Integumentary System

what are the functions of the skin

all of these are functions of

- protection

- immunity

- thermoregulation

- sensation

- sweat

- synthesis of vitamin D

- water barrier

normal range of skin pH

4 to 6.5 is the skins normal range of

the acid mantle of the skin helps maintain normal skin by serving as a

what helps the skin be

- a protective barrier against bacterial and fungal infections

skin conditions that increase the skins surface pH

these conditions do what to the skins surface pH

- eczema

- contact dermatitis

- atopic dermatitis

- dry skin

systemic disease that increase the skins surface pH

these systemic diseases do what to the skins surface pH

- diabetes

- chronic renal failure

- cerebrovascular disease

thermal receptors (thermoreceptors)

Sensory receptors that detect changes in temperature

noxious receptors

painful stimulation receptors

mechanical receptors

Sensory receptors that detect changes in pressure, movement, temperature, or other mechanical forces.

Stereognosis

what is the ability to recognize objects by feeling their form, size, and weight while the eyes are closed

pacinain corpuscles: found in the dermis towards the hypodermis

this sensory receptor functions are deep pressure and vibrational sensations

Meissner's corpuscles

this sensory receptor is

- highly specialized mechanoreceptors found in hairy and glabrous (hairless) skin

- responsible for sensing light touch

dermatones

a strip of skin innervated by a particular spinal nerve

A-delta fibers in the skin

this kind of fiber in the skin is

- superficial (acute) pain to a local area

- transmitted by very rapid nerve impulses

- sharp pain but ceases when pain stimulus stops

C fibers in the skin

this kind of fiber in the skin is

- deep (chronic) pain

- impulses are transmitted slowly

- last longer periods of time

- remains even after the pain stimulus is gone

direct cutaneous vessels

vessels in subcutaneous fat layer of skin

musculocutaneous vessels

vessels pass through muscle and deep fascia to reach the skin

fasciocutaneous systems vessels

vessels run in intermuscular septa and fan out at deep fascia to reach skin

thermoregulation

this is controlled by the HYPOTHALAMUS in response to internal core body temp

Melanocytes

cells that produce melanin

melanin

protects the skin against the harmful effects of UV radiation on DNA

oncogenes

- genes that help cells grow, divide, and stay alive

- causes cancer

tumor suppressor genes

genes that keep cell growth in check or cause cells to die at the right time

ABCDEs of melanoma

asymmetry, border, color, diameter, evolution

epidermis

- top layer of the skin

- self-renewing stratified epithelial tissue containing mainly of keratinocytes

layers of the epidermis

- stratum corneum

- stratum granulosum

- stratum spinosum

- stratum basale

Stratum corneum (horny layer)

this layer of the epidermis

- consists of dead keratinocyte cells

- flakes and sheds

stratum granulosum (granular layer)

this layer of the epidermis

- contains langerhans cells (immune survelliance)

- contains keratinocytes

stratum spinosum (spiny layer)

this layer of the epidermis

- contains keratinocytes

- contains langerhans cells

stratum basale (germinating layer)

this layer of the epidermis

- contains melanocytes

- can regenerate (mediated by STEM CELLS)

- important for wound healing and skin health

langerhans cells

these cells are involved in

- antimicrobial immunity

- skin immunosurvelliance

- migrate out of the epidermis to lymphoid tissue

what is the role of lymphoid tissue

this type of tissue removes excess fluid from the interstitial spaces between the cells and also plays a significant role in immune control

Dermis layers

- consists of

1. papillary layer

2. reticular layer

- dense layer of collagen and elastic fibers

papillary dermis

- composed of collagen and reticular fibers

- its distinct, unique pattern allows fingerprint identification

reticular dermis

- composed of collagen bundles that anchor the skin to the subcutaneous tissue

- sweat glands, hair follicles, nerves, and blood vessels can be found in this layer

collagen and elastic fibers in the dermis give the skin its ability to

these two things give the skin the ability to be mobile

Hypodermis (subcutaneous layer)

- its function is to promote an ongoing blood supply to the dermis for regulation

- primarily composed of adipose tissue, which provides a cushion between skin layers, muscles, and bones

- promotes skin mobility, molds body contours, and insulates the body

- contains major blood vessels, nerves, and lymphatic p

retinaculum cutis superficialis

- attaches the superficial fascia to the skin

- fibrous septa usually almost perpendicular

retinaculum cutis profundus

- attaches the superficial fascia to the deep fascia

- fibrous septa usually more oblique and thinner then the superficial septa

pilosebaceous unit

consists of

- the hair and its follicle

- an associated arrector pili muscle

- sebaceous gland

- apocrine gland

contraction of the arrector muscles

causes the hairs to stand up straight

compressing the sebaceous glands

helping them secrete their oily product onto the skin

sebum

- component of the epidermal barrier

- body odor

dermis of the nail bed is anchored to the

periosteum

Venous hypertension

- distends the superficial veins

- causes edema of venous insufficiency

superficial burn

- damage is limited to the epidermis

- sunburn

partial thickness burn

- epidermis and superficial dermis are damaged with blistering or loss

- nerve endings are damages, making this variety the most painful

full thickness burn

- entire thickness of the skin is damaged and often the subcutaneous tissue

- no pain because sensory endings are destroyed

4th degree burn

- damage extends through the entire thickness of the skin into underlying fascia, muscle, or bone

three factors that increase the risk of death from burn injuries

- age older than 60 years

- partial thickness and full thickness burns of over 40% of body surface area

- the presence of inhalation injury

wound healting - hemostasis

- causes vascular injury and initiates fibrin-fibrin clot formation

- clot consists of platelets

- contribute to inflammatory cell recruitment

wound healing - inflammation

- neutrophils and monocytes are recruited to wound sites within minutes of injury by a variety of chemotactic signals

- monocytes differentiate into macrophages

wound healing - proliferation

1. re-epithelialization

- stimulated by cytokines

- an epidermis is re-established from the margins of the wound inwards

2. granulation tissue formation

- granulation tissue contains numerous capillaries that invade the initial wound clot and become organized into microvascular network

- wounds that fail to granulate do not heal satisfactorily

wound healing - remodeling

- fibroblasts are responsible for remodeling

- myofibroblasts play a key role in wound healing

- scar maturation is associated with increases in collagen type I