Skin Flashcards by amo x

What are the four primary tissues that form skin?

Epithelium

Connective

Muscle

Nerve

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Does skin have its own nerve and blood supply?

Yes

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What are the three main layers of skin?

Epidermis

Dermis

Hypodermis

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What is the epidermis layer of skin?

Formed from epithelium tissue.

Top layer

Stratified, which means cells form more than one layer

Formed from five layers which are stratified too

Ectodermal origin

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What is the function of the epidermis layer?

Form boundaries between the internal and external environment

Prevent water loss by evaporation

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What is the dermis layer of skin?

Layer underneath epidermis.

Formed from connective tissue.

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What is the function of the dermis layer?

Give skin structural strength

Reduce risk of external injury

Permit body cooling

Maintain the epidermis by its blood flow

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What is the hypodermis layer of skin?

Layer underneath skin.

Adipose layer

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What is the function of the hypodermis layer?

Anchor skin to underlying structures

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What are the four main functions of skin?

Immune surveillance

UV protection

Energy storage

Sensory information

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What are the five layers of the epidermis?

Stratum basale

Stratum spinous

Stratum granulosum

Stratum lucidum

Stratum corneum

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What are the four basic cell types that form the epidermis?

Keratinocytes

Melanocytes

Langerhan Cells

Merkel Cells

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What are keratinocytes?

Most frequent cell type in epidermis.

Contain keratin, makes skin resistant to abrasion as it makes it hard.

Extrude lipids, which allows the cells to be waterproof

Constantly divide and regenerate which allows them to protect the skin from any damage

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What are melanocytes?

Allow pigment formation

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What are Langerhan cells?

Allow immune surveillance

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What are Merkel cells?

Touch receptors

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What is each epidermal layer formed from?

Squamous keratinising epithelium tissue.

Maturing keratinocytes from the basement membrane of the dermis

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What is the stratum basal layer? What is its function?

Bottom layer

Formed from tall columnar cells

Cells are bound to the basement membrane through hemidesmosomes

Basement membrane allows the cell to form connections with the top dermis layer, the dermal papillae. Keeps skin together.

Continuously proliferates stem cells

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What is the stratum spinosum layer? What is its function?

Cells in this layer shrink, meaning that their desmosome junctions form ‘spines’

Prepares for keratinisation

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What is the stratum granulosum layer?

Cells within this layer contain granules of keratohyalin

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What are the stratum lucidum and corneum layers? What are their functions?

Cells within these layers do not have any organelles and are bound together through desmosomes. There are also lots of disulphide linkages, which add to the layers strength.

These layers are replaced every 15-30 days.

Convert keratohyalin to keratin through a process known as keratinisation

What is psoriasis?

Autoimmune condition where the skin over produced keratin.

Why does the thickness of the epidermis and dermis vary around the body?

Dynamic tissue that responds to activity changes

Mainly due to stratum corneum

What are the two layers of the dermis?

Papillary layer

Reticular layer

What is the papillary layer?

Top layer of dermis Composed of loose regular connective tissue - smooth Filled with blood vessels Nerve endings present Connects with the bottom epidermis layer, status basale

What is the function of the papillary layer?

Protect the skin from any pathogens Thermoregulation and supplies nutrients

What is the reticular layer?

Bottom layer of dermis Composed of dense irregular connective tissue - rough Fibrous layer - formed from collagen fibres and elastic fibres. Give skin its elastic property

How is skin waterproof?

Epidermis layer contains keratin and lipids

What is skin colour due to?

Blood, carotene and melanin Melanocytes in the stratum basale produce melanin

What is the function of hair on our skin?

Thermoregulation Skin repair

How are hair follicles formed in the skin?

Derived from epidermis layer, in utero Form as a result of down growth of epithelial cells, which are then invaded by a knot of hair cells.

What are arrector pilli muscles? What are their function?

Attached to hair follicles and the base of the epidermis Hold the hair follicle at a particular angle and straightening this follicle when the muscle contracts Sebacous glands are found between the follicle and the arrector pilli muscle . They secrete sebum.

How is thermoregulation of skin obtained?

Sweat glands Hair Vessel dilation

What are the steps of skin repair?

1. A blood clot forms at the site of injury as a result of an inflammatory reaction 2. Clot starts to hard and dry out of form a scab 3. Granulation tissue is new connective tissue and blood vessels which forms on the surface of the injury 4. Scar forms

What are the nerve endings?

Where a neutron pathway terminates and interacts with a muscle or a gland cell.

Where are nerve endings found?

Papillary level of the dermis

What are the four types of nerve endings found in skin?

Meissners corpuscles - sensitivity to light touch and are found in fingertips Paccinian corpuscles - vibration and pressure Pain receptors Thermoreceptors

What are the three glands found in the skin?

Sebaceous Apocrine sweat Eccrine sweat

What is the function of sebaceous glands?

To produce sebum

What is the function of apocrine sweat glands? Where are they located?

To produce sweat Axilla (armpit)

What is the function of eccrine sweat glands? Where are they located in the skin?

To produce sweat Thermoregulator Coiled secretory portion of the dermis. Forms a spiral channel in the epidermis Simple tubular gland

What are the role of myopeithelial cells in relation to sweat glands?

To squeeze the glands and push the secretion onto the surface

What is the nail?

A strong plate of keratin that grows out from the nail bed

What is the nail bed?

A specialised form of skin epithelium

What are the six structures that form the nail?

Root Nail bed Nail plate Eponychium Paronchyium Hyponchium

What is the nail root?

Also known as the lunula Appears as a white crescent

What is the nail bed?

Extends from the edge of the nail root to the hyponchium

What is the nail plate?

Actual fingernail, pinkish appearance due to blood vessels underneath

What is the eponychium?

Cuticle Situated between the skin of the finger and the nail plate

What is the perionchium?

Skin that overlaps onto the sides of the nail plate

What is the hyponchium?

Area between the edge of the nail plate and the skin of the fingertip