God is the Light

God is the Light

Did you ever wonder what it would be like to be God? Einstein, whose genius unraveled space and time, presented the world with relativity physics that examined the characteristics of matter as they approached the speed of light. But this deeply spiritual man neglected to ask the important question, how does the world appear, if you are the light, which most religions believe to be God.

When you are the light, as outlined in Einsteins' equations above, you have the following characteristics:

• Your Energy, relative to matter that you are traveling by, is infinite
• Time, relative to matter that you are traveling by, is zero
• Your Mass, relative to matter you are traveling by, is infinite
• Your size, relative to matter you are traveling by, is zero

So the implications are profound. You are all powerful as your mass and energy are infinite and is contained in an infintismal point. You see from beginning to end, in a moment. This coorelates with many of our understandings of God.

The next thing to realize is that all of us are a subset of God. A significant fraction of the energy we all burn in form of calories is light, released by the process of metabolism. The light of God shines in all of us. This light is the carrier of intelligence for every atom in the universe. We "hear" the answers to our prayers through the light, whether from a loved one, a forest, an ocean, or the source of the majority of the light in our tiny solar system, the sun.

The Universe has One Voice.
The Language is not Words.
The Language is Love
Love speaks in the Waves of Vibration,
the Language of Light and
the Language of the Heart.
Love is the Language of the Heart
And the Language of Love is the Light
But Always it is One Voice
The Voice of Our Past Speaking Through Us.
The Voice of Our Future Waiting to Embrace Us
It is One Infinite Voice
One Blood
One Body
One Earth
Forever
One PainOne EvilOne Loss,One Fear.
Forever
We are Here as One
To Be Love
To Be Light
To Be One
Forever
One Voice
Forever
We are the Light of the Universe
We are the Soul of Creation
We are the Voice of Love
One Love
One Light
One Voice
Forever

DNA - Human Software

Deoxyribonucleic acid (DNA)

DNA is a nucleic acid that contains the genetic instructions for the biological development of a cellular form of life or a virus. All known cellular life and some viruses have DNAs. DNA is a long polymer of nucleotides (a polynucleotide) that encodes the sequence of amino acid residues in proteins, using the genetic code.

Inheritance of DNA

DNA is responsible for the genetic propagation of most inherited traits. In humans, these traits range from hair color to disease susceptibility. The genetic information encoded by an organism's DNA is called its genome. During cell division, DNA is replicated, and during reproduction is transmitted to offspring.

In eukaryotic cells, such as those of plants, animals, fungi and protists, most of the DNA is located in the cell nucleus, and each DNA molecule is usually packed into a chromosome that are passed to daughter cells during cell division. By contrast, in simpler cells called prokaryotes, including the eubacteria and archaea, DNA is found directly in the cytoplasm (not separated by a nuclear envelope) and is circular. The cellular organelles known as chloroplasts and mitochondria also carry DNA. DNA is thought to have originated on earth approximately 3.5 to 4.6 billion years ago.

Mitochondrial DNA and Y Chromosome Used for Lineage Studies

In humans, the mother's mitochondrial DNA together with 23 chromosomes from each parent combine to form the genome of a zygote, the fertilized egg. As a result, with certain exceptions such as red blood cells, most human cells contain 23 pairs of chromosomes, together with mitochondrial DNA inherited from the mother. Lineage studies can be done because mitochondrial DNA only comes from the mother, and the Y chromosome only comes from the father.

The Sun

Earth's Sun

The Sun is the star at the center of the Solar System. The Earth and other matter (including other planets, asteroids, meteoroids, comets and dust) orbit the Sun, which by itself accounts for more than 99% of the solar system's mass. Energy from the Sun—in the form of insolation from sunlight—supports almost all life on Earth via photosynthesis, and drives the Earth's climate and weather.

About 74% of the Sun's mass is hydrogen, 25% is helium, and the rest is made up of trace quantities of heavier elements. The Sun has a spectral class of G2V. "G2" means that it has a surface temperature of approximately 5,500 K, giving it a white color, which, because of atmospheric scattering, appears yellow. Its spectrum contains lines of ionized and neutral metals as well as very weak hydrogen lines. The "V" suffix indicates that the Sun, like most stars, is a main sequence star. This means that it generates its energy by nuclear fusion of hydrogen nuclei into helium and is in a state of hydrostatic balance, neither contracting nor expanding over time. There are more than 100 million G2 class stars in our galaxy. Because of logarithmic size distribution, the Sun is actually brighter than 85% of the stars in the Galaxy, most of which are red dwarfs.

The Sun orbits the center of the Milky Way galaxy at a distance of approximately 25,000 to 28,000 light-years from the galactic center, completing one revolution in about 225–250 million years. The orbital speed is 217 km/s, equivalent to one light-year every 1,400 years, and one AU every 8 days.

The Sun is a third generation star, whose formation may have been triggered by shockwaves from a nearby supernova. This is suggested by a high abundance of heavy elements such as gold and uranium in the solar system; these elements could most plausibly have been produced by endergonic nuclear reactions during a supernova, or by transmutation via neutron absorption inside a massive second-generation star.

Sunlight is the main source of energy near the surface of Earth. The solar constant is the amount of power that the Sun deposits per unit area that is directly exposed to sunlight. The solar constant is equal to approximately 1,370 watts per square meter of area at a distance of one AU from the Sun (that is, on or near Earth). Sunlight on the surface of Earth is attenuated by the Earth's atmosphere so that less power arrives at the surface—closer to 1,000 watts per directly exposed square meter in clear conditions when the Sun is near the zenith. This energy can be harnessed via a variety of natural and synthetic processes—photosynthesis by plants captures the energy of sunlight and converts it to chemical form (oxygen and reduced carbon compounds), while direct heating or electrical conversion by solar cells are used by solar power equipment to generate electricity or to do other useful work. The energy stored in petroleum and other fossil fuels was originally converted from sunlight by photosynthesis in the distant past.

The Solar System

The solar system is the stellar system comprising the Sun and the retinue of celestial objects gravitationally bound to it: currently eight official planets (according to the International Astronomical Union) and their 162 known moons,[1] as well as dwarf planets, asteroids, meteoroids, planetoids, comets, and interplanetary dust. From 1930 to 2006 there were nine official planets, but Pluto's status was changed to that of a "dwarf planet" on August 24, 2006 by the IAU.

The principal component of the solar system is the Sun; a main sequence G2 star that contains 99.86% of the system's known mass and dominates it gravitationally. Because of its large mass, the Sun has an interior density high enough to sustain nuclear fusion, releasing enormous amounts of energy, most of which is radiated into space in the form of electromagnetic radiation, including visible light. The Sun's two largest orbiting bodies, Jupiter and Saturn, account for more than 90% of the system's remaining mass. (The currently hypothetical Oort cloud, should its existence be confirmed, would also hold a substantial percentage).

In broad terms, the charted regions of the solar system consist of the Sun, four rocky bodies close to it called the terrestrial planets, an inner belt of rocky asteroids, four gas giant planets, and an outer belt of small, icy bodies known as the Kuiper belt. One planet, Pluto, is also a member of the Kuiper belt. In order of their distances from the Sun, the major planets are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. All planets but two are in turn orbited by natural satellites (usually termed "moons" after Earth's Moon) and the largest are encircled by planetary rings of dust and other particles. The planets (with the exception of Earth) are named after gods and goddesses from Greco-Roman mythology.The definition of the term "planet" was decided by the International Astronomical Union, in a vote on August 24, 2006. This new definiton most directly affects Pluto, which is now not considered one of major planetary bodies, leaving our Solar System with eight major planets.

Energy

Energy

Energy is a fundamental concept of physics, with applications throughout the natural sciences. Everything in the known universe is composed fundamentally of energy.

Conversavation of Energy

Energy is subject to a strict global conservation law; that is, it can neither be created nor destroyed. Most kinds of energy (with gravitational energy being a notable exception) are also subject to strict local conservation laws, as well. In this case, energy can only be exchanged between adjacent regions of space, and all observers agree as to the volumetric density of energy in any given space. There is also a global law of conservation of energy, stating that the total energy of the universe cannot change; this is a corollary of the local law, but not vice versa. Conservation of energy is associated with the symmetry of the laws of physics, namely invariance with respect to time (via Noether's theorem).

Total Energy of a System

The total energy of a system can be subdivided and classified in various ways. For example, it is sometimes convenient to distinguish kinetic energy from potential energy. It may also be convenient to distinguish gravitational energy, electrical energy, thermal energy, and other forms. These classifications overlap; for instance thermal energy usually consists partly of kinetic and partly of potential energy.

Transfer of Energy

The transfer of energy can take various forms; familiar examples include work, heat flow, and advection. The word "energy" is also used outside of physics in many ways, which can lead to ambiguity and inconsistency. The vernacular terminology is not consistent with technical terminology. For example, the important public-service announcement, "Please conserve energy" uses vernacular notions of "conservation" and "energy" which make sense in their own context but are incompatible with the technical notions of "conservation" and "energy" that are used in the law of conservation of energy.

Special Relativity

In classical physics energy is considered a scalar quantity, having no direction in space. In special relativity energy is not a Lorentz scalar, but rather one component of the energy-momentum 4-vector, such that energy is associated with the timelike direction. In other words, energy is invariant with respect to spacelike rotations, but not invariant with respect to boosts.

Astronomy and cosmology

The phenomona of stars, nova, supernova, quasars and gamma ray bursts are the universe's highest-output energy transformations of matter. All stellar phenomena (including solar activity) are driven by various kinds of energy transformations. Energy in such transformations is either from:

1. Gravitational collapse of matter, usually molecular hydrogen, into various classes of astronomical objects (stars, black holes, etc.)


2. or from nuclear fusion of lighter elements, in this case, primarily hydrogen.

Dark Energy

Dark energy is believed to make up 70% of the universe. Light elements, primarily hydrogen and helium, were created in the Big Bang. These light elements were spread too fast and too thinly in the Big Bang process through nucleosynthesis to form the most stable medium-sized atomic nuclei, like iron and nickel. This fact allows for later energy release, as such intermediate-sized elements are formed in our era. The formation of such atoms powers the steady energy-releasing reactions in stars, and also contributes to sudden energy releases, such as in novae.

Black Holes

Gravitational collapse of matter into black holes is also thought to power the very most energetic processes, generally seen at the centers of galaxies. Some believe black holes lead to an alternate web of universes as mass entering the black holes accelerates beyond the boundaries of Relativistic Physics. This is a moment where the universe contracts to an infinitesimal point, relatively speaking and then expands equally and oppositely in a completely different dimension of space and time.

Cosmologists are still unable to explain all cosmological phenomena purely on the basis of known conventional forms of energy, for example those related to the accelerating expansion of the universe. Dark Energy is necessary to describe certain cosmological observations, particularly regarding black holes, where light travels faster than the speed of light.

Etymology

Energy comes from the Greek ενέργεια, where εν- means "in" and έργον "work". The compound εν-εργεια in Epic Greek meant "divine action" or "magical operation"; it was later used by Aristotle with the meaning of "activity, operation" or "vigour", and by Diodorus Siculus for "force of an engine."

Gulf War Syndrome - Washington's Dirty Little Secret

Gulf War Syndrome - Washington's Dirty Little Secret

In November of 2008, the Committee on Gulf War Veterans' Illnesses presented a 450 page report to Secretary of Veterans Affairs James Peake. The report stated that the Gulf War Syndrome (GWS), previously dismissed as a psychosomatic disorder, is a very real illness affecting between 25-50 percent of the 700,000 U.S. Veterans who participated in the 1991 Gulf War.

GSI was likely caused by repeated exposure to toxic chemicals, including overused pesticides, drugs given to the U.S. troops for protection against nerve gas, smoke from oil fires, anthrax vaccines, and exposure to depleted uranium. Additionally, a 2004 British study found that Gulf War veterans (GWV) were 40-50 percent more likely to be unable to start a pregnancy and were 2 to 3 times more likely to having children with birth defects.

Pesticides

According to the report, 62 percent of ground troops interviewed reported some form of pesticide use. Forty-four percent used pesticide sprays daily and 26 percent used pesticide lotions a median of 20 times per month. The most commonly used compound was DEET, used by half of all personal almost daily. Permethrin was used by fewer personnel but was on average, used daily.

The Pesticide Information Project of Cooperative Extension Offices of Cornell University states that "Everglades National Park employees having extensive DEET exposure were more likely to have insomnia, mood disturbances and impaired cognitive function than were lesser exposed co-workers". Additionally, the Environmental Protection Agency classified permethrin as "Likely to be Carcinogenic to Humans" by the oral route. This classification was based on two reproducible benign tumor types (lung and liver) in the mouse, equivocal evidence of carcinogenicity in Long- Evans rats, and supporting structural activity relationship information.

Permethrin also has been shown to kill 1 in 10 cats exposed to permethrin with 90 percent of them displaying symptoms of twitching and convulsions. Furthermore, a study by the Predictive Toxicology Research Group in Inda found significant functional impairment of the blood-brain barrier following pesticide exposure during development in rats, even after one exposure.

Depleted Uranium

Depleted uranium, used in tank kinetic energy penetrator and autocannon rounds on a large scale in the Gulf War, has been recognized as a neurotoxin. Uranium is a heavy metal and chemical toxicant with nephrotoxic (kidney damaging), teratogenic (birth defect causing), and carcinogenic properties and is usually associated with a variety of illnesses. In a study of U.K. troops serving in the gulf, the risk of malformation among pregnancies reported by men was 50 percent higher in GWV, compared to non-GWVs.

Depleted uranium has been shown to induce cancer development and genetic mutations, autoimmune diseases and the core functionality of T cells, which play a central role in cell-mediated immunity. (See image above for the effects of Depleted Uranium on Iraqis and GWV children).

Chemical Weapons

Many of the symptoms of GWS are similar to the symptoms of organophosphate, mustard gas, and nerve gas poisoning. GWV were exposed to a number of sources including nerve gas and pesticides. Over 125,000 U.S. troops were exposed to nerve gas and mustard gas when an Iraqi depot in Khamisiyah, Iraq was bombed in 1991.

Additionally there is speculation that residual chemical agents from the Iran-Iraq war caused environmental contamination and chronic exposure to the troops, consistent with the increased observation of birth defects amongst the Iraqis during the period of the Gulf War.

Nerve Gas Protection

Pyridostigmine bromide (PB), an acetylcholinesterase inhibitor intended to protect against nerve agents was used extensively by GWV. According to the National Academy of Sciences, excess illness in Persian Gulf War veterans (GWV) can be explained in part by exposure of GWV to organophosphate and carbamate acetylcholinesterase inhibitors (AChEis), including pyridostigmine bromide (PB), pesticides, and nerve agents. Evidence germane to the relation of AChEis to illness in GWV was assessed. Many epidemiological studies reported a link between AChEi exposure and chronic symptoms in GWV.

It has been suggested that intake of PB by GWV may induce a condition termed bromism, a condition induced from the excessive intake of bromide, with neurological, psychiatric, dermatological, and possibly endocrine effects. Psychiatric symptoms may include, in the earlier stages, disinhibition, self-neglect, fatigue, sluggishness, impairment of memory and concentration, irritability or emotional instability, and depression.

Symptoms of more advanced disease may include confusion but occasionally schizophrenic-like behavior or hallucinations in clear consciousness. Behavior can become violent, especially at night or under the influence of drugs or alcohol and there may be severe auditory and visual hallucinations.

Anthrax Vaccines

During Operation Desert Storm, 41 percent of U.S. combat soldiers were vaccinated against anthrax. This was a source of serious side effects relating to GWS, as well as local skin reactions, some lasting for weeks or months. Remarkably, while approved by the FDA, it never went through any large scale clinical trials, unlike almost all other vaccines in the United States. Even after the war, troops that had never been deployed overseas developed GWS symptoms after receiving the vaccine. The Pentagon additionally failed to report 20,000 cases where soldiers were hospitalized after receiving the vaccine.

A U.S. Federal Judge ruled that there was good cause to believe it was harmful, and ordered the Pentagon to stop administering it in October of 2004. The ban was lifted in February 2008 after the FDA re-examined and approved the drug again. The vaccine is the only substance suspected in GWS to which forced exposure has been banned.

Homeless and Incarcerated Veterans

According to the National Coalition for Homeless Veterans, as of 2001, 23 percent of the homeless populations in America are veterans, accounting for between 529,000 and 840,000 of the total homeless population. 33 percent of these were stationed in a war zone, 89 percent received a dishonorable discharge and 75 percent experience alcohol, drug or mental health problems. For comparison, as of July 2008, there were 147,000 troops deployed in Iraq.

A 2000 report from the Bureau of Justice Statistics indicated another 225,000 veterans were held in Nation's prisons or jails in 1998. 60 percent of incarcerated veterans had served in the Army. 35 percent of veterans in state prison were convicted of a violent crime, compared to 20 percent of non-veterans and surprisingly, the average sentence of veterans was 50 months longer than the average of non-veterans.

Summary

Gulf War Syndrome profiles typically include some combination of chronic headaches, cognitive difficulties, widespread pain, chronic fatigue syndrome, chronic diarrhea, skin rashes, respiratory problems, increased birth defects, sleep disorders, memory problems, blurred vision and a variety of other symptoms. To date there is no identified treatment for Gulf War Syndrome that affects a significant number of veterans 17 years after the war.

The Veteran's Administration has been slow to even acknowledge the problem, less alone, provide treatment for these veterans. Many have lost their families, are unable to hold a job or have even been incarcerated as an indirect result of illnesses caused during their tour in the Gulf War. It's time that the U.S. Government to take responsibility for exposing unsuspecting soldiers to a toxic soup that will kill Gulf War veterans for years to come.

Human Digestion

Digestion

In humans, digestion begins in the oral cavity where food is chewed (mastication) with the teeth. The process stimulates exocrine glands in the mouth to release digestive enzymes such as salivary amylase, which aid in the breakdown of carbohydrates. Chewing (mechanical catabolism) also causes the release of saliva, which helps condense food into a bolus that can be easily passed through the oesophagus. The oesophagus is about 20 centimeters long. Saliva also begins the process of chemical catabolism, hydrolysis. Once food is chewed properly, the food is swallowed. The bolus is pushed down by the movement called peristalsis, which is an involuntary wave-like contraction of smooth muscle tissue, characteristic of the digestive system. The mechanism for swallowing is co-ordinated by the swallowing centre in the medulla oblongata and pons. The reflex is initiated by touch receptors in the pharynx as a bolus of food is pushed to the back of the mouth by the tongue. The uvula is a small flap that hangs from the roof of the mouth. During swallowing it and the soft palate retract upward and to the rear to close the nasopharynx, which prevents the food from entering the nasal passages by triggering closure of the soft palate. When swallowed, the food enters the pharynx, which makes special adaptations to prevent choking or aspiration when food is swallowed. The epiglottis is a cartilage structure that closes temporarily during swallowing, preventing food and liquids from entering the trachea.

The food enters the stomach upon passage through the cardiac sphincter, also known as the oesophageal sphincter. In the stomach, food is further broken apart through a process of heuristic churning and is thoroughly mixed with a digestive fluid, composed chiefly of hydrochloric acid, and other digestive enzymes to further denature proteins. The parietal cells of the stomach also secrete a compound, intrinsic factor which is essential in the absorption of vitamin B-12. As the acidic level changes in the small intestines, more enzymes are activated to split apart the molecular structure of the various nutrients so they may be absorbed into the circulatory or lymphatic systems. Absorption is when smaller molecules, such as glucose or alcohol, pass through the membrane of the stomach directly into the blood stream.

After being processed in the stomach, food is passed to the small intestine via the pyloric sphincter. This is where most of the digestive process occurs as chyme enters the first 10 inches (25 cm) of the small intestine, the duodenum. Here it is further mixed with 3 different liquids: bile (which helps aid in fat digestion, otherwise known as emulsification), pancreatic juice and enzymes, (made by the pancreas), and intestinal enzymes of the alkaline mucosal membranes. The enzymes include: maltase, lactase and sucrase, to process sugars. Trypsin and chymotrypsin are other enzymes added in the small intestine. (Bile also contains pigments that are by-products of red blood cell destruction in the liver; these bile pigments are eliminated from the body with the feces.) Most nutrient absorption takes place in the small intestine. The nutrients pass through the small intestine's wall, which contains small, finger-like structures called villi. The blood, which has absorbed nutrients, is carried away from the small intestine via the hepatic portal vein and goes to the liver for filtering, removal of toxins, and nutrient processing. The primary activity here is regulation of blood glucose levels through a process of temporary storage of excess glucose that is converted in the liver to glycogen in direct response to the hormone insulin. Between meals, when blood glucose levels begin to drop, the glycogen is converted back to glucose in response to the hormone glucagon.

After going through the small intestine, the food then goes to the large intestine. The large intestine has 3 parts: the cecum (or pouch that forms the T-junction with the small intestine), the colon, and the rectum. In the large intestine, water is reabsorbed, and the foods that cannot go through the villi, such as dietary fibre, can be stored in large intestine. Fibre helps to keep the food moving through the G.I. tract. The food that cannot be broken down is called feces. Feces are stored in the rectum until they are expelled through the anus.

Carbon 6 Atom and It's Fundamental Particles

Carbon

Overview

Carbon occurs in all organic life and is the basis of organic chemistry. This nonmetal also has the interesting chemical property of being able to bond with itself and a wide variety of other elements, forming nearly ten million known compounds. When united with oxygen it forms carbon dioxide, which is vital to plant growth. When united with hydrogen, it forms various compounds called hydrocarbons which are essential to industry in the form of fossil fuels. When combined with both oxygen and hydrogen it can form many groups of compounds including fatty acids, which are essential to life, and esters, which give flavor to many fruits. The isotope carbon-14 is commonly used in radioactive dating.

Notable characteristics

Carbon is a remarkable element for many reasons. Its different forms include the hardest naturally occurring substance (diamond) and one of the softest substances (graphite) known. Moreover, it has a great affinity for bonding with other small atoms, including other carbon atoms, and its small size makes it capable of forming multiple bonds. These attributes are mostly responsible for carbon's unique ability to form such numerous compounds, in fact, the majority of all chemical compounds.

We Are Carbon Based Life

Carbon compounds form the basis of all life on Earth and the carbon-nitrogen cycle provides some of the energy produced by the Sun and other stars. Moreover, carbon has the highest melting/sublimation point of all elements. At atmospheric pressure it has no actual melting point. Its triple point is at 10 MPa (100 bar), so it sublimates above 4000 K. Thus it remains solid at higher temperatures than the highest melting point metals like tungsten or rhenium, regardless of its allotropic form.

Carbon Not Present during Early Period of Big Bang

Carbon was not created during the initial expansion of the Big Bang. This is due to the fact that it needs a triple collision of alpha particles (helium nuclei), in order to be produced. The universe initially expanded and cooled too fast for that to be possible. It is produced, however, in the interior of stars in the horizontal branch, where stars transform a helium core into carbon by means of the triple-alpha process. It was also created in a multi-atomic state.

Applications

Carbon is a very important component of all known living systems, along with Hydrogen, Oxygen and Nitrogen. Without it, life as we know it could not exist. The major economic use of carbon is in the form of hydrocarbons, most notably the fossil fuel methane gas and crude oil (petroleum). Crude oil is used by the petrochemical industry to produce, amongst others, gasoline and kerosene, through a distillation process, in refineries. Crude oil forms the raw material for many synthetic substances, many of which are collectively called plastics.

Other uses

• The isotope carbon-14 was discovered on February 27, 1940 and is used in radiocarbon dating.
• Graphite is combined with clays to form the 'lead' used in pencils.
• Diamond is used for decorative purposes, and also as drill bits and other applications making use of its hardness.
• Carbon is added to iron to make steel.
• Carbon is used as a neutron moderator in nuclear reactors.
• Carbon fibre, which is mainly used for composite materials, as well as high-temperature gas filtration.
• Carbon black is used as a filler in rubber and plastic compounds.
• Graphite carbon in a powdered, caked form is used as charcoal for grilling, artwork and other uses.
• Activated charcoal is used in medicine (as powder or compounded in tablets or capsules) to adsorb toxins, poisons, or gases from the digestive system.
• The chemical and structural properties of fullerenes, in the form of carbon nanotubes, has promising potential uses in the nascent field of nanotechnology.

History and Etymology

Carbon was discovered in prehistory and was known to the ancients, who manufactured it by burning organic material in insufficient oxygen (making charcoal). Diamonds have long been considered rare and beautiful. One of the last-known allotropes of carbon, fullerenes, were discovered as byproducts of molecular beam experiments in the 1980s.

The name comes from French charbone, which in turn came from Latin carbo, meaning charcoal. In German and Dutch, the names for carbon are Kohlenstoff and koolstof respectively, both literally meaning "coal-stuff".

Human Heart

Human Heart

The heart is a hollow, muscular organ in vertebrates, responsible for pumping blood through the blood vessels by repeated, rhythmic contractions, or a similar structure in annelids, mollusks, and arthropods. The term cardiac (as in cardiology) means "related to the heart" and comes from the Greek καρδιά, kardia, for "heart." The heart is composed of cardiac muscle, an involuntary muscle tissue which is found only within this organ.

Structure

In the human body, the heart is normally situated slightly to the left of the middle of the thorax, underneath the breastbone. The heart is usually felt to be on the left side because the left heart (left ventricle) is stronger (it pumps to all body parts). The left lung is smaller than the right lung because the heart occupies more of the left hemithorax. The heart is enclosed by a sac known as the pericardium and is surrounded by the lungs. The pericardium is a double membrane structure containing a serous fluid to reduce friction during heart contractions. The mediastinum, a subdivision of the thoracic cavity, is the name of the heart cavity.

The apex is the blunt point situated in an inferior (pointing down and left) direction. A stethoscope can be placed directly over the apex so that the beats can be counted. This physical location is between the sixth and seventh rib, just to the left of the sternum. In normal adults, the mass of the heart is 250-350 g (9-16 oz), but extremely diseased hearts can be up to 1000 g (2 lb) in mass due to hypertrophy. It consists of four chambers, the two upper atria (singular: atrium ) and the two lower ventricles.

The function of the right side of the heart is to collect deoxygenated blood, in the right atrium, from the body and pump it, via the right ventricle, into the lungs (pulmonary circulation) so that carbon dioxide can be dropped off and oxygen picked up (gas exchange). This happens through a passive process called diffusion. The left side (see left heart) collects oxygenated blood from the lungs into the left atrium. From the left atrium the blood moves to the left ventricle which pumps it out to the body. On both sides, the lower ventricles are thicker and stronger than the upper atria. The muscle wall surrounding the left ventricle is thicker than the wall surrounding the right ventricle due to the higher force needed to pump the blood through the systemic circulation.

Regulation of the cardiac cycle

Cardiac muscle is myogenic (able to contract and relax on its own). It is a specialized muscle found nowhere else but in the heart because it has its own conducting system. This is in contrast with skeletal muscle, which requires either conscious or reflex nervous stimuli. The heart's rhythmic contractions occur spontaneously, although the waves or nerves can be changed by nervous frequency influences such as exercise or the perception of danger.

The rhythmic sequence of contractions is coordinated by the sinoatrial and atrioventricular nodes. The sinoatrial node, often known as the cardiac pacemaker, is located in the upper wall of the right atrium and is responsible for the wave of electrical stimulation (See action potential) that initiates atria contraction. Once the wave reaches the atrioventricular node, situated in the lower right atrium, it is conducted through the bundles of His and causes contraction of the ventricles. The time taken for the wave to reach this node from the sinoatrial nerve creates a delay between contraction of the two chambers and ensures that each contraction is coordinated simultaneously throughout all of the heart. In the event of severe pathology, the Purkinje fibers can also act as a pacemaker; this is usually not the case because their rate of spontaneous firing is considerably lower than that of the other pacemakers and hence is overridden.