Integumentary SystemAccessory Structures

Accessory structuresNails, hair follicles, skin glands

NailsProtective covering on the ends

of fingers & toes◦Nail plate (keratinized cells)◦Nail bed◦Lunula

Cells divide at lunula, pushing older cells toward tip of nail

Q. What is the most actively growing region of the nail?

A. Lunula

Fun Nail FactsNail appearance mirrors health.

◦Bluish nail beds may indicate a circulatory problem

◦White nail beds may be due to anemia

◦A dark spot not related to injury may be melanoma

◦Horizontal furrows may indicate a period of illness or malnutrition

Hair FolliclesHair grows from a tube-like

depression called a hair follicleHair root – under

the skin surfaceHair bulb – where

cells are dividingNew cells push

older cells up, they be come keratinized and die (this is the part you see!)

Hair FolliclesLosing 20-100 hairs a day is

normal!◦A hair grows for 2-6 years then takes

a break for 2-3 months◦When a new hair begins to form in

this follicle, the old one is pushed out

Q. What is the area called where hair is growing?

A. Hair bulb

Hair follicleArrector pili muscle is attached to

each follicle◦When a person is cold, these

muscles contract, causing hair to stand straight up (goose bumps)

Hair FolliclesHair color

◦Genes determine what type and how much pigment is produced by melanocytes in the follicle Eumelanin – brownish/black Pheomelanin – red/yellow

Q. What causes goose bumps?

A. The hair standing on end is caused by the arrector pili muscle contracting.

Skin GlandsSebaceous glands – usually

associated with hair follicles◦Secrete fatty material called sebum◦Helps hair and skin soft, pliable, and

waterproof

Skin GlandsSweat glands – coils down deep

into dermis or subcutaneous layer◦Eccrine glands – most common

Respond to elevated body temperature Forehead, neck, back, palms and soles

◦Apocrine glands – (smelly sweat) Respond to emotions, pain, and being

frightened Armpits and groin

Skin Glands

Skin GlandsSpecialized sweat glands

◦Ceruminous glands: ear wax◦Mammary glands: milk

Q. What is the function of sebaceous glands?

A. Secrete sebum to keep hair and skin soft, pliable, and waterproof

Word Bank for LabelingHair shaftHair follicleSebaceous glandDermisSubcutaneous tissueArrector pili muscleSweat glandBlood vesselsDpidermis