MODULE 1 Flashcards by Parnz Tkt

THREE LAYERS OF THE SKIN ARE….

EPIDERMIS, DERMIS AND HYPODERMIS

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LIST SOME FUNCTIONS OF THE SKIN

PROTECT, EXCRETE, STORE LIPIDS, DETECT, SYNTHESIZE VITAMIN D, MAINTAIN NORMAL BODY TEMP, PRODUCE MELANIN, PRODUCE KERATIN.

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What are the different layers of the epidermis?

Stratum corneum
Stratum lucidum (only in thick)
Stratum granulosum
Stratum spinosum
Stratum basale

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What is the role of the stratum basale?

contains stem cells which divide over and over again, pushing the daughter cells upwards to the other layers.

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What is the role of the stratum spinosum?

Begins to flatten cells

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What is the role of the stratum granulosum?

promotes dehydration of the cell

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What is the role of the stratum corneum?

dead cells that are the physical barrier (1st line of defense)

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What are the layers in the dermis?

Papillary and reticular

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Describe the papillary layer

Has highly vascularised tissues for nourishment, are the fold of the dermis layer, contain blood vessels, lymphatics, sensory nerve fibres and accessory structures.

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Describe the reticular layer

Mesh like structure mostly consisting of collagen and elastin fibres for strength, contains blood vessels, lymphatics, sensory nerve fibres and accessory structures.

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What are the plexuses of the dermis?

Cutaneous plexus and subpapillary plexus

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What is the cutaneous plexus and what does it do?

Network of blood vessels present at the junction of the dermis and hypodermis and it supplies nutrients to the hypodermis and the deeper dermis including the capillaries for hair follicles and sweat glands. It also has bigger tubes than subpapillary plexus.

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What is the subpapillary plexus and what does it do?

It branched from the cutaneous plexus and lies deep in the papillary layer. The network of blood vessels provide oxygen and nutrients to the upper dermis and epidermis.

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describe the hypodermis

not considered as part of the skin
dominated by adipocytes that produce subcutaneous fat
common site for injections

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Why is the subcutaneous fat (fat in hypodermis) important?

stores energy and provides insulation

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Why is the hypodermis best place for injections?

Aren’t many blood vessels and the fat can move around.

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What is a 1st degree burn?

only involves the outer layers of the epidermis
usually no blisters
skin remains a water and bacterial barrier
usually heals in 3-10 days

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What is a 2nd degree burn?

Can at times be tame or at times be serious. Can contain the epidermis and some of the dermis, just depends on what kind of 2nd degree burn it is.

What is a 3rd degree burn?

affects all layers
no pain in areas because sensory nerve ending are destroyed
hard, dry and leathery
weeks to regenerate with some scarring

How does hair get produced?

within the hair follicle and is made of dead, keratinised cells and grows outwards towards the skin.

What is the muscle attached to the hair follicle and what does it do?

Arrector pili muscle, contracts making the hair stand up and causing goosebumps which creates a tiny pocket of sealed air for insulation.

What is the nerve ending on the hair follicle and what does it do?

Root hair plexus, network of nerve endings at the base of each hair follicle and detects things that touch the hair.

What do sebaceous glands do?

produce sebum

- nourishes hair and moisturizes skin

What are the two main sweat glands?

Eccrine and Apocrine

Describe the eccrine

- closer to the skin - pours watery secretion directly onto the skin - important to thermoregulation

Describe the apocrine

- found deeper - produces sticky/oily secretions - influenced by hormones - pours secretion into the base of hair follicle which makes its way to the skin

What happens to the skin as people age?

- Epidermis becomes thinner - Dermis becomes thinner - slower skin repair - drier epidermis - impaired cooling - less pigmentation

When aging, why does the epidermis become thinner?

Because the stem cells aren't dividing as actively.

What happens when the dermis becomes thinner?

The collagen is being replenished so less is being produced, hence the skin becoming saggy and wrinkly

What is the relationship between smoking and skin aging?

- contains agents that accelerate aging - damages collagen and elastin - nicotine reduces blood circulation in the dermis

How is skin pigmented and what are the benfits?

Melanocytes in the basale layer neatly package melanin in vesicles called melanosomes, which are released into gaps of the cells in the layers and when reached the skin they act as a protection layers against UV damage as they absorb UV light.

What happens to the melanosomes when they reach the top?

melanosomes can shed within the epidermis with other keratinocytes.

What is a mole?

Cluster of melanocytes that are too much in umber and eventually pop out to the skin, this happens as a result of too much exposure to the sun.

What is a freckle?

Melanocytes over producing melanosomes, over-production triggered by sun exposure

Decribe free nerve endings

- go right into the epidermis - sensory terminals which function as cation channels - unmyelinated - most common receptor in skin

What do free nerve endings mostly respond to?

- temperature - pain - some movement and pressure

Describe tactile discs

- located in deepest layer of epidermis - detects stimuli and relays it to the sensory nerve endings causing an action potential to be generated - abundant in fingertips and very small receptive fields

What are tactile discs sensitive to?

- texture, shape and edges | - fine touch and light pressure

Describe the tactile corpuscles

- located in papillary layer (especially in hairless skin) - encapsulated by modifies schwann cells and a thin oval fibrous connective tissue - spiralling/branching unmyelinated sensory terminals - activated by deformation of the capsule

What is a tactile corpuscle sensitive to?

- delicate/fine/discriminative touch - light pressure - low frequency vibration

Describe lamellar corpuscles

- deep in the dermis and hypodermis - single dendrite within layers of collagen fibres - layers separated by gelatinous interstitial fluid - activated by deformation of capsule

What are lamellar corpuscles sensitive to?

- deep pressure | - vibration

Describe bulbous corpuscles

- located in dermis and subcutaneous tissue - network of nerve endings intertwined with a core of collagen fibers with a capsule surrounding whole thing - found in joint capsules important for signalling continuous states of deformation of tissues

What are bulbous corpuscles sensitive to?

- sustained deep pressure | - stretching/distortion of the skin