HOMEOSTASIS AND COAGULATION

The principle function of blood is to keep the internal environment of the body tissues constant and in this way to maintain homeostasis. Homeostasis is a term used to describe normal body functions, which include blood pressure, heart rate, body temperature, respiration and blood composition. In order to perform the processes involved in homeostasis, blood must be fluid. A mechanism known as hemostasis keeps the body fluid within the confines of the circulatory system.

Table of Contents
Hemostasis
Abnormal Hemostasis
Mechanisms Involved in hemostasis
Clotting Factors
Plasmatic Coagulation
Inhibitors
Extrinsic Pathway
Intrinsic Pathway
Intrinsic and Extrinsic Pathway
Antithrombin III

Normal Hemostasis
Blood normally is a fluid tissue as it circulates through out the body via the blood vessels. When vessels are injured, blood escapes and bleeding continues for a period of time but then slowly subsides. Several biologic systems play a role in stopping the flow of blood from an injured vessel. In addition to the vessels themselves, platelets and clotting factors interact to form a haemostatic clot. The formation of a haemostatic clot is a temporary measure and as the wound heals the clot slowly dissolves

Abnormal Hemostasis
There are two forms of abnormal hemostasis, which are described as follows:
a. Prolonged Bleeding: Following an injury bleeding may not stop in the same length of time it normally should. This may be the result of an abnormality involving the blood vessels, the platelets, clotting factors or increased activity of the fibrinolytic system. Hemophilia A is an example of prolonged bleeding directly related to an abnormal form of factor VIII, where the coagulant portion of the factor VIII molecule is deficient.
b. Thrombosis:
A thrombus or a clot in a blood vessel is formed by the coagulation of the blood. The formation of this clot is abnormal because its presence in a blood vessel obstructs the flow of blood to the tissues in that area, resulting in cellular changes. A heart attack can be one of the consequence of abnormal clot formation.

Mechanism Involved In Hemostasis
In the case of healthy subjects there exists a equilibrium between the coagulation potential on the one side and fibrinolytic potential + coagulation inhibitors on the other. In the fibrinolytic potential outweighs the coagulation potential or the coagulation factors are diminished then there is a risk of hemorrhage. If the coagulation potential outweighs the fibrinolytic potential or the inhibitors are diminished, there is a risk of thrombosis.
A delicate balance of components on both sides of the scale is required to maintain hemostasis.
1. Blood vessels:
The vascular system is composed of arteries, veins and the microcirculatory system. The blood vessels provide a non-thrombogenic surface allowing the blood to circulate in a closed vascular system. The nonthrombogenic surface is attributed to properties of the vessel walls and activities of platelets.
2. Platelets:
Platelets or thrombocytes are produced in the bone marrow by large cells called megakarycocytes. The normal numbers of platelets circulating are 150,000 to 450,ooo per cubic millimeter blood. To aid in hemostasis, platelets must be present in adequate number and must be functioning normally.
Platelets have Three major Functions:
a. Support Vascular integrity
Platelets support vascular integrity in two ways,
i. They help the blood vessels to maintain vascular integrity by donating membrane materials to the endothelial cells lining the vessel walls.
ii. Platelets also fill gaps that may occur between endothelial cells because of minimal damage or vasodilatation. By filling the gap a non trombogenic surface is maintained.
If a gap were allowed to remain and became larger, sub endothelial structures which are foreign to platelets and clotting factors would initiate fibrin formation.
b. Adhesion/Aggregation:
Platelets are considered to be first kind of defense in a haemostatic response to an injury. Following injury to a vessel wall, platelets adhere to the injured surface and quickly form a platelet plug. This activity keeps the blood within a closed vascular system. In the formation of the plug, platelets change as they aggregate irreversibly.
Irreversible aggregation causes platelet constituent to be released. Many of the constituent have an immediate effect upon the haemostatic response. One platelet constituent, known as platelet factor 3, becomes available on the surface of the platelets. Platelet factor 3 is a phospholipid and participates with certain clotting factors to produce thrombin with the ultimate formation of fibrin.

Clotting Factors
The clotting factors designations with some of the commonly used synonyms are as follows:
Factor I Fibrinogen
Factor II Prothrombin
Factor III Tissue thromboplastin
Factor IV Calcium
Factor V Plasma AcGLOB, Proaccelerin Labile factor
Factor VI Not assigned
Factor VII Proconvertin, Stable factor
Factor VIII Anti-hemophilic Globulin Hemophilia-A
Factor IX Christmas factor, Plasma Thromboplastin component
Factor X Stuart prower factor
Factor XI Plasma thromboplastin Antecendant (PTA)
Factor XII Hageman factor
Factor XIII Fibrin stabilizing factor, Prekallikrein, Fletcher factor, HMWK, Fitzgerald.
The clotting factors with the exception of factor III and factor IV are plasma proteins. Factor III is found in all tissues and is released when cells are damaged. factor IV is needed fro several interactions between clotting factors to occur in the production of fibrin.
Each clotting factor is designated by a Roman numeral and its most common synonym. Roman numerals are used most often referring to the clotting factors.
Notice that factor VI is missing. A plasma protein was given a Roman numeral but later studies showed it did not fulfill all the criteria established by the international nomenclature committee to qualify as a factor.
Prekallikrein, also known as Fletcher factor, and kininogen are plasma proteins. Although they are members of the kinin system, they are required for the complete activation of factor XII.
T simplify and for easy remembrance of clotting factors, they are separated into three major groups and each group shares certain characteristics. These three groups are:
a. Fibrinogen Group:
Factor I, V and XIII are produced in the liver. A portion of factor VIII molecule is produced in the liver and another portion by the endothelial cells. These factors are present in fresh normal plasma and adsorbed plasma.
They are not present in serum because they are consumed during the clotting process.
Coumarin, which is an oral anti-coagulant, has no effect upon their production, therefore, these factors are present in plasma obtained from individuals taking oral anticoagulants.
Factors VI and VIII are labile and their activity is rapidly lost in stored plasma. this is an important consideration in coagulation testing and in therapy.
b. Prothrombin Group:
Members in this group includes Factor II, VII, IX and X.
These clotting factors are produced in the Liver and Vitamin K is required for their synthesis.
These clotting factors are present in stored plasma. With the exception of Factor II, they are not totally consumed during the clotting process, therefore they are present in serum.
Because of the antogonistic action on Vitamin K by Coumarin medication, the concentration of these factors is reduced in plasma obtained from individuals taking oral anticoagulants.
c. Contact Group:
Members in this group include Factors XII, XI Prekallikrein and kininogen.
Factor XII, XI prekallikrein and Kininogen are synthesized in the liver.
Factor XII and XI are fairly stable and may be found in stored plasma and adsorbed plasma. they are not consumed during the clotting process, therefore, they are also present in serum.

Plasmatic Coagulation
About 20 factors (proteins) are involved which circulate in blood as inactive precursors (A substance that precedes the formation of another substance).
Activation signifies conversion to an enzyme which in its turn activates the subsequent factor.
Distinction is to be made between two activation pathways Namely:
a. Intrinsic pathway: in which only intravascular plasmatic factors and those released by platelets are involved.
b. Extrinsic Pathway: in which what are known as tissue thromboplastine are released from the surrounding tissue by injury and initiate the coagulation process.
Both pathways lead to the conversion of prothrombin to thrombin, which converts ion of fibrin webs provides the basis for measurements of coagulation times.
Activation Process:
Coagulation factors are present in the blood as inactive precursors awaiting activation together with calcium and phospholipids by their activated antecedent factor. Activation means consumption, and hence a transitory fall in concentrating.

Inhibitors
The achievable coagulation system conceals potential risk for the individual. Hyper and hypo function disturb the equilibrium. It must be adaptable enough to maintain the theological (flow) properties of the blood the one hand, and on the other hand to prevent the passage of blood into the tissue by sealing the capillaries. Activation of the system has therefore to remain limited to the extent and location of the need. This task is performed by inhibitors which block the enzymatic activity. The most important inhibitor is antithrombin III. Others include alpha-macro-globulin and alpha-antitrypsin.
Fibrinolysis:
After the fibrin has fulfilled its function, it must be catabolised in a process known as fibrinolysis. Two possible activation pathways lead finally to conversion of the protein plasminogen into the enzyme plasmin, which in its turn cleaves fibrin into even smaller, and hence soluble, degradation products.
Extrinsic Pathway
In the case of injury, tissue thromboplastin passes into the blood and activates Factor VII to Factor VII a, which in turn activates Factor X. Here begins the section of the cascade common to both activation pathways. Namely, Factor X a- with Factor V as accelerator- activates the prothrombin (Factor II) to thrombin (Factor II a). Thrombin cleaves fibrinogen, thereby initiating the formation of fibrin.
The extrinsic pathway is monitored with the aid of the prothrombin time test. In the test, we create the same conditions as in vitro in order to launch this part of the cascade. The time required for the formation of first fibrin web is the prothrombin time which is measured in terms of seconds. This test measures the collective activity of clotting factors I, II, VII and X.
Use of Prothrombine Time Test:
1. The test is most often used to monitor oral anticoagulation therapy.
2. It is also used as a sensitive indicator for dysfunction of the liver.
Intrinsic Pathway
Contact with a foreign surface effects the activation of Factor XII. This triggers a regular cascade of activity namely via Factor XI, IX and VII to the common end pathway and hence the formation of fibrin. The intrinsic pathway is monitored with the aid of a Partial thromboplastin time.
Uses of activated partial thromboplastin time:
1. It is used as screening procedure to detect clotting factors.
2. It is used to monitor heparin therapy.
3. It is used to monitor replacement therapy in individuals with a clotting factor deficiency.
Extrinsic and Intrinsic Pathway
The inactive coagulation factors present in the plasma are to some extent assigned to two different activation pathways. From factor X onwards the cascade then proceeds jointly upto fibrin. This fibrin clot is initially of a loose structure. In the presence of activated factor XII it is stabilized to a mechanically firm clot which makes the haemostasis permanent. Since Factor XII does not act on the fibrin until the latter is formed, determination of this factor requires a separate test system.
Screening for Coagulation Disorders:
The activated partial thromboplastin time in conjunction with prothrombin time frequently permits a crude localization of a coagulation defect is probably to be found in Factor XII, is prolonged, the defect is probably it could well be matter of a factor VII deficiency. If, however, both screening tests are pathological, then the deficiency is more likely to have arisen in the joint end pathway of factors X, V, II and I.
Thrombin Time:
The end point of plasmatic coagulation is the activation of Prothrombin (factor II) to Thrombin(II a). Thrombin rapidly converts fibrinogen into fibrin. Antithrombins as the name implies are counteractive.
Thrombin normally converts fibrinogen into fibrin. This reaction is inhibited by fibrin, FDP and by antithrombins. If such products are present in the plasma to an increased extent, then the TT is prolonged.
The same occurs when the fibrinogen level is lowered, as in the case of augmented fibrinolysis or during a fibrinolytic therapy. One of the uses of this test is therefore in the monitoring of fibrinolytic (Strepto Kinase) or thrombolytic (Heparin) therapy.

Antithrombin III
Antithrombin III is a plasma protein. It is a naturally occurring inhibitor to the coagulation system. It is also the cofactor for heparin. Adequate levels of Antithrombin III must be present in plasma for heparin to exert its anticoagulant effect. Antithrombin III slowly inhibits the activity of activated clotting factors XII a, XI a, IX a and X a. It also neutralizes the active enzyme thrombin.
In order for heparin to exert the its anticoagulant effect, it must form a complex with antithrombin III. Once heparin is given, it complexes with antithrombin III and immediately the AT III heparin complex increases the speed of inhibitory activity.

Urgent and Massive Transfusion

Urgent Transfusion
Urgent transfusion refers to administration of Red Blood Cells (RBCs) before the completion of standard pretransfusion testing, when a delay in transfusion may imperil the patient. Implicit is the understanding that it is necessary to reestablish both oxygen-carrying capacity and intravascular volume. In hypovolemic shock, most authorities recommend immediate volume restoration with crystalloid or colloid solutions, however a warning has recently been issued regarding possible adverse effects of albumin so-
lutions in critically ill patients.1"3 If volume replacement leads to clinical stabilization, transfusion is less urgent and should await the completion of compatibility testing.
If transfusion is necessary before completion of compatibility testing, group O RBCs should be used. Whenever possible, D-negative RBCs should be used in females of childbearing potential and children to avoid the possibility of sensitization to the D antigen. The patient's physician must sign a statement indicating the nature of the emergency either before or after the uncross-matched blood is issued. If the patient's screen for unexpected red cell antibodies is negative, the transfusion of uncrossmatched but type-specific Whole Blood or of type-compatible RBCs carries a very low risk of being incompatible.3This safety margin is dependent, however, on correct identification of the patient, the pretransfusion blood sample, and the blood components to be infused. Guidelines for conditions under which it is safe to switch the patient to type-specific blood are available.7 In the near future, administration of artificial oxygen carriers may provide a therapeutic bridge to the use of fully compatible blood when emergency transfusion is required.
Massive Transfusion
Massive transfusion is defined as the replacement of one or more blood volumes within 24 hours. A blood volume is estimated as 75 mL/kg or about 5000 mL (10 or more units of Whole Blood) in a 70-kg adult Patients requiring massive transfusion frequently develop multiple complications related to hypovolemia, tissue ischemia, and acid-base disturbances. Many of these metabolic, coagulation, respiratory, and other complications have been ascribed solely to the transfusion of stored blood, but are caused principally by tissue damage or hypoperfusion secondary to trauma or hemor-rhage.l2>14 Hypothermia may impair hemostasis and should be avoided by warming the patient, the crystalloid solutions administered, and if indicated, the blood.
Massive transfusion may be an indication for the use of Whole Blood. However, Whole Blood may not be available, and RBCs administered with crystalloid or colloid solutions are
equally effective in restoring blood volume and oxygen-carrying capacity.15 The patient's history, vital signs, clinical situation, and hematocrit determine the urgency of red cell support. Plasma and platelet support should be based on the presence or absence of microvascular (not surgical) bleeding and on the results of screening tests of hemostasis [prothrombin time (PT), partial thromboplastin time (PTT), fibrinogen, and platelet count].
Many patients with major hemorrhage who require massive transfusion develop a coagulopathy, but not all develop diffuse microvascular bleeding as a result. This coagulopathy may be characterized by thrombocytopenia, hypofibrinogenemia, and prolongation of the PT and the PTT. The etiology of this coagulopathy can be multifactorial, and may be caused by consumption of coagulation factors or hemodilution. Patients with severe tissue injury and prolonged hypotension are more likely to develop diffuse microvascular bleeding and require greater hemostatic support." Preestablished formulas to guide component replacement, such as giving 2 units of Fresh Frozen Plasma (FFP) or 6 units of Platelets with every 5 units of RBCs, are not efficacious." Strict reliance on these formulas may provide insufficient support to patients with consumptive coagu-lopathies and unnecessary transfusion of components to those who do not develop disseminated intravascular coagulation (DIG). Through careful monitoring of laboratory tests of hemostasis, the timely and judicious transfusion of Platelets, FFP, or Cryoprecipitated AHF can be reserved for patients with documented deficiencies.
Mild-to-moderate prolongation of the PT or the PTT does not accurately predict subhemostatic clotting factor levels. Marked prolongations of these tests Often reflect factor levels below 20-30% (see Overview of Hemostasis), however, and supplemental FFP or Cryoprecipitated AHF may then be indicated." In bleeding patients with thrombocytopenia, platelets should be administered to maintain a platelet count of 50,000/pL. Patients who continue to bleed despite adequate levels of platelets or coagulation factors should be thoroughly re-evaluated and considered for surgical exploration. Close communication between
clinicians and the transfusion service director is essential in these cases.

CARDIAC MUSCLE CELLS

In order to understand how the heart regulates itself, there are some characteristic features of cardiac muscle cells to consider more closely.
All resting muscle cells, including cardiac muscle cells, are polarized, i.e. the interior of the cells are negative with respect to the exterior. Each cell is surrounded by a membrane being permeable to particular ions, especially Na*, K*.
In the resting cell, there is an equilibrium between the concentration of these ions within the cell and outside of the cell, but the distribution of the ions is unequal, there being a high extracellular concentration of Na* and a high intracel-lular concentration of K*. Since there are more extracellular Na+ ions than intracellular K* ions, the interior of the cell will be negative with respect to the exterior, creating the membrane potential.
If a microelectrode is inserted into the cell, this resting membrane potential can be measured as negative, approx. -90 mV.
When the cell receives a stimulus, e.g. if an electrical current is applied to to its surface, the membrane potential changes and becomes less negative, triggering an influx of Na* ions into the cell.
If only a very weak current is applied, it will result merely in a transient, moderate reduction of the membrane potential. A stronger stimulus, however, will cause the number of Na+ ions pouring into the cell to become so great that the resting membrane potential breaks down: the cell is activated and contracts. The formerly negative membrane potential rises abruptly to zero and beyound to an overshoot of approximately +30 mV. For cardiac cells this depolarisation occurs at approx. -50 mV, called the threshhold potential.
After the rapid cell depolarization and contraction, Na* ions are pumped out of the cell again, causing at first a rapid phase of repolarisation towards zero potential, then a plateau phase with the potential maintained at or near zero, and finally a rapid repolarisation phase to restore the resting membrane potential.
Tiie entire process of potential changes from the beginning of depolarization to the end of repolarisation is called the action potential of the cell.
Depolarization in cardiac muscle cells is a rather short process that lasts only a few milliseconds, whereas repolarisation lasts for about 500-600 ms.
The cardiac muscle cell can only depolarize when the membrane potential is more negative than the threshold potential, i.e. it is not possible to depolarize the cell in the repolarization period, the cell is said to be in the refractory period. This indicates that impulses can only spread to non-excited cells.
In ordinary muscle, the cells lie parallel and the depolarization of one cell does not influence its neighbouring cells. Myocardial cells, however, are joined end-to-end by structures to form an interrelated network. Therefore, they are able not only to contract but also to initiate a depolarisation of their neigbour cells and propagate the contraction to each other. In this way all cells are stimulated, providing coordinated contraction of the heart and effective pumping.

IS SEX NECESSARY?

The best that modern science can say for sexual abstinence is that it's harmless when practiced in moderation. Having regular and enthusiastic sex, by contrast, confers a host of measurable physiological advantages, be you male or female. (This assumes that you are engaging in sex without contracting a sexually transmitted disease.)
In one of the most credible studies correlating overall health with sexual frequency, Queens University in Belfast tracked the mortality of about 1,000 middle-aged men over the course of a decade. The study was designed to compare persons of comparable circumstances, age and health. Its findings, published in 1997 in the British Medical Journal, were that men who reported the highest frequency of orgasm enjoyed a death rate half that of the laggards. Other studies (some rigorous, some less so) purport to show that having sex even a few times a week has an associative or causal relationship with the following:
- Improved sense of smell: After sex, production of the hormone prolactin surges. This in turn causes stem cells in the brain to develop new neurons in the brain's olfactory bulb, its smell center.
- Reduced risk of heart disease: In a 2001 follow-on to the Queens University study mentioned above, researchers focused on cardiovascular health. Their finding? That by having sex three or more times a week, men reduced their risk of heart attack or stroke by half. In reporting these results, the co-author of the study, Shah Ebrahim, Ph.D., displayed the well-loved British gift for understatement: "The relationship found between frequency of sexual intercourse and mortality is of considerable public interest."
- Weight loss, overall fitness: Sex, if nothing else, is exercise. A vigorous bout burns some 200 calories--about the same as running 15 minutes on a treadmill or playing a spirited game of squash. The pulse rate, in a person aroused, rises from about 70 beats per minute to 150, the same as that of an athlete putting forth maximum effort. British researchers have determined that the equivalent of six Big Macs can be worked off by having sex three times a week for a year. Muscular contractions during intercourse work the pelvis, thighs, buttocks, arms, neck and thorax. Sex also boosts production of testosterone, which leads to stronger bones and muscles. Men's Health magazine has gone so far as to call the bed the single greatest piece of exercise equipment ever invented.
- Reduced depression: Such was the implication of a 2002 study of 293 women. American psychologist Gordon Gallup reported that sexually active participants whose male partners did not use condoms were less subject to depression than those whose partners did. One theory of causality: Prostoglandin, a hormone found only in semen, may be absorbed in the female genital tract, thus modulating female hormones.
- Pain-relief: Immediately before orgasm, levels of the hormone oxytocin surge to five times their normal level. This in turn releases endorphins, which alleviate the pain of everything from headache to arthritis to even migraine. In women, sex also prompts production of estrogen, which can reduce the pain of PMS.
- Less-frequent colds and flu: Wilkes University in Pennsylvania says individuals who have sex once or twice a week show 30% higher levels of an antibody called immunoglobulin A, which is known to boost the immune system.
- Better bladder control: Heard of Kegel exercises? You do them, whether you know it or not, every time you stem your flow of urine. The same set of muscles is worked during sex.
- Better teeth: Seminal plasma contains zinc, calcium and other minerals shown to retard tooth decay. Since this is a family Web site, we will omit discussion of the mineral delivery system. Suffice it to say that it could be a far richer, more complex and more satisfying experience than squeezing a tube of Crest--even Tartar Control Crest. Researchers have noted, parenthetically, that sexual etiquette usually demands the brushing of one's teeth before and/or after intimacy, which, by itself, would help promote better oral hygiene.
- A happier prostate? Some urologists believe they see a relationship between infrequency of ejaculation and cancer of the prostate. The causal argument goes like this: To produce seminal fluid, the prostate and the seminal vesicles take such substances from the blood as zinc, citric acid and potassium, then concentrate them up to 600 times. Any carcinogens present in the blood likewise would be concentrated. Rather than have concentrated carcinogens hanging around causing trouble, it's better to evict them. Regular old sex could do the job. But if the flushing of the prostate were your only objective, masturbation might be a better way to go, especially for the non-monogamous male. Having sex with multiple partners can, all by itself, raise a man's risk of cancer by up to 40%. That's because he runs an increased risk of contracting sexual infections. So, if you want the all the purported benefits of flushing with none of the attendant risk, go digital. A study recently published by the British Journal of Urology International asserts that men in their 20s can reduce by a third their chance of getting prostate cancer by ejaculating more than five times a week.
While possession of a robust appetite for sex--and the physical ability to gratify it--may not always be the cynosure of perfect health, a reluctance to engage can be a sign that something is seriously on the fritz, especially where the culprit is an infirm erection.
Dr. J. Francois Eid, a urologist with Weill Medical College of Cornell University and New York Presbyterian Hospital, observes that erectile dysfunction is extension of vascular system. A lethargic member may be telling you that you have diseased blood vessels elsewhere in your body. "It could be a first sign of hypertension or diabetes or increased cholesterol levels. It's a red flag that you should see your doctor." Treatment and exercise, says Dr. Eid, can have things looking up again: "Men who exercise and have a good heart and low heart rate, and who are cardio-fit, have firmer erections. There very definitely is a relationship."
But is there such a thing as too much sex?
The answer, in purely physiological terms, is this: If you're female, probably not. If you're male? You betcha.
Dr. Claire Bailey of the University of Bristol says there is little or no risk of a woman's overdosing on sex. In fact, she says, regular sessions can not only firm a woman's tummy and buttocks but also improve her posture.
Dr. George Winch Jr., an obstetrician/gynecologist in Elko, Nev., concurs. If a woman is pre-menopausal and otherwise healthy, says Dr. Winch, her having an extraordinary amount of intercourse ought not to pose a problem. "I don't think women can have too much intercourse," he says, "so long as no sexually transmitted disease is introduced and there's not an inadvertent pregnancy. Sometimes you can have a lubrication problem. If you have that, there can be vaginal excoriation--vaginal scrape."
Women who abstain from sex run some risks. In postmenopausal women, these include vaginal atrophy. Dr. Winch has a middle-aged patient of whom he says: "She hasn't had intercourse in three years. Just isn't interested. The opening of her vagina is narrowing from disuse. It's a condition that can lead to dysparenia, or pain associated with intercourse. I told her, 'Look, you'd better buy a vibrator or you're going to lose function there.'"
As for men, urologist Eid says it's definitely possible to get too much of a good thing, now that drugs such as Viagra and Levitra have given men far more staying power than may actually be good for them.
The penis, says Eid, is wonderfully resilient. But everything has its limits. Penile tissues, if given too roistering or prolonged a pummeling, can sustain damage. In cases you'd just as soon not hear about, permanent damage.
"Yes," says Dr. Eid, "It is possible for a young man who is very forceful and who likes rough sex, to damage his erectile tissue." The drugs increase rigidity; moreover, they make it possible for a man to have second and third orgasms without having to wait out intermission.
"I see it in pro football players," says Eid. "They use Viagra because they're so sexually active. What they demand of their body is unreasonable. It's part of playing football: you play through the pain." This type of guy doesn't listen to his body. He takes a shot of cortisone, and keeps on going. And they have sex in similar fashion."
There's a reason the penis, in its natural state, undergoes a period of flaccidity: That's when it takes a breather. The blood within it is replenished with oxygen. "During an erection," explains Eid, "very little blood flows to the penis. During thrusting, pressure can go as high as 200 mil of water. Zero blood flows into penis at that time." To absorb oxygen, the tissue must become relaxed. "If you do not allow the penis to rest, then the muscle tissue does not get enough oxygen. The individual gets prolonged erections, gets decreased oxygen to tissue, and could potentially suffer priapism." (We recommend you get a medical encyclopedia and look it up.) "The muscle becomes so engorged, it's painful. Pressure inside starts to increase. Cells start dying. More pressure and less blood flow. Eventually the muscle dies. Then there's scarring. That's why it's considered an emergency."

APPLICATION OF COMPUTER

The dawn of the new age. The computer Era - glows before up with the promise of new and improved ways of thinking, living and working. The amount of information in the world is said to be doubling every six to seven years. The only way to keep up with there horsebsed amounts of data and information is to understand how computers works and the ability to control them for a particular purpose. A computer can be defined as an electronic processing device, capable of accepting data as input [softcopy], perform series of logical operation through Central Processing Unit [C.P.U]. Process data as information, store data for futre retrival, send information out through the output unit [printer] as a hardcopy. It is binding fact that computer are very productive, efficient and make our personal and professional lives more rewarding. There 'magical' machines can do just about anything imaginable, moreover they really excel in certain areas. Below is the list of some of the principal applications of the computer systems. BUSINESSES: Businessmen make bar graphs and she charts from tendinus figures to convey information with far more impact than numbers alone can convey. Furthermore, computers help businesses to predict their future sales, profits, cost etc. Making companies more accurate in theire accounts. Computers may also play a vital sold in aiding thousands of organizations to olle judgemental and hard provoking decision amberming financial problems and poppeative trends. BUILDINGS: Architects use computer animated graphics to experiment with possible exteriors and to gived clients a visual walk through of their proposed buildings. The computers provide architects a numerous amount of facilities to create different buildings with greater accuracy, better dashinging and editing tools, and work done at the fastest speed possible. Finally, a new kind of artist has emerged, one who user computers to express his or her creativity. EDUCATION: Most good schools in the world have computers available for use in the classroom. It is been provened that learning with computers has been more successful and this is why numerous forms of new teaching methods have been introduced. This enhancads the knowledge of the student at a much faster race than the old traditional methods. Likewise, colleges and various univeritifs have extended the use of computers as many educators prefer the 'learning by doing' method - an approbhi uniquely suited to the computer. RETAILING: Products from meats to magazines are packed with zebra striped bar codes that can be read by the computer scanners at supermarket checkout stands to determine prices and help minge inventory. ENERGY: Energy companies use computers to locate oil, coal, natural has and uranium. With the use of there technological machines, there companies an figure out the site of a natural resources, its concentration and other related figure. Electric companies use computers to monitor trasu power each month in homes and offices. LAW ENFORCEMENT: Recent innovation in computerized law enforcement include national fingerprint files, a national file on the mode of operation of serial killers. And computer modeling of DNA, which can be used to match traces from an alleged criminal's body, such as alone at a crime scene. In addition, computers also antago a complete databases of all the names, pictures and information of such people who choose to break the law. TRANSPORTATION: Computers are used in cars to oniouns fluid levels, temperatures and electrical systems. Computers are also used to help run rapid transit systems, load containerships and track railroads cars across the country. An important part is the aris control traffic systems, where computers are used to control the flow of traffic between airplanes which offer a lot of precision and accuracy to be dealt with. MONEY: Computers speed up record keeping and allow banks to offer same day services and even do it yourself banking over the phone and internete. AGRICULTRE: Farmers use small computers to help with billing, arms information, and cost per acre, feed combinations, and market price checks. Battle ranchers can also use computers for information about livestock breeding and performance. GOVERNMENT: Among other tasks, the federal government uses computers to forecast the weather, to manage parks and historical river, to process immigrants, to produce social security checks and to collect taxes. HEALTH AND MEDICINE: Computers are helping immensely to omitns the extremely ill in the intensive care unit and provid cross sectional views of the body. This eliminates the need for hired nurses to watch the patient twenty four hours a day, which is greatly tiring and error prone. Doctors use computers to assist them in diagnosing certain diseases of the post. This type of computer is called the Expert System, which is basically a collection of accumulated expertise in a specific area of field.

SEX EDUCATION

1. Sex ducation for kids, teens, and adults. 2. Sex therapy and revitalization for teen and adults. 3. Sex products for adult only. Sex education very often you hear the words 'sex education' randomly tossed around especially in safe sex advertisement campaigns and other programs aimed specifically at teenagers and loosely at the general public. Truth be told, sex education has been a very difficult subject especiallly here in Africa, for obvious reasons. How can societies that six away from 'sex talk' be able to educate their children and citizens in general about sex? They simply cannot and for this very reason sex education has not succeeded in our part of the world. Unwanted pregnancieas, HIV / AIDS and other transmitted diseases remain on the increase here in Africa as proof that we are not making progress in this area. This is not to say that effort has not been made over the years concerning this issue, but a lot more needs to be done. Simply putting out the information, AIDS kills. Use a condom, does not begin to qualify as adequate and effective sex education. We need to drive more into the subject of sex with the aim of familiarizing our people with comfortable and helpful sex information, intended to enlighten up and hopefully share our habits. Thanks for reading.