Integumentary System
Consists of the skin and is accessory organs i.e hair, nails and cutaneous glans
-this is the most visible and vulnerable organ
-lagest organ (1.5-2m2)
-heaviest organ (15% body weight)
Dermatology
scientific study and medical treatment of the skin system
How many layer of skin are there
2
epidermis and dermis
epidermis
keratinized stratified squamous epithelium
- surface consists of dead cells packed with keratin protein
dermis
The connective tissue layer beneath the epidermis. Contains blood vessels, hair fallicles, sweat glands, and oil glands, nerve cells. Middle Layer.
ranges from 0.2mm-4mm thick
this is were the piloerector muscles are that respond to stimuli
hypodermis
another connective tissue layer below the dermis that helps ti, AKA subcutaneous tissue. This is the layer beneath the skin. Has more areolar and adipose tissue tha the dermis. pads body and binds the skin to underlying tissues. Highly vascularized
layers of the epidermis
stratum corneum
stratum lucidum
stratum granulosum
stratum spinosum
stratum basale
thick skin
on the palms and soles of your feet
no hair follicles or sebaceous glands
6 Functions of the skin
1. resistance to trauma and infection
2. other barrier functions (water barrier for absorption and secretion, UV barrier)
3. Vitamin D synthesis
4. Sensation
5. Thermoregulation
6. nonverbal communication
Cells in the epidermis
stem cells
keratinocytes
melanocytes
tactile cells
dendritic cells
Stem cells
undifferentiated cells that divide and give rise to keratinocyctes. found only in the deepest layer of the epidermis.
grow more tissue so that we can loose dead skin cells
Keratinocyctes
most numerous of the epidermal cells, known of their role in synthesizing keratin, occurs in the stratum basal.
become fat and squamous and fall off
30-40 day life span for cells, slower in old age and faster in wounds
melanocytes
occurs in the stratum basal, they synthesize the brown to black pigment melanin. The pigment shields the DNA from UVA radiation, this is a tanning defence mechanism
Tactile cells
Located in the basal layer of epidermis. Tough receptor cells associated with dermal nerve fibers
Dendritic cells
Are found in the stratum spinosum and granulosum. First defence against infectious disease, stand guard against toxins, microbes and other pathogens that penetrate. They are immune cells that originate in the bone marrow
lipid-filled membrane-coating vesicles
as keratinocytes are shoved upward by the dividing cells below, they flatten and produce more keratin filament and these vesicles
3 developments in the granulosum
1. keratohyalin granules release a protein filaggrin. binds the keratin filaments together into coarse, tough bundles
2. membrane-coating vesicles release lipid mixture that spreads out over cell surface and waterproofs it
3.keratinocyte nucleus and other
epidermal water barrier
-formed by the process in the granulosum and is in-between the stratum spinosum and granulosum.
- consists of tight junctions between keratinocytes that secrete lipids and have a thick layer of insoluble protein on the inner surface of the plasma membrane
dermal papillae
upward fingerlike extensions of the dermis
these re friction ridges on our finger tips that leave fingerprints
dermal papillary layer
Superficial thin zone of the dermis composed of areolar tissue near dermal papilla. The loosely held tissue allows for mobility of leukocytes and other defence cells
-especially rich in smal;l blood vessles
reticular layer
deeper and much thicker layer of the dermis, consists of dense, irregular connective tissue, this is where stretch marks occur
melanin
most significant factor in skin colour. people have different skin colour but have the same amount of melanocytes just produce different quantities of melanin
-amount also varies with UV exposure
-concentrated areas such as freckle and moles have more of
Factors in skin colour
-amount of melanin
-hemoglobin gives the red pigment of red blood cells (angry/embarrased)
-carotene - yellow pigment acquired from egg yolks and y/o veggies
cyanosis
blueness of the skin from deficiency of oxygen in blood
erythema
abnormal redness of the skin due to dilated cutaneous vessels exp. exercise
pallor
pale or ashen colour when there is so little blood flow through the skin that the white colour of the dermal collagen shows through exp emotional stress, low blood pressure
albinism
genetic lack of melanin that results in white hair, pale skin, and pink eye.
jaundice
yellowing of skin and sclera due to excess of bilirubin in blood
-cancer, hepatitis
hematoma
bruise
-mass of clotted blood showing through skin
friction ridges
markings on the finger tips that leave an oily fingerprint
-they enhance sensitivity to texture, improve grasp, and have unique patters
flexion lines
are the lines on the flexor surfaces of the digits, palms, wrist ect. Shows were the skin folds during flexion and extension
freckles
are flat melanized patches that vary with heredity
mole
elevated patch of melanized skin, often with hair.
they are considered beauty marks
birthmarks
hemangiomas
patches of discoloured skin of benign tumours of the blood capillaries
accessory organs
hair, nails, and cutaneous glands
pilus
other name for hair
its a slender filament of keratinized cells that grow in a oblique tube
lanugo hair
type of hair
fine downy, unpigmented hair that appears on the fetus in last three moths of development, falls off quickly
vellus hair
fine, pale hair that replaces lanugo by time of birth, more permanent, this is the type women retain when we grow up
terminal hair
longer, coarserm and usually heavily pigmented, this is on your head and beard, type of hair men change to over time. facial hair
Functions of the hair
1. helps retain scalp heat
2. protection against sun burn
3. gender identification
4. signal sexual maturity
5. guard hairs protect and filter
6. nonverbal communication
7. hair receptors notify us of things o our skin
Nails
clear, hard derivatives of the stratum corneum.
-composed of very thin, dead cells packed with hard keratin.
-nails allow for more fleshy and sensitive fingertips
Nails Plate
the hard part of the nail
free edge
overhangs finger tip
nail body
visible attached part
nail root
extends under overlaying skin
nail fold
surrounding skin rising a bit above the nail
nail groove
separates nail fold from nail plate
nail bed
skin underlying the nail plate, its epidermis is called hyponychium
nail matrix
growth zone at the proximal end of the nail made up of thickened stratum basal
-mitosis here accounts for the nail growth which is around 1mm per week
lunule
the white crescent at the proximal end of our nails
cuticle/eponychium
a narrow zone of dead skin that commonly overhangs the end of the skin
5 types of skin glads
1. Merocrine sweat glands
2. Apocrine sweat glands
3. Sebaceous Glands
4. Ceruminous Glands
5. Mammary glands
Sweat glands/sudoriferous (2)
Merocrine
apocrine
Merocrine sweat glands
-most numerous skin glands all voer the body but especially in palms, forehead and feet.
--primary function is to cool the body, but also excrete some wastes.
- about 3-4 million in the adult skin
Apocrine Sweat glands
-occur in groin, anal region, axilla, areola, bearded area in mature males
ducts lead to nearby hair follicles
- ducts lead to near by hair follicles rather than the skin
-produce sweat that is thicker, milky, and contains fatty acids
-scent glands that r
pheromones
chemical secreted by the apocrine sweat glands that influences the physiology and sexual behaviour of others
bromhidrosis
disagreeable body door produces by bacterial action on the fatty acids hen we have clothes on for an extended period of time
sweat
begins as a protein-free filtrated of blood plasma produced by deep secretory portion of gland
-potassium ions, urea, lactic acid, ammonia, and some sodium chloride remain in the sweat, most sodium chloride reabsorbed by duct
diaphoresis
sweating with wetness of the skin
loss of water during exercise, you could loose up to 1L per hour
-the white rings on your shirt afterwards is from sodium secretion
insensible perspiration
500ml per day
does no produce visible wetness of skin
sebaceous glands
-produce an oily secretion called sebum
-they are flask shaped glans with short ducts opening into hair follicles
- these are holocrine glands
-keeps skin and hair from becoming dry, brittle and cracked
sebum
an oily secretion produced in the sebaceous gland
holocrine gland
are sebaceous glands, secretion consists of broken down cells
ceruminous glands
- found only in the external ear canal
-secretion combines with sebum and dead epidermis cells and cerumen to produce ear wax
-glands lead to the skin surface
cerumen
-ear wax
- keeps eardrum pliable, waterproofs the canal, kills bacteria, makes guard hairs sticky to help block entering foreign particles
mammary glands
- the milk producing glands that are produced in females breast during pregnancy an lactation
-they are modified apocrine sweat glands that produce richer secretion through the nipples
mammary ridges/milk lines
are two rows of mammary glands that occurs in most mammals
-primates only keep anterior most glans
skin cancer
- majority of the cause is from UV rays from the sun
-1/5 people get it in the use
-most common tumour occur on the head and neck, and on fair skinned and elderly
3 types of skin cancer
- named for the epidermal cells where they originate
1. basal cell carcinoma
2. squamous cell carcinoma
3. malignant melanoma
basal cell carcinoma
- the most common type
- the least dangerous because it seldom metastasizes, but can disfigure the face
-forms from cells in the stratum basal
-lesion is a small shiny bump with central depression and beaded edges
Squamous cell carcinoma
-arises from keratinocytes of the squamous spinosum
-lesions usually appear on scalp, ears, lower lip, or back of hand
-have raised reddened scaly appearance later forming a concave ulcer
-second most sever
malignant melanoma
-skin cancer that arises from melanocytes, often a preexisting mole
-less then %5 of cancer but it is the most deadly
-metastasizes rapidly- unresponsive to chemotherapy
-high incidence in men, red heads, people who have sever sun burns and family history
UVA/UVB
tanning rays
burning rays
- both initiate skin cancer
-rick of skin cancer increases by 75% for thoes who use tanning beds by the age of 30
burns
leading cause of accidental death
-deaths result primarly from fluid loss, infection and toxic effects of eschar
eschar
burned, dead tissue
dibridement
removal of eschar
first degree burn
partial thickness burn
only in the epidermis
second degree burns
partial thickness burn
epidermis and part of the dermis
third degree burn
full thickness burn
epidermis, dermis and often some of the deeper tissue (muscle or bones) are destroyed
-requires a skin graft
autograft
a type of skin graft
-tissue taken from another location on the same persons body
isograft
skin from an identical twin
homograft (allograft)
from unrelated person
temporary graft
heterograft (xenograft)
from another species
temporary grafts
skin grafts
most come from the butt and low back