Skin, Nails and Hair Flashcards
(40 cards)
1
Q
What is the name of system that comprises of the skin and its associated components such as the hair and nails?
A
Integumentary
2
Q
The skin is one of the largest _______ of the body, covering the majority of the outside area of the individual.
A
Organ
3
Q
What are the functions of the skin? (8)
A
- Provides a protective barrier between the inner body and the external environment. It offers the first level of non-specific resistance.
- Regulates temperature. Sweating and increasing the blood flow to the skin cools the body. Decreasing the blood flow to the skin, and raising the hair on the surface of the skin, insulates it.
- Provides sensitivity via the skin’s sensory nerve endings and receptors so that temperature, pressure and pain can be detected.
- Allows the excretion of water, heat, some toxic waste and small amounts of salt.
- Allows the secretion of sebum.
- Provides a reservoir of blood that can be used elsewhere if required.
- Synthesizes vitamin D when stimulated by ultra-violet light.
- Allows the absorption of certain substances, although it is generally impermeable.
4
Q
The skin is made up of three main layers. Name them.
A
The top layer of the skin is the epidermis** (epi- = above, dermis = skin). Under the epidermis is the **dermis**. The deepest part of the skin is the **subcutaneous layer (sub- = under, cutaneous = pertaining to the skin).
5
Q
Epidermis offers the body a _______(a)_________? There are no ___(b)____ or ____(c)_____.
The epidermis is composed of 4 types of cells and has 5 layers. This complex cellular structure allows new cells to be continually produced to replace those that get worn away and facilitates the healing of damaged skin. The new cells are produced in the deepest epidermal layer and then push up to the surface. The top layer consists of flat, dead cells that are continually shed but replaced.
A
Epidermis offers the body a _(a)_waterproof protective coating_There are no _(b)_blood vessels_ or _(c)_nerve endings_.
a) waterproof protective coating.
b) blood vessels
c) nerve endings
6
Q
The epidermis is composed of epithelium. The epidermal cells are closely packed and arranged in layers. There are 4 types of epidermal cell, name and describe them:
A
Keratinocytes
- make up about 90% of the epidermis.
- They produce keratin. Keratin is a protein that helps to waterproof and protect the skin.
- As cells make their way up through the epidermis, they form more and more keratin. By the time the cells reach the surface of the skin they are completely filled with keratin. This process is called keratinization.
Melanocytes
- Make up about 8% of the epidermis.
- Melanocytes produce melanin.
- Melanin is a brown-black pigment that contributes to skin colour.
- Melanocytes have long, thin projections that transfer granules of melanin to the keratinocytes.
Langerhans cells
- Originate in the bone marrow and migrate to the epidermis.
- they play a part in immune response because they have the ability to recognise certain antigens.
Merkel cells
- Are found in the deepest layer of the epidermis of hairless skin.
- They make contact with sensory neurons and are thought to have a part to play in the sensation of touch.
7
Q
Keratinocytes
A
- Make up about 90% of the epidermis.
- They produce keratin.
- Keratin is a protein that helps to waterproof and protect the skin.
- As cells make their way up through the epidermis, they form more and more keratin. By the time the cells reach the surface of the skin they are completely filled with keratin. This process is called keratinization.
8
Q
Melanocytes
A
- Make up about 8% of the epidermis.
- Produce melanin.
- Melanin is a brown-black pigment that contributes to skin colour.
- Have long, thin projections that transfer granules of melanin to the keratinocytes.
9
Q
Langerhans cells
A
- Originate in the bone marrow and migrate to the epidermis.
- They play a part in immune responses because they have the ability to recognize certain antigens.
10
Q
Merkel cells
A
- Are found in the deepest layer of the epidermis of hairless skin.
- They make contact with sensory neurons and are thought to have a part to play in the sensation of touch.
11
Q
In most areas, the epidermis is about _____ thick and consists of 4 layers. Where the skin is exposed to the most friction (e.g. soles of the feet and palms of the hands) it consists of 5 layers and is ______ deep.
Name the 5 layers from deepest to surface and identify the extra layer found in areas of friction.
A
a) 0.1mm
b) 1-2mm
Stratum basale, Stratum spinosum, Stratum granulosum, Stratum lucidum (extra) and Stratum corneum.
This graphic represents the 5 layers of the epidermis. The surface layer is the stratum corneum. The deepest layer is the stratum basale.
12
Q
Stratum basale
A
- (or stratum germinativum or basal cell layer) consists of just 1 layer of cells.
- It contains stem cells, melanocytes and Merkel cells (hairless skin only).
- The stem cells continually divide to produce keratinocytes, which push up towards the surface.
- Some stem cells migrate into the dermis and form sweat glands, sebaceous glands and hair follicles.
13
Q
Stratum spinosum
A
- or prickle cell layer.
- This layer consists of 8-10 layers of cells, closely packed together.
- The long, thin projections of melanocytes extend among keratinocytes. This enables the melanocytes to transfer melanin to the keratinocytes.
14
Q
Stratum granulosum
A
- (or granular layer)
- Consists of 3-5 layers of flattened keratinocytes, whose nuclei are in various stages of degeneration.
- These cells have begun the keratinization process. They contain granules of keratohyalin, a compound produced in the first step of keratin formation.
15
Q
Stratum lucidum
A
- or clear layer)
- This layer only exits in places where the skin is thickest, such as on the palms of the hands and soles of the feet.
- It consists of 3-5 rows of clear, flat, dead cells. These cells contain a substance, formed from keratohyalin, which is eventually transformed into keratin.
16
Q
Stratum corneum
A
- (or horny layer)
- The top stratum of the epidermis contains 25-30 rows of flat, dead cells.
- They are completely filled with keratin.
- These cells are continually shed and replaced by cells that are being pushed up from the lower strata.
- A protective barrier against light, heat, bacteria and many chemicals.
17
Q
- Under the epidermis is the dermis - the second major layer of the skin. The dermis is ___(a)___ than the epidermis, ___(b)__ and _______.
- It is composed of what?
- The dermis contains what?
A
- Under the epidermis is the dermis - the second major layer of the skin. The dermis is _(a)_thicker__ than the epidermis, _(b)_tough_ and _elastic_.
- The dermis is composed of connective tissue,
- The dermis contains: collagen (a protein) and elastic fibres. Also blood vessels, lymph vessels, nerve endings, sebaceous (oil) glands, sweat glands and ducts, hair follicles and hairs.
18
Q
- The upper portion of the dermis is called the ? Describe:
- The lower portion is called the ? Describe:
A
- Papillary region.
- It consists of connective tissue that contains fine elastic fibres.
- The papillary region is characterized by small, finger-like projections called dermal papillae that indent the epidermis. Dermal papillae can contain loops of capillaries and nerve endings that are sensitive to touch.
- Reticular region.
- It contains connective tissue and a network of collagen fibres and coarse elastic fibres.
- These fibres provide the skin with strength, extensibility and elasticity.
- The reticular region contains the hair follicles, nerves, sebaceous (oil) glands and ducts, and sweat glands.
19
Q
- Sweat glands play an important role in ________________.
- Sweat, containing a mixture of _______________________ _____________________________,
- is secreted from the ___________ and
- travels up the ____ _______.
- When the duct reaches the surface of the epidermis it forms a ___ from which the sweat is released.
A
- Sweat glands play an important role in _temperature control_. They release sweat which removes heat from the body.
- Sweat, containing a mixture of _water, salts, urea, uric acid, amino acids, ammonia, sugar, lactic acid and ascorbic acid_,
- is secreted from the _coiled gland_ and
- travels up the _sweat duct_.
- When the duct reaches the surface of the epidermis it forms a _Pore_ from which the sweat is released.
20
Q
There are two types of sweat gland, name them & describe:
A
Eccrine glands
- Most sweat glands are eccrine.
- They release the sweat directly onto the surface of the skin.
- They are distributed throughout the body except for the lips, nail beds and parts of the external genitals.
- They are most numerous on the palms of the hands, soles of the feet and under the arms.
Apocrine glands
- open onto hair follicles and secrete a more viscous secretion than the eccrine glands.
- They are found mainly under the arms, in the genital areas and on the areolae of the breasts.
- begin to function at puberty and are stimulated during emotional stress and sexual excitement.
21
Q
- The subcutaneous layer connects the dermis to the underlying tissues (e.g. muscle or bone). It consists mainly of which two tissue?
- The subcutaneous layer also contains many ______?
- Pressure sensitive ____________ are also located in the subcutaneous layer.
A
- adipose and areolar tissue. Adipose tissue insulates, protects and is an energy store. Areolar tissue protects, supports and connects the skin to the underlying structures.
- subcutaneous layer also contains many blood vessels.
- Pressure sensitive nerve endings are also located here.
22
Q
There are a variety of skin colours. Skin colour is affected by the presence of three pigments:
A
Melanin
- is located mostly in the epidermis.
- It varies the skin colour from pale yellow to black.
- The more melanin the melanocytes produce and transfer to the keratinocytes, the darker the skin.
- Melanin-filled cells can cluster in patches to form freckles or, in older people, liver spots.
- Melanin is also a major contributor to the colour of the hair.
- Melanin absorbs ultra-violet (UV) light. When stimulated by UV light, melanin granules in the keratinocytes form protective shields over the nuclei, protecting the genetic material from being damaged.
- Exposure to UV light also increases melanin production. This both darkens the skin and further protects the cells.
Carotene
- Carotene is located mainly in the dermis.
- It is a yellow-orange pigment. The less melanin in the epidermis, the more the colour of carotene can be seen.
Haem
- Haemoglobin is found in red blood cells. It contains a red pigment called haem.
- As the blood flows through the capillaries in the dermis, the red colour can be seen, providing there is not too much melanin in the epidermis.
23
Q
The health and appearance of the skin is affected by:
A
-
Diet,
- nutritionally balanced diet helps the skin to grow and repair and therefore skin condition will be lost if essential nutrients are not available.
- If the body becomes dehydrated the skin becomes dry and toxins build up and so it is important to drink adequate amounts of water and avoid the excessive consumption of alcohol.
-
Lifestyle
- Like most other parts of the body, the skin will suffer in cases of sleep deprivation and excessive stress. The skin needs rest to regenerate and excessive tension can cause skin sensitivities and create lines.
- Exercise promotes circulation, increasing the supply of nutrients to the skin.
- Smoking has the opposite effect – it causes vasoconstriction and also releases chemicals that destroy vitamins that are vital to the health of the skin
-
Environmental factors,
- Skin damage can be caused by contact with various chemicals (such as detergents). These chemicals can remove the sebum from the skin and so cause dehydration.
- Skin condition can also be affected by the climate, air pollutants, and some medications.
- Ultra-violet radiation can cause serious skin damage. It can burn, dehydrate and damage the collagen and elastin fibres, resulting in wrinkling and sagging or serious skin conditions including cancer.
-
Skin type - there are 5 main types
- Dry -
- Oily
- Normal
- Sensitive
- Combination
- and, of course, Age
24
Q
Skin type - there are 5 main types:
A
Dry Skin
- Caused by underactive or inactive sebaceous glands.
- Usually has a dull appearance and it feels dry and itchy and may also be sensitive.
Oily Skin
- Caused by overactive sebaceous glands.
- The excessive quantity of sebum results in skin that has a greasy, slippery texture.
- Appears shiny and frequently has large, clogged pores.
Normal (Balanced) Skin
- The sebaceous glands produce sebum at a moderate rate, resulting in skin that is not too oily and not too dry.
- Normal skin looks consistently plump, moist, and vibrant.
Sensitive Skin
- Can be dry, oily or normal.
- Reacts excessively to environmental conditions and substances that it comes into contact with.
- When sensitive skin reacts, it becomes sore and may appear flushed.
Combination Skin
- Most people have more than one type skin - even on just one area of the body. Facially, for example, it is quite common to have oily skin around the forehead, nose and chin and normal or dry skin around the cheeks, eyes and mouth.
25
Sadly, no matter how hard we try, the body shows signs of age and the skin is no exception.
Young skin is thicker, smoother, moister and more elastic than mature skin. The skin is constantly ageing, but the effects become more noticeable in the late forties. In older skin, it takes longer for cells to migrate to the surface. Aged skin is less elastic, thinner, drier and is slower to heal.
As the skin ages, a number of changes occur: (7)
* Collagen fibres decrease in number and elastic fibres lose their elasticity, causing wrinkles and less springy skin.
* Langerhans cells decrease in number, reducing immunity.
* Sebaceous glands become smaller, leading to drier, broken skin that is more susceptible to infection.
* Sweat production decreases, increasing the likelihood of heat stroke.
* Melanocytes reduce in number and increase in size, resulting in grey hair and different skin pigmentation.
* Subcutaneous fat is lost, causing thinner skin.
* Hair and nails grow more slowly.
26
Nails are \_\_\_\_(a)\_\_\_\_\_ growths. They are plates of hard, clear, \_(b)\_\_\_\_\_\_\_\_\_\_ cells covering and protecting the tips of the fingers and toes. They grow \_(c)\_\_\_\_\_\_\_\_\_\_\_ throughout life. As well as protecting the digits, they aid \_(d)\_\_\_\_\_\_\_\_\_ by making it easier to handle small objects.
Nails are \_(a)\_**_epidermal_**\_ growths. They are plates of hard, clear, \_(b)\_**_keratinized_**\_ cells covering and protecting the tips of the fingers and toes. They grow \_(c)\_**_continuously_**\_\_ throughout life. As well as protecting the digits, they aid \_(d)\_**_dexterity_**\_ by making it easier to handle small objects.
27
1. The nail \_\_\_(a)\_\_ is the portion that is **visible**. Below this is the nail \_\_(b)\_\_, this serves to _ \_\_\_\_\_\_\_\_\_\_\_(c)\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_.
2. The \_\_\_\_\_(a)\_\_\_\_\_ is the growth that may **extend** past the end of the digit, and the \_\_(b)\_\_ is the part of the nail that is **buried** in the skin.
3. Skin overlaps the nail at the proximal and lateral edges of the nail to form the ____ \_(a)\_\_\_\_. A narrow band of epidermis extends from the proximal nail wall to the base of the nail. This is called the \_\_\_\_\_\_(b)\_\_\_\_\_\_. This sheds an epidermal layer of skin to the newly formed nail plate. This layer of non--living, almost invisible _____ \_\_(c)\_\_\_\_\_\_ is called the **cuticle**. The \_\_\_\_\_(b)\_\_\_\_\_\_ and the cuticle help to prevent \_\_\_\_\_\_\_\_\_(d)\_\_\_\_\_\_\_ from getting under the nail. This proximal skin is sometimes called the \_\_\_(e)\_\_\_\_.
1. The nail \_(a)\_**_body_**\_ is the portion that is visible. Below this is the nail \_(b)\_**_bed_**\_, this serves to \_(c)\_**_attach the nail to the underlying tissues_**\_\_.
2. The \_(a)\_**_Free edge_**\_ is the growth that may extend past the end of the digit, and the \_(b)\_**_root_**\_ is the part of the nail that is buried in the skin.
3. Skin overlaps the nail at the proximal and lateral edges of the nail to form the \_(a)\_**_nail walls_**\_. A narrow band of epidermis extends from the proximal nail wall to the base of the nail. This is called the \_(b)\_**_eponychium_**\_. This sheds an epidermal layer of skin to the newly formed nail plate. This layer of non--living, almost invisible \_(c)\_**_stratum corneum_**\_ is called the cuticle. The \_(b)\_**_eponychium_**\_ and the cuticle help to prevent \_(d)\_**_harmful substances_**\_ from getting under the nail. This proximal skin is sometimes called the \_(e)\_**_mantle_**\_.
28
1. The tissue on the lateral sides of the nail is called \_\_\_\_\_\_\_\_\_\_. This forms the lateral skin folds. The longitudinal indentation between the lateral skin folds and the nail forms the lateral **nail grooves** into which the nail appears to be embedded.
2. The epidermis that is located beneath the nail plate at the junction between the free edge and the skin of the fingertip is called the \_\_\_\_\_\_\_\_\_\_\_\_.
3. Most of the nail body appears pink because of the blood following through the capillaries below. There is, however, a whitish semi-circular area called the \_\_\_\_\_\_\_. This appears lighter because the stratum basale under the nail is thicker in this area and blocks the sight of the vascular tissue.
1. The tissue on the lateral sides of the nail is called \_**_PARONYCHIUM_**\_. This forms the lateral skin folds. The longitudinal indentation between the lateral skin folds and the nail forms the lateral nail grooves into which the nail appears to be embedded.
2. The epidermis that is located beneath the nail plate at the junction between the free edge and the skin of the fingertip is called the \_**_HYPONYCHIUM_**\_.
3. Most of the nail body appears pink because of the blood following through the capillaries below. There is, however, a whitish semi-circular area called the \_**_LUNULA_**\_. This appears lighter because the stratum basale under the nail is thicker in this area and blocks the sight of the vascular tissue.
29
1. The epithelium under the nail root is the \_\_\_(a)\_\_\_\_. It is here that Cells undergo \_\_\_(b)\_\_\_\_\_ to create nail **growth**. This area receives a rich blood supply and has nervous connections. The cells created by\_\_\_(b)\_\_\_\_ differentiate to form nail cells. The cells are pushed forward over the \_\_\_\_\_\_(c)\_\_\_\_\_\_. They \_\_\_\_(d)\_\_\_\_\_ and die to form the strong, hard nail.
2. Nail growth is determined by the turnover rate of the \_\_\_\_\_(a)\_\_\_\_\_. Nails grow continually throughout life but various factors, including \_\_\_\_\_List 6\_\_\_\_\_\_\_\_\_\_, affect the growth speed.
3. The finger itself also affects the nail growth. Generally, the \_\_\_a)\_\_\_\_\_ the digit the faster the nail grows.
4. Fingernails grow \_\_\_\_\_(a)\_\_\_\_\_\_\_ than toenails. It takes about \_\_\_\_(b)\_\_\_\_\_ for a fingernail to grow out, and about \_\_\_\_\_\_(c)\_\_\_\_\_\_\_ for a toenail to be replaced.
1. The epithelium under the nail root is the \_(a)\_**_nail matrix_**\_. It is here that Cells undergo \_(b)\_**_mitosis_**\_ to create nail growth. This area receives a rich blood supply and has nervous connections. The cells created by\_(b)\_**_mitosis_**\_ differentiate to form nail cells. The cells are pushed forward over the \_(c)\_**_stratum basale_**\_. They \_(d)\_**_kerantize_**\_ and die to form the strong, hard nail.
2. Nail growth is determined by the turnover rate of the \_(a)\_**_matrix cells_**\_. Nails grow continually throughout life but various factors, including \__1. **age** (slows with age) 2. **Season** (quicker in summer) 3. **Nutritional state** 4. **Trauma** 5. **Some medications** and 6. **Various diseases**_\_, affect the growth speed.
3. The finger itself also affects the nail growth. Generally, the \_a)\_**_longer_**\_ the digit the faster the nail grows. (The nail on the middle finger therefore grows faster, at about 0.1mm per day, than the nail on the little finger.)
4. Fingernails grow \_(a)\_**_3-4 times faster_**\_ than toenails. It takes about \_(b)\_**_6 months_**\_ for a fingernail to grow out, and about \_(c)\_**_18 months_**\_ for a toenail to be replaced.
30
Label the diagram:
31
1. Hair protrudes from the surface of the \_\_\_\_(a)\_\_\_\_\_\_. It is an epidermal growth, composed of \_\_(b)\_\_, \_\_\_\_\_(c)\_\_\_\_\_ cells.
2. The primary function of hair - called\_\_(a)\_\_ is \_\_\_\_\_(b)\_\_\_\_\_. Hair on the head protects the skin from sunlight. Eyebrows & eyelashes protect the eyes, and hair in the nostrils help to prevent foreign particles from being inhaled. Hair is also \_\_\_(c)\_\_\_\_. When the hair are raised, more air is trapped providing an \_\_\_(c)\_\_\_ layer.
1. Hair protrudes from the surface of the \_(a)\_**_epidermis_**\_. It is an epidermal growth, composed of \_(b)\_**_dead_**\_, \_(c)\_**_keratinized_**\_ cells.
The primary function of hair - called\_(a)\_**_pili_**\_ is \_(b)\_**_protection_**\_. Hair on the head protects the skin from sunlight. Eyebrows & eyelashes protect the eyes, and hair in the nostrils help to prevent foreign particles from being inhaled. Hair is also \_(c)\_**_insulating_**\_. When the hair are raised, more air is trapped providing an \_(c)\_**_insulating_**\_ layer.
32
1. The hair ____ is the portion of hair that **projects** from the skin.
2. The portion of hair **below** the skin is called the \_\_\_\_\_?
3. Surrounding the root is the \_\_\_\_\_\_\_\_. This consists of an **external root sheath** & an **internal root sheath**.
4. The external root sheath is a downward continuation of the epidermis. The internal root sheath forms a tubular covering between the external root sheath and the hair. The base of each hair follicle is enlarged and layered and called the \_\_\_\_.
1. Shaft
2. root
3. follicle
4. bulb
33
1. The bulb has an indentation at the bottom called the \_\_\_(a)\_\_\_\_. These contains _____ \_\_(b)\_\_\_\_\_\_ tissue. Blood vessels loop into the \_\_\_(a)\_\_\_\_ to supply nutrients to the follicle.
2. The bulb contains a ring of cells called the \_\_\_(a)\_\_\_. The cells in the \_\_\_(a)\_\_\_ are responsible for the \_\_\_(b)\_\_\_ of the exciting hair and produce ____ \_\_(c)\_\_ by ___ \_\_\_(d)\_\_\_\_\_ when the older hair is \_\_(e)\_\_.
3. As the cells push up the bulb they quickly fill with _____ & \_\_\_.
4. The follicles also have a \_\_(a)\_\_\_ supply. Root hair \_\_\_\_(b)\_\_\_\_\_ allow sensory information to be received when the hair is \_\_\_\_(c)\_\_\_\_.
5. Links to the _________ \_\_(a)\_\_ _______ facilitates the stimulation of the \_\_(b)\_\_\_\_ ______ muscle by motor neurons. The \_\_\_(b)\_\_\_\_ is a \_\_\_(c)\_\_\_\_ muscle that attaches to the side of the hair follicle. It contracts when the body is under \_(d)\_\_, ____ or \_\_\_\_\_\_\_\_\_\_- to pull the hair into an \_\_\_\_(e)\_\_\_ position.
1. The bulb has an indentation at the bottom called the \_(a)\_**_papilla_**\_. These contains \_(b)\_**_areolar connective_**\_ tissue. Blood vessels loop into the \_(a)\_**_papilla_**\_ to supply nutrients to the follicle.
2. The bulb contains a ring of cells called the \_(a)\_**_MATRIX_**\_. The cells in the \_(a)\_**_matrix_**\_ are responsible for the \_(b)\_**_growth_**\_ of the existing hair and produce \_(c)\_**_new hair_**\_ by \_(d)\_**_cell division_**\_ when the older hair is \_(e)\_**_shed_**\_.
3. As the cells push up the bulb they quickly fill with \_**_keratin_**\_ & \_**_die_**\_.
4. The follicles also have a \_(a)\_**_nerve_**\_ supply. **Root hair** \_(b)\_**_PLEXUSES_**\_ allow sensory information to be received when the hair is \_(c)\_**_moved_**\_.
5. Links to the \_(a)\_**_autonomic nervous system_**\_ facilitates the stimulation of the \_(b)\_**_arrector pili_**\_ muscle by motor neurons. The \_(b)\__arrector pili_\_ is a \_(c)\_**_smooth_**\_ muscle that attaches to the side of the hair follicle. It contracts when the body is under \_(d)\_**_stress_**\_, \_**_cold_**\_ or \_**_freightened_**\_- to pull the hair into an \_(e)\_**_upright_**\_ position.
34
1. A __________ gland is also connected to the follicle. These lie in the dermis and open into the neck of the hair follicles.
2. These glands secrete \_\_\_\_\_\_\_. Which is a mixture of fats, cholesterol, proteins and inorganic salts that prevent the hair from drying and becoming brittle.
3. This secretion \_\_\_\_(a)\_\_\_\_ the skin, \_\_\_(b)\_\_\_ it, \_\_\_(c)\_\_\_\_ the growth of some \_\_\_\_(d)\_\_\_\_\_ and \_\_\_\_(e)\_\_\_\_\_ excessive \_\_\_\_\_\_(f)\_\_\_\_\_\_\_ of water.
4. The vast majority of these glands are attached to \_\_\_(a)\_\_\_\_ but some secret directly onto the surface of the skin (e.g. On the \_\_(b)\_\_\_, the distal end of the \_\_(c)\_\_ and the medial ____ (d) \_\_\_\_).
5. Together \_\_\_(a)\_\_\_- and \_\_\_(b)\_\_\_ form a protective barrier referred to as the ___ (c) \_\_\_\_.
1. A \_**_SEBACEOUS (oil)_**\_ gland is also connected to the follicle. These lie in the dermis and open into the neck of the hair follicles.
2. These glands secrete \_**_SEBUM_**\_. Which is a mixture of fats, cholesterol, proteins and inorganic salts that prevent the hair from drying and becoming brittle.
3. This secretion \_(a)\_**_moisturises_**\_ the skin, \_(b)\_**_protects_**\_ it, \_(c)\_**_inhibits_**\_ the growth of some \_(d)\_**_bacteria_**\_ and \_(e)\_**_prevents_**\_ excessive \_(f)\_**_evaporation_**\_ of water.
4. The vast majority of these glands are attached to \_(a)\_**_follicles_**\_ but some secret directly onto the surface of the skin (e.g. On the \_(b)\_**_lips_**\_, the distal end of the \_(c)\_**_penis_**\_ and the medial \_(d)\_**_pubic labia_**\_).
5. Together \_(a)\_**_Sebum_**\_ and \_(b)\_**_sweat_**\_ form a protective barrier referred to as the \_(c)\_**_acid mantle_**\_.
35
1. The outer layer of the hair is called the \_\_(a)\_\_\_\_. This consists of a single layer of scale-like heavily \_\_\_\_\_(b)\_\_\_\_ cells that overlap.
2. The layer beneath the \_\_\_(a)\_\_\_\_ is called the \_\_\_(b)\_\_\_.
3. This forms the major part of the \_\_\_(a)\_\_\_. The elongated cells contain ____ (b) ____ in \_\_(c)\_\_ hair but mostly air in \_\_\_(d)\_\_\_ hair.
4. The inner part of the hair is the \_\_\_\_(a)\_\_\_\_\_. This consists of loose cells containing ______ (b) _____ with much air between the cells. The reflection of \_\_(c)\_\_\_ on these air spaces plays a part in determining the ____ (d) ____ and ___ (e)\_\_\_\_ of the hair.
5. Not all hair contains this \_(a)\_\_\_\_\_\_ and, when present, it may not run for the \_(b)\_\_\_\_\_\_\_ of the hair.
1. The outer layer of the hair is called the \_(a)\_**_CUTICLE_**\_. This consists of a single layer of scale-like heavily \_(b)\_**_keratinized_**\_ cells that overlap.
2. The layer beneath the \_(a)\_**_cuticle_**\_ is called the \_(b)\_**_CORTEX_**\_.
3. This forms the major part of the \_(a)\_**_shaft_**\_. The elongated cells contain \_(b)\_**_pigment granules_**\_ in \_(c)\_**_dark_**\_ hair but mostly air in \_(d)\_**_white_**\_ hair.
4. The inner part of the hair is the \_(a)\_**_MEDULLA_**\_. This consists of loose cells containing \_(b)\_**_pigment granules_**\_ with much air between the cells. The reflection of \_(c)\_**_light_**\_ on these air spaces plays a part in determining the \_(d)\_**_colour tone_**\_ and \_(e)\_**_sheen_**\_ of the hair.
5. Not all hair contains this \_(a)\_**_inner layer_** and, when present, it may not run for the \_(b)\_**_full length_**\_ of the hair.
36
Label the diagram
As below:
37
There are three main types of hair, what are they?
**_Lanugo_**
* Grows on the body of the developing foetus.
* Lanugo hair is soft, fine and lacks a medulla.
* It is usually shed about a month before birth, to be replaced by vellus hair.
**_Vellus_**
* Vellus hair is soft and downy.
* It covers the whole body except for the palms of the hands, soles of the feet, lips and parts of the genitals.
* Tends to lack pigment and a medulla, has a shallow follicle and a bulb that is not well developed.
* Hormonal changes can stimulate the development of the follicle and alter the hair produced from the soft, downy vellus to the stronger terminal hair.
**_Terminal_**
* Terminal hair is longer and coarser than vellus hair and contains pigmentation.
* The follicles are deeply seated and the bulb is well developed.
* Terminal hair is found on the scalp, under the arms, in pubic regions, on arms and legs, and makes up the eyebrows and eyelashes.
* Hormonal influences also cause facial and chest hair in men.
38
1. The growth of terminal hair is influenced \_\_\_\_(a)\_\_\_\_\_ by \_\_\_\_(b)\_\_\_\_, which changes hair growth in teenagers, \_\_\_\_\_(c)\_\_\_\_\_, during which hair growth may increase on certain areas of the body (particularly the abdomen), and the \_\_\_\_(d)\_\_\_\_\_, during which characteristic male hair growth may occur.
2. As well as \_\_\_\_\_(a)\_\_\_\_\_ influences, hair growth can also be affected by excessive _____ (b) \_\_\_\_, _____ (c) _______ (including race), \_\_\_\_(d)\_\_\_\_\_ and some \_\_\_\_(e)\_\_\_\_\_\_.
3. Hair loss may take place \_\_\_\_, due to factors such as skin damage and localised skin conditions.
1. The growth of terminal hair is influenced \_(a)\_**_Hormonally_**\_ by \_(b)\_**_puberty_**\_, which changes hair growth in teenagers, \_(c)\_**_pregnancy_**\_, during which hair growth may increase on certain areas of the body (particularly the abdomen), and the \_(d)\_**_menopause_**\_, during which characteristic male hair growth may occur.
2. As well as \_(a)\_**_hormonal_**\_ influences, hair growth can also be affected by excessive \_(b)\_**_stress_**\_, \_(c)\_**_hereditary factors_**\_ (including race), \_(d)\_**_illness_**\_ and some \_(e)\_**_medications_**\_.
3. Hair loss may take place \_**_topically_**\_(_in one place, not generally_)\_, due to factors such as skin damage and localised skin conditions.
39
1. Although the amount of air spaces in the hair can affect its colour, \_\_\_(a)\_\_\_\_ is primarily responsible for hair colour. It is synthesised by \_\_\_\_(b)\_\_\_\_\_ in the \_\_\_(c)\_\_\_ and is passed to cells in the \_\_\_(d)\_\_\_ and \_\_\_(e)\_\_\_.
2. Generally the more \_\_\_(a)\_\_\_ the \_\_\_(b)\_\_\_\_ the hair, but \_\_\_(a)\_\_\_\_ with more __ (c) ____ shows as blond or red hair.
3. As people age, \_\_\_(a)\_\_\_\_ production slows, causing the hair to appear \_\_(b)\_\_. \_\_\_(c)\_\_\_ hair results from the accumulation of air in the \_\_\_\_(d)\_\_\_\_\_.
1. Although the amount of air spaces in the hair can affect its colour, \_(a)\_**_melanin_**\_ is primarily responsible for hair colour. It is synthesised by \_(b)\_**_melanocytes_**\_ in the \_(c)\_**_matrix_**\_ and is passed to cells in the \_(d)\_**_cortex_**\_ and \_(e)\_**_medulla_**\_.
2. Generally the more \_(a)\_melanin\_ the \_(b)\_**_darker_**\_ the hair, but \_(a)\_**_melanin_**\_ with more \_(c)\_**_iron & sulphur_**\_ shows as blond or red hair.
3. As people age, \_(a)\_**_melanin_**\_ production slows, causing the hair to appear \_(b)\_**grey**\_. \_(c)\_**_white_**\_ hair results from the accumulation of air in the \_(d)\_**_medulla_**\_.
40
It may take a few months to several years for hair to become fully grown and then shed. Each hair develops at its own rate but will be at one of **three** stages of the hair growth cycle, name & describe them:
**_Anagen_**
* This is the active growing stage. Under hormonal stimulation the germinal cells in the matrix undergo mitosis to create new cells.
* The cells make their way up the follicle and differentiate to form the hair structure.
* They also keratinize and the hair eventually emerges through the surface of the skin.
* Can last a few months to several years.
**_Catagen_**
* When the hair is fully grown it no longer requires its connection to the papilla to receive a supply of nutrients.
* The hair separates from the papilla and moves slowly up the follicle.
* The follicle shrinks and some parts of the follicle break down or remain dormant until another hair is produced.
**_Telogen_**
* During the final stage of the hair growth cycle, the hair is shed from the shortened follicle and the follicle rests.
* This resting stage ends when the follicle is once again activated by hormones, triggering the growth of another hair.
