular, outer hoof
Perioplic Corium
Coronary Corium
Laminar Corium (Dermis) - sensitive laminae - contains nerves and vessels

44
Q

What are the epidermal layers of the hoof wall and describe them.

A

Stratum Tectorium/Externum - external “glaze” layer, continuation of perioplic epidermis
Stratum Medium - main supportive layer, tubular and intertubular horn produced by the stratum basale and stratum spinosum of the epidermis of the coronary groove
Stratum Lamellatum/Internum - lamellar horn, insensitive lamellar

RUSVM Microanatomy Orange 2016 (10 decks)

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