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.
What are the receptors found in the deep dermis
- Ruffini corpsucles
- Pacinian corpsucles
- Meissner’s corpsucles
- Nociceptors
- Thermoreceptors
What are Ruffini corpsucles?
Ruffini corpsucles are mechanoreceptors that detect stretching and pressure
Pneumonic: Stretching is Ruff ini?
What are Pacinian corpsucles?
Pacinian corpsucles are mechanoreceptors that perceive touch, pressure, and vibrations
Al Pacino creates corpses through touching his machine gun trigger while feeling the pressure and vibration of the machine gun.
What are Meissner’s corpsucles?
Meissner corpsucles detect light touch and sensitivity.
Reinhold Messner froze off all his skin, so he can’t detect light touch and sensitivity anymore.
What are Nociceptors?
Nociceptors are pain receptors
These are myelinated nerve endings that branch freely through the dermis
You yell NO! when you’re in pain
What are thermoreceptors?
Heat detection. Hot vs Cold
What are the structural elements of the dermis?
- Collagen
- Elastin
- Extracellular Matrix
What is Collagen?
- Most abundant fibrous protein which provides strength
- Has a triple helix
- Highly abundant in glycine
- Contains hydroxy lysine and hydroxyproline (Vitamin C hydroxylates proline and lysine)
- Every third position is occupied by glycine
- Breaks down as we age causing wrinkles
What is Elastin?
- A fibrous protein that provides elasticity
What is the extracellular matrix?
- A jelly like substance that consists of polysaccharides and proteins.
What is the hypodermis?
- The hypodermis is not a layer of skin, but rather what’s directly under the skin.
- It contains blood vessels
- It’s also called the subcutaneous fat layer
Tattooing
This is the insertion of pigment into the dermis. An inflammatory response occurs and macrophages will try to get rid of the pigment, but they will fail. Some may end up in the lymph nodes, carried by the macrophages, but the vast majority of the pigment will stay.
Psoriasis
An increase in the dividing cells in the stratum basale and stratum spinosum and an accelerated cell cycle results in an increase in keratin-producing cells and a thickening of the epidermis.
Lesions are common.
Warts
Benign epidermal growths caused by infection of the keratinocytes by a virus.
This is an example of hyperplasia (increase of cell number)
What is hyperplasia?
Hyperplasia is an increase in cell number
-ex: Warts
Hyper: A Lot
Plasia: Formation (especially referring to cells)
What is metaplasia?
Metaplasia is the conversion of one cell type into another.
Ex: If you smoke you lose the cilia on your ciliated cells. The cells become non-ciliated cells. This can be reversible
Meta: Lots of definitions, but changing is one. Like in metamorphosis
Plasia: Formation (especially referring to cells)
What is dysplasia?
Dysplasia is size, shape, and alteration of the cell components. Think of it as pre-cancerous
Dys: bad
Plasia: Formation
What is Anaplasia?
Anaplasia is the loss of cellular and organization differentiation.
- Usually cancerous
- These cells vary in size and shape, we call this pleomorphism
Ana: Moving backward
Plasia: Formation
What is pleomorphism?
The occurrence of more than one natural form.
ex: cancerous cells may have a ton of different sizes and shapes within a tumor.
pleo: More
Morph: Forms
What is hyperchromatism
Very dark staining nuclei. Tons of mitotic figures… Weird abnormal cells.
Hypertrophy
An increase in the cell size of a tissue or organ.
Runners of marathons often have larger hearts
Atrophy
Decrease in cell or organ size
Usually caused by inadequate nutrition of cells
Thymus shrinks after puberty
Ovaries and breasts shrink after menopause
