The Integumentary System Flashcards by Elsa Lees

What membrane does skin have

Cutaneous membrane

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What are the 3 layers of skin

Epidermis, dermis and subcutaneous layer

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What are the accessory structures in skin

Hair, nails, exocrine glands (sweat, oil and wax)

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Where are the accessory structures in skin found

Anchored in dermis and extend through epidermis

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What cells is the epidermis of skin composed of

Keratinised, stratified (4-5 layers), squamous (flattened) epithelial cells

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What is meant by keratinised epithelial cells in the epidermis

Cells are protected by tough, intracellular fibrous insoluble protein keratin

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What is the function of keratin in the epidermis

Protection and to provide water repellent glycolipid

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What are the features of the epidermis

-Relatively thin outer layer that can be sloughed off and replaced
-No blood vessels as nutrients/o2 diffuse from the capillaries in the dermis
-Contains a few melanocytes (produces skin colour)

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Where are langerhans cells located

The epidermis of skin

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What is the function of langerhans cells

Part of skin immune response by acting as macrophages to engulf microorganisms

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What do sensory cells and receptors in the skin respond to

Thermal, pain (noicieption) and pressure

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What is the inner basal layer of the epidermis

A single row of columnar cells that divide and replaced the sloughed off outer cells

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What separates the inner basal layer of the epidermis and the underlying dermis

Basement membrane

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What is the dermis

Inner layer of skin that is thicker than the epidermis and composed of fibrous connective tissue (collagen fibres) to support the epidermis

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What are the features of the dermis

blood and lymph vessels
muscle fibre and nerve fibres
hair follicles and sweat glands
elastin fibres
-Phagocytes
melanocytes
adipocytes (fat stores)

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What is the function of elastin fibres in the dermis

Return the skin to normal shape

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How does sweat secreted from the sweat glands in the dermis aid thermoregulation

Evaporation from skin surface results in the loss of thermal energy by radiation

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Where are melanocytes mostly located

The dermis

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What is the function of melanocytes

Synthesise melanin (skin pigment) to protect skin from UV rays

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What is the subcutaneous layer of skin

Hypodermis, innermost and thickest layer of skin that attaches skin to underlying bone and muscle

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What are the features of the subacutaneous layer

consists of fibroblast, connective tissue, larger nerves, blood vessels and macrophages and adipocytes

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What are the function of adipocytes in the subcutaneous layer of skin

Energy storage and act as an insulator

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What are keratinous filaments

Dead keratinised cells that originate in the hair follicles and grow out of the epidermis via the hair follicle

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Where is the hair root anchored

At the hair bulb in the hair follicle

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What is the hair shaft

The part of the hair not anchored to the follicle

What is the hair matrix

Part containing mitotically active basal cells

What is the hair papilla

Part containing blood capillaries and nerve endings from the dermis

What is the medulla in hair

Forms the central core of the hair and is surrounded by the cortex

What is the cortex in hair

Component that surrounds the medulla and is covered by an outer layer of hard keratinised cells (the cuticle)

What is the cuticle in hair

Layer of hard keratinised cells that cover the cortex

What determines hair texture

Shape of hair follicle and cortex

What provides hair colour

Melanocytes in hair papilla

What is the function of hair

Provides protection from sun, traps dust particles, prevents sweat from entering eyes, enables sensory input to air movement, thermoregulation and communication (more in non humans)

How does the hair provide thermoregulation

Rare for pili muscle contracts in response to nervous signals to make hair stand up and trap air as insulation

What are sudoriferous glands

Sweat glands

What are the two types of sudoriferous glands

Eccrine and apocrine

What are eccrine glands

Sudoriferous glands that open directly onto the skin surfaces, produce hypotonic sweat and are involved in thermoregulation

Where are eccrine glands located

All of the body but in highest concentrations in foot soles and palms

What are apocrine glands

Sudoriferous glands that open onto associated hair follicles, lie deeper in the dermis and include organic compounds to reduce thicker sweat that is susceptible to bacterial decomposition under nervous and hormonal control

Where are apocrine glands located

Armpits, anogenital, external ear canal and areola

Describe the structure of sudoriferous glands

Slender coiled tubes embedded deep in the dermis with a secretory glomerulus that is surrounded by myoepithelial cells

How is sweat released from sudoriferous glands

By exocytosis

How does sweat reach the skin from sudoriferous glands

Long ducts transport sweat and open on skin surface

What does sweat contain

Water, salts, antibodies, traces of urea and dermicidin (antimicrobial)

What are ceruminous glands

Modified apocrine glands found in cartilaginous section of external auditory canal that produce earwax (cerumen)

Where are the secretory cells found in ceruminous glands

On the myoepithelial cells

What is function of ear wax (cerumen)

Clean ear canal (aided by jaw movements), protects ear from physical damage and microbial invasion and lubricates the ear canal

What are mammary glands

Modified sweat glands that produce milk

Describe the structure of mammary glands

Alveoli, lined with milk secreting epithelial cells, joined together to form lobules that have lactiferous ducts that drain into the nipple

What surround the alveoli in mammary glands

Myoepithelial cells

What is the function of myoepithelial cells in mammary glands

Contract to push milk from alveoli towards the nipple

How does breastfeeding work

The milk collects in sinuses in the ducts of mammary gland,which the baby squeezes the milk out of by sucking

How many complex mammary glands do humans have

How many simple glands each complex mammary gland consist of

10-20

What is a simple mammary gland

Milk secreting tissue leading to a single lactiferous ducts

What hormones control development of mammary glands

Oestrogen

What hormones cause the branching a differentiation of duct cells and increase adipose tissue and blood flow to mammary glands during pregnancy

Oestrogen and progesterone

What hormone inhibits mammary gland development

Testosterone

What is secreted from the mammary glands in the first few days after birth/end of pregnancy

Colostrum (rich in immunoglobulins)

What initiates lactation a few days after birth

Decrease in progesterone and presence of prolactin (hormonal)

What stimulates the contraction of the myoepithelial cells in mammary glands

Suckling of baby which released oxytocin

What is the nail bed

Specialised epidermis at tips of fingers and toes under the nail which is rich in blood vessels

What does the nail body consist of

Densely packed keratinocytes

What is the function of the lateral nail fold

Overlaps the nail on sides to help anchor the nail body (nail plate to nail bed)

What is ten lunula

Crescent shaped thick layer of epithelium over the nail matrix

What is the function of the lunula

Protects mitotically diving cells that synthesise new nail

What is the hyponychium

Area beneath the free edge of the nail and underlying skin

What are the functions of nails

Protects the part of the body that experiences maximal mechanical stress, aids picking up small objects

What is the eponychium

Nail cuticle

What are sebaceous glands

Secretory epithelial cells that are attached to hair follicles that consist of multiple acinar cells that converge towards a common secretory duct

What is the size of the sebaceous gland inversely proportional to

The diameter of hair

Where are sebaceous glands found

All over body (apart from hands and foot soles) but mainly scalp, face, axillaw and groins

What do sebaceous glands secrete

Oily antimicrobial sebum into the hair follicles

What are the functions of sebum

Keeps hair dry/ dead keratinised cells soft and pliable, prevents drying cracking of skin, provides waterproofing to surface and has bactericidal and fungicidal properties

What stimulates sebum secretion

Hormones after puberty