Integumentory System

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)


scientific study and medical treatment of the skin system

How many layer of skin are there

epidermis and dermis


keratinized stratified squamous epithelium
- surface consists of dead cells packed with keratin protein


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


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
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


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


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


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


blueness of the skin from deficiency of oxygen in blood


abnormal redness of the skin due to dilated cutaneous vessels exp. exercise


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


genetic lack of melanin that results in white hair, pale skin, and pink eye.


yellowing of skin and sclera due to excess of bilirubin in blood
-cancer, hepatitis


-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


are flat melanized patches that vary with heredity


elevated patch of melanized skin, often with hair.
they are considered beauty marks


patches of discoloured skin of benign tumours of the blood capillaries

accessory organs

hair, nails, and cutaneous glands


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


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


the white crescent at the proximal end of our nails


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 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


chemical secreted by the apocrine sweat glands that influences the physiology and sexual behaviour of others


disagreeable body door produces by bacterial action on the fatty acids hen we have clothes on for an extended period of time


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


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


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


-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


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


leading cause of accidental death
-deaths result primarly from fluid loss, infection and toxic effects of eschar


burned, dead tissue


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


a type of skin graft
-tissue taken from another location on the same persons body


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