Dermatology: Skin Basic Concepts

Front 1

Multilayer organ:
The 2nd largest in the body. Occupies 10% of total body weight.

Is thinest in... and thickest in...

Back 1

Thickness of 0.5 mm on eyelids and 4 mm in the hips.

Front 2

Several specialized organs, including:

Back 2

-Nails
-Hair
-Types of glands

Front 3

Functions:

Back 3

-Protection
-Thermoregulation
-Sensitive
-Secretion
-Excretion

Front 4

Layers

Back 4

Epidermis
Dermis Hypodermis

Front 5

Epidermis

Back 5

Compact cell layer, measuring 120 to 200 microns. Formed by specialized epithelium derived from ectoderm.

Hint 5

By the third week of embryological development are undifferentiated cells that are then divided and specialized.

Front 6

Cells that form the epidermis

Back 6

-Keratinocytes: produce keratin
-Melanocytes: produce melanin
-Langerhans cells (antigen presenting cells and activators of T cells in hypersensitivity reactions.)
-Merkel cells

Front 7

Cells that form the epidermis

Back 7

-Keratinocytes: produce keratin
-Melanocytes: produce melanin
-Langerhans cells (antigen presenting cells and activators of T cells in hypersensitivity reactions.)
-Merkel cells

Front 8

Cells layers from bottom to top (epidermis)

Back 8

1.- Basal or germinative
2.-Malpighian or spinous
3.-Granular
4.-Cornea
*On palms and soles we find the stratum lucidum.

Front 9

Stratum basale

Back 9

Is composed of a single layer of cuboidal columnar cells, wich are attached to the basement membrane by hemidesmosomes. These cells express keratin intermediate filament pairs 5 and 14.
-This layer contains the stem cell population and occasional mitotic figure.

Hint 9

Melanocytes (1 for every 36 keratinocytes) can be identified .

Front 10

Basement membrane

Back 10

The border between the epidermis and dermis known as the dermal-epidermal junction is irregular because numerous upward interdigitations known as dermal papillae indent the undersurface of the epidermis.

Hint 10

Papillae are far more prominent in thick skin than in thin skin since they serve to help these surfaces resist trauma and friction.

Front 11

Stratum granulosum

Back 11

Is composed of increasingly flattened rectangular shaped cells filled with keratohyalin granules

Hint 11

The large accumulation of basophilic granules in these cells is composed of filaggrin and keratin filaments

Front 12

Stratum granulosum

Back 12

Is composed of increasingly flattened rectangular shaped cells filled with keratohyalin granules

Hint 12

The large accumulation of basophilic granules in these cells is composed of filaggrin and keratin filaments

Front 13

Stratum corneum

Back 13

Consisting of keratinized cells, lacking nuclei and few desmosomes that disappear in the last layers, wich allows spontaneous desquamation

Hint 13

The time that used a keratinocyte to traverse the epithelium from de basal layer ou to peel ranges is from 28 to 45 days.

Front 14

Malpighi mucus body: metabolically active or living epidermis.

Back 14

Basal or germinative layer
Espinous layer

Front 15

Metabolically dead epidermis

Back 15

Stratum pre-corneum:
-granular layer
-stratum lucidum
Corneum layer

Front 16

Dermis

Back 16

Formed by dense connective tissue, derived from mesoderm

Front 17

Dermis Subdivision

Back 17

Papillary dermis
-Reticulate dermis

Front 18

Dermis Functions

Back 18

-Nutrition of the epidermis (Papillary dermis). -Protection from mechanical injury of the body and maintain homeostasis (Reticulate dermis).
-Is involved in thermoregulation.

Front 19

Cells of the Dermis

Back 19

Fibrocytes or fibroblasts
-Are the specific cells of the dermis, responsible for producing fibers and ground substance.

Histiocytes
-Are cells of the mononuclear phagocyte system and are able to produce reticular fibers.

Mast cells
-Contain abundant intracytoplasmic granules of heparin, hyaluronic acid, histamine, …

Front 20

Collagen fibers

Back 20

-Produced by fibroblast from specific proteins.
-In middle and deep dermis are parallel to the surface, and in the superficial or papillary dermis are vertical.
-In the dermis is mainly type I collagen (85-90%), type III (8-11%) and type IV (2-4%).

Hint 20

-The type II collagen is only found in cartilage and vitreous humor.
-Others, VIII, IX, X, XI, XII, XIII.

Front 21

Reticular fibers

Back 21

Are rare, and are arranged around the vessels and annexes, forming a grid in the papillary dermis.

Front 22

Elastic fibers

Back 22

-Determine the cutaneous extensibility.
-Consisting of elastin

Front 23

Hypodermis

Back 23

Derived from Mesenchyme
-Appears as an extension deep dermis
-The density governs the mobility of the skin.
-It has a variable number of fat cells, and is rich in triglycerides.

Hint 23

-Functions:
1. Heat insulator
2. Protect from trauma.
3. Nutritional storage.

Front 24

Sebaceous

Back 24

-Most are attached to hair follicle.
-Hair are independent and open at the surface of the skin.
-Developed by action of circulating androgens in the placenta in the newborn.

Hint 24

They are in the dermis, covered by a connective tissue capsule.
-Responsible for the secretion of sebum or oil.

Front 25

Sweat glands (sudoriparous glands)

Back 25

Eccrine type

-Are distributed widely in the skin (palms, soles, and forehead).
-They do not appear on the lips, penis, ear drum and nail bed.
-Consist of secretory portion located in the dermis or hypodermis and excretory portion traces a winding path to the epidermis, reaches the free surface of the skin ending in sweat pore.
-Responsible for the crystalline secretion. (Odorless and colorless)

Hint 25

Apocrine type
-Located in areola, pubic bush, labia minora, prepuce, scrotum and perianal region, periumbilical
-External ear canal (ceruminous glands ).
-Eyelids (glands of Moll)
-Responsible for the “milky”
secretion.(Odorless)

Front 26

Cutaneous blood vessels

Back 26

Blood flow is controlled by the hypothalamus and mediated by the central nervous system,

Hint 26

Functions
-Skin nutrition.
-Is involved in thermoregulation

Front 27

Lymphatics

Back 27

Begins as endothelium-lined clefts in the papilla.
Run parallel to the vascular plexus.
Have valves in their light.

Hint 27

Functions:
-Transport and filtration of lymph, returning it to the venous system.
-Remove protein, water and materials of the dermis.

Front 28

Sensory receptors

Back 28

Pacini: Pressure

Rufini: Elongation and Heat

Meissner: Light touch

Krause: Cold