Hair – Accessory Structures of the Skin (Nursing)

00:01 So let's talk a little bit about some of the accessory structures of the skin.

00:07 The hair is found all over the body.

00:11 And the only place you don't find hair is on the palms of your hands and the soles of your feet.

00:17 The hair is composed of dead keratinized epidermal cells very similar to the stratum corneum layer of the epidermis And there are lots of different influences that determine the thickness and the distribution of our hair including genetic influences and hormonal influences.

00:40 There are multiple parts of the hair.

00:43 The part that you see or the part that is above the skin surface is referred to as the hair shaft.

00:50 Below the level of the skin, you have the hair root.

00:55 The hair root is surrounded by the structure known as the hair follicle.

01:01 The hair follicle itself is made of two sheaths or coverings.

01:07 The first sheath, the epithelial root sheath is an extension of the epidermis.

01:12 The dermal root sheath is the part of the dermis that is going to surround the follicle.

01:19 Also on the hair, you have three major structures that are very important for hair growth.

01:25 You have the hair bulb which is shaped like an onion or like the bulb at the hair root.

01:32 The second structure in this bulb is going to be the hair matrix.

01:37 The hair matrix is actually dervived from the same cells that make up the stratum basale in the epidermis and therefore consist of growing cells or stem cells So it is this part of the hair that is responsible for hair growth.

01:53 Hair growth cannot occur without the presence of nutrients and so we need a way to get blood toward the bottom of the hair or the root of the hair so that the hair can grow.

02:05 And for this, we have the hair papillae.

02:08 This is an indentation in the bulb of the hair where the blood vessels are able to come in and nourish the matrix so that your hair is able to grow.

02:19 Speaking of hair growth, our hair actually grows in stages.

02:24 So starting with the growth stage, hair from the matrix is going to start to grow from that matrix out toward the surface of the skin.

02:34 Ultimately over time, the regression stage occurs where the matrix stops dividing and the hair follicle begins to atrophy.

02:45 After this stage, there's a stage of rest or a period of rest where the follicle is not active at all.

02:53 Shortly after this, the growth stage is going to begin again and the hair matrix is going to be reactivated This new hair is going to then push the resting hair out of the way as a new strand of hair grows.

03:09 Interestingly, all of the hair all over your head is in different points of this cycle and that is a good thing because if it wasn't that way, then what we would do is our hair would grow then it would fall out and then new hair will grow so we will go through periods of having hair and then going bald.

03:29 But fortunately, that's not the way it is but at any given point, multiple hair follicles are going through one of these stages of hair growth.

03:40 So along with the different stages of hair there's also different types of hair.

03:45 First, in the fetus, you have lanugo.

03:49 Lanugo is a type of a very fine pigmentless layer of hair on the fetus and is also present just as the baby is born.

04:01 Terminal hair is probably the hair that you think most about as that's the kind of hair that you find on your head.

04:10 Covering the remainder of your body is vellus hair.

04:14 Vellus hair are the short, fine pale hairs found all over all of the surfaces of your skin minus the areas where you have thick skin such as the palms of your hands and the soles of your feet.

04:28 The interesting thing about vellus hair is, it is actually in the place of lanugo hair so it replaces lanugo hair as you grow.

04:40 Just like our skin, our hair is also pigmented.

04:44 And just like our skin, the pigment that is responsible for hair color is melanin.

04:51 There are two types of melanin that are found in hair.

04:55 For people who have dark har, they have an abundance of eumelanin which is the black or brownish pigment.

05:04 For those who have more blonde hair or red hair, they have an abundance of pheomelanin which gives off this reddish-brownish colour As you age, you start to decrease the production of melanin in your hair and that is when your hair begins to turn grey, like mine.

05:23 And then finally, when you have white hair, this is due to a lack of melanin as well as the presence of air bubbles in the hair shaft.

05:34 Located in the dermis of the skin, you have several different types of glands.

05:39 First, you have the sebaceous or oil glands which are glands that are directly connected to the hair follicles in the dermis.

05:49 You then have two different types of sweat glands.

05:52 There are eccrine sweat glands, which are the most numerous and found all over the body and are not associated with a hair follicle.

06:00 And then you have the apocrine sweat glands which are associated with hair follicles.

06:06 Finally, in the ears, you have a modified sweat gland known as a ceruminous glands.

06:13 Ceruminous glands produce cerumen or what we refer to as earwax.