the integumentary system Flashcards
the integumentary system refers to what
the body covering
what does the integumentary system include
skin
nails
hair
what is the structure of skin also known as
as the cutaneous membrane or integument
explain the skin
- one of larges organs in human body
- essential for life
- has multilayer structure seen through microscope. The layers help perform its function
name and describe the 2 main parts of skins structure
Epidermis #
- surface epithelial layer
Dermis
-deeper connective tissue layer
- Deep dermis not part of the skin = subcutaneous(fat) layer or Hypodermis
explain the skin layers and structure
Skin consists of two basic tissues (epithelium and connective tissue) arranged as two fundamental layers:
- an outer EPIDERMIS (epithelium) and
- an inner DERMIS (connective tissue)
- In addition a subcutaneous (“under skin”) layer of connective tissue connects the skin to deeper structures but is not part of the skin. This layer is called SUPERFICIAL FASCIA or HYPODERMIS.
Connective tissue found in the epidermis layer is adipose tissue, these cells are full of lipid
Reticular layer is a main fibrous bed of the dermis, and consist of course, dense and interlacing collagen fibres, which are intermingled with a few reticular fibres and numerous elastic fibres. The predominant direction of these fibres is parallel to surface.
Cuts parallel to these lines heal faster and less scaring than those cut across collagen fibres
Within the reticular layer are epidermal derivatives such as hair follicles, glands and erector pili muscle , blood vessels, and nerve receptors
Papillary layer comprises of 20%of layer and composed primarily of loose areolar connective tissue. The surface forms dermal papillae, these are richly supplied with blood vessels and nerves and are exaggerated in size on our hands and feet, resulting in finger and toe prints and palm and sole prints
Papillary dermis contain a vast network which has 2 functions: supporting avascular epidermis with vital nutrients. And providing a network for thermal regulation.
The vasculature is organised in a way that by increasing or decreasing blood flow it can either be conserved or dissipated
Papillary dermis also contains 3 sensitive nerve endings and structures called Meissner corpuscles which found in sensitive areas.
whats the epidermis for
protection
what is the epidermis composed of
of Keratinised stratified squamous epithelium
name the 4 cell types the epidermis is made from
Keratinocytes – major group
Melanocytes
Langerhans cells
Merkel cells
describe keratinocytes
Comprise 90% of epidermal cells
4-5 layers
Produce keratin, which help Protect and Waterproof skin
explain KERATINOCYTES in the Epidermis
stacked on top of each other more or less in layers
sizes and shapes depend on where the epithelium is located
basal cells are generally low columnar or cuboidal
surface (apical) cells are squamous
intermediate cells have shapes that progress from cuboidal or columnar to squamous
differences in shape reflect the stage of maturity and development
how many strata/ sublayers does the epidermis have
4 or 5
each cell in the epidermis strtas have what
particular features
Some cell types are found in both layers such as melanocytes and Langerhans cells
name the 4 epidermis strata/ sublayers
- stratum basale
- stratum spinosum
- stratum granulosum
stratum lucidum - stratum corneum
what cell types overlap into other epidermis strava
melanocytes in layers basale and spinosum and Langerhans cells in spinosum and granulosum
explain the stratum basale
the single layer of low columnar or cuboidal cells at the base of the epidermis (basal layer).
These are the stem cells of the epidermis
Renewal of the epidermis takes about 3-4 weeks.
explain the stratum spinosum
several layers of polyhedral cells joined by many desmosomes (specialised cell junctions that increase adhesion)
(spinous layer)
Towards the surface the cells become flattened.
The surface of the cells is covered with short cytoplasmic spines or projections which form intracellular bridges with adjacent cells
explain the STRATUM GRANULOSUM
In thick skin, a few layers of flattened cells with cytoplasmic granules (granular layer).
In thin skin only one layer may be visible.
Nuclei begin to degenerate.
Cytoplasm contains many fine grains of keratohyalin granules, which release their lipid contents into the interstitial space. This acts as a protective barrier.
As cells push upward keratohyalin changes into keratin
explain stratum lucidum
Cannot be identified in thin skin.
Several layers of flattened cells, closely packed
Nuclei are hardly visible, either absent or
indistinct
Translucent layer of cells
3-5 cells deep
explain stratum corneum
Outermost layer of epidermis and is layer of skin we see on outside
Its comprised of dead cells filled with protein keratin. Flat and squamous shape
Arranged in overlapping layers making skin tough and waterproof
Protection of the body by the epidermis is essentially due to the functional features of this layer.
Consists of several to many layers of flattened keratinised (dead) cells (keratinised layer)
Cells are completely filled with keratin filaments embedded in a dense matrix of proteins.
Individual cells are difficult to observe because nuclei are not very visible, cells are very flat and the space between cells is full of lipids that cement the cells together.
Closer to the surface of the epidermis the stratum corneum has a looser appearance.
Cells are constantly lost from this layer
Variation in skin thickness of the epidermis (~0.1mm - >1mm) are due to the varying thickness of the stratum corneum.
explain the structure diff between thick and thin skin
In thick skin 5 strata are seen
Thin skin layer has no stratum lucidum, and the stratum corneum is loosely packed
give a quick summary of the epidermal layers
There are generally 4 visible strata (layers):
Stratum basale
– includes stem cells
Stratum spinosum
– 8-10 cell layer
Cells beginning to look flattened
Stratum granulosum
– increase in keratin
Losing cell organelles and nuclei
Include lamellar granules = waterproofing lipid
(Stratum lucidum in thick skin only)
Stratum corneum
– flattened dead cells
Cells shed and are replaced from below
mostly keratin-filled
describe the regional differences of thick skin
covers the palms of the hands and soles of the feet
is different from skin everywhere else in the body
has a very thick stratum corneum
although thick, this skin is very sensitive to mechanical stimuli, especially the epidermis on the fingertips.
the basal surface of the epidermis of thick skin is formed into deep folds that makes its attachment to the dermis very strong.
explain the folds in thick skin
the folds correspond to the valleys between the surface ridges of the epidermis that we see as fingerprints on the hands.
- also called FRICTION SKIN because it helps us get a grip on objects in our external environment.
- also called GLABROUS (SMOOTH) SKIN because it completely lacks hairs.
explain melanocytes in terms of melanin
produce melanin, which produces colour and protects skin damage from uv light. People of diff races have same number of melanocytes, but amount of melanin produced varies depending on DNA.
Other factors also affect melanin production such as uv rays, biomedical chemicals and drugs like antibiotics
melanocytes Account for what percent of epidermal cells
8%
what do melanocytes do to pigment melanin as dont store it
instead they transport pigment to keratinocytes
name to more epidermal cells
- Langerhans Cells- immune response
- Merkel cells – sensory
Include tactile disc and neuron = touch sensation
explain langerhans cells
collectively form a defensive network in the epidermis. Important in skins immune system
are found mostly in the stratus spinosum.
are phagocytic cells that engulf foreign materials that invade the epidermis.
in contact with an antigen (foreign protein), they migrate out of the epidermis and skin to lymph nodes.
explain merkel cells
Merkel Cell Complexes are found in the stratum basale, they are abundant in thick skin in the palms of hands and soles of feet (planter surfaces) and interact with free nerve endings (non-myelinated), which are sensitive to touch (mechanoreceptors).
They are mostly found in thick skin, on the palms of hands and soles of feet.
They are difficult to tell apart from Melanocytes.
what 3 factors contribute to skin colour
- The amount and kind of (yellow, reddish brown, or black) melanin in the epidermis. – more melanin more dark the skin
- The amount of carotene deposited in the stratum corneum and subcutaneous tissue. This can give the skin a yellow tinge
- The amount of oxygen bound to haemoglobin in the dermal blood vessels – cyanosis = blueish tinge when oxygen levels are low
name and describe some abnormalities in skin pigmentation
albinism
- inherited recessive disorder - little or no melanin
melasma
- dark brown symmetric areas on face and neck
pigment loss after skin damage
- burns, scars etc.
vitiligo
- smooth white patches in skin due to loss of melanocytes
birthmarks
- abnormal blood vessels or malformed pigment cells
what are the 3 types of skin cancer
Basal cell carcinoma
- 75% of all skin cancers, highly treatable and starts in the basal cell layer of the epidermis, grows very slowly
Squamous cell carcinoma
- approx 20%, more aggressive (can spread) but treatable
Melanoma -
~5% but 73% of deaths, starts in melanocytes, usually in a mole and spreads very quickly
describe jaundice
an abnormal yellow skin tone usually signifies a liver disorder in which bile pigments are absorbed into the blood, circulated throughout the body, and deposited in the body tissues.
explain haematomas
bruises or black and blue marks: reveal sites where blood has escaped from the circulation and has clotted in the tissue spaces. Such clotted blood masses are called haematomas.
An unusual tendency to bruising may signify a deficiency of vitamin C in the diet or haemophilia – also a sign of leukaemia
- Elderly people bruise more easily as epidermis is thinner and capillaries are more delicate
what are the 3 accessory structures
hair
skin glands
nails
explain where hair is found
on most skin surfaces
Not on palmar surfaces of hand and fingers or plantar surfaces of feet i.e. not in thick skin
what is hair made of
fused keratinized cells
Consists of shaft & root
Surrounded by hair follicle
Base is bulb which includes growing matrix producing cells
what are hair nerves
hair root plexuses
describe hair muscle
arrector pili – connects to the papillary dermis and is composed of ribbons of smooth muscle.
When stimulated the arrector pili pull the hair follicles and elevate the hair.
This contraction may be caused by emotional states like fear or rage
explain the full hair structures
Hair is composed of columns of dead keratinised cells, bound together by extracellular protein
Hair shaft of the follicle is located in dermis
The superficial portion of hair sticks out of the skin
Surrounding the root of the hair is the hair follicle
At base of the hair is the onion shaped structure called the bulb
The root of the hair penetrates into the dermis
Matric within the papillary bulb is where hair is produced
epidermal glands participate in what
body temp regulation
name the 3 epidermal glands
sebaceous glands
sudoriferous or sweat glands
ceruminous glands
explain the epidermal gland sebaceous
secrete oily sebum
Connected to hair follicles. And keep skin soft and moist, and protect hair from getting brittle
explain the epidermal gland sudoriferous
or sweat glands
Eccrine sweat gland
– most common
- Wide distribution – thermoregulation
- Regulate body temp by evaporation. Contain water salt and urea
Apocrine sweat gland
– for cold sweat associated with stress
- Axilla, groin, areolae (pigmented area surrounding nipples), beard
- Contain other cell material and produce pheromones
- Found in pubic regions and are responsive for BO
explain the epidermal gland apocrine
external auditory canal
Combine with sebum to produce earwax
what are nails made up of
Plates of packed hard dead keratinized cells
name the 3 parts to the nail
Nail body- major visible portion
Free edge- part extending past finger or toe
Root – part not visible
where does nail growth occur
nail matrix
describe the functions of integumentary system
Temperature Regulation
Protection and immunity
Sensory reception
Excretion & Absorption
– small amount
- Urea is excreted in small amounts, O2, CO2 & N2 are absorbed as well as certain drugs e.g. (ibuprofen) and hormones (HRT).
Vitamin D synthesis
- sunlight converts cutaneous 7-dehydrocholesterol to previtamin D3, which in turn becomes vitamin D3 (calcitriol - steroid hormone
describe the affect of aging in the integumentary system
Adolescence- can develop acne - stimulated by androgens
Aging processes mainly in dermis - visible ~ age 40
Loss of collagen fibres
Loss of elasticity
Loss of immune responses
Decreased melanocyte functions-
grey/white hair, blotches
Thinning
whats a pneumonic for remembering the layers of the epidermis
come
lets
get
sun
burnt
