Histology, function, health, virus, dermatitis

epidermis, dermis, and hypodermis/ subcutis

layers of skin

hairshaft, pili-arector mm, sebaceous/ oil gland, hair follicle, nerve fiber, vein, nerve, artery, sweat/sudoriferous gland, sensory nerve ending for touch (epidermis, dermis, hypodermis)

specific skin structures

➢ stratum basale – cuboidal cells which replenishes lost epidermal surface cells

➢ stratum spinosum – thickest in hairless regions wherein keratinization and desquamation take place

➢ stratum granulosum – granules of keratin present

➢ stratum lucidum – clear due to accumulation of keratin fibers in cytoplasm; not present in all species; when present are in areas which wear and tear

➢ stratum corneum – layers of dead, highly keratinized flattened cells

BSGLC

layers of epidermis:

stratum basale

cuboidal cells which replenishes lost epidermal surface cells

stratum spinosum

thickest in hairless regions wherein keratinization and desquamation take place

stratum granulosum

granules of keratin present

stratum lucidum

clear due to accumulation of keratin fibers in cytoplasm; not present in all species; when present are in areas which wear and tear

stratum corneum

layers of dead, highly keratinized flattened cells

1. Meissner’s (tactile/touch)

2. Pacinian (pressure)

3. Krause (cold)

4. Ruffini’s (heat)

MPKR

sensory nerve endings

Meissner’s

sensory nerve endings

(tactile/touch)

Pacinian

sensory nerve endings

(pressure)

Krause

sensory nerve endings

(cold)

Ruffini’s

sensory nerve endings

(heat)

• anagen

• catagen

• telogen

ACT

hair cycle

• anagen – growing phase

• catagen – transitory phase between growing and resting phases

• telogen – resting phase of hair cycle

• ______ – growing phase

• _______ – transitory phase between growing and resting phases

• _______ – resting phase of hair cycle

1. barrier – by limiting water and nutrient loss

2. temperature regulation – through sweating

3. sensory perception – through nerve endings responsible for sensation of touch, pressure, heat, cold, and pain stimuli

4. blood pressure control - through vasoconstriction or vasodilation of arterioles on it

5. secretion of sebum and excretion of sweat

6. flexibility – by the aid of connective tissues

7. synthesis - vitamin D/ calciferol synthesis under influence of sunlight

8. storage of nutrients

9. immune function – by the aid of skin substances with natural antibacterial & antifungal properties

10. pigmentation – melanin secretion by melanocytes for skin protection against ultraviolet radiation

BTSBS FSSIP

Functions of Skin

barrier

Functions of Skin

by limiting water and nutrient loss

temperature regulation

Functions of Skin

– through sweating

sensory perception

Functions of Skin

through nerve endings responsible for sensation of touch, pressure, heat, cold, and pain stimuli

blood pressure control

Functions of Skin

through vasoconstriction or vasodilation of arterioles on it

flexibility

Functions of Skin

by the aid of connective tissues

synthesis

Functions of Skin

vitamin D/ calciferol synthesis under influence of sunlight

immune function

Functions of Skin

by the aid of skin substances with natural antibacterial & antifungal properties

pigmentation

Functions of Skin

melanin secretion by melanocytes for skin protection against ultraviolet radiation

• exogenous

• endogenous

Factors Affecting the Condition/ Health of Skin

1. physical

2. chemical

3. nutritional

4. infectious

5. actinic

6. allergic

exogenous types

actinic

chemical changes due to radiation

1. age

2. heredity

3. congenital

4. metabolic

5. hormonal

6. immunologic

7. emotional

8. internal diseases

   AHCMH IEI

endogenous types

1. poxviruses

2. herpesviruses

3. rickettsial organisms

4. Dermatophilus congolensis (ruminants)

5. Bacteria

6. mycotic/ fungal organisms

Microorganisms That Causes Skin Diseases

– orf/ contagious ecthyma, human/ chickenpox (variola), swinepox

poxviruses

herpes simplex virus, (causes lesions on skin around the mouth)

herpesviruses

R. rickettsii (RMSF), R. akari (rickettsialpox)

rickettsial organisms

causes dermatophilosis and streptotrichosis

Dermatophilus congolensis (ruminants)

Bacteria

dermatophytes: Microsporum, Trichophyton and Epidermophyton; subcutaneous: Sporothrix, Madurella

mycotic/ fungal organisms

• insect bites (lice and fleas)

• acarid bites (ticks and mites)

• burrowing activities of mites

• migrating stages of parasites

General Causes of Parasitic Dermatitis

acute or chronic inflammation

Major Effects of Skin Parasites

activation of inflammatory cells:

acute phase: neutrophils and eosinophils

chronic phase: plasma cells, macrophages and proliferating fibroblasts

activation of inflammatory cells:

acute phase: ______ and _______

chronic phase: _____ cells, ______ and proliferating ______

stylostome

sucking tubes of chiggers

1. protozoan – Globidia sp. (Besnoitia)

2. simuliasis – Simulium (blackflies)

3. hypodermyiasis – Hypoderma bovis and H. lineatum (larva)

4. gasterophilomyiasis – Gasterophilus (larva in mouthparts of horse)

5. trombiculiasis – Trombicula mites (chiggers: larva mites)

6. gamasoidiasis – Dermanyssus gallinae, Ornithonyssus sylviarum and O. bursa

7. acariasis

8. trematodiasis

9. nematodiasis

PSHGT GATN

Parasites That Causes Dermatitis

Globidia sp. (Besnoitia)

Parasites That Causes Dermatitis

protozoan

Simulium (blackflies)

Parasites That Causes Dermatitis

simuliasis

Hypoderma bovis and H. lineatum (larva)

Parasites That Causes Dermatitis

hypodermyiasis

Gasterophilus (larva in mouthparts of horse)

Parasites That Causes Dermatitis

gasterophilomyiasis

Gasterophilus

(larva in mouthparts of horse)

Trombicula mites (chiggers: larva mites)

Parasites That Causes Dermatitis

trombiculiasis

Dermanyssus gallinae, Ornithonyssus sylviarum and O. bursa

Parasites That Causes Dermatitis

gamasoidiasis

1. Sarcoptes

2. Demodex

3. Cnemidocoptes

4. Psoroptes

5. Chorioptes

6. Notoedres

7. Cheyletiella

8. Argas persicus

9. Laminosioptes cysticola

SDCPC NCAL

acariasis

Sarcoptes

sarcoptic mange

Demodex

(demodectic mange)

Cnemidocoptes

(scaly leg

Psoroptes (psoroptic mange

suck lymph and tissue fluids)

Chorioptes

chorioptic mange

Notoedres

(notoedric mange)

Cheyletiella

walking dandruff mite

Laminosioptes cysticola

subcutaneous mite of poultry

1. schistosome metacercariae

2. Collyriclum faba

trematodiasis

schistosome metacercariae

causing cercarial dermatitis

Collyriclum faba

causing subcutaneous cyst in fowl

habronemiasis (summer sores);

strongyloidiasis: Strongyloides stercoralis and Rhabditis strongyloides (causes papular and pustular dermatitis);

microfilariasis – Onchocerca, Parafilaria, Dirofilaria (in tropics and warmer regions; there is dermatitis and skin ulceration);

elaeophoriasis – Elaephora schneideri (microfilaria also causes dermatitis )

creeping eruptions in human – Ancylostoma spp.

nematodiasis

habronemiasis

summer sores

Strongyloides stercoralis and Rhabditis strongyloides

strongyloidiasis(causes papular and pustular dermatitis)

– Onchocerca, Parafilaria, Dirofilaria

microfilariasis (in tropics and warmer regions; there is dermatitis and skin ulceration)

Elaephora schneideri

elaeophoriasis

microfilaria

also causes dermatitis

Ancylostoma spp.

creeping eruptions in human

• benign

• malignant

Neoplastic Disorders of Skin

benign

marked by disorganization especially of the granular layers of the epidermis, swollen and eosinophilic cytoplasm, and sometimes contain viral particles of poxvirus

malignant

hyperchromatism (with darker color of cells), increased mitotic activity, enlargement of cell nuclei, and can lead to carcinoma

malignant

melanoma, malignant melanoma, papilloma, squamous cell carcinoma