Topic 9: Integumentary System Flashcards
what does the integumentary system consist of?
-skin
-hair
-nails
-glands
-nervous sense receptors
-hypodermis
-muscles surrounding
how many layers does the skin have? what are these layers called?
-2 layers
-epidermis (superficial layer)
-dermis (deep layer)
what is the layer below the skin?
-hypodermis
is the hypodermis considered to be apart of the skin?
-NO
what are the characteristics of the epidermis?
-stratified squamous epithelium (from ectoderm)
-avascular
-seperated into 4-5 strata (sub-layers) depending on the cell type
what are the 5 layers of the epidermis?
-stratum basale
-stratum spinosum
-stratum granulosum
-stratum lucidum
-stratum corneum
what is the stratum basale composed of?
-single row of cells
-two cell types (keratinocytes + melanocytes)
what are the abundances of the two cell types present in the stratum basale?
-keratinocytes (90%)
-melanocytes (10%)
what are the basics of keratinocytes?
-undergo mitosis
-make keratin (a very tough protein)
what happens when new cells are produced in the stratum basale?
-keratinocytes are pushed to the surface
what are the basics of melanocytes?
-produce pigment (melanin) for UV light protection
-protects from sunburns, wrinkles (collagen damage), and cancer (DNA damage)
why do humans differ in skin colour?
-we all have the same relative number of melanocytes
-cells will produce different amounts/shades of melanin
-albinism is a lack of melanin produced by melanocytes
-blood (hemoglobin) in the dermis can give fair skinned people a pinkish tinge (areas of thin skin)
what is the stratum spinosum?
-above the stratum basale
-has low levels of mitosis
what is within the stratum granulosum?
-dark staining granules that help to produce keratin and begin to produce waterproofing glycolipids
-last layer of living cells
-no mitosis occuring
what is contained in the stratum lucidum?
-flat, dead cells
-they are too far away from the blood supply
in what type of skin is the stratum lucidum?
-thick skin
what is the stratum corneum composed of? what happens to this layer?
-many layers of flat dead cells filled with keratin which are surrounded by waterproofing glycolipids
-shed and replaced from below
what is the purpose of the glycolipids surrounding the dead cells in the stratum corneum?
-to prevent water loss
what does the dermis layer of the skin contain?
-blood vessels
-nerves
-glands
-hair follicles
-arrector pili muscles
what are the two sub-layers of the dermis?
-papillary layer
-reticular layer
what is the papillary layer of the dermis?
-directly beneath the epidermis
-made of areolar CT
-vascular (lots of blood flow)
-has projections into the epidermis called dermal papillae
what do the dermal papillae form in thick skin?
-fingerprints
-improved grip
what is the reticular layer of the dermis?
-majority of the dermis
-made of dense irregular CT
what is the hypodermis?
-subcutaneous layer (lies under the skin)
-superficial fascia
-composed of adipose CT
what is fascia?
-connective tissue layers that surround and support organs
how much adipose tissue does the hypodermis store?
-half of the bodies total
-used for insulation
what differentiates thin skin?
-lucidum is absent
-has hair follicles, sebaceous glands, and arrector pili muscles
-covers most of the body
what differentiates thick skin?
-found on palms of hands and soles of feet
-lucidum is present
-no hair follicles, sebaceous glands, or arrector pili muscles
what structures are formed by the epidermis?
-hair
-nails
-skin exocrine glands
what cells make up our hair?
-dead cells
what are the parts of hair?
-root
-shaft
-hair follicle
what is the hair root?
-part of the hair embedded within the skin
what is the hair shaft?
-visible part of the hair that is above the surface of the skin
what is the hair follicle?
-surrounds the hair root
-contains the epithelial root sheath, bulb, and matrix
-also contains the outer CT sheath, hair papilla, root hair plexus, sebaceous gland, arrector pili muscle
what is the epithelial root sheath?
-several epidermal layers that extend into the dermis
what is the bulb of the hair follicle?
-expanded region at the base of the root
what is the matrix of the hair follicle?
-single layer of cells (derived from basale cells)
-site of hair growth and melanin for hair colour
-not associated with the extracellular matrix
what is the outer CT sheath?
-formed from the dermis
-holds the follicle in place
what is the hair papilla?
-extends upwards, beneath the matrix
-contains blood supply for hair growth (blood vessels)
-formed from the dermis
what is the hair root plexus?
-free nerve endings (touch)
-why pulling of hair hurts
-generates nerve impulses if the hair shafts are moved
what is a sebaceous gland?
-oil gland (exocrine)
-opens into the follicle
-secretes sebum
-prevents hair from becoming dry and brittle by coating the surface of hairs
-also lubricates skin
-antibiotic function as well
what are arrector pili muscles?
-smooth muscle tissue
-causes goosebumps
what do our nails consist of?
-heavily keratinized epidermal cells
-has a nail root (buried in the skin)
-body (visible portion)
-free edge (end of nail)
what are sudoriferous glands?
-sweat glands
-have secretory portions in the dermis of thick and thin skin
-ducts open onto the skin surface
what is the purpose of sudoriferous glands?
-temp. regulation (cools the body)
-antibiotic (acidic)
-removes small amounts of waste (urea)
what are ceruminous glands?
-modified sweat glands
-in the ear canal
-produce ear wax (ex: prevents insects from entering)
what is the most active layer of the epidermis?
-stratum basale
-constantly undergoing mitosis
what epidermis layers contain living cells?
-stratum basale
-stratum spinosum
-stratum granulosum
what epidermis layers contain dead cells?
-stratum lucidum
-stratum corneum
what are mammary glands?
-modified sweat glands
-produce milk
what are the skin exocrine glands?
-sebaceous glands
-sudoriferous glands
-ceruminous glands
-mammary glands
what is the tissue type of the exocrine glands in the skin?
-glandular epithelium
why are nails heavily keratinized?
-they need to be strong
-stops them from breaking and being brittle
what are cutaneous sense receptors?
-sensory neurons part of the nervous system (long in order to pass signals)
-specialized cells that respond to stimuli (touch, temp,pain)
-have 4 major types
what are the 4 major types of cutaneous sense receptors?
-touch receptors
-pressure receptors
-thermoreceptors
-nociceptors
what are touch receptors?
-free nerve endings that branch into the epidermis
-root hair plexuses
-meissner’s corpuscles (dermal papillae)
-all need little pressure to fire
what is a corpuscle?
-connective tissue capsule that surrounds nerve endings
what are the types of pressure receptors?
-free nerve endings that branch in the dermis
-lamellar (pacinian) corpuscles
-these need more pressure to fire
where are pacinian (lameller) corpuscles located?
-deep in the dermis or in the hypodermis
what are thermoreceptors?
-free nerve endings that respond to temperature
what are nociceptors?
-free nerve endings that respond to pain
what degree of burn destroys the nociceptors?
-3rd degree
-cant feel the pain
do all sensory receptors contain pain? or just nociceptors?
-all contain pain reactions
-nociceptors are more prominent/general
what composes sebum?
-mix of fats, salts, and proteins
what is psoriasis?
-autoimmune disorder
-causes accelerated mitosis of keratinocytes in the stratum basale which delays maturation and differentiation
-immature keratinocytes accumulate in the epidermis
-stratum corneum fails to shed
-thick scaly layer on the surface of the skin (plaque)
