Integument

Biology 4000 with Kempf at Auburn University

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By: Kelly Anderson
Created: 2012-04-26
Size: 38 flashcards
Views: 11

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___ is the heaviest single organ in the body.

Skin: 16% body weight

Skin's 2 Major components

epidermis - ectoderm- stratified squamous epithelium

dermis - mesoderm - CT

Dermal papillae - dermal folds up
Epidermal ridge - epidermal folds dowm

not part of skin
CT that binds dermis to underlying tissue
subcutaneous layer

EPIDERMIS CELL TYPES

1) Keratinocytes

2) Melanocytes

3) Langerhans cells

4) Merkel cells

Keratinocytes

most abundant
stratified squamous epithelium
form protective layer of skin that is shed & replaced

5 sublayers of epidermis

Stratum corneum

Stratum lucidum

Stratum granulosum

Stratum spinosum

Stratum basale = germinativum

Stratum Basale

- basophilic, low columnar
- desmosomes
- hemi-desmosomes
- lots of mitosis: provides cells to replace loss
- make keratin, stored as intermediate filaments in cytoplasm

- Largest portion of living cells in epidermis
- Varying cell shape
- Spiny appearance bc of processes
aka "prickly" layer
- Larger in thick skin
- bottom layer = germative

Malpighian layer

basal layer of spinosum + stratum basale

Psoriasis

Chronic skin condition producing red lesions covered with silvery scales

Due to over production of skin cells in stratum spinosum & basale

Stratum Granulosum

A 3-5 layers of flattened cells containing two types of granules:
- lamellated granules - contain a waterproofing glycolipid that is secreted
- keratohyaline granules - contain histidine proteins, NO membrane around

- formed by golgi bodies
- membrane bound
- glycosaminoglycans & phospholipids
- cement cells together to waterproof: prevent dehydration

Found in thick skin ONLY
translucent layer right underneath s. corneum rich in keratin filaments and eleidin (electron-dense matrix).
*transition layer between living and dead cells

- Outermost Layer
- Horny cells -dead keratinized cells (lack nuclei)
- Thick where lots of abrasion
- no organelles

Keratinization Process

autophagosomes & lysosomes in epidermal cells to rid cytoplasm of organelles

Pigment producing cells derived from neural crest cells found between or beneath s. spinosum & s. basale.

Synthesize melanin by tyrosinase on AA tyrosine.

TYROSINASE is KEY
- made on ribosomes, packaged in GB
- melanin formed in vesicles by the Golgi Body
4 Stages:
Stage I vesicle - slight tyrosinase activity
Stage II vesicle - intermediate filaments
Stage III vesicle - [melanin] increase
Stage IV vesicle - mature melanin granule - no filaments visible

Pigmentation

due to accumulation of melanin in keratinocytes, not increase of melanocytes in epidermis

skin color - concentration of melanin

- specialized macrophage in s. spinosum
- aka Histocytes
- act as APC
- rod (racket) shaped granules called Birbeck granules in cytoplasm

granules in Langerhans cells in s. spinosum

Merkel cells

Possible secretory and hormonal function

Merkel cell carcinoma

Aggressive form of skin cancer that develops when Merkel cells undergo uncontrolled proliferation.
-caused by UV radiation
-metastasize via lymph vessels early on
-people over 60
-can lead to death

Papillary - thin
Reticular layer - thick

Papillary Layer

- Dermal layer
- Loose CT
- wandering cells (leukocytes, mast cells, macrophages, fibroblasts)
- collagen & elastic fibers
- anchoring fibers to epidermis
- capillary bed: nutrients to epidermis
- contain Miessner's Corpuscles

- sense to touch
- in dermis
- axon runs through middle bw stacks of fibroblasts or modified Schwann cells
- outside: myelinated
- inside: unmyelinated axon

Reticular Layer

- dermal layer
- dense, irregular CT: lower cell density
- elastin & collagen fibers
- ** Elasticity of skin**
- provides nutrients to epidermis through diffusion
- contain hair follicles, glands, and Pacinian corpuscles

- Pressure Sensor
- Deep in Dermis
- Concentric layers of fibroblasts & collagen

Appendages of Skin

hair/hair follicle
finger and toe nails
sebaceous glands (holocrine)
sweat glands (apical or merocrine)

Hair follicle

-part of dermis: dermal ridge into hypodermis
-hair production: part of epidermis- specialized s.corneum
-hair bulb + hair follicle

Matrix cell

specialized keratinocytes that produce shaft of hair

bulb of hair follice

matrix cell + dermal papillae

3 Regions of Hair Shaft

Medulla - middle, cuboidal
Cortex - melanin, hair color, flatter
Hair cuticle - overlap like scales

medulla
cortex
cuticle
(inner layer cuticle)
Huxley's Layer
Henley's Layer
Outer/external root sheath
Glassy membrane

Huxley's layer

Granule layer
Trichohyalin granules
- type of kerotohyalin granule
- between cuticle & Henley's layer

Henley's Layer

lots of keratin

single layer of flat, clear cells

no granules

between Huxley's & external rooth sheath

External Rooth Sheath

still from epidermis bc from s. spinosum & basale

thick!

Glassy membrane

thin, hyalin, modified basement membrane of external rooth sheath

About this deck

By: Kelly Anderson
Created: 2012-04-26
Size: 38 flashcards
Views: 11

About StudyBlue

“Simply amazing. The flash cards are smooth, there are many different types of studying tools, and there is a great search engine. I praise you on the awesomeness.”
Dennis