A&P-integumentary system

Dermatology

the scientific study and medical treatment of the integumentary system

What is the integumentary system composed of?

• skin

• hair

• nails

• cutaneous glands

What are the different functions of the skin?

1. protection

resistance to trauma and infection; barrier to UV rays

2. vitamin D synthesis

skin carries out 1st step

3. nonverbal communication

facial expressions

4. sensation

receptors for temperature, touch

5. thermoregulation

perspiration and vasoconstriction + vasodilation

The epidermis

composed of avascular keratinized stratified squamous epithelium

What are the cells of the epidermis?

• stem cells

undifferentiated cells giving rise to keratinocytes

• keratinocytes

synthesize keratin

• melanocytes

synthesize melanin

• tactile cells

sensory receptors

• dendritic cells

macrophages fighting infection and bacteria

What are the different layers of the epidermis?

• stratum basale

deepest layer composed of highly active cells (stem cells, melanocytes)

• stratum spinosum

second layer, very thick

• stratum granulosum

third layer that has granules of keratin

• stratum lucidom

only found in thick skin (palms and soles)

• stratum corneum

superficial layer with up to 30 layers of dead, keratinocytes

What layers of the epidermis are considered living and nonliving?

living: basale, spinosum, granulosum (half)

nonliving: lucidum, corneum

What is the life history of a keratinocyte?

The dermis

vascular layer composed mainly of collagen and well supplied with blood vessels and nerve endings

houses all accessory organs

What are the two layers of the dermis?

• papillary layer

• reticular layer

Papillary layer

superficial layer of the dermis

composed of areolar tissue with finger-like projections that connect to the epidermis

Reticular layer

deeper layer of dermis

composed of dense irregular connective tissue

ex. stretch marks come from tears in the collagen fibers

Dermal papillae

upward finger-like extensions of the dermis

ex. contain blood vessels

The hypodermis

subcutaneous tissue composed of adipose tissue that binds skin to underlying tissues

ex. not considered part of the skin

What is the function of subcutaneous fat?

• energy regulation

• pads the body

What are the two pigments responsible for skin color?

• melanin

• hemoglobin

• carotene

Melanin

the most important factor in skin color

produced from melanocytes

Do darker skinned people have increased melanocytes?

no, they simple produce more melanin

ex. cells work harder and more independently

What are the two main pigments from melanin?

• eumelanin

• pheomelanin

Eumelanin

brownish-black pigment

Pheomelanin

reddish-yellow pigment

Hemoglobin

pigment found in RBCs that adds a pinkish hue

Carotene

yellow pigment acquired from egg yolks and vegetables

What are the different skin colors (diagnostic)

• cyanosis

blueness due to oxygen deficiency

• erythema

increased redness

• pallor

paleness due to decreased blood flow

• albinism

whitening of skin due to lack of melanin

• jaundice

yellowing of skin due to bilirubin

• hematoma

bruising due to clotting

Friction ridges

produce fingerprints

Flexion lines

marks sites where skin folds during flexion of joints

Freckles and moles

accumulations of melanocytes

freckles are flat

moles are raised

Lanugo

unpigmented hair covering head of fetus

Vellus

pale hair replacing lanugo at time of birth

Terminal

thick pigmented hair found on the eyebrows, eyelashes and scalp

Piloerector muscle

smooth muscle attaching follicle to dermis

contracts to make hair stand upright and produces goosebumps

ex. termed “arrector pilli”

Hair bulb

swelling of hair at the base composed of living active cells

Hair root

hair not visible on surface

Hair matrix

located in hair bulb

site of the hair’s growth cells

What are the components of a cross-section of hair?

• medulla

hollow tube only found in thick hair

• cortex

thickest layer composed of keratinized epithelium

• cuticle

outermost layer that seals hair

Hair shaft

visible portion of hair

What are the functions of the hair?

• scalp hair

functions for protection

• trunk and limb hair

functions for sensory purposes

• pubic and axillary hair

functions for sign of puberty

• guard hairs

function to protect nostrils and ear canals

Where do the different shades of color come from?

combination of eumelanin and pheomelanin

Nails

clear hard derivatives of the stratum corneum, composed of thin, dead cells packed with keratin

What are the different parts of the nail?

• nail plate

visible portion that includes free edge, body, and root

• nail fold

surrounding skin rising above nail

• nail groove

separates nail fold from nail plate

• nail bed

skin underneath nail plate

• nail matrix

growth zone of thickened stratum basale

Hirsutism

excessive or undesirable hairiness in unusual areas of the body

What tissue type are nails and hair composed of?

keratinized squamous epithelium

Apocrine glands

• inactive until puberty

• thick secretions

• usage of ducts attached to hair follicle

location: groin, anal region, axilla, and beard area

function: respond to stress and sexual stimulation

Merocrine sweat glands

• produce most of sweat

• usage of ducts that open directly onto the skin

• thin secretion

location: palms, soles, and forehead

function: produce sweat to cool off body and keep the homeostasis of temperature

Sebaceous glands

produce oily secretion, sebum

ex. attached to hair follicle

Ceruminous glands

produce cerumen (earwax), a yellow secretion

What are the functions of ceruminous glands?

• keeps eardrum pliable

• waterproof canal

• kills bacteria

• blocks foreign particles

Insensible perspiration

secretion of 500 mL of sweat per day

ex. not noticeable

Diaphoresis

secretion of 1 L of sweat per day

ex. noticeable wetness

Cutaneous transpiration

water loss due to escape of liquid through gaps in cells

Mammary glands

develop only during pregnancy and lactation to produce milk

ex. usage of lactiferous ducts

Basal cell carcinoma

least aggressive type of cancer

small shiny bump with central depression

Squamous cell carcinoma

arises in stratum spinosum

location: lesions on scalp, lips, and back of hand

Malignant melanoma

fatal condition

arises from melanocytes

Where is skin damage most often found?

the head, neck, and hands

Deaths related to burns most often result from?

• dehydration

• infection

• eschar

What are the different types of burns and their effects?

• first-degree

affects just the epidermis

• second-degree

affecting epidermis and dermis

• third-degree

affecting epidermis, dermis, and deeper layers