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Wednesday, July 21, 2004

Pag Mataas ang Presyon Mo, Bawal ang Maalat...

Actually, mahaba ang litanya ng mga "bawal" sa mga taong may hayblad (high blood pressure po! aka hypertension). "Bawal ang maalat" is just one in the long list of pointers given by the doctor. (other bawals: mamantika, sigarilyo, especially when there's heart complications: bawal masyadong magpagod, bawal masyadong matuwa, etc., etc.)

Usually the doctor does not really bother to explain the why's of each pointer. Aside from being time-consuming (and there is a queue of patients waiting for their turn), the explanation can be so technical, and can lead to further explanations.

Pero sige, focus tayo sa MAALAT (salty) and its relation to hypertension.

Alam nyo ba, kahit sa medisina, me math? And that's not limited to calculating the charges for each item and hours spent during the consultation, the calculations for pediatric dosages...even during the first year of study, many would-be doctors would be dismayed to find out that they are not spared from  mathematical (specifically physics, more specifically in this topic, fluid dynamics) concepts.

Blood Pressure has an equation:

BP = CO x PR


  • BP = blood pressure
  • CO = cardiac output (yung dugo na binobomba palabas ng puso), and
  • PR = peripheral resistance (this is the tendency of the arteries to resist the incoming blood from the heart)

This means that blood pressure is influenced by these two factors.

Cardiac output also has an equation:

CO = HR x SV


  • HR = heart rate (bilis ng tibok ng puso)
  • SV = systolic volume (dami ng lamang dugo ng puso bago mag-pump)

If you combine the two equations,

BP = HR x SV x PR

So there are 3 factors that operate in increasing the BP:

  • HR - can be increased, for example, by exercise, extreme emotions like fear, anger and excitement
  • SV - can be increased by increasing the blood that flows back to the heart (ex.: elevate your legs, lie down, position yourself upside down, increasing fluid intake and salt intake - but these are usually temporary. The normal body tends to compensate through other woderful mechanisms to bring back the pressure to the normal levels as efficiently as it can)
  • PR - can be increased by decreasing the diameter of the arteries (kaya kung me atherosclerotic plaque, liliit and butas na dadaanan ng dugo), having stiff arteries ( ex. pa rin ang me atherosclerosis), vasoconstriction (constriction of arteries as in nicotine's effect on the circulation - kaya kawawa ang baby ng mga buntis na naninigarilyo)

(For more readings on blood pressure physiology, here is a good educational website by an anatomy and physiology academician)

In human physiology, the two major cations (positively charged ions) are Na (sodium) and K (potassium) ions. They directly affect the normal functioning of all cells.  Na is the main cation in the extracellular fluid (nasa labas ng cells, meaning nasa dugo, in-between ng cells, basta wala sa loob ng cells). K is (nahulaan nyo na siguro) the main cation inside the cells. And when we talk of these ions, we are concerned about electrolyte balance (narinig nyo na siguro ito pag me diarrhea kayo at kelangan nyo ng oresol).

From Martini's Anatomy and Physiology:

The total amount of sodium in the ECF represents a balance between two factors:

  • Sodium ion uptake across the digestive epithelium. Sodium ions enter the ECF by crossing the digestive epithelium through diffusion and carrier-mediated transport. The rate of absorption varies directly with the amount of sodium in the diet.
  • Sodium ion excretion at the kidneys and other sites. Sodium losses occur primarily by excretion in urine and through perspiration. The kidneys are the most important sites of Na+ regulation. (Kaya bawal din ang maalat sa me sakit sa bato.)

A person in sodium balance typically gains and loses 48–144 mEq (1.1–3.3 g) of Na+ each day. When sodium gains exceed sodium losses, the total Na+ content of the ECF goes up; when losses exceed gains, the Na+ content declines. However, a change in the Na+ content of the ECF does not produce a change in the Na+ concentration. When sodium intake or output changes, a corresponding gain or loss of water tends to keep the Na+ concentration constant. For example, if you eat a very salty meal, the osmotic concentration of your ECF will not increase. When sodium ions are pumped across your digestive epithelium, the solute concentration in that portion of the ECF increases, whereas that of the intestinal contents decreases. Osmosis then occurs. Additional water enters the ECF from the digestive tract, elevating blood volume and blood pressure. Thus, persons with high blood pressure are advised to restrict the amount of salt in their diets.

Ngayon, hindi lang "maalat" ang equivalent ng "restrict the salt intake". In particular, pay attention to the sodium content of your food. Gaya ng MSG (monosodium glutamate), peanut butter, etc. To see a list of sodium-rich foods, click here.

Gets nyo na? Kaya kayong me hayblad, WAG MATIGAS ANG ULO (If you still need more convincing to lower your BP, ask doc emer about the complications of HPN.)


  1. Naalala ko medschool days ko, Manang. Sana ikaw na lang teacher ko. Busog pa ako. :)

  2. Doc Emer,
    Papasa ba akong teacher? Haha...wannabe physio/biochem/anatomy teacher sana ako, kaya lang...dito ko na lang bubuhos ang hilig.

  3. 'Yung biyenan kong lalaki, nung nabubuhay pa, ang definition niya ng bawal ay yung nahuhuli lang. Pag walang nakatingin, hindi bawal.

  4. Sassy, guilty rin ako dyan...shhhhh!



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