BB1701 integumentary system Flashcards
what is an organ?
multiple tissues with similar structures that work together to perform a specialised function
what is the largest organ in the integumentary system?
the skin (cutaneous membrane)
what are the two important layers of the skin?
epidermis
dermis
which tissues in the skin are most important?
epithelial
connective
what is the epidermis?
- outer layer of the skin
what is the epidermis composed of?
stratified squamous epithelium
what are the four layers of the epidermis?
stratum basale
stratum spinosum
stratum granulosum
stratum corneum
what are the characteristics of the stratum basale?
- the deepest layer
- contains a thin layer of dividing cells
- nourished by blood vessels of the dermis
what are the characteristics of the stratum corneum?
- the outermost/superficial layer
- consists of layers of dead, flattened, dehydrated, densely packed, keratinised cells
what causes epidermal cells to die?
blocked blood supply
where is the stratum lucidum located?
on the hairless and thickened skin
palms, soles
role of desmosomes in the epidermal layers/strata?
hold together keratinocytes
function of epidermis?
- protective
- shields moist underlying tissues against excess water loss, mechanical injury and harmful chemicals
- keep out pathogens
- epidermal cell production in the stratum basale balance loss and shedding of dead cells
- allow thickness to remain constant
what happens as new epidermal cells are produced?
keratinocytes are pushed from the dermis towards the skin surface
they die as nutrient supply is poorer
keratinisation
what is keratinization?
- process where epidermal cells harden
- cytoplasm fills with strands of tough, fibrous, waterproof keratin
layers of the keratinised cells gather and shed in the stratum corneum
what is the dermis?
inner layer of the skin
thicker than epidermis
function of dermis?
binds the epidermis to underlying tissues
dermal blood vessels supply nutrients to all skin cells
vessels regulate body temperature
what is the dermis composed of?
areolar connective tissue
connective tissue
what does the connective tissue include?
collagen fibres
elastic fibres with gel like ground substances
smooth muscle tissue
nervous tissue
blood
function of connective tissue?
bind epidermis to subcanteous layer
function of collagen?
strength
function of elastic fibres?
ability to stretch
function of blood?
bring oxygen and nutrients to cells
function of nerve tissue?
detection of changes
function of smooth muscle tissue?
allow hair and hair follicles to change position
which accessory structures does the dermis contain?
hair follicles
sebaceous glands
sweat glands
what is the dermal papillae?
- uneven boundary between epidermis and dermis
- extends into spaces between ridges
how is dermal papillae formed?
due to epidermal ridges projecting inwards and conical projections of dermis
where is dermal papillae found?
skin
hands and feet
what is the role of epidermal ridges?
leave patterned impression (fingerprint)
what determines a fingerprint?
genes
the fetus pressing against the uterine wall
what separates the epidermis and dermis?
a basement membrane by anchoring the epidermis to the dermis
what is the subcutaneous layer?
is beneath the dermis
composed of areolar and adipose tissue
function of the subcutaneous layer
bind skin to deeper organs
insulates body from heat loss
supplies skin with major blood vessels for nutrient and oxygen delivery
features of epithelial tissue
- cover body surface, and line internal organs
- secrete portions of glands
- lacks blood cells
- continuously replaced
- readily divide
- closely packed
- single or multiple layers
- contain an apical surface
- contain lateral surface, which communicates with other cells
function of epithelial tissue
protection
secretion
absorption
excretion
types of epithelium tissue
simple squamous
simple cuboidial
simple columnar
stratified squamous
stratified cuboidal
pseudostratifed columnar
transitional
features of simple squamous epithelium
- single layer
- thin flattened cells
- cells fit tightly together
- nuclei are broad and thin
line alveoli
features of simple cuboidal epithelium
- single layer
- cube shaped cells
- central, spherical nuclei
- cells arent elongated
covers ovaries
features of simple columnar epithelium
- single layer
- elongated nuclei
- oval nuclei
- nuclei in middle of cell
- taller > wide
goblet cells
features of stratified squamous epithelium
- many cell layers
- tissues relatively thick
- cells divide in deeper layers
- flatter cells on the surface
- bottom layer is cuboid
- stem cells
epidermis
features of stratified cuboidal epithelium
- 2-3 layers
- cuboidal cells
- form lining of lumen
- provide protection
lines ducts of mammary glands
features of pseudostratified columnar
- not layered
- nuclei lie at 2+ levels in the row
- cilia
- lie on basal membrane
line passage of respiratory system
features of transitional epithelium
- change in response to increased tension
- expands
form inner lining of urinary bladder
features of connective tissue
- widely distributed throughout body
- rich blood supply
- highly vascularised
- cells further apart
- extracellular cells due to matric
function of connective tissue
bind
support
protect
fill spaces
store fat
produce blood cells
main connective tissues
adipose
areolar
blood
bone
bone marrow
features and functions of areolar tissue
binds organs
beneath skin and epithelial tissues
between muscles
features and functions of adipose tissue
protection
insulation
store fat
beneath skin
around kidneys
behind eyeballs
on heart surface
features and functions of bone marrow/ hyaline cartilage
supports
protects
framework
end of bones
nose
walls of respiratory passages
flexible
features and functions of bone
suports
protects
framework
bones of skeleton
solid because of positions of salts in membrane
features and functions of blood
transport
maintain homeostasis
whole body within closed system of blood vessels and heart chambers
abundant matrix
what are melanocytes?
specialised cells which produce and store melanin within melanosomes
where are melanocytes loaced?
deepest portion of epidermis
what is melanin?
- pigment that provides skin colour
- protects skin cells from mutation in DNA
which types of melanin determine colour?
eumelanin
pheomelanin
which colour does eumelanin produce?
brown black
which colour does pheomelanin produce?
red yellow
what determines the darkness of skin colour?
- the more melanin , the darker the skin
- distribution and size of melanin
- genetics
- disease
- environmental and physiological factors
how does sunglight, uv and xray affect melanin?
- darken melan in granules
- stimulate more melanin production
how can diet affect melanin?
high colourful foods rich in carotene can turn skin orange as carotene builds up in stratum corneum and adipose tissues
how does melanin protect skin cells from mutations in DNA?
melanin granules lie over the top of the nucleus and absorb UV in sunlight
how does melanin work?
melanin granules are transferred into neighbouring cells by cytocrine secretion, which darkens cells
functions of integumentary system?
- protection and touch
- vitamin d production
- temperature regulation
- healing wounds
what features of the integumentary system provide protection?
- epidermis is a waterproof protective barried, which keeps microorganisms out
- melanocytes produce melanin which provide protection from UV
- sensory receptors in nerves in the skin
how does integumentary system provide sense of touch
sensory receptors
detect pressure, change in temperature and pain
how is vitamin d produced + why?
by skin cells
necessary for bone and tooth development
forms of vitamin D
- inactive form, cholecalciferol when exposed to sunlight
- cholecalciferol is modified to active form, calcitriol in livewr and kidneys
how are shallow breaks in the skin healed?
epithelial cells alone the margin divide more rapidly
newly formed cells fill the gap
what happens when an injury extends into the dermis or subcutaneous layer?
- blood vessels break
- blood released forms a clot which combines with dried tissue, forming a scab
- fibroblasts migrate to the wound and secrete collagen fibres, which bind to the edges of the wound
- blood vessels extend beneath the scab
- phagocytic cells remove dead cells
- damaged tissue is replaced, scab is removed
- more collagen fibres are produced which form a scar
function of scab
cover and protect underlying tissues
what happens in large open wounds
granulations develop in exposed tissues
some blood vessels are resorbed
fibroblasts move away
leaves a scar
what is a granulation?
- small rounded masses
- consist of new branch of blood vessels
- contain collagen secreting fibroblasts, nourished by vessle
how does the tissue respond to inflammation?
blood vessels dilate
increase metabolic activity
why do blood vessels dilate when inflammation occurs?
increases blood vessel permeability
brings more fluid to the area
brings more blood containing oxygen, nutrients and phagocytes
what is hair?
composed of dead epithelial cells
present on almost al skin surfaces
develops from a group of stem cells at the base of hair follicle
what is the hair follicle?
- contains hair root which extends from the surface into subcutaneous layer
- hair bulb is deepest portion of hair root at the base of the follicle
- hair matrix lies within the bulb
what is the hair matrix?
growth region
composed of epithelial cells
nourished from dermal vessels in a projection of connective tissue
what happens to the hair follicle
older cells become keratinised and move towards surface after epithelial cells divide and grow
how’s hair shaft formed
remains from keratinised cells
extends outwards
what determines the characteristics of hair
genes
arrector pilli muscles
how do genes determine hair colour?
- abundance and type of pigment epidermal melanocytes produce
- dark hair has more eumelanin
- light hair has more pheomelanin
how do arrector pilli muscles contribute to hair characteristics
formed by smooth muscle cells
positioned so a short hair within the follicle stands on the end when the muscle contracts
stimulated by emotions or the nervous system
purpose of the nail?
protective covering
consist of nail plate which overlies the nail bed
features of nail
nail bed
nail plate
lunula
how is the nail bed formed
- produced by specialised epithelial cells which are continuous with the
- epithelium of the skin
thin layer of skin under the hardened nail plate
what is the lunula and where is it located?
- at the base of the nail plate
- most actively growing region due to stem cells
why is the lunula pale?
because of pressure of nail on the nail bed
what happens to keratinized cells?
keratinized scales become part of the nail plate and push it forward over the nail bed
- the keratin is harder than usual epidermal stratum corneum keratin
What can influence the appearance of nails?
genetics
injury
deficiencies in nutrition
disease
aging
how can disease affect the appearance of nails?
- carbon monoxide poisoning can cause a red lunula
- liver disease may cause a yellow lunula
how can age affect the appearance of nails?
nails become more thin because cell division slows with age
types of glands
sebaceous glands
sweat
- merocrine
- apocrine
- ceruminous
- female mammary
features of sebaceous glands
- contains groups of specialised epithelial cells
- holocrine glands
- their cells produce globules of fatty material
function of fatty material globules in sebaceous glands
- accumulate, swell and burst cells
- sebum moves through small ducts into follicles and keeps hair and skin soft, pliable and waterproof
disorders associated with sebaceous glands?
cradle cap
acne
what is cradle cap
overactive sebaceous glands secrete too much sebum
causes pinkish plaques on the scalp that form greasy yellow crust
what is acne
overactive and inflamed glands become plugged
produce blackheads of surrounded by pimples
features of sweat glands?
- exocrine
- narrow lumen
- consist of tiny ball shaped coil tube in deeper dermis/superficial subcutaneous layer
- coiled portion closed at deep end
- lined with sweat secreting epithelial cells
features of merocrine sweat glands
respond to body temp changes or emotional stress
on forehead, neck, back
produce profuse sweat
carried away by pore
what is sweat?
composed of mostly water, salt, urea, uric acid
excretory function
feature of apocrine sweat gland
- during puberty
- secrete by exocytosis
- in axillary regions and groin
- ducts open into hair follicles
- secrete protein and lipids, within sweat
- body odor produced
when is body odor produced
when metabolised by skin bacteria
features of ceruminous glands
external ear canal
secrete earwax
feature of female mammary glands
secrete milk
