The skin is composed two major types of skin glands. Sweat or sudoriferous glands are simple glands that show a characteristic shape of a tube and produce sweat through different mechanisms. Merocrine or eccrine sweat glands are essential in maintaining the temperature of the human body. There are approximately 3 million sweat glands distributed across the body (Balin et al., 1997). The region that produces the sweat is known as the tubulus while the primary excretory duct is circularly condensed and situated along the perimeter of the dermis and the hypodermis. Cuboidal or low columnar epithelial cells line the epithelium of sweat glands. There are two types of epithelial cells in sweat glands. The light type epithelial cells produce watery sweat while the dark type of epithelial cells produce a thick secretion, like mucous. Merocrine sweat glands drain their secretions out to the exterior of the skin.
Apocrine sweat glands are normally located in the axillary regions of the human body. These sweat glands are activated by sexual hormones which are developed during puberty. The product of apocrine sweat glands is similar to what is generated by merocrine sweat glands. However, a bigger lumen is present in the tubulus of apocrine sweat glands hence these sweat glands are bigger than merocrine sweat glands. In addition, the sweat produced by apocrine sweat glands is milky, odorless and rich with proteins. Should an odor be present in the sweat of apocrine glands, this is due to the action of bacteria that are present in these areas of the body. Apocrine sweat glands have excretory ducts that are connected to hair follicles. Ceruminous sweat glands on the other hand are located in the epithelia of the ear and these produce a modified type of sweat which is otherwise known as ear wax. Mammary sweat glands are situated in the breasts of the human body and secrete milk.
The second major type of skin glands are the sebaceous glands. These glands are present throughout the body except in the palms of the hands and the soles of the feet because these areas do not have hair. Sebaceous glands secrete sebum, an odorless fatty material that produces odors upon bacterial degradation, is incorporated in the hair follicles. Sebum functions as protection for the hair and skin, as well as bacterial infection.
Eczema and psoriasis are diseases of the skin that generally needs immediate medical attention. However, it is important the eczema and psoriasis are differentiated from each other so that the proper treatment regimen can be administered by a physician. In terms of timing of infection, psoriasis often observed among adults, while eczema is generally seen among children. However, if eczema is not treated properly, this skin disease may be carried on by an individual until his adult years. These two skin diseases have different causes. Eczema is usually caused by environmental insults such as contact with items that are composed of abrasive chemical constituents. Psoriasis, in the mean time, is normally caused by biological factors that are present within the human body. Eczema may also be caused by particular kinds of food hence a practical measure to prevent future eczema outbreaks is to refrain from eating the same particular food type that caused the reaction.
The appearance of eczema and psoriasis are usually the same, wherein both show characteristic patches that are also inflamed and uncomfortable because these cause itchiness (Brynie, 1999). However, there are minor differences between the two skin diseases. Psoriasis patches are often raised with red spots that are rough in texture. In addition, these spots and patches generally flake as they cause itchiness. Eczema, on the other hand, looks like typical dry skin, yet it is also itchy but does not show any flakiness.
These two skin disorders are treated with topical ointments, yet each skin disorders can only be treated with a specific active ingredient. Hence it is important that a correct diagnosis is performed with regards to these two skin diseases.
Classification of skin tumors is based on whether or not a tumor can expand to the rest of the body by invasion and metastasis, or uncontrolled proliferation of cells. A tumor is thus classified as benign if it is determined that it can not spread out to the rest of the organs of the body through invasion or metastasis. It is thus known that benign skin tumors will stay in the same place and these often grow at a very slow rate. In cases wherein the benign tumor is of substantial size, the adjacent organs are often subjected to pressure from the significant size of the benign tumor and this affects the normal activities of the adjacent organs. The pressure causes hindrance of the blood vessels, nerves and the entire organ itself that it is a common medical practice is to surgically remove a benign tumor and this procedure often results in the total eradication of the tumor cells.
Malignant skin tumors, on the other hand, have the capability to spread to the other parts of the body through the process of invasion and metastasis. The term cancer is thus generally used to pertain to malignant tumors. A malignant tumor poses a more serious health problem than a benign tumor because the tumor cells are known to travel to other parts of the body. This occurs when metastatic cells in the skin tumor travel through the blood or the lymphatic system and end up in the other organs of the body such as the liver or the brain. The malignant tumor cells that reach the liver are thus categorically known as metastatic melanoma because these cancer cells originated from a malignant skin tumor that re-emerged in the liver (Kenet and Lawler, 1998). These metastatic melanoma cells can interrupt normal functioning of the liver and any other organs that these have invaded. Such invasion are generally deleterious.
There are two types of twins. Fraternal twins pertain to the fertilization of two separate eggs that were ovulated at the same time. On the other hand, identical twins arise from the splitting of a single fertilized egg hence these two eggs carry the same DNA sequence. Identical twins appear to be exactly the same in features, as well as in the sex. On the other hand, fraternal twins will show some similarities in terms of features, but they may or may not be of the same sex. Hence it is possible to see fraternal twins that are composed of one boy and one girl.
Ultrasound detection is a procedure that is generally employed in prenatal screening (Pharoah, 2006). Identical twins are often observed through ultrasound as encapsulated in one single sac. In other cases, identical twins may also be observed ultrasonographically as two separate sacs with one or even two placentas. Hence, the determining factor in generating identical twins remains mainly on the timing when the fertilization egg was cleaved into two identical eggs. In terms of fraternal twins, ultrasound results will always show two sacs and two placentas because these twins originated from two ovulations and two independent fertilizations.
Pregnancy with identical twins is often observed to be more risky because there is a great chance that the twins may suffer from entanglement of the umbilical cord, causing fetal death. Pregnancy with fraternal twins is therefore less risky of cord entanglement because each fetus is individually encapsulated.
The integumentary system changes as an individual grows older. The epidermal cells of the skin are generally expected to decrease in their rate of proliferation. This slow down of skin cell division results in bigger and irregular features of the skin. In addition, the skin itself will look more translucent and thin and this age-related transformation commonly causes skin injuries, cuts, tears and infections. Ageing is also involved with modifications in the hormonal levels of the body, as well as changes in an individual’s lifestyle hence the components of the integumentary system are influenced by these changes. It has been observed that the healing time among elderly individuals takes twice the duration as that among younger individuals.
Ageing also influences the ability to reduce heat or temperature in the body (Turkington and Dover, 1998). This is mainly due to the lowering of the blood supply to the skin, as well as a decrease in the activity of sweat glands. Elderly individuals thus sweat less than younger individuals hence it is much more difficult for them to lower their internal body temperature when exposed to heat. Extended exposure times to warm temperatures may be an increase in the body temperature of an elderly individual and this may pose deleterious effects to them.
Elderly individuals also have a lower number of macrophages and other cells that play a major role in the immunity of the body. This often results in a greater risk for skin damages and skin infections. The production of melanin in the skin is also lower among elderly individuals hence they have poorer shielding capabilities from ultraviolet light, which in turn makes them more prone to sunburn and skin cancer. The decrease in the amount of melanin production also results in paler skin and the graying of their hair. Other elderly individuals have brown pigmentation in their skin, which shows that there are particular areas in the skin that abnormally increase their rate of melanin production when exposed to sunlight.
Elderly individuals also lose fat and collagen in their skin, which in turn results in the wrinkling and sagging of their skin. During the ageing process, sebaceous glands decrease their activity in producing sebum. There is also a decrease in the amount of sweat production, resulting in dry and flaky skin. The nails of elderly individuals are often hard and brittle because the fingernails have slowed down in terms of growth. It is also often observed among elderly individuals that toenails lose their color and become thick.
Different sensory receptors are present in the body. The sensory receptors for hearing are situated in the ear, which is composed of three major areas that are responsible for sound conduction (Ardley, 1992). The pinna, external auditory canal and the eardrum or tympanic membrane are outer ear structures that serve as the receptacle for sound. The ossicles and auditory tube are the middle ear structures that relay the vibrations that are received from the eardrum. The pressure created is equalized by the auditory tube. The cochlea, vestibule and semicircular canals are inner ear structures that are responsible for maintaining equilibrium to the rest of the body. The hearing receptors are situated along the membranes of the cochlea. In addition, the organ of Corti is another hearing receptor located in the cochlea that is activated by vibrations that come from the air, fluids and membranes. When there is an abnormal disturbance to the external and middle areas of the ear, hearing loss is experienced. In addition, if there is any damage to the nerve structures that are present in the ear, deafness ensues.
Taste or gustatory receptors, on the other hand, are located in the taste buds of the tongue. These are situated in the tongue because the mouth is the primary organ that interacts with food consumption. Four major taste sensations are present, including sweet, salt, sour and bitter. The taste receptors are significantly influenced by smell receptors, temperature receptors and feeling receptors. Hence it is interesting to know that an individual can feel so many sensations from the simple act of eating a particular food item.
The taste and smell sensory mechanisms are often interrelated. For example, cold food is often regarded as tasteless because the smell receptors are not stimulated during the act of eating cold food. Taste or gustatory buds in the tongue facilitate in the perception of only four major tastes, such as bitter, sweet, salty and sour. The body is thus dependent on the odor that is coming from the food to know that there is a certain taste associated with a particular food.
Upon ingestion of food, the smell or olfactory receptors which are situated above the nasal cavity detect the odor molecules that are present in the food. These olfactory receptors then transmit a signal to the brain that will relay the details of the food, including odor and taste (Alvin and Silverstein, 1992). In cases wherein an individual is sick with a cold, he then experiences thick mucous along his sinuses and nasal passages. The presence of mucous impedes the olfactory receptors to sense the odor molecules hence the sick individual often claims that the food does not taste well because his perception is blocked during his illness.
Another case can be observed when an individual attempts to have cold soup. This cold brew will give a different message to the olfactory receptors of the individual who is having the cold soup. The olfactory receptors will not be able to detect the aroma of the herbs and spices that were incorporated into the soup because it is cold, hence the individual will claim that the cold soup does not taste good.
Lacrimal fluid is produced by the lacrimal gland which is a simple tubular epithelial structure situated in the eyes. Lacrimal fluid, also known as tears, is composed of salts, proteins and the enzyme lysozyme. Lacrimal fluid is responsible for the delivery of nutrients and essential gases to the cornea. It is also important to the transport of waste products from the eye. It also facilitates in protecting the eyes from corneal infection and is essential in regulating the tonicity of the tear film. Lacrimal fluid is isotonic and is approximately equal to 0.9% saline (Ohashi et al., 2006). One interesting feature of lacrimal fluid is that the hydrophilic mucin layer of the tear film is generated by the epithelial goblet cells of the cornea, so that the tear layer to stay on the surface of the cornea and will keep it moist (Gipson, 2004).
The aqueous fluid, on the other hand, is secreted by the ciliary body of the eye, which is located behind the iris. The aqueous fluid permeates the eye through the structure of the ciliary body and moves between the lens and the iris. The fluid then is transported out of the eye through the trabecular meshwork, which is a tissue that serves as the drainage system of the eye. The aqueous fluid thus provides nutrients to the lens and cornea, as well as removes any waste products from the eye.
An individual’s hearing may be affected by extremely loud noise or by extended exposure to loud noise. Hearing loss is due to damages that have been inflicted in the components of the inner ear, including the hair cells, which are tiny sensory structures that are responsible in converting sound waves into electrical impulses that are sent to the brain. Hair cells are fully differentiated cells that do not have the capability of growth and reproduction once these are damaged. Noise-induced hearing loss may be experienced from a single intense sound such as an extremely loud explosion. Hearing loss can also be caused by exposure of an individual to loud noises for extended durations, such as playing in a rock band.
The ear is receptive to different levels of sound and this is measured through decibel units, which increased as a particular sound gets louder. The ticking of a clock is regarded as to be of approximately 40 decibels, which normal talking has been determined to be of approximately 60 decibels in loudness. Firecrackers are known to be of around 150 decibels in loudness. It has been determined that chronic exposure to sound that is above 85 decibels in loudness may result in hearing loss (Conlin and Parnes, 2007). Hence both intensity of the sound and exposure time are major factors that should be considered during testing for hearing loss. If an individual is only exposed for a few seconds, there is a small chance that hearing loss will result. But if the extremely loud noise lasts for months, the chance of suffering from hearing loss in the future will be greater.
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