The pressure in any pump-pipes system can shift with changes in any one or a combination of three things: pumping intensity, rate, and output; fluid volume of the system; and resistance on the pipes. Here’s how these factors correspond to the pressure of blood in your own pump-and-pipes system.
Pumping intensity, rate, and outputThe more intense or rapid the heartbeat, the greater the volume of blood pumped out of the heart with each beat (known as cardiac output) and the higher the blood pressure throughout the system. Stress or exercise, for example, prompts the adrenal glands to secrete hormones that speed up heart rate and cardiac output. This in turn elevates blood pressure.
Fluid volumeThe more blood in the system, the greater the pressure against the blood vessel walls. Blood volume increases – and blood pressure rises – when sodium levels increase and cause water to be retained by the body. This results from dietary indiscretions and mineral imbalances.
Resistance on the pipesAs blood flows through the vessels, it encounters friction or a phenomenon known as peripheral resistance (because the greatest friction is in the peripheral arterioles, away from the heart). Three things contribute to peripheral resistance. One is blood viscosity, or thickness. The thicker the blood, the less easily it flows and the higher the blood pressure. Excess fat in the diet may contribute to increased blood viscosity. Another contributor to peripheral resistance is total blood vessel length – the longer the length, the greater the resistance. Every extra pound on your body requires additional blood vessels to sustain it, and this is one reason why weight gain is associated with increases in blood pressure.The third and perhaps most significant cause of peripheral resistance and increased blood pressure is decreased diameter and responsiveness of the arteries and arterioles. The muscular walls of your arteries and arterioles enable them to constrict and expand to divert blood to various areas, depending on your body’s needs. When they constrict and become smaller – decreasing the diameter of the pipes – blood pressure goes up. The arteries and arterioles constrict in response to hormones and other chemical messengers associated with stress, exercise, and other factors, as well as to mineral imbalances at the cellular level. In addition, arteriosclerosis (stiffening and thickening of the arteries) and atherosclerosis (buildup of plaque in the arteries) also decrease the diameter and flexibility of the arteries, thus contributing to peripheral resistance and higher blood pressure.*12/313/5*

The cost of BDD isn’t known, but is certainly high. The economic cost includes medical costs for bodily harm and accidents, the cost of ineffective medical and surgical evaluation and treatment, and the cost of medical and psychiatric hospitalization. It also includes the costs of incomplete education, decreased productivity, lateness, and days lost from work, and the cost of disability payments.Some people with BDD have significant financial problems because of these costs or because they spend so much money on wigs, clothes, makeup or surgery. One woman was more than $10,000 in debt because she’d spent so much money on clothing and wigs. Several other people were more than $20,000 in debt.Richard’s experience illustrates how costly BDD can be. Richard had dropped out of school because he constantly went to the bathroom to check the mirror and couldn’t concentrate on his studies. He tried several jobs, but quit each of them because of his symptoms. He then moved in with his family and went on disability.Richard had made three suicide attempts, usually after looking in the mirror and feeling devastated by what he saw. After each attempt, he was hospitalized. After he overdosed, he had a long stay in an intensive care unit. In the six months before I saw him, he’d been hospitalized four times. Richard had also had three operations on his lips, which were costly and ineffective. Two had such devastating results, in his view, that he had to be psychiatrically hospitalized. “I had to be hospitalized because after the surgery my lips were black and blue and swollen,” he said. “They looked deformed. I went wild, screaming and smashing things. I thought they were worse than ever, and I thought I’d done irreparable damage to myself.”Although Richard had had BDD for only several years, the cost of his illness had been staggering—already well over $100,000. But the greater cost of BDD is the human cost—the severe suffering and pain. Years lost to the illness can’t replaced. One man told me, “It’s crazy because I’ve wasted so much of my life. I grieve for all the years this disorder took from me.”*143\204\8*

When micro-organisms invade the body a battle ensues between them and the body’s defenses. White blood cells are mobilized and some of them release active substances into the local circulation. A similar release of active substances occurs during allergic reactions, or when a weal of a blister following a burn forms on the skin. These substances cause intense pain, as well as an increased sensitivity to pain; they can be divided into two groups, kinins which are derived from protein breakdown, and amines, especially histamine, which causes more inflammation and makes blood vessel walls porous, to produce swelling and redness.
SinusitisThis pain often affects the area over the eye (frontal sinus) or below it (maxillary sinus). The pain often comes on after a cold which blocks the nose and occurs each day, being worse in the afternoons. The pain is caused by inflammation and stretching of the periosteum and vessels by pus under tension. The area is often tender to pressure or tapping and the diagnosis can be confirmed by X-rays.
MeningitisThis is an inflammation of the brain’s coverings (meninges) and is always associated with headache. The intense pain from the head gives rise to contraction of the muscles of the neck to produce the stiff neck which is a symptom of meningitis. It is a serious condition and when suspected, a spinal tap (lumbar puncture) is necessary to examine the cerebrospinal fluid. With modern antibiotics, over 90 per cent of cases should be cured.
EncephalitisThis means inflammation of the brain and is another very serious cause of headache.
Dental infectionThis is sometimes a cause of headache but is more likely to cause pain in the jaws, and the lower more commonly than the upper.
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