BIOLOGICAL EQUILIBRIUM

Balance in Body System

Equilibrium is the maintenance of the body’s balance. Balance is controlled by three interacting parts of the nerve system; the visual organs, the vestibular apparatus of the ear, and the mid brain. The vestibular system is the most important, but even without it, body orientation in space could still be maintained through information supplied to the brain from visual cues and nerve endings and position of the body.

The vestibular system consists of a membranous labyrinth of delicate structure containing sensory and supporting cells. There are two saclike structures –the utricle and the saccule - and tree semicircular canals. These structures are filled with a specialized fluid. this labyrinth is encased within a larger, bony labrint that also is filled with fluid.

Utricle and Saccule

Two types of sensory hair cells are found in a section of the wall, called a macula, in both the utricle and saccule. Vestibular hair cells, which a contain a single motile hair, the kinocilium, and multiple stereocilia, are embedded in a gelatinous material, called a cupula, that contains a mass of calcium carbonate crystal, called a otolith. An otolith forms a weighted mass above the sensory cells; movements of the mass deflect the sensory hairs and thus trigger neural activity.

The utricle is particularly sensitive to linear acceleration such as vertical or horizontal movement. The saccule’s function is not completely understood.

ENZYME

Enzim as Catalyst

Various kind of protein molecules known as enzyme serve to accelerate, or catalyze, the chemical reactions of living cell. Without enzyme, most biochemical reactions would proceed to slowly to effectively carry on life processes.

The manufacture of these enzymes is regulated by the cell’s genetic material, deoxyribonucleic acid (DNA) through the process of protein synthesis. The potential of a cell to grow and divide is determined largely by the number and different kinds of enzyme it contains. Certain cell also perform specialized function, such as transmitting nerve impulses or producing hormones, that are regulated by enzyme. Several hundred different reaction may proceed simultaneously within a cell, each one catalyzed by one or more enzymes.

Enzymes differ from in organic catalysts, such as platinum and palladium, in two important ways; the sequence of amino acid in an enzyme molecule is specific that enzyme and essential for the molecule’s catalytic action only on specific substance in specific reaction. A nonbiological catalyst, by contrast, catalyzes, a wide variety of chemical reactions.

Catalysis of Reaction

The defining property of all catalysts is that they increase the speed of chemical reaction without being used up or appearing as one of the product of the reactions.

Before the end of the 19th century, chemist understood that molecule must obtain extra energy before they can interact. The extra energy, or energy of activation, may be supplied when one molecule collides with another, or it may be supplied by an external source of energy, such as heat or ultraviolet radiation. The primary barrier to interaction , therefore, is the energy of activation, which is some times called the energy barrier.

The Higher the energy barrier, the fewer the molecules that will pass over it, and thus the slower the rate of reaction.

In 1889 the Swedish chemist Svante Arrhenius suggested that a catalyst (C) acts as follow ; it first forms intermediate compound (CS) with the reactant, or substrate (S) . The compound (C) then enters a so called transition state, which presents a lower energy barrier to chemical reactions; finally (CS) decomposes into (C)catalyst, whish is unchanged, and the product, of the raction again and again.

If the word catalyst is replace by the word enzyme (E), the fundamental equation of enzyme catalyst is:

E + S ó ES -> E + P

This equations is often called the Michaelis-menton equation. And ES is called the Enzyme-substrat complex, enzyme reduce the activation energy, or energy barrier, for a biochemical reaction . Enzyme are far more effective then inorganic catalyst in reducing activation energies; thus, they permit biochemical processes to take place at temperatures compatible with life.

HEREDITY

Heredity Factor

Heredity is the transmission from one generation to the next of factors that determine the traits of offspring. The development of the understanding of how these factors are inherited is the focus of this article.

Early History.

The Greek philosopher Pythagoras postulated that all traits of an offspring are derived solely from its father’s semen. Aristotle thought that female also produce semen and that embryo is formed by a fusion of both types of semen. He further postulated that both male and female semen are produce by the body’s blood.

Until the 17th century, European medical school thought that hereditary factors in semen were derived from vapors emanating from each body organ. Antony Van Lewenhook, however, viewing human semen through his miscroscope, saw ‘animacules’ . It became generally accepted that sperm were the actual carries of hereditary factors from male to their offspring.

Other biologist studied the ovaries of animal, note the presence of swollen bodies-which they correctly assumed contained eggs –and hypothesized that these eggs were also units of transmission of hereditary factors.

Some biologist of the 17th and 18th centuries believed they saw miniature individuals in sperm or eggs, which led to the doctrine of preformation. According to this theory all parts of an adult are already formed at the beginning of embryonic life, but are formed during the developmental period. His doctrine of development, known as epigenesist, has been substantiated by countless observations and experiments.

It is important to note that the biologist who disproved preformation and advanced the idea of epigenesist 200 years ago still held beliefs similar to those of the ancient Greeks on the origin of the hereditary material. The 18th century scientist thought that the individual body organs produced tiny particles that had the potential parent. These biologist postulated that the articles that the particles from the various organs would be transferred to either sperm or egg, which, upon fusing, would have the potential of forming a total individual.

BIOLOGICAL CLOCK

Human Biological Clock

A biological a clock is a self–sustained- internal timing mechanism that controls cyclic pattern, or rhytms, of a living organism. By providing temporal information , such as the time of day, month, or season, nearly all organism are adapted to event in both their internal or external environments. The product of this internal timing are physiological or behavioral even that, over time , vary in intensity.

Such biology time - dependent variability is expressed as a rhythm, or oscillation, with frequency equal to that of the underlying biological clock. Rhythms that occur more than once a day are called ultradian rhythm; one a day circadian; once a lunar day, lunar; and a once of year, circanual.

Ultradian Rhythm

In some cases the frequency of an oscillation may be high, or, conversely, the period of the oscillation may be brief. Certain rhythms of brain associated with sleep can occur with frequency of approximately seven cycle per second. Another ultradian rhythm is the release of luteinizing hormone from pituitary gland of male mammal. This chemical, wich helps maintain reproductive activity of the testes, is release from the pituitary of male in pulses approximately 1-2 hours a part throughout the day.

Circadian Rhythms .

Circadian rhythms correspond to the solar day (24 hours). These are most pervasive rhythms, regulating the temporal spacing and organization many even for every day in the lives of most living organism.

It is more natural for circadian rhythms to be synchronized to an external time giving stimulus than to exist in the free running state. In theory external time giving stimuli may be any rhythmically occurring events, for example, temperature, barometric pressure, gravitational change, or other cues that impinge on the organism.

In reality, however, only the external stimulus is important for most organism.

Lunar Rhythms are exemplified by the patterning of locomotor activity in fiddler crabs that, under constant laboratory conditions, exhibit an activity rhythms of 24 hours , 50 minute -the lunar day. The rhythms patterning of the crabs, activity is synchronized with daily low tides that are caused ultimately by the gravitational effect of the moon, although the laboratory has no water movements or light from the sun or the moon.

The Circannual Rhythms theoretically consist of a series of stages called interval timers. Each stage requires a fixed a mount of time and lead to the next stage.

In many species of animal a nerve pathway from the eye to region of the hypothalamus , the suprachiasmatic nuclei, allow light to exert internal synchronization. This region of the brain has been shown to be necessary for rhythmicity and entrainment of several forms of behavior. When the nuclei are destroyed, the rhythmic release of ACTH, an activating hormone from the pituitary stops. Thus, these nuclei appear to be at or near the top of the hierarchical control of bodily circadian rhythms, and they may be the site of predominant circadian rhythms clock in mammal, acting as a pacemaker for other body clock or biologist clock.

POPULATION BIOLOGY

Population of Biology

Population biology is the biology study of factor involved in the stability, variability, and density of populations of plants or animal. Among such factors are predator-prey relationships, birthrates, death rates, food supply, migration pattern, age and sex distribution relationships between members of different species living in the same species, in the same area , cooperation and competition among members of the species.Genetically controlled behavior pattern, and environmental influence. Population biologists attempt to develop general mathematical models that incorporate the many factors regulating the size and density of population. The Equations are useful for predicting in a given population.

Population dynamic seeks to describe changes in population densities and explain these change in term of underlying biological forces. It is the basis of an ecological patterns and is also necessary to solve problem of human economy, such as biological conservation, pest management, and optimal harvesting of wild life population. A population comprises the organism of a single species in defined region- for example, the yellow fever mosquitoes Aedes aegypty in Singapore. For meaningful scientific analysis, the region over which the population is defined should be small enough that all of organisms have the potential to interact; for example, they could interact sexually or by fighting.

Density. The first problem addressed in population study is the measurement of density. Only a few populations, such as human and large mammalian grazers, can be counted completely , but often a complete census can be taken of some life stage or subclass of a populations.

Normally some kind of statistical sampling of small areas within the region is required. Finally, for some species, such as those which lived in or under the ground or which are active at night, only a relative index of density can be obtained. These estimated can be made from the various products of their activity-track, excrement, pelts of kills, discarded shells, tailings forms burrows, and vocalization.

Systematic and Evolution

Schematic of Biology

Modern nomenclature based on a practical binomial system originated with Carolus Linnaeus. In addition to arranging plants and animals into genus and species based on structure, he introduced the categories of class and order. In 1817, Georges, Baron Cuvier, become the first to divide the entire animal’s kingdom into subgroups, for example, vertebrate, mollusca, articulate, and radiate.

During the 18th and 19th centuries numerous biological expedition were organized. On perhaps the most famous voyage, Charles Darwin circumnavigated (1831-36) the globe on the Beagle. His observation of birds, reptiles, and flowering plants in the Galapagos Island in 1835 laid the foundation for his theories on evolution.

The Discovery of Microorganisms

Argument about the spontaneous generation of organisms had been going on since the time of Aristotle. Louis Pasteur clearly demonstrated in 1864 that no organisms emerged from his heat sterilized growth medium as long as the medium remain in sealed flasks, thereby disproving spontaneous generation. Based on Edward Jenner’s studies of smallpox, Pasteur later developed a vaccine for anthrax and in 1885 became in the first to successfully treat a human bitten by a rabid dog. Beginning in 1876, Robert Koch developed pure culture techniques for microorganisms. His work verified the germ theory of disease. One of his students, Paul Ehrlich, developed chemotherapy and in 1909 devised a chemical cure for syphilis.

The value of antibiotics became evident when Sir Alexander Fleming discovered penicillin in 1928. Many additional antibiotics have since been developed, and their use has resulted in a decreased incidence of most infectious diseases.

History of Biology

History of Biology Last Few Century

As a science, biology did not develop until the last few centuries BC. Although hippocrates, known as the father of medicine, influence the development of medicine apart from the role in religion, it was Aristotle who established observation and analysis as the basic tools of biology.

From the 3rd century BC to the 2d century AD, studies primarily focused on agriculture and medicine. The Arabs dominated the study of biology during the middle ages and applied their knowledge of the Greeks discoveries to medicine.

The renaissance was a period of rapid advances. In the 15th and 16th centuries. Leonardo da Vinci and Michelangelo became skilled anatomists though their search for perfection in art, Andreas Vesallius initiated the use of dissection as a teaching aid. In the 17th century, William Harvey introduced the use of experimentation in his studies of the human circulatory system. His work marked the beginning of mammalian physiology.

Lack of communication was a problem for early biologists. To overcome this, scientific societies were organized. The first were in Europe, beginning with the Academy of the Lynx (Rome, 1603). The Boston Philosophical Society, founded in 1683, was probably the first such society to be organized in colonial America. Later, specialized groups organized themselves, among them the American Association for the Advancement of Sciences founded in 1848.

Another important development of the 17th century began with the invention of the microscope by Galileo Galilei about 1610. Microscopy originated in 1625 when the Italian Francesco Stelluti published his drawings of a honeybee magnified 10 times. The 17th century produced five microscopists whose works are considered classics.