Integumentary System Flashcards
What does the integumentary system consist of?
Skin, hair, nails, and glands
Where is your skin the thickest?
palms of hands and soles of feet. This is where the most wear and tear occur.
Where is your skin the thinnest?
External genitalia, eyelids, and tympanum (inner ear)
What are the primary functions of skin?
- First line of defense: protects us from injury and disease
- Prevents water loss. (keratin is involved with waterproofing the skin)
- Regulates temperature: think sweating
- Stimuli reception: sensory receptors perceive pain, touch, pressure, etc.
- Vitamin D production, with sunlight
What are the layers of skin?
Epidermis (derived from ectoderm)
Dermis (derived from mesoderm)
Hypodermis (subcutaneous fat layer, it’s not really a layer of skin, but a superficial fascia deep to the skin)
What is the cell type of the epidermis?
stratified squamous keratinized epithelium
What are the characteristics of the epidermis?
- All but the deepest layers are made of dead cells that contain a fibrous protein called keratin.
- No blood vessels are found in the epidermis
- Consists of four types of cells: Langerhans, melanocytes, merkel cells, keratinocytes.
What are Langerhans cells?
- Langerhans cells are antigen presenting cells
- Dendritic cells of the skin
- Similar in morphology and function to macrophages
Longhorns present their horns as threats. Langerhans present antigens as threats to T helper cells. Longhorns also have dandruff so they are dendritic. Longhorns like to eat a lot, so they are macrophages
What are Melanocytes?
- Melanocytes produce melanin pigment that gives a brown color to skin
- Protects you from skin cancer. Melanin absorbs UV light
- Resides mostly in the Stratum Germinativum (Stratum Basale)
What are the layers of the epidermis from top to bottom?
The layers of the epidermis with the important info needed for the DAT
- Stratum Corneum - Surrounds layers of flattened, keratin containing dead cells called horny cells or squames
- Stratum Lucidum - Only present in thick skin
- Stratum Granulosum
- Stratum Spinosum
- Stratum Basale (Stratum Germinativum)
- Deepest epidermal layer.
- Mitosis is most active - contains stem cells, keratinocytes do mitosis at night, and new cells are being pushed upward toward the surface.
- NB: Melanocytes and Merkel cells are located here
- Desmosomes bind this layer of skin together allowing it to function as a single unit.
Pneumonic: From superficial to deep: Corn lovers grow several bales
What are Merkel Cells
Function as mechanoreceptors (a sensory receptor that responds to pressure or distortion)
- Angela Merkel responds to Trumps distortion and pressure
What are Keratinocytes?
- 80% of the cell population of the epidermis
- Produce keratin. This waterproofs the skin and protects it from damage. The skin has a lot of desmosomes (cell staples with keratin)
Where is keratin found in nature?
- Turtle shells
- Claws of reptiles
- nails
- horns
- shells
- feathers
- beaks
Describe the Dermis
Contains:
- Hair Follicles
- Sweat Glands
- Sebaceous (oil) glands
- Rich supply of nerves and muscles
Derived from the mesoderm, unlike the epidermis which was derived from the ectoderm
What’s unique about the derivation of some dermis residents?
Sweat glands, sebacecous glands, and hair follicles are all derived in the epidermis and then migrate into the dermis and hypodermis during embryogenesis and then reside there permanently.
