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2.6.1 Function and physiology of nails

Nails are very tough sheet of keratin growing from the epidermis of the dorsal surface of

the toes and fingers. They are another form of skin appendage. Nails protect the distal tips of the

fingers and toes, enable the fingers to grasp very fine obects, increase the sensitivity of the digits,

as well as increase the stregth of the fingers and toes. !n addition, the condition of the nails also

reflects the health of the body.

!n healthy individuals, nails grow by about ".1#".1$ mm per day. The growth rate varies with

the individual, being faster in children and young people, and slower in older people. The growth rate

is also different between toes and fingers, with finger nails growing faster than toe nails. There are

also seasonal growth differences with faster growth in summeer and slower growth in winter.

2.6.2 %tructure and composition of nails

Fig.2.1& shows the stucture of nails. 'hat is generally called the nail, is actually the nail plate.

The nail is e(uivalent to the horny layer of the skin. !t has no living cells, is composed of very

tough keratin and is formed of closely#linked sheets of keratin cells. Fifs. 2.1$ and 2.16 show

scanning electron micrographs of the outer surface and cross section of the nail and the layered

stucture is clearly evident

!n comparison to the horny layer of the skin, the nail has a lower lipid content of ".1$#".)$*.+n the other hand, the sulfur content of * is relatively higher than that of the skin keratin. -lthough

the form of the nails is different from that of hair, since the proteins from which this is composed

are the same, the amino acids in nails are very similar to those of hair in comparison to the horny

layer of the epidermis.

ike hair, the nail is produced by the nail matri/. The nail grows out over the nail bed

towards the fingertip

.

Fig. 2.1&.

%tructure of a nail.

Fig. 2.1$.

%canning electron

micrograph of the

outer nail surface

Fig. 2.16.

%canning electron micrograph of

nail cross#section

The nail bed supplies water to the nail and plays a role in ensuring that the nail grows along

the nail wall 0described below in a fi/ed direction. The nail separates from the nail bed at the free

margin of the nail and since water is no longer supplied from bed to the nail at this point, the water

content falls, e/plaining why the free margin of the nail is easily broken.

The milky#white half#moon shape at the root of the nail is called the lunula. The nail at thispart is not fully keratinied. !n comparison to other parts of the nail plate, the lunula is softer and is

not in complete contact with the nail bed

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The parts of the skin surrounding the nail are called the nail wall. The root of the nail is called

the back nail and the sides are called the side nail walls

The skin touching the nail at the root of the nail is called the eponychium. !ts role is to protect

the imperfectly#formed nail. 'hen the eponychium is missing, the nail is often scarred and the

newly#formed nail shows abnormalities.

The nail matri/ contains melanocytes which produce melanin pigment and there are small

amounts of melanin in the nail.

2.6. 3hysical characteristics of nails

Nails contain from $* to 2&* water depending on the e/ternal environment. ike hair, they absorb

and lose water (uite easily.

'hen nails absorb water, they swell in volume and the thickness changes more than the

lenght and witdth. This is believed to be result of the layered construction seen in

The change in the toughness caused by water absorption and loss is the same as that of

hair becoming softer with water absorption and brittle with water loss. The tendency for nails to

break easily is the result of our daily lifestyle such as bathing and washing each day

Fig. 2.16. %canning electron micrograph of nail cross#section

2.6.&. Nail damage

Nail damage is very common, split nails in which the free margin of the nail looks like mica is

called onychoschisis.

+ne cause of splitt nails at the free margin is reduced water content due to the inability of

the nail bed in this area to supply water to the nail.

-nother physical cause is e/cessive use of nail enamel and enamel remover, which cause

water and lipid loss, as well as l ipid loss due to e/posure to soap and detergents. 4onse(uently,

when using nail enamel and remover, it is important to choose products that take lipid and water

loss from the nail into consideration and to use naiol treatments as part of the daily care routine

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2.1".1. Functions and types of manicure preparations

ike hair, nails are modified epidermal tissue and have keratin, a type of protein, as their main

constituent. Their main purpose is to protect the area at the ends of the fingers and toes. 5ealthy

nails grow at an average rate of about mm per month. anicure preparations are cosmetics

which protect the nails and make the fingers look attractive. Fig. 2.2 shows the order in which

manicure products are used along with their purposes, while table 2.) highlights the different types of

nail care products and their functions.

Nails vary from person to person, they are thick, thin, large, small, long, short, flat or curved

and their physical properties vary also. Nail hardness depends on the water content of the nail plate

and composition of the keratin forming it. 7enerally speaking, children have soft nails which have high

elasticity whereas adults have harder nails which break more easily

3urpose 8+rder of use9

Nail care 4are of nails and finger tips ########

####

Nail care product

:ase 4oat Fills in the grooves in the nails!mproves adhesion

############

:ase coat

;namel 4olors the nail ########

####

Nail enamel

Top coat ;nhances luster, durability ########

####

Top coat

Nail dryer %peeds up drying and gives a

luster to the nail enamel

########

####

Nail dryer

;namel remover

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2.1".2.1. =uality re(uirements for nail enamel

01 !t should have a viscosity permitting easy application to the nails

02 !t %hould dry#(uickly 0#$ min. and form an even film

0 The film should not be cloudy or have pin holes in when dry

0& 3igments should be evenly dispersed and the prescribed color and luster should be

maintained

0$ The nail enamel should adhere well and not come off during daily activities

06 !t should be easy to remove with enamel remover and come off cleanly, it should not

damage the nails or be to/ic to them

2.1".2.2. ain ingredients of nail enamel

Film formers

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2.1".$.0&. Nail 3olish

Nail polish is applied to the nails and then they are polished in with charmois leather to keep them in

a helathy condition by filling in the grooves, making them smooth and giving them a shine. !t also

makes the enamel film more durable and gives the nails a greater luster. The main ingredients are

inorganic powders and small (uantity of pigment is used to give the nails a healthy color. !t comes in

powder, paste or compact form.

2.1".$.0$. +ther manicure preparation

;/ample of other manicure products are nicotine remover and nail bleach, a similar product, for

making the nails whiter. %uch products are not seen on the market any more.