Accessory Structures

Accessory Structures

• Accessory structures are tissues that are located in the dermis and epidermis that are not considered skin• These structures include hair,

nails and glands• These structures play a vital role

to in the function and purpose of the skin

Accessory Structures

• Accessory structures derive from the epidermis during fetal development• This means that the same cells

that create the epidermis also create all of the accessory structures• Since they come from the

epidermis during development, we often refer to them as epidermal derivatives

Accessory Structures• The accessory structures are

located in the dermis• However accessory structures

should have access to the outside environment through the epidermis• The only times this does not

happen is if a gland is blocked or a hair is ingrown

https://www.youtube.com/watch?v=zWh_eA-9S7E

https://www.youtube.com/watch?v=Aj7aRGQ0DyI

Hair

• Hair is an accessory structure that projects from the dermis to the outer environment• It covers most parts of the body• This excludes the palms, bottom

and sides of feet, lips and parts of the genitals• Only around 25% of the bodies hair

is located on the head• The rest are located around the

body

Hair

• Hair serves three main functions• Insulate the skin• Protect the skin from damage• Sense changes to the skin from

the environment

• These different functions happen all over the body in many different ways• The purpose they serve makes

sure we survive

Hair Structure

• Hairs are non living structures that are pushed upward from the dermis• Hairs originate from a point

called the hair follicle• This hair follicle is surrounded by

connective tissue (root hair plexus) and smooth muscle (arrector pili)

Hair Structure

• Hairs tissues are located below the surface and above the surface• The part that is below the

surface and anchors the hair into the skin is called the hair root• The part that is above the

surface and exposed to the environment is called the hair shaft

Hair Fun Facts

• Hairs are present for around two to five years• During this time they grow

around 8mm (1/3 of an inch) a month• When new hairs grow, they push

out the old hairs• Humans lose around 100 hairs

from their head a day

Hair Fun Facts

• There are two main different types of hair• Vellus hairs are located all over

your body and are less thick and lightly colored• Terminal hairs are heavy and

darkly pigmented• Types of hairs that are produced

can change with age and the levels of hormones produced

Hair Fun Facts

• Hair color is derived from melanin• Melaninicytes near the hair

follicle produce melanin that give the hair is color• The melanin type produced is the

color of hair• As hair grows older, less melanin

is produced and air finds its way into hair• This causes hair to have a white

or grey appearance

Hair Fun Facts

• Hair coloring can produce a false color on the shafts of hair• However these hair dyes need to

penetrate the hair so they damage the outer cuticle of the hair• This often leaves hair damaged

and thin• Conditioners and specialized

shampoos can partially restore the cuticle and leave hair hydrated

Video

• Not everyone’s hair grows the same…

• http://videos.howstuffworks.com/discovery/30742-one-step-beyond-hypertrichosis-video.htm

Video

• Even more differences… • www.youtube.com/watch?v=OU93tt3w_eQ

• http://www.dailymail.co.uk/health/article-2647395/Alopecia-big-life-doesnt-define-Teenager-15-lost-hair-disease-fronts-new-campaign.html

Nails

• Nails protect the exposed dorsal surfaces of the fingers and toes• They also provide physical

protection to the fingers when gripping an object• They give it a backing so the cells

do not distort to the point where they are not able to hold the object

Nails

• The nail body is the visible portion of the nail that covers part of your finger• This part of your finger that is

covered by the nail body is the nail bed• The nail hyponychium occurs at the

far distal edge of the nail and provides a seal to protect the nail bed• This part of your body requires

protection due to the amount of physical damage that It can and will receive over its lifetime

Nails

• The nail grows from an area called the nail root• The nail root is an epidermal fold

that is not visible from the surface• The deepest portion of the root

lies very close to the bones in the fingers and toes• The cuticle is a section of nail root

that comes over the exposed surface of the nail

Nails

• The condition of nails often tells a story of the health of an individual• Persons that have yellowing nails

might have various disorders that can inhibit or damage the nails during development• Other signs of problems are

pitted nails or nails that are concave as opposed to convex

Sebaceous Glands

• Found within the skin there are two major exocrine glands• These glands are used to

lubricate/hydrate the skin and maintain levels of temperature• Sebaceous glands are glands

that discharge an oily secretion • Sweat glands are designed to

release a

Sebaceous Glands

• Sebaceous glands are linked to a hair follicle • This means that they share their

opening to the skin with a follicle of hair• They produce a large quantity of

lipids that will dump onto the hair as it grows and the surrounding skin

Sebaceous Glands

• The mixture of lipids that are produced is called sebum• Sebum is made of cholesterols,

triglycerides, proteins and electrolytes• It serves many purposes• It inhibits microbial growth• It lubricates and protects the hair

shaft• It lubricates and protects the skin

Sebaceous Glands

• Sebaceous follicles are large sebaceous glands that are not associated with hair follicles• These are located mostly on the

face, back, chest, nipples and genitals• These are most active during

fetal development and during puberty

Sweat Glands

• There are two main types of sweat glands• Apocrine sweat glands are

secrete their products onto hair follicles• Merocrine sweat glands

discharge their products onto skin

Sweat Glands

• Apocrine sweat glands are coiled under the skin• They are located in the arm pits,

around the nipples and in the genitals• They produce a sticky and oily

secretion• They start producing at puberty

and will continue for the rest of your life

Sweat Glands

• The sweat produced by these glands is rich in nutrients and can be a good source for bacteria• This tends to create a large

amount of odor• Several different methods can be

used to neutralize these odors, however many can have side effects

Sweat Glands

• Merocrine sweat glands will produce a very watery sweat that is dumped directly on the surface of the skin• These sweat glands are designed

to help cool the surface of the skin• This robs heat from the body

and will cool the body quickly

Demo

Sweat Glands

• The sweat produced by these glands is around 99% water• Small amounts of other chemicals

are in the sweat • NaCl is the most major

• It functions to cool the skin• It also helps dissolve/dilute other

harmful chemicals that can be on the skin• It also helps excrete water or

electrolytes to maintain homeostasis

Video

• https://www.youtube.com/watch?v=IAAt_MfIJ-Y