The Integumentary System Flashcards
What membrane does skin have
Cutaneous membrane
What are the 3 layers of skin
Epidermis, dermis and subcutaneous layer
What are the accessory structures in skin
Hair, nails, exocrine glands (sweat, oil and wax)
Where are the accessory structures in skin found
Anchored in dermis and extend through epidermis
What cells is the epidermis of skin composed of
Keratinised, stratified (4-5 layers), squamous (flattened) epithelial cells
What is meant by keratinised epithelial cells in the epidermis
Cells are protected by tough, intracellular fibrous insoluble protein keratin
What is the function of keratin in the epidermis
Protection and to provide water repellent glycolipid
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)
Where are langerhans cells located
The epidermis of skin
What is the function of langerhans cells
Part of skin immune response by acting as macrophages to engulf microorganisms
What do sensory cells and receptors in the skin respond to
Thermal, pain (noicieption) and pressure
What is the inner basal layer of the epidermis
A single row of columnar cells that divide and replaced the sloughed off outer cells
What separates the inner basal layer of the epidermis and the underlying dermis
Basement membrane
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
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)
What is the function of elastin fibres in the dermis
Return the skin to normal shape
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
Where are melanocytes mostly located
The dermis
What is the function of melanocytes
Synthesise melanin (skin pigment) to protect skin from UV rays
What is the subcutaneous layer of skin
Hypodermis, innermost and thickest layer of skin that attaches skin to underlying bone and muscle
What are the features of the subacutaneous layer
consists of fibroblast, connective tissue, larger nerves, blood vessels and macrophages and adipocytes
What are the function of adipocytes in the subcutaneous layer of skin
Energy storage and act as an insulator
What are keratinous filaments
Dead keratinised cells that originate in the hair follicles and grow out of the epidermis via the hair follicle
Where is the hair root anchored
At the hair bulb in the hair follicle
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
2
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
