Accessory Structures of the Skin (a.k.a. Skin Appendages) Hair Nails Glands

3 Protective Functions of Hair Protection for the head Shields the eyes Helps to keep foreign particles out of the respiratory tract Protects against bumps? Another function of hair: insulation

Hair

Hair

Parts of a Hair Hair root is enclosed in the hair follicle Hair shaft is the part of the hair that projects from the surface of the skin Growth zone of follicle is called the Hair bulb matrix Most of the shaft is dead keratinized material Papilla of the hair is projection of connective tissue that contains blood vessels

Hair

Internal Structure of Hair Medulla (central core of hair shaft)) Cortex (second layer) Melanocytes = pigment-producing cells Produce varying amounts and colors of pigment - Cuticle of the hair is the outermost layer; Contains the most keratin Wears away at end = “split ends”

Around the Hair Small bands of smooth muscle muscle cells called arrector pili muscles connect to each side of the hair follicle to the cells of the dermis. When they contract we get “goosebumps”

Nails

Nails A nail is a scale-like modification of the epidermis Like claws or hooves

Nails

Structure of a Nail Free edge is that part of the nail that extends out from the epidermis Nail body or plate is the visible part of the nail that is attached to the epidermis Nail root is the part that is embedded inside the epidermis of the skin

Structure of a Nail Skin fold that is thick at the base of the nail is the cuticle. The thickened – proximal area of the stratum basale of the epidermis is the *Nail matrix which is responsible for nail growth As nails are produced by this matrix, they become heavily keratinized

Structure of a Nail Like hairs, nails are mostly dead keratin Nails are transparent, but look pink due to the blood supply of the underlying dermis The white crescent of the nail, which falls over the nail matrix is called the lunula

Glands

Glands Glands of the SKIN - Cutaneous glands are all exocrine glands, which means they have ducts to release their secretions. Two major types in the skin: Sebaceous glands = oil glands Sudoriferous glands = sweat glands

Sebaceous Glands

Sebaceous Glands = OIL Glands Found all over the skin except for the palms of the hands and the soles of the feet Ducts mostly empty into a hair follicle sebum is a lubricant; mixture of oily substances that keeps skin soft

Sebaceous Glands Acne is an active infection of the sebaceous glands Results in “pimples” or bumps on the skin Caused by overproduction of oil, which blocks pores

Sudoriferous Glands = SWEAT Glands Have own ducts to surface PORES of the skin. These glands can be  eccrine glands which are far more numerous and found all over the body  Apocrine sweat glands are mostly in axillary and genital areas of the body

Glands