Integumentary System > Skin and derivatives
Study online at https://quizlet.com/_hrnz8o
1. Skin Largest organ ((15-20% total mass))
2. Layers of skin Skin has 2 main layers + one underlying layer:
1. Epidermis - ectoderm ((majorly made of kerakinocytes))
2. Dermis - mesoderm ((connective tissue))
3. Hypodermis - adipose tissue / subcutaneous fascia
3. Epidermal Deriv- *derivatives = other structures in skin*
atives of Skin - Keratinised Structures ((protective/defensive structures)):
1. Hair follicles and hair
2. Nails
3. Horns, antlers
- Other Non-keratinised Structures:
1. Sweat ((sudoriferous)) glands
2. Sebaceous glands
3. Mammary glands
4. Thick VS Thin Skin - histologically skin is categorized for its thickness
- thickness refers to only the epidermal layer
Thick Skin ((much thicker epidermal layer)):
- found on protective parts of the body
- example = plams of hand / soles of feet
- resists tearing, abrasions, mechanical damage
- hairless
- contains stratum lucidum
Think Skin ((thin epidermal layer))
- found on other parts of the body
5. Epidermis -Stratified squamous epithelium
*stratified = multiple layers*
*squamous = thin elongated/flattened cells*
, Integumentary System > Skin and derivatives
Study online at https://quizlet.com/_hrnz8o
- keratinised
- renewed every 15-30 days
- builds keratin on top of skin layer
- has 5 distinct layers:
1. Stratum corneum
2. Stratum lucidum ((seen only in thick skin))
3. Stratum granulosum ((is granulated))
4. Stratum spinosum
5. Stratum basale ((germinativum))
6. Epidermis > Stra- - basement layer
tum Basale - single layer of cell on basal lamina
*basal lamina = border between epidermis and dermis*
- germinated and replenishes the epidermis through mitosis > provides for epi-
dermal cell renewal
- contains stem cells for new keratinocytes to rise by intense mitotic division.
- Keratinocytes:
--> are small, cuboidal/low columnar
--> have basophilic cytoplasm + contain melanin
- New keratinocytes move into the next layer > upward migration.
- Dermis brings nutrients and O2 needed by the basale for mitosis and takes away
the waste. ((by diffusion))
- The keratinocyte stem cells are connected to each other by desmosomes.
- keratinocytes are connected to underlying basal lamina by hemidesmosomes.
*desmosomes & hemidesmosomes = protein groups/connecting tissues*
- Stratum basale also contains Melanocytes and Merkel cells.
7. Epidermis >Stra- - exhibits spinous processes
tum Spinosum - has multiple layer of cells > is the thickest epidermis layer
- keratinocytes here are bigger than basale layer
- keratinocytes are polygonal
- between cells there are cellular bridges filled with tonofilaments.
Study online at https://quizlet.com/_hrnz8o
1. Skin Largest organ ((15-20% total mass))
2. Layers of skin Skin has 2 main layers + one underlying layer:
1. Epidermis - ectoderm ((majorly made of kerakinocytes))
2. Dermis - mesoderm ((connective tissue))
3. Hypodermis - adipose tissue / subcutaneous fascia
3. Epidermal Deriv- *derivatives = other structures in skin*
atives of Skin - Keratinised Structures ((protective/defensive structures)):
1. Hair follicles and hair
2. Nails
3. Horns, antlers
- Other Non-keratinised Structures:
1. Sweat ((sudoriferous)) glands
2. Sebaceous glands
3. Mammary glands
4. Thick VS Thin Skin - histologically skin is categorized for its thickness
- thickness refers to only the epidermal layer
Thick Skin ((much thicker epidermal layer)):
- found on protective parts of the body
- example = plams of hand / soles of feet
- resists tearing, abrasions, mechanical damage
- hairless
- contains stratum lucidum
Think Skin ((thin epidermal layer))
- found on other parts of the body
5. Epidermis -Stratified squamous epithelium
*stratified = multiple layers*
*squamous = thin elongated/flattened cells*
, Integumentary System > Skin and derivatives
Study online at https://quizlet.com/_hrnz8o
- keratinised
- renewed every 15-30 days
- builds keratin on top of skin layer
- has 5 distinct layers:
1. Stratum corneum
2. Stratum lucidum ((seen only in thick skin))
3. Stratum granulosum ((is granulated))
4. Stratum spinosum
5. Stratum basale ((germinativum))
6. Epidermis > Stra- - basement layer
tum Basale - single layer of cell on basal lamina
*basal lamina = border between epidermis and dermis*
- germinated and replenishes the epidermis through mitosis > provides for epi-
dermal cell renewal
- contains stem cells for new keratinocytes to rise by intense mitotic division.
- Keratinocytes:
--> are small, cuboidal/low columnar
--> have basophilic cytoplasm + contain melanin
- New keratinocytes move into the next layer > upward migration.
- Dermis brings nutrients and O2 needed by the basale for mitosis and takes away
the waste. ((by diffusion))
- The keratinocyte stem cells are connected to each other by desmosomes.
- keratinocytes are connected to underlying basal lamina by hemidesmosomes.
*desmosomes & hemidesmosomes = protein groups/connecting tissues*
- Stratum basale also contains Melanocytes and Merkel cells.
7. Epidermis >Stra- - exhibits spinous processes
tum Spinosum - has multiple layer of cells > is the thickest epidermis layer
- keratinocytes here are bigger than basale layer
- keratinocytes are polygonal
- between cells there are cellular bridges filled with tonofilaments.
