Blood: composition and functions

Blood: composition and functions
Everybody is familiar with the sight of blood - the red fluid that oozes out of your body when you've sustained a cut or an deep injury. The composition of blood is actually quite complex. Also, as we shall see in this essay, blood is crucial to our survival.
Blood is the medium in which dissolved gases, nutrients, hormones and waste products are transported. Blood along with the heart and the blood vessels (e.g. veins and arteries) comprises the circulatory system of the body. The circulatory system helps in maintaining balanced conditions within the body (i.e. homeostasis). For example oxygen is picked up by blood as it passes through the lungs- this blood in turn flows through successively narrower blood vessels: from arteries to arterioles and finally the capillaries, where the oxygen rich blood delivers its oxygen to the cells.
Blood is composed of a straw-colored liquid called plasma which contains suspended cells. The different specialized cells found in blood are
red blood cells
white blood cells
platelets Approximately 90% of plasma is water
blood's solvent with the rest composed of dissolved substances, primarily proteins (e.g. albumin, globulin, fibronogen). Plasma typically accounts for 55% by volume of blood and of the remaining 45% the greatest contribution is from the red blood cells.
Red blood cells (also called erythrocytes):
These are the familiar discotic shaped cells which make up 99% of the cells in the blood. They are the principal carriers of the red colored hemoglobin molecules. Hemoglobin is an iron containing protein and binds about 97% of all oxygen in the body. We know that oxygen is not very soluble in water hence if oxygen were simply dissolved in the fluid of blood not much could be carried by the bloodstream. Each hemoglobin molecule binds four oxygen molecules to itself- consequently hemoglobin permits human blood to carry more than 70 times the amount of oxygen that it could have carried otherwise. The unique surface shape of red blood cells is nature's design to maximize surface area in order to facilitate absorbtion and release of oxygen. (Given a spherical and a discotic cell of the same volume which do you think has a greater surface area and hence more ability to absorb?)
Not all blood is equal: this fact was learnt the hard way in the mid 1600's when blood from a lamb was transfused into a human with fatal results. The cell membrane of red blood cells contains different proteins, which are responsible for different types of blood. There are primarily two types of proteins found in the cell membrane of red blood cells- protein A and B. Different combinations of these proteins and their antibodies results in four types of blood
type A : have protein A and antibodies to B protein
type B : have protein B and antibodies to A protein
type AB : have both protein A and B but neither of the antibodies
type O : have neither proteins but have both the antibodies Type AB is called 'universal acceptor' and type O is called 'universal donor' because of the ability of people with this blood group to accept blood or donate blood to all other blood groups respectively.
White blood cells (also called leukocytes):
The role of blood is not confined to the transportation of materila within the body. The white blood cells are a vital source of defense against external organisms. White blood cells also serve as 'sanitary engineers' cleaning up dead cells and tissue debris that would otherwise accumulate to and lead to problems. There are five classes of leukocytes: neutrophil, eosinophil, basophil, monocyte and lymphocytes. Many infections stimulate the body to release into the bloodstream large number of protective leukocytes thate are normally held in reserve, causing the white cell number to rise. The increased number of white cells is easily detected in a blood test and is an a very useful first approximation in diagnosis. Some white blood cells may die in the process of fighting against an infection and their dead bodies accumulate and contribute to the white substance that is commonly seen at the sight of infections, usually called 'pus'. Not all infections lead to an increase in the white blood count- the virus that is responsible for AIDS results in a reduced white blood count and hence reduced ability to fight other infections.
Plasma and platelets in clotting:
If damage occurs to a blood vessel, circulating platelets immediately get trapped at the injury site. On accumulating the platelets 'plug' the leak in the vessel providing a first step in damage control. This mechanism is supplemented by 'blood coagulation', or clotting, which is the most important means of defense against bleeding. As mentioned plasma contains several dissolved proteins. Fibrinogen is a rod shaped soluble protein which in the presence of a catalyst thrombin gets converted to an insoluble protein fibrin . Fibrin molecules make a tangled net of fibers by adhering end-to-end and side-to-side which immobilizes the fluid portion of blood (causing it to solidify) and also traps the red blood cells.

Here we see a red blood cell (which actually looks blue in the picture!) snared in the fibrin mesh (thin lines) of a blood clot. The combined action of the platelets and 'fibrin web' is sufficient to prevent a dangerous loss of blood. In cases where the formation of fibrin and hence formation of a clot is impaired due to some reason (e.g. a genetic disorder as in hemophilia) a person is at great risk of bleeding to death.

Blood

Blood is a specialized bodily fluid that delivers necessary substances to the body's cells — such as nutrients and oxygen — and transports waste products away from those same cells.
In vertebrates, it is composed of blood cells suspended in a liquid called blood plasma. Plasma, which comprises 55% of blood fluid, is mostly water (90% by volume),[1] and contains dissolved proteins, glucose, mineral ions, hormones, carbon dioxide (plasma being the main medium for excretory product transportation), platelets and blood cells themselves. The blood cells present in blood are mainly red blood cells (also called RBCs or erythrocytes) and white blood cells, including leukocytes and platelets. The most abundant cells in vertebrate blood are red blood cells. These contain hemoglobin, an iron-containing protein, which facilitates transportation of oxygen by reversibly binding to this respiratory gas and greatly increasing its solubility in blood. In contrast, carbon dioxide is almost entirely transported extracellularly dissolved in plasma as bicarbonate ion.
Vertebrate blood is bright-red when its hemoglobin is oxygenated. Some animals, such as crustaceans and mollusks, use hemocyanin to carry oxygen, instead of hemoglobin. Insects and some molluscs use a fluid called hemolymph instead of blood, the difference being that hemolymph is not contained in a closed circulatory system. In most insects, this "blood" does not contain oxygen-carrying molecules such as hemoglobin because their bodies are small enough for their tracheal system to suffice for supplying oxygen.
Jawed vertebrates have an adaptive immune system, based largely on white blood cells. White blood cells help to resist infections and parasites. Platelets are important in the clotting of blood.[2] Arthropods, using hemolymph, have hemocytes as part of their immune system.
Blood is circulated around the body through blood vessels by the pumping action of the heart. In animals having lungs, arterial blood carries oxygen from inhaled air to the tissues of the body, and venous blood carries carbon dioxide, a waste product of metabolism produced by cells, from the tissues to the lungs to be exhaled.
Medical terms related to blood often begin with hemo- or hemato- (also spelled haemo- and haemato-) from the Ancient Greek word αἶμα (haima) for "blood". In terms of anatomy and histology, blood is considered a specialized form of connective tissue, given its origin in the bones and the presence of potential molecular fibers in the form of fibrinogen.

Side-effects of blood donation

I tottered all the way to the blood donation center and almost managed to persuade myself to make it another day, but then I pushed the door open and I was in. No turning back. I filled out the forms, almost subconsiously ticking 'no' for everything, because the first question was 'did you have male to male sex' and of course it was no so when it came to the 'are you feeling well and healthy' I almost ticked no, too. XD

So then the standard procedure is to have your weight and blood pressure taken, and your finger pricked so your blood can be tested (for iron levels or something?). The first thing the woman said when she took my hand: "You're freezing cold!"

And being the retarded person I am: "I am?"

No, honestly, I wasn't feeling very cold at all once I'd gotten inside the building. From past blood donation experience, I was bracing myself for the sharp prick of the needle that I completely hate - but surprisingly it didn't hurt at all, really. Guess I was number than I thought...

I bled all over the form I was signing. XD Bad idea to have the middle finger on my right hand pricked.

The actual donation involving the scary big-ass needle was less painful than remembered, too. I must've had a bad expression on my face, because two different people asked me, twice, whether I was feeling all right. XDD Sorry, I was just nervous as heck. I was squeezing the thing they gave us (to improve blood flow) so hard I left permanent little indents.

Anyway, all was cheery and well and I got a bottle of free orange fizzy drink.

And THEN the 'side effect' showed up in the afternoon. I knew I wasn't supposed to do anything to exert myself, but I didn't, but I was waiting outside mum's office when I first felt that my bag was suddenly getting unreasonably heavy. I unshouldered my bag and propped it againt my leg. There. That should feel better.

It didn't. It felt as if I still had a heavy weight on my shoulders. I shrugged a little, brushing it off as fatigue. Sometimes, my bag really does get very heavy.

Then I felt very tired, and I promptly closed the book I was reading. After all, I'd been standing there reading for almost 15 minutes...maybe I'd improve if I looked around a bit, took a walk or something.

Dropped the book in my bag, and immediately a ringing sound started in my ears. I felt dizzy, so I bent and fished out the remains of the orange juice, hoping it was just a lack of sugar/insulin in my blood. As I remained crouched on the pavement (I adamantly refuse to sit and ruin my coat) the ringing started getting louder and louder. At that most embarrassing point, my mother came out of the office.

When I saw her I tried to get up, but then the ringing just grew deafening and I couldn't hear anything but the weird ringing sound. Then to my alarm, things started getting blurry, and then it went black altogether. I just couldn't see anything, or hear anything. Then my mum started whacking my chest, and I kept trying to tell her, "C'mon, mum, stop it, I'm fine." but apparently she couldn't hear me. XD She made me drink water out of my water bottle and had me remain crouching (I still refused to sit completely) and after maybe 3 minutes my vision started coming back. My mum was so concerned she cancelled the trip to Medibank. n__________n''

To be honest, I wasn't scared. Much. I was more like....WHAT THE HECK I DON'T WANT MY MUM TO SEE THIS!! Geez. Why can't I have the panic attack before she came down? *grumbles* And then she started saying that I should eat something, but I wasn't really feeling the stomach for it. In the end we just hopped on the car and drove home. I sat outside the food court (on a respectable chair) to wait while she fetched the car. XD

Hmmmm. I'd better eat more the next time I head off for a blood donation. I thought having pasta instead of bread in the morning would be better, but maybe not?

So anyway. I'm spacing out my last donation for the year so it'll give my blood some time to replenish...I hope...

In happier news, I was digging through my stuff last night looking for Kim's address when I found a box of old letters from friends! :DDD I was delighted! I spent last night rereading them, and I cried a little when I thought of all the friends I miss. And then I unearthed the three or four love letters (the only ones I ever received) and reading them, frankly, it makes me wonder what sort of reply I have him, to get something so mushy in return. XD Actually, I think I sounded clingy because he was assuring he wasn't flirting. XD How bad of me.

And of course there were tons of letters from when I used to write heaps to a friend. We used to write lots, like, a few every month (since she lives in the next town 6 hours away) so the letters get by rather quickly. So many of them...and the birthday cards I've kept, the earliest from 1997 from my aunts and uncles. XDD How nice. Just last week I was wishing I could find certain letters, and then I found them, plus a treasure of others! XD I love letters, I really do. Oh, and the good news is, awin, I found some pretty envelopes from when I used them to send letters to Kim who was sitting a few rows away from me! XD We used to decorate them with 'Kenshin' (her choice) and Athrun (my choice). :P Yes, I found some pretty envelopes!!

...Now, where are my pretty papers...?

How to minimize side effects of blood donation?

When I used to donate blood, I would feel tired the next
day, but I had no other significant side effects. I always
drink plenty both before and after donating, but the last
two times I've had a low-grade fever (chills/sweats) and
significant joint stiffness for two days afterward.

Are there other steps I can take to minimize thes side
effects?

• 3 years ago

Additional Details

One of the answerers pointed to a web
site which states there are no side
effects. So do I believe an expert
or do I believe my "lying eyes" :-)
I've gotten slightly sick both of the
last two times.

I wonder if the beds in the blood
mobile could be a vector for the flu
virus? Maybe the puncture wound makes
me more susceptible to infection?

I will mention that the Red Cross
person who took my blood did mention
that some people report "flu-like"
symptoms after donation, so maybe I'm
not the only person to experience this.

3 years ago

Gay men still can’t donate blood

WASHINGTON - Gay men remain banned for life from donating blood, the government said Wednesday, leaving in place — for now — a 1983 prohibition meant to prevent the spread of HIV through transfusions.

The Food and Drug Administration reiterated its long-standing policy on its Web site Wednesday, more than a year after the Red Cross and two other blood groups criticized the policy as “medically and scientifically unwarranted.”

“I am disappointed, I must confess,” said Dr. Celso Bianco, executive vice president of America’s Blood Centers, whose members provide nearly half the nation’s blood supply.

Who Can’t Donate Blood?

Temporary Reasons
Condition and Length of time before you can give blood

• Not feeling well for any reason, until symptoms are over.
• Cold, sore throat, respiratory infection, flu, until symptoms are over.
• Difficulty of breathing, shortness of breath, asthma, no difficulty breathing on day of donation.
• Antibiotics, two days after treatment is over if taken for infection.
• Blood transfusion, one year after receiving blood.
• Full–term pregnancy, six weeks after delivery.
• Abortion or miscarriage, six weeks if after the first trimester (12 weeks).
• Surgery, serious injury, when healing is completed.
• Dental work, seventy–two hours after root canal or after extraction of tooth.
• Sexually transmitted disease: Venereal disease, chlamydia, genital herpes, syphilis, gonorrhea.
• Have had sex with a male or female prostitute within the past twelve months..
• Open–heart surgery, three years after surgery.
• Measles, mumps, chicken pox, three weeks from day of exposure.
• Tuberculosis (T.B.), two years after completion of treatment.
• Aspirin.
• Sniffed cocaine or any other restricted drugs within last 12 months.
• A woman who is menstruating, (safer to donate a week after it).

Permanent Reasons
Please do not give blood if you

• Have used narcotic drugs by intravenous route (injecting directly in the vein), even once.
• If you are suffering from conditions like hemophilia , Thallasemia or any other blood disorder.
• Had a positive antibody test for HIV (aids virus).
• If you are a commercial sex worker.
• Have had hepatitis any time after your eleventh birthday.
• Have had cancer.
• Have multiple sclerosis.
• If ever had myocardial infarction, coronary artery bypass surgery.
• Have had a stroke.
• Have had Chagas disease.

Induction of the chemotactic S100 protein, CP-10

The murine S100 protein CP-10 is a potent chemotactic factor for murine and human myeloid cells in vivo and in vitro. This is the first report describing regulations of the CP-10 gene by a proinflammatory stimulus, lipopolysaccharide (LPS), in cells of the monocyte/macrophage lineage. Murine monocyte/macrophage-like WEHI 265 and RAW 264.7 cells preexposed to 5 to 50 ng/mL LPS expressed significant levels of CP-10 mRNA 4 hours, and maximal at 20 hours, after a secondary LPS challenge. This was accompanied by increasing levels of cell-associated and released CP- 10 protein. In contrast, a single dose of LPS upregulated CP-10 mRNA in elicited peritoneal macrophages, whereas mRNA and protein levels decreased following LPS challenge. The state of macrophage differentiation may control responsiveness as LPS had no effect on CP- 10 basal levels in bone marrow derived macrophages. LPS-induced CP-10 expression was controlled at the transcriptional level and nuclear run- on and protein synthesis inhibition assays indicated that LPS priming and challenge of RAW cells occurred via distinct pathways. MRP14, another S100 protein generally coordinately expressed with human MRP8, was not induced by LPS under the same conditions. We propose that CP-10 may play a key role in recruitment of leukocytes into tissues in response to gram-negative bacterial infection.

Effects of Blood and Crystalloid Cardioplegia

Methods. Pigs were placed on cardiopulmonary bypass and hearts were arrested with a hyperkalemic crystalloid cardioplegic solution (Cryst CP) or blood cardioplegic solution (Blood CP) for 1 hour. Hearts of selected pigs were then reperfused for 1 hour (Rep) and separated from cardiopulmonary bypass. Left ventricular perfusion and contractility and ß- and ₂-adrenergic and myogenic responses of the coronary circulation were examined.

Results. Relaxation of isolated, precontracted microvessels to isoproterenol (ß-adrenoceptor agonist) was reduced to a lesser extent after Blood CP as compared with Cryst CP. Relaxation to forskolin (adenylate cyclase activator) was reduced after Cryst CP, but was preserved after Blood CP. After 1 hour of postcardioplegia reperfusion, the respective responses to isoproterenol and forskolin were similar in vessels from the Cryst CP-Rep and Blood CP-Rep groups. The ₂-adrenoceptor-mediated, endothelium-dependent vascular relaxation to clonidine was decreased more after Cryst CP than after Blood CP. The relaxation to nitroprusside was not affected by either Cryst CP or Blood CP. Myogenic tone was decreased to a lesser extent after Blood CP versus Cryst CP. Baseline coronary blood flow, isoproterenol-induced increases of coronary blood flow, and indices of myocardial contractility were similar in the Blood CP-Rep and Cryst CP-Rep groups, both 5 and 60 minutes after initiation of reperfusion.

Conclusions. Although Blood CP was superior to Cryst CP in preserving ß- and ₂-adrenoceptor function and myogenic tone in vitro, there was no demonstrable benefit of blood cardioplegia in the preservation of myocardial contractility or perfusion in this model of cardioplegia.

Blood cardioplegia delivery

Delivery of cardioplegic (CP) solutions to all regions of the myocardium is critical for optimal myocardial protection during cardiac surgery. However, there are little data regarding the effects of CP agents upon coronary vascular resistance (CVR) and CP delivery. Accordingly, we evaluated blood CP (Hct 30) delivery and CVR during 75 minutes of multi-dose hypothermic blood CP arrest in an in vivo isolated dog heart preparation. Three groups of dogs were studied: K(K+ = 30 mEq/L; n = 6), L (Lidocaine = 400 mg/L; K+ = 4 mEq/L; n = 6), and KL (K+ = 30 mEq/L, Lidocaine 400 mg/L; n = 6) during total cardiopulmonary bypass and moderate systemic hypothermia (28 C). Basal CVR was calculated by measuring total coronary flow (HR 120/min; mean aortic pressure = 80 mmHg) in the empty beating heart. After aortic cross-clamping, the blood CP solution was infused into the aortic root at a constant pressure (80 mmHg) and constant temperature (16 +/- 2 C) for 60 seconds at 15 minute intervals for a total arrest time of 75 min. Total CP flow, CVR, O2 consumption, lactate extraction/production, and K+ balance during 75 minutes of arrest and 30 minutes of reperfusion were determined. The distribution of the CP solution in the left ventricle was measured with radioactive microspheres (9 +/- 1 mu). Biopsy specimens were taken to measure wet to dry ratios. Values are mean +/- SEM. Data were analyzed by BMDP-P2V. During the first CP infusion, after aortic cross-clamping, no differences in CVR or CP distribution were found among the three groups. However, CVR was increased significantly in the K group during the second CP infusion (O': 0.98 +/- 0.20 mmHg/ml/min/100 g; 15': 2.66 +/- 0.82; p less than 0.001). The CVR remained high for the remainder of the arrest period. Moreover, total, epi- and endocardial flow decreased significantly (54%, p less than 0.001). In groups L and KL, no significant changes in CVR were seen. Groups K and KL showed a significant K+ extraction during the first CP infusion. During the early reperfusion period, K+ washout occurred in these two groups, which was not seen in the L group. There was no significant difference between the three groups in myocardial O2 consumption, lactate metabolism, and water content during the arrest and the reperfusion period. In conclusion, high concentrations of K+ (30 mEq/L) can markedly increase CVR and impair blood CP delivery and distribution. These effects can be prevented by lidocaine. These findings warrant reassessment of the various additives to CP solutions and their effects on CVR and CP distribution during multi-dose hypothermic CP arrest.

Who Can Donate Blood, and How?

Who Can Donate Blood, and How?

Blood: A Continuous Need

The need for blood is ongoing and must be met every day. One pint of blood, yielding red cells, platelets, plasma and cryoprecipitate (a clotting component), can benefit as many as four people. Thousands of patients, including those being treated for accidents, routine surgeries and serious diseases such as cancer, heart diseases and hemophilia, rely on the generosity of blood donors daily.

Blood Donor Requirements

To donate blood, you should be in good health, be at least 17 years of age, and weigh at least 110 pounds. You can donate blood every 56 days. Provided you are in good health there is noupper age limit.

If you are well but take medications or have a chronic health condition such as asthma or diabetes, refer to our eligibility requirement to determine whether you qualify.

We accept blood only from volunteer donors.

How and Where to Make An Appointment to Donate

If you wish to donate blood or have questions about your eligibility, call 1-800-GIVE LIFE. We will advise you about the many convenient donation sites throughout the South Bay (counties of Santa Clara, Santa Cruz, Monterey and San Benito) and the EastBay (Alameda and Contra Costa counties). Scheduling an appointment to donate blood can minimize waiting. The entire donation process takes about one hour.

What Happens When I Go to Donate Blood?

• Registration
  When you arrive, a volunteer will greet you and give you a medical history form. You'll register using the same name, date of birth and social security number each time you donate. You'll be asked for some form of identification such as a driver's license.
• Health History
  You'll meet with our health historian who will ask you about your past and present health. These questions serve 2 safety goals: (i) to ensure it is safe for you to donate; and (ii) to ensure that your blood is safe to transfuse to a patient. Next we'll test a drop of blood to make sure you're not anemic. Then we'll do a "mini-physical", checking your pulse, blood pressure and temperature.
  If you've been taking any medicines in the past month, be prepared to give us the name and reason for taking them.
• Donation
  The actual blood donation takes 6 - 10 minutes. A trained Red Cross professional will be at your side all the way.
  
  We'll cleanse an area over the front of your arm at the elbow. All of the supplies, including the needle, are sterile, and used only once - for YOU - so you cannot get AIDS or any other disease.
  
  When we start the actual donation, you'll feel a brief "sting". In about 10 minutes when we've removed about one pint of blood, you're finished. Your body replaces the lost blood promptly - within hours for the plasma (liquid part) and a few weeks for the red cells.
• Refreshment Area
  Now you can relax and enjoy our refreshments. Most people feel fine when they give blood and afterward. You'll be given a phone number to call if you have any questions or concerns.

What should I do after donating blood?

It is recommended you:

• Increase your fluid intake for the next 24 to 48 hours.
• Avoid strenuous physical exertion, heavy lifting or pulling with the donation arm for about five hours.
• Eat well balanced meals for the next 24 hours.
• People seldom experience discomfort after donating. However, if you feel light-headed, lie down until the feeling passes.
• If some bleeding occurs after removal of the bandage, apply pressure to the site and raise your arm for three to five minutes.
• If bruising or bleeding appears under the skin, apply a cold pack periodically to the bruised area during the first 24 hours, then warm, moist heat intermittently.

Who Can Donate Blood?

In general you ARE ELIGIBLE to donate blood if:

You are 17 years old or older. There is no upper age limit.

You weigh at least 110 pounds

You are in good health. If taking medication, you may be able to donate depending on the reason for and the type of medication. .

Persons taking most medications are able to donate blood.

Medications that do not prevent you from donating:

High Blood Pressure Medications
Insulin (by mouth or injection)
Allergy Medications
Asthma Medications
Anti-depressants
Aspirin
Cholesterol Lowering Medications
Seizure Medications
Diet Pills

You ARE NOT ELIGIBLE to donate if:

You had hepatitis after the age of 10.

You are pregnant.

You have had a tattoo within the last 12 months.

You participate in high-risk behaviors.

Medications that preclude you from donating:

Coumadin
Proscar
Propecia
Accutane
Avodart

What about:

Anemia (low iron)

Iron levels in the blood vary daily. These levels are checked at the time of donation. If you were previously deferred because of your iron level, please try again.

Breast Feeding

You may donate if you are breastfeeding.

Menstrual Period

You may donate if you are feeling well.

Hemochromatosis

You may be eligible do donate blood for others if you have hereditary hemochromatosis. To do so you must present an appropriately completed prescription or requisition from your physician. You must meet all other criteria for volunteer whole blood donors, except the donation interval. For further information call the Blood Bank at 863-297-1840.

Some Hints for a Very Successful First-Time Donation:

Realize that it’s normal to be nervous. Many people experience a natural hesitancy towards donating. Once you have done it, the fear of the unknown is overcome and you’ll feel very good about yourself.
Drink lots of water and try to eat a good meal before donating. The water helps to replace the small amount of fluid that you lose when you donate.
Familiarize yourself with the donation process. Ask questions. Understanding the process helps you relax.
Think about the fact that with one donation, you are helping 3 people to have another birthday, another hug, another chance at life.

What Causes Low Blood Pressure?

Many things can make your blood pressure too low. These range in severity from normal changes caused by pregnancy to dangerous underlying conditions, like heart problems or hormone disturbances. Some low blood pressure causes are simple cases of dehydration brought on by vomiting, intense exercise, or the overuse of diuretics. Some studies have shown that a dehydration-induced weight loss of 1 percent is enough to trigger dizziness, confusion, or other symptoms of low blood pressure.

One especially important cause of low blood pressure is orthostatic hypotension, which is sometimes referred to as postural hypotension. This happens when blood pressure drops rapidly during changes to body position--usually when changing from sitting to standing--inducing classic signs that the blood pressure is too low, like dizziness, blurry vision, and fainting.

Other important causes of low blood pressure include:

• Heart problems that cause low heart rate, diminished heart strength, or a decrease in the amount of blood supplied to the body
• Normal changes associated with the first and second trimesters of pregnancy
• Side effects from certain medications, especially diuretics or other high blood pressure medications, like beta blockers. Medicines used to treat erectile dysfunction and certain psychiatric disorders can also cause low blood pressure.
• Hormone problems such as adrenal insufficiency or thyroid disease (overactive or underactive thyroid)
• Problems with the nervous system--especially disorders of the autonomic nervous system, including POTS and vasovagal syncope--can cause low blood pressure after extended periods of standing.
• Deficiencies of essential nutrients, such as folic acid, can cause the number of red blood cells to decrease (anemia)
• Alterations in blood sugar, like those caused by diabetes
• Age: Some older patients, especially those with existing high blood pressure, can experience postprandial hypotension, where the blood pressure drops suddenly after eating a large meal

While most cases of low blood pressure are not considered medical problems, cases where the low blood pressure is accompanied by symptoms should always be evaluated by a physician. A complete medical workup will often be needed in order to rule out the possibility of an underlying disorder.

What Causes High Blood Pressure?

Blood pressure tends to rise with age, unless you take steps to prevent or control it.

Certain medical problems, such as chronic kidney disease, thyroid disease, and sleep apnea, may cause blood pressure to rise. Certain medicines, such as asthma medicines (for example, corticosteroids) and cold-relief products, also may raise blood pressure.

In some women, blood pressure can go up if they use birth control pills, become pregnant, or take hormone replacement therapy.

Women taking birth control pills usually have a small rise in both systolic and diastolic blood pressures. If you already have high blood pressure (HBP) and want to use birth control pills, make sure your doctor knows about your HBP. Talk to him or her about how often you should have your blood pressure checked and how to control it while taking the pill.

Taking hormones to reduce the symptoms of menopause can cause a small rise in systolic blood pressure. If you already have HBP and want to start using hormones, talk to your doctor about the risks and benefits. If you decide to take hormones, find out how to control your blood pressure and how often you should have it checked.

Children younger than 10 years who have HBP often have another condition that's causing it (such as kidney disease). Treating the underlying condition may resolve the HBP.

The older a child is when HBP is diagnosed, the more likely he or she is to have essential hypertension. This means that doctors don't know what's causing the HBP.

Blood Pressure Range

Low blood pressure - a forgotten disease?

In many countries low blood pressure is regarded as a sign of excellent health, and it is certainly true that it is associated with a good outlook from the point of view of risks of strokes an heart attacks. In others, such as Germany, It is regarded as a disease responsible for symptoms of weakness and fatigue. A survey of 254 healthy Irish bank workers has now looked to see how common it is in the general population. All the subjects wore a 24- hour blood pressure recorder, which obtained readings every 30 minutes throughout the day and night. It was decided to define low blood pressure as the lowest 5 per cent of all the blood pressure readings. This gave levels of 115/70 mm Hg for daytime readings in men, and 105/65 in women (women generally have lower pressures than men). Corresponding nighttime values were 97/56 in men and 92/52 in women.

In both genders, episodes of at least two consecutive readings of low blood pressure (that is below the limits described above) during the day were common, occurring in 59% of women and 43% of men. By definition, 5% of each gender had average levels below the limits. Women with low blood pressure tended to be shorter and to weight less than women with higher pressures, but there was no connection between body size and low blood pressure in then men.

Doctor’s comments

The purpose of this study was not to see if people with low blood pressure have symptoms, but merely to learn how common episodes of low pressure are in the general population. The main finding is that approximately 50% of healthy people have episodes lasting one hour at least where the pressure may be considered “low”, and that the phenomenon is commoner in women than in men. Obviously, the definition of what is meant by “low” is arbitrary, and this result emphasizes the normal variability of blood pressure that occurs in all of us.

Other studies have suggested that low blood pressure may be associated with fatigue, weakness, and depression. There may be overlap with the “chronic fatigue syndrome”, which remains poorly defined, and we do not know if it is the low pressure that is actually responsible for any of these symptoms.

Where it was published

Blood Pressure Rising around the Globe

ALMOST 1 billion people worldwide have high blood pressure, and over half a billion more will harbor this silent killer by 2025. It's not just a problem for the ever-fattening Western world. Even in parts of Africa, high blood pressure is becoming common.

That translates into millions of deaths from heart disease alone. Yet hypertension doesn't command the attention of, say, bird flu, which so far has killed fewer than 200 people.

"Hypertension has gone a bit out of fashion," says Dr. Jan Ostergren of Sweden's Karolinska University Hospital, who co-authored a first-of-its-kind analysis of the global impact of high blood pressure.

The idea: to rev up world governments to fight bad blood pressure just as countries have banded together in the past to fight infectious diseases.

International heart specialists welcome the push.

"Even in the U.S., the majority of people with high blood pressure are not treated adequately," says Dr. Sidney Smith of the University of North Carolina at Chapel Hill, who advises the World Heart Federation. "Look at China, look at Africa, go around the world. It is a major risk factor."

And the dangers go well beyond the heart. High blood pressure is a leading cause of strokes and kidney failure. It also plays a role in blindness and even dementia.

Patients seldom notice symptoms until organs already have been damaged.

Yet treating high blood pressure before that happens is a medical best-buy. Improving diet and exercise can help. When that's not enough, blood pressure drugs are among the oldest and thus cheapest on the market — 21 cents a day for a leading diuretic.

Ostergren joined experts from the London School of Economics and the State University of New York to assemble two teams of specialists and map what they call the coming crisis of hypertension: 1.56 billion people are expected to have it by 2025.

With funding from drug maker Novartis Pharma AG, they're providing copies to governments and health officials around the globe; a briefing in Washington is set for Thursday.

The report essentially calls for a cultural change. Consider: In the U.S., commiserating over blood pressure readings is an accepted dinner-table topic. Because black Americans are at especially high risk — roughly 40 percent are affected — hypertension has become a sermon topic at majority-black churches, and post-service screenings aren't uncommon. The government even advertises about the condition.

That adds up to an openness about blood pressure not seen in much of the world, says report co-author Dr. Michael Weber of SUNY's Downstate College of Medicine.

In some regions, "it's sort of an insult to your manhood if you have to take a blood-pressure medicine," Weber says, citing estimates that hypertension affects about one in three adults in Mexico, Paraguay and Venezuela.

"We need to break those barriers as well and make it perfectly fashionable. We need to get role models in those countries to say, 'You know what? I've got high blood pressure.'"

The U.S. still needs to improve, too, Weber hastens to add. High blood pressure affects nearly one in three adult Americans as well, or 72 million people. About a third have their condition well-controlled, not nearly enough but better than other countries that track treatment, the report found.

Normal blood pressure is measured at less than 120 over 80. Anyone can get high blood pressure, a level of 140 over 90 or more. But being overweight and inactive, and eating too much salt, all increase the risk. So does getting older.

The world's population is aging and fattening, fueling a continued increase in blood pressure problems. Remarkably, the report cites worse hypertension rates in much of Western Europe than in the U.S., despite cultural similarities: 38 percent in England, Sweden and Italy; 45 percent in Spain; 55 percent in Germany.

But the biggest jump is expected in developing countries and nations rapidly moving to more Western-style economies, the report warns. In parts of India, studies suggest one in three urban adults has high blood pressure, while it's still rare in rural areas with more traditional lifestyles. More than a quarter of adults in China have hypertension. So do one in four in Ghana and South Africa.

Treatment is difficult, because patients often quit their medicine, not understanding it's necessary even when they feel good. Also, doctors may be reluctant to prescribe the two- or three-drug combinations that half of patients wind up needing.

For poorer countries, the tab for even low-cost diuretics is an issue — not to mention public education about sticking to treatment, notes Smith, the World Heart Federation adviser, who was not involved in the new report.

But fighting bad blood pressure could mean that developing countries avoid epidemics of full-blown heart disease, which they definitely can't afford, Smith stresses. World health and economic groups already are brainstorming strategies to help, such as whether industries that move into poor countries should be required to screen their workers for high blood pressure.●

What is Blood Pressure?

Blood is carried from the heart to all parts of your body in vessels called arteries. Blood pressure is the force of the blood pushing against the walls of the arteries. Each time the heart beats (about 60-70 times a minute at rest), it pumps out blood into the arteries. Your blood pressure is at its highest when the heart beats, pumping the blood. This is called systolic pressure. When the heart is at rest, between beats, your blood pressure falls. This is the diastolic pressure.

Blood pressure is always given as these two numbers, the systolic and diastolic pressures. Both are important. Usually they are written one above or before the other, such as 120/80 mmHg. The top number is the systolic and the bottom the diastolic. When the two measurements are written down, the systolic pressure is the first or top number, and the diastolic pressure is the second or bottom number (for example, 120/80). If your blood pressure is 120/80, you say that it is "120 over 80."

Blood pressure changes during the day. It is lowest as you sleep and rises when you get up. It also can rise when you are excited, nervous, or active.

Still, for most of your waking hours, your blood pressure stays pretty much the same when you are sitting or standing still. That level should be lower than 120/80. When the level stays high, 140/90 or higher, you have high blood pressure. With high blood pressure, the heart works harder, your arteries take a beating, and your chances of a stroke, heart attack, and kidney problems are greater.

What causes it?
In many people with high blood pressure, a single specific cause is not known. This is called essential or primary high blood pressure. Research is continuing to find causes.

In some people, high blood pressure is the result of another medical problem or medication. When the cause is known, this is called secondary high blood pressure.

What Is High Blood Pressure?

igh blood pressure (HBP) is a serious condition that can lead to coronary heart disease, heart failure, stroke, kidney failure, and other health problems.

"Blood pressure" is the force of blood pushing against the walls of the arteries as the heart pumps out blood. If this pressure rises and stays high over time, it can damage the body in many ways.

Overview

About 1 in 3 adults in the United States has HBP. HBP itself usually has no symptoms. You can have it for years without knowing it. During this time, though, it can damage the heart, blood vessels, kidneys, and other parts of your body.

This is why knowing your blood pressure numbers is important, even when you're feeling fine. If your blood pressure is normal, you can work with your health care team to keep it that way. If your blood pressure is too high, you need treatment to prevent damage to your body's organs.

Blood Pressure Numbers

Blood pressure numbers include systolic (sis-TOL-ik) and diastolic (di-a-STOL-ik) pressures. Systolic blood pressure is the pressure when the heart beats while pumping blood. Diastolic blood pressure is the pressure when the heart is at rest between beats.

You will most often see blood pressure numbers written with the systolic number above or before the diastolic, such as 120/80 mmHg. (The mmHg is millimeters of mercury—the units used to measure blood pressure.)

The table below shows normal numbers for adults. It also shows which numbers put you at greater risk for health problems. Blood pressure tends to goes up and down, even in people who have normal blood pressure. If your numbers stay above normal most of the time, you're at risk.

Categories for Blood Pressure Levels in Adults (in mmHg, or millimeters of mercury)

Category	Systolic (top number)		Diastolic (bottom number)
Normal	Less than 120	And	Less than 80
Prehypertension	120–139	Or	80–89
High blood pressure
Stage 1	140–159	Or	90–99
Stage 2	160 or higher	Or	100 or higher

The ranges in the table apply to most adults (aged 18 and older) who don't have short-term serious illnesses.

All levels above 120/80 mmHg raise your risk, and the risk grows as blood pressure levels rise. "Prehypertension" means you're likely to end up with HBP, unless you take steps to prevent it.

If you're being treated for HBP and have repeat readings in the normal range, your blood pressure is under control. However, you still have the condition. You should see your doctor and stay on treatment to keep you blood pressure under control.

Your systolic and diastolic numbers may not be in the same blood pressure category. In this case, the more severe category is the one you're in. For example, if your systolic number is 160 and your diastolic number is 80, you have stage 2 HBP. If your systolic number is 120 and your diastolic number is 95, you have stage 1 HBP.

If you have diabetes or chronic kidney disease, HBP is defined as 130/80 mmHg or higher. HBP numbers also differ for children and teens. (For more information, see "How Is High Blood Pressure Diagnosed?")

Outlook

Blood pressure tends to rise with age. Following a healthy lifestyle helps some people delay or prevent this rise in blood pressure.

People who have HBP can take steps to control it and reduce their risks for related health problems. Key steps include following a healthy lifestyle, having ongoing medical care, and following the treatment plan that your doctor prescribes.

Blood Diseases

Blood is the life-maintaining fluid that circulates through the body's heart, arteries, veins, and capillaries. It carries away waste matter and carbon dioxide, and brings nourishment, electrolytes, hormones, vitamins, antibodies, heat, and oxygen to the tissues.

Because the functions of blood are many and complex, there are many disorders that require clinical care by a physician or other healthcare professional. These conditions include benign (non-cancerous) disorders, as well as cancers that occur in blood.

HIV/AIDS

A Blood-borne disease of the human immune system that is characterized cytologically especially by a reduction in the numbers of CD4-bearing helper T cells, to 20% or less of normal, rendering the subject highly vulnerable to life-threatening conditions, such as pneumonia. There are others that become life-threatening (such as Kaposi's sarcoma) and that are caused by infection with HIV. HIV has been found in Blood, semen, saliva, tears, nervous system tissue, breast milk, and female genital tract secretions; however, only Blood, semen, female genital tract secretions, and breast milk have been proven to transmit HIV to others. It is most commonly transmitted in infected Blood and bodily secretions (e.g. semen), commonly during illicit IV drug use and/or sexual intercourse.

LYMPHATIC FILARIASIS

Lymphatic filariasis is a debilitating Blood disease caused by nematode worms of the genera Wucheriaand Brugia. Larval worms circulate in the Bloodstream of infected persons, and adult worms live in the lymphatic vessels. Lymphatic filariasis is not life threatening, but it does cause extreme discomfort, swelling of the limbs and genitals, damage to the kidneys and lymphatic system, impairment of the body’s ability to fight infection, and general malaise. In addition, it produces immeasurable emotional and economic costs in terms of the disruption of family and community life. Approximately 120 million people in 73 endemic countries world-wide located primarily throughout tropical and subtropical regions of South America, Asia, the Pacific Islands and Africa. Although designated by the World Health Organization (WHO) as the world’s second leading cause of permanent and long-term disability, this mosquito-transmitted Blood borne disease is "potentially eradicable" through drug therapy and vector control. Infection rates are increasing with the continued expansion of urbanization that is underway in the tropics.

BLOOD CHOLESTEROL

An important attribute in deciding a person's risk of getting coronary heart disease. When you have too much cholesterol in your Blood, the excess builds up on the walls of the arteries that carry Blood to the heart. This buildup is called "atherosclerosis" or "hardening of the arteries." It narrows the arteries and can slow down or block Blood flow to the heart. With less Blood, the heart gets less oxygen. With not enough oxygen to the heart, there may be chest pain, heart attack, or even death. Cholesterol buildup is the most common cause of heart disease, and it happens so slowly that you are not even aware of it. The higher your Blood cholesterol, the greater your chance of this buildup.

BLOOD DISORDERS AND DISEASES

First a word about Blood tests in general. Physicians rely on "Blood-work," or clinical laboratory diagnostic Blood testing to diagnose medical conditions. From this Blood testing the medical professional then prescribes therapies and remedies, based on those Blood tests. Good Blood tests make possible state-of-the-art lab procedures that can be provided directly to the public in private and these Blood tests can be provided affordably.

Some of the most common Blood tests are:

Allergy Blood Testing
Blood Tests for Autoimmune Diseases
Blood Diseases Testing
Cancer Detection Blood Testing
Blood Cholesterol Test
Diabetes Blood Tests
DNA, Paternity and Genetic Testing
Blood Tests for Drug Screening
Environmental Toxin Blood Testing
Fitness, Nutrition and Anti-Aging
Gastrointestinal Diseases Revealed by Blood Tests
Blood Testing for Heart Health
Hormones and Metabolism
Infectious Disease Blood Tests
Kidney Disease Blood Test
Liver Diseases Blood Testing
Sexually Transmitted Diseases (STD's) Blood Tests
Thyroid Disease Blood Tests

ANEMIA - A common Blood disorder condition that is caused by an acquired or inhered abnormality of red Blood cells to provide adequate oxygen supplies to body tissues. Anemia may, in some cases, be a manifestation of an non-hematologic disorder. The condition may be due to decreased number of red Blood cells, decreased amount of substance in red Blood cells which transports oxygen hemoglobin, or decreased volume of red Blood cells. There are several diseases properly known as Anemia. These include: anemia of B12 deficiency, anemia of chronic disease, anemia of folate deficiency, drug-induced immune hemolytic anemia, hemolytic anemia, hemolytic anemia due to g6pd deficiency, idiopathic aplastic anemia, idiopathic autoimmune hemolytic anemia, immune hemolytic anemia, iron deficiency anemia, megaloblastic anemia, pernicious anemia, secondary aplastic anemia, and sickle cell anemia.