Research and Rationale Hair colouring is a chemical process involving a series of complex reactions between chemicals in the hair-colouring product with chemicals and biochemical in hair to change the hair colour. The chemicals prepare the hair to accept the hair dye, alter the hair shaft biology to maximize colour change and set the dye to make the colour change permanent.
The hair shaft is composed of two major components – the cortex (largely keratins) and the cuticle (made up of thin scales of dense keratin and a lipid coating). To change hair colour, the protective oils on the hair shaft have to be partially removed by a bleaching agent, commonly hydrogen peroxide that oxidizes the melanin pigment in hair, making it colourless. The most common chemical hair dyes used are para dyes, containing paraphenylenediamine (PPD) solutions which combine with hydrogen peroxide to create insoluble molecules which are contained within the cortex and are unable to pass through the cuticle layers, leaving colour to the hair., Due to the bleaching agent and ammonia present in dyes, changes in the structural keratins and protective oils make the hair shaft drier and more brittle, weakening the whole hair structure.
Natural substitutes have been explored to minimize the risk of side effects of chemical hair dyes. In fact, many natural agents like plants and minerals have been used for hair colouring for thousands of years. These agents contain natural bleaching agents that change hair colour by coating the hair shaft with colour. For example, henna (Lawsonia inermis) is a small tree growing to six meters high. Its colouring properties are due to the presence of lawsone, an organic compound that has an affinity for bonding with protein. This compound is highly concentrated in the leaf petioles and gives a red-orange colour. Natural hair dyes like henna are non-toxic but some believe that they are not necessarily safer or gentler than modern formulations as consistent results are hard to be obtained and allergic reactions may arise in different individuals.
Therefore, this experiment was aimed to compare the extent of damage to the hair shaft caused by natural and chemical hair dye. In this experiment, the extents of damage caused by respective dyes are compared in terms of their response to moisture in the air. Hair expands as air humidity increases and vice versa. Due to the damage by hair dyes, the ability of the hair strand to absorb water is affected.
The results from this study can be used to show that chemical hair dyes alter the hair shaft structure more than natural hair dyes. This proves that natural hair dyes are able to provide a non-toxic choice for hair dyeing that produces good results. Hence, this also eliminates the risks of harmful chemicals present in the chemical hair dyes whereby some carcinogenic chemicals believed to be present has become a great concern.
Experimental Hypothesis There is a significant difference between the damage to hair structure due to chemical hair dye and natural henna dye. Chemical hair dye causes more damage to the hair shaft structure compared to the henna dye.
There is no significant difference between the damage to hair structure by chemical and natural henna dye.
Manipulated : Types of hair dye
Responding : Mean length of hair extension
Fixed : Condition of hair strands before dye-ing, length of hair on hygrometer, humidity in bell jar, temperature of surroundings
Apparatus and Materials Apparatus
Boar bristle brush, plastic gloves, two 250ml beakers, hair colouring brush, glass rod
Pestle and mortar, sift, 10ml measuring cylinder
50g henna leaves, vinegar
Chemical Hair Dye
50ml permanent cream hair colour (Ingredients: aquq, stearyl alcohol, ammonium hydroxide, isostearic acid, oleth-10, propylene glycol, ammonium laurl ulphite, dehydrol 2409, merouat plus 3330, sodium ulphite, sodium erythorbate, tetrasodium edentate dehydrate, perfume, p-phenylenediaminesulfate), 6% cream peroxide
Wood piece (7.5cm X 20cm), plastic paper, 2 small nails, dime, tape, hammer, scissors, bell jar, two 100ml beakers, metre rule, vernier caliper
Hair strands (undyed, henna dyed and chemically dyed), distilled water
Planning Determining observation method
Occipital Lobe: Function in the Brain
The occipital lobe is the center for visual processing in the human brain. It is the smallest of the four lobes in the cerebral cortex and is located in the posterior region of the cerebral cortex. The occipital lobe is responsible for visuospatial processing and interpreting conscious visual percepts (Canevin et al). The purpose of this paper is to investigate any pathological diseases or damage that may affect the brain area, along with identifying the major neurotransmitters, and the different connections the occipital lobe has with other brain regions. Additionally, this paper will discuss the functional aspects of the occipital lobe.
The occipital lobe is not particularly vulnerable to injury due to its location at the back of the brain. Although, when damage does occur it presents a variety of symptoms ranging from hallucinations, illusions, the loss of vision, and the inability to recognize faces and objects.
Visual illusions often take the form of objects appearing larger or smaller than they really are. This is usually the first sign that there is an abnormality in the occipital region. Often patients experience more severe symptoms such as, visual hallucinations. Complex visual hallucinations are associated with right occipital injuries, tumors, seizures, and other abnormalities ( Benizky, 2001). Visual hallucinations may accompany many neurological and psychiatric disorders. Determining whether hallucinations are the result of damage to the occipital lobe or due to a psychiatric disorder requires an extensive assessment of the individuals past history. Further investigation provides insight into the subjective nature of visual hallucinations, and provides new theories of perception and recall.
Patients who have suffered damage to their occipital lobe due to a stroke may not experience any problems other than difficulties with their vision. Some of the symptoms include problems recognizing objects, loss of hand eye coordination, and visual reduction. Some patients may recognize the sound of something but not the sight. For instances, a patient can recognize a bell ringing by hearing it only, and not by visually seeing it.
To function properly the occipital lobe utilizes various neurotransmitters from a variety of brain regions. Many neurotransmitters are needed to accurately identify a potential threat and execute a reaction. The main neurotransmitter involved in the occipital lobe is serotonin. The functions of serotonin are numerous and appear to involve the control of appetite, sleep, memory, and learning. (Canevin et al). Numerous brain regions become activated when the occipital lobe sends visual information. Most important is the activation of the frontal lobe, which allows an individual to logically process the information. The neurotransmitter most associated with the frontal lobe is dopamine. Dopamine is responsible for motivation, cognition, punishment and reward. It is easy to see the relationship dopamine has on visual input (Anderson and Rizzo, 1994).The neurotransmitter dopamine plays a crucial role in positive reinforcement. Organisms are rewarded for behaviors and visual stimuli they perceive as positive. Positive reinforcement is the basis for all learning.
Because the occipital lobe is the visual processing center of the brain, it provides mental representations of reality, which is then processed and sent to other brain regions. For example, when a person sees a train coming at them, the occipital lobe interprets this information and sends it to the frontal lobe. The frontal lobe processes the information and motivates the person to react. Once this is accomplished, the information is sent to the cerebellum which produces the reaction to get out of the way.
The functions of the occipital lobe are numerous and extensive. First and foremost, the occipital lobe is the visual processing center of the brain, It creates a mental representation of visual stimuli. In addition, it regulates our sleep and synchronizes all the cerebral lobes. The occipital lobe produces delta brain waves and the neurotransmitter serotonin. Moreover, the occipital lobe is involved with the brain’s ability to recognize objects. The occipital lobe is not only responsible for visual recognition of objects but it also helps us differentiate between shapes. Identifying and interpreting different shapes such would be much harder if the occipital lobe did not function as it does.
Furthermore, the occipital lobe contains the primary visual cortex which is highly specialized in processing visouspatial information. The occipital lobe is divided into four extrastriate visual cortical areas which are identified as V1, V2, V3, and V4. Neurons in this area respond very well to visual stimuli within their field. Studies have shown that this area is responsible for conscious perception (Canevin et al). Each visual cortical area transmits information in two ways; the dorsal route and the ventral route. The dorsal pathway is associated with motion and object location. The ventral route is most associated with the storage of long term memory.
In conclusion, the occipital lobe is one of the most important structures of the cerebral cortex. It is highly specialized in recognizing shapes, faces, objects, and colors. The extremely complex interaction between the occipital lobe and other brain regions emphasizes the elaborate relationship that is required for visual processing. Without such a system it would be impossible to perceive reality in any meaningful way.
Anderson SW, Rizzo M (1994). Hallucinations following occipital lobe damage. The pathological activation of visual representations. J Clin Exp Nueropsychology ,16, 651-653.
Caveni, MP., Saeti, Sw (2001) Visuoperceptive Impairment in Adults with Occipital Lobe Epilepsy. Epilepsy and Behavior, 205-206.
Benzky, S., Ker, S.(2002) Complex Hallucination Following Occipital Lobe Damage. European journal of nuerology, 9, 175-176