43-Histology of the Skin Flashcards by Adam Rasmussen

3 regions of skin

Epidermis
Dermis
hypodermis

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What is the epidermis

Most superficial layer

Physical barrier and immunological protection

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What is the dermis

2nd layer
Support and elasticity of the skin
Contains immune cells
Vascular, neural and adnexal structures

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What is the hypodermis

Subcutaneous connective tissue

adipose tissue

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What are the layers of the epidermis

corneum
granulosum
spinulosum
basale

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Thickest and thinnest layers of epidermis

Palms and soles

Genital and face

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keratinocytes

90% of cells in epidermis

Continuously turned over every 28 days

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Keratin intermediate filaments

tonofilaments aggregate and form tonofibrils

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Basal keratinocytes

5 and 14

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suprabasal keratinocytes

1 and 10

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What is the stratum basale

mitotically active

Columnar cells attacted to basement membrane by hemidesmosomes

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What are hemidesmosomes

Connect cell to basement membrane, 1 plaque composed of bulbous pemphigoid antigen 1

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What are desmosomes

Connect cell to cell, 2 plaques

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What makes up a desmosome

2 electron dense attachment plaques

plakoglobin and desmoplakin

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What are the cytoplasmic plaques made of

plakoglobin and desmoplakin

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What are cadherins

glycocalyx between desmosomal plaques that contain desmogleins and desmocollins
Involved in calcium binding and adhesion

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What makes the Keratin filaments

Basal and spinous layer

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What is the spinous layer

Progressive maturation, accumulation of keratin

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What is the granular layer

keratinocytes are flattened and filled with keratohyaline granules

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What are keratohyaline granules

Not membrane bound, contain proteins and lipids

For interfibrillary matrix of fillaggrin and the marginal band

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What layer changes thickness depending on location

Granular layer
1-3 usually
Up to 10 in palms and soles

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What is the interfibrillary matrix of filaggrin

Cements Keratin filaments together

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What is the marginal band

Inner lining of horny/cornfield cells

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What forms waterproof barrier

keratohyalin granules and desmosomal connections

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What do granular cells contain

lysosomal enzymes to dissolve nucleus and organells

What is the stratum coneum

Dead and dying cells with mature Keratin, no nucleus, verticals stacks

What are the layers of the basement membrane

Plasma membrane lamina lucid Lamina dense (type 4) Sub basal lamina

What is the function of the dermis

thermoregulation, vascular network, support and elasticity of skin

What are the 2 zones of the dermis

Papillary and reticular

What is the papillary dermis

Superficial dermal layer | Loose connective tissue-type 3

Where and what are the meissners corpuscles

Papillary dermis | mediate touch

What is the function of the papillary dermis

Vasculature to epidermis and thermoregulation

What is the reticular dermis

Below papillary dermis | Dense irregular CT-type 1

what is the function of the reticular dermi

Strength and elasticity

What do autonomic nerves supply

Blood vessels arrector pile eccrine glands apocrine glands NOT sebaceous

What and where are vater pacini corpuscles

subcutis | Sense pressure

what are melanocytes

dendritic cells from neural crest origin

What are epidermal melanin units

A melanocyte that supplies melanin to group of keratinocytes

Where is melanin produced

Organelles called melanosomes

What is tyrosinase

Enzyme that converts tyrosine to malanin

How are melanosomes transferred

To keratinocytes through phagocytosis

What does pigmentation depend on

Amount of melanin and distribution of melanosomes

Most melanocytes

face and genitals

melanization of light vs. dark skin

L- stage 1 and 2 | D- stage 4

melanosome size L. vs D

L-small | D-big

Number of melanosome per cell L vs D

L-20 | D-200

Distribution of melanosomes L vs. D

L-grouped | D-single

Degradation of melanosomes L vs D

L-fast | D-slow

What are Langerhans cells

Bone marrow derived dendritic cells | Antigen presenting cell, immunity

What destroys Langerhans cells

UV light

Where are Langerhans cells found

suprabasilar epidermis and dermis

What and where are sebaceous glands

Everywhere but palms and soles Secrete sebum holocrine glands (decomposition of their cells)

What are sebaceous glands on eyelids

Glands of Zeis and meibomian glands

What controls sebaceous glands

endocrine

What and where are apocrine glands

Scent glands axillae and genitals, external auditory meatus (ceruminous glands), eyelid (molls) Scent glands Decapitation secretion

What controls apocrine gland secretion

Adrenergic sympathetic innervation

What are eccrine glands

sweat glands | heat regulation

What controls eccrine secretion

cholinergic stimuli

What are the 2 cell types of eccrine glands

Clear cells-aqueous material and glycogen | Dark cells-sialomucin

What supplies arrector pile muscle

Adrenergic nerves during cold or emotional stress

What is the hair bulb

Lower end of hair shaft with hair matrix for rapidly dividing cells

What produces hair pigment

mealanocytes

How do hair and nails keritinize

NO keratohyalin granules | Use tonofilaments that harden using disulfide bonds

3 cycles of hair growth

anagen-actively growing 80-90% of hair Cartage-catatonic/growth arresting, decrease mitosis activity, bulb shrinks telogen-resting phase, shedding

Function of nails

Protective covering and grasping objects

What in the lunula

Distal portion of matrix, determine shape of free edge

Lateral and proximal nail folds

Folds of skin covering nail

hyponychium

Skin under the free edge

Things that decrease nail growth

Viruses, starvation, anemia

Things that increase nail growth

Pregnancy, nail biting, trauma