3.1 Introduction to the Integumentary System

integument

covering membrane of the body, AKA the skin

combining form: integ/o = to cover

accessory structures of the integument

nails, hair, sebaceous glands, and sweat glands

function of the skin

• protect the body, regulate temperature, sense surrounding environment, and secrete various substances

• protects deeper tissues from invasion from foreign bodies such as bacteria and viruses

• can prevent mechanical injury and excessive water loss, store both food and water, and guard body from too much exposure to UV rays from the sun

relationship between body temperature and blood vessels

• when body temperature rises

  • blood vessels in the skin dilate and enable more blood to be brought to the surface of the body and heat to radiate out from the skin

  • sweat glands will secrete more sweat to evaporate and cool the body

• when body temperature drops

  • blood vessels constrict which keeps blood and heat closer to the core of the body

how does the skin secrete substances?

sweat glands and sebaceous glands

sweat glands

• secrete sweat which is made up of H2O, salt, and other chemicals.

• This functions to cool the body

• can be found in every part of the body except for the lips, tip of penis, and area around the clitorus

• sweat itself does not have odor but when left on the skin, bacteria can interact and cause BO

sebaceous glands

• secrete sebum, which is an oily substance that protects the skin from dehydration

• sebum lubricates the hair and the skin

• controlled by the endocrine system

what layers are the skin made up of?

epidermis and dermis

epidermis

• outer layer of the skin and it is made up of 5 layers

• not every layer is present in every area of the body

• deepest layer is where the new skin cells are generated

layers of the epidermis from deep to superficial

stratum germinativum, stratum spinosum, stratum granulosum, stratum lucidum, and stratum corneum

melanin

pigment that colors the skin

this is found in the stratum germinativum

stratum spinosum

• “spiny layer”

• contains the Langerhans cells: function to protect the skin from invading microorganisms

keratin

• protein that forms hair, nails, and the thick skin of the palms and soles

• stratum granulosum and stratum lucidum are formed from this

stratum corneum

most superficial layer of the skin made of dead skin cells and functions to protect the deeper layers

dermis

• deep to the epidermis and is made of connective tissue

• contains nerves and nerve endings, blood vessels, sebaceous and sweat glands, elastic fibers, hair follicles, and lymphatics

skin signs

objective evidence of an illness or disorder that can be seen, measured, or felt

macule

flat, discolored spot on the skin

aka a mole

wheal

localized, temporary elevation of the skin that is itchy

urticaria or hives are examples

papule

solid, confined, elevated area on the skin ex) pimple

vesicle

small fluid filled sac ex) blister

pustule

small elevated confined lesion that is filled with pus ex) pimple

ulcer

erosion or eating away of healthy tissue

fissure

crack like slit that extends through the epidermis into the dermis

hair

• thin stringlike structure that develops out of a hair follicle

• each hair has root embedded in the hair follicle and a shaft which is the visible portion of the hair

• each also have a small muscle called the arrector pili muscle which is attached to the follicle

• muscle contracts when skin is cooled or the person has goosebumps

hair color is the result of?

melanin and is determined by the persons genetics

production of melanin decreases as a person ages and grey hair develops

nails

• made of hard keratin

• made of nail body and nail root

nail body

visible portion of the nail and covers the part of epidermis called the nail bed

nail bed

epithelial tissue located deep to nail body and it is a pink color due to the blood vessels that are located in the tissue

nail root

fold of epithelial tissue that is not visible

cuticle/eponychium

small portion of the epithelial fold that extends over the base of the nail body

lunula

• crescent shaped area at the base of the nail body that is lighter than the rest of the nail

• caused by compression of the blood vessels that are under the nail body

free edge

top of the nail body and it projects over tip of finger or toe, portion of the nail that is trimmed

2 types of sweat glands

apocrine and merocrine glands

merocrine

located throughout the body and release sweat directly to the skins surface

most prevalent on the soles of the feet and palms of the hands

apocrine

located in the axillae, around the nipples, and the groin

they begin to secrete sweat during puberty and secrete sweat into the hair follicles located in those areas