Smorgasbord Health – The Circulatory System Part Two. What causes network outages?

In the second part of the series on the circulatory system I am going to look at the outages and problems that can occur when you have 60,000 miles of network.

What causes network outages?

Unfortunately, much of what goes on with your blood vessels is internal and we tend to miss the early signs of problems, unless they pop to the surface as in the case of varicose veins or bruising. Our modern lifestyle has resulted in most of us reducing our activity levels to well below normal for a human body. Cars, computers, online shopping, school buses, remote controls are just some of the enablers of immobility.

Here are some of the problems that most of us are at risk of and the early signs that there is a problem. With the more serious issues such as thrombosis and aneurysms medical attention is needed immediately. Even if you do not suffer from these, knowing what the symptoms are means that you might be in a position to help a family member, friend of colleague should they suddenly experience pains in the abdomen or back.

Varicose veins

As we get older our blood-vessels, as with any part of our body, begin to suffer from wear and tear. Varicose veins can appear at any time and one of the most common causes is during pregnancy when the circulatory system is put under pressure due to additional weight and the responsibility of supplying blood to the growing foetus.

The most common site for varicose veins is in the back of the calf. The veins in the legs are divided into two systems one with deep veins that run deep into the muscles and superficial veins that lie in the layer of fat close to the skin. It is the veins that you can see close to the surface that are likely to become varicose.

Veins have delicate valves to prevent the blood from moving backward in the blood-vessel. If there is a defective valve the blood can drain backwards and pool in the veins nearest the skin surface, which then become swollen and painful. Because the capillaries just under the skin also become damaged, blood is unable to enrich the skin immediately above the site and this can become thin and dry leading to ulceration or varicose eczema.

Leg with Varicose veins

Another cause of blood pooling is the damage to perforating veins that connect the deep veins to the superficial ones. If the valves in these interconnecting blood-vessels are damaged, blood rushes from the deep veins and floods the veins closer to the surface.

Apart from the valve weakening in the vein there is also a problem with the strength of the wall of the blood-vessel. Collagen, which gives the elastic sheath of the vein its strength, can become depleted causing blood to pool in small pockets in the wall. This applies usually to the deep veins, which I will cover later, but if there is a general lack of collagen it could also apply to the superficial veins nearer the skin.

Who is at risk of varicose veins?

There are a number of contributing factors to the development of varicose veins. In the Western world around 30% of women will develop the condition, particularly if they have been pregnant. It used to be that men were at a lower risk of developing varicose veins but this is changing and in a recent study more men than women were suffering from this problem.

There is evidence that the problem is mainly confined to the Western world with only 2% found in Indian women and around 5% in other women in Africa. This may lead to a conclusion that diet and lack of exercise may be a very definite contributing factor.

Age certainly plays its part but people who remain active into their 70’s and 80’s seem to have much better blood-vessel health in general.

There is obviously an assumption that being overweight and inactive might contribute, but research is non-committal. Since the problem is more common in pregnancy there might be a correlation between additional weight, increased blood supply to the foetus and also hormonal changes that may have an effect on vein walls. This is backed up somewhat by the fact that with more pregnancies there tend to be more varicose veins.

In studies, there is some evidence to show that people who stand on their feet all day at work might be more likely to develop varicose veins, particularly those who stand still, allowing blood to pool in their legs.


An aneurysm is an abnormal swelling in an arterial wall. This can be caused by disease or by an internal injury and in some rare cases the result of a birth defect. The most common place for an aneurysm to appear is in the aorta, the main artery from the heart. The elderly can develop them further down in the abdominal aorta just below the kidneys.

Cerebral Aneurism 1

An aneurysm can also develop in the brain and is called a cerebral or intracranial aneurysm. The bulge is similar to the one you would see in an inner tube or a thin balloon and they tend to form where arteries divide or branch off.

Who is at risk of an aneurysm?

There are rare incidences where a person is actually born with a small aneurysm, which then grows, causing problems in childhood and adolescence. It is far more common in older people where there are contributing factors associated with the development of the aneurysm such as arterial disease and wear and tear.

Smokers, and people suffering from high blood pressure, are also at risk and there is some indication that the risk might be hereditary.

Aneurysms can also form after trauma and surgery when internal damage may go undetected.

What are the symptoms of an aneurism?

If the aneurysm is in the lower part of the aorta, it may be several years before the condition becomes symptomatic. Different people will experience a variety of symptoms but they usually include a pulsating feeling in the abdomen, abdominal pain and back pain.

If the aortic aneurysm gets too large it can rupture, causing agony in the abdomen and the back and obviously leading to internal bleeding.

If the aneurysm is higher up in the aorta in the chest area other symptoms will be present including pain in the upper back, coughing and wheezing and difficulty swallowing.

The person suffering from this type of aneurysm may also exhibit symptoms of Horner’s syndrome, where one side of the face suffers from a drooping eyelid, constricted pupil and dry skin.

A brain aneurysm is usually accompanied by severe headaches and in some cases nausea and vomiting, stiff neck or neck pain, blurred vision or double vision, pain above and behind the eyes, dilated pupils, sensitivity to light and loss of feeling in some areas of the body.


A Thrombosis is a blood clot that forms in either a vein or artery, preventing the normal circulation of blood. This is often a result of hardened arteries, or atherosclerosis, when fatty deposits (plaque) has lined the blood-vessel narrowing and constricting blood flow. This can occur in various parts of the body and can be life threatening. The most common cause of strokes is a thrombosis in the arteries supplying the brain.

There has been a great deal of concern in recent years with the incidences of DVT or Deep Vein Thrombosis and increased air travel. The risk appears to be associated with passengers who sit for an extended period of time and air travel is not the only culprit as long journeys in cars, trains and coaches can also cause the problem as can sitting all day at a computer without a break every couple of hours.


The DVT usually forms in the calf muscles and you would experience an extreme pain in that area. This can happen days or even weeks after a trip so do not assume that you are not at risk and seek medical attention immediately.

Who is at risk?

There is still not a great deal of research into who is more susceptible to a DVT but there are indications that there are factors that increase the risk.

  1. Immobility for extended periods of time in any form of travel or even sitting constantly in the office or home.
  2. Recent leg surgery.
  3. Obesity
  4. Existing clotting problems.
  5. Varicose veins.
  6. Hormones, including during pregnancy.
  7. Heart problems
  8. Existing vascular problems such as high blood pressure.
  9. Dehydration.

How can you reduce the risk of developing a DVT?

If you are planning on taking a trip and you are in any of the risk categories then you should consult your doctor first before booking.

Once on your trip you should try and exercise once an hour for 10 minutes or so by rotating your ankles and exercising the calf muscles by walking around the plane or if that is not possible massaging upward from the ankles to the knees.

There are some products on the market that may help. In-flight stockings and socks have become more widely available. These stockings do not restrict circulation but increase blood flow to the lower legs.

Wear comfortable clothing and do not wear very tight trousers or even all in one corsets for travelling that may restrict blood flow. Changes in pressure at altitude can also increase the gas in your body causing it to expand making restrictive clothing not only uncomfortable but possibly dangerous too.

Avoid drinking alcohol as this can dehydrate your body which can thicken the blood, raise blood pressure and cause the smaller capillaries and blood vessels to close off putting increased stress on the main parts of the network. Make sure that you drink plenty of water before and during any extended travel.


An embolism occurs when particles dislodge from one area in the body and travel in the bloodstream to another point where they can form a blood clot leading to a thrombosis. The embolism could be made up of a variety of substances fatty debris, cholesterol, and debris from internal damage to bones etc. If an embolism lodges in a main artery, particularly the pulmonary artery, it can be fatal.

Abdominal Aortic Aneurism


What are the causes of an embolism?

There are a number of risk factors involved, including: bed rest following a stroke, broken bone, or spinal cord injury allowing clots to form in the arms and the legs. Trauma and injury to the legs, recent surgery, obesity, heart disease (particular where there is an irregular heartbeat), burn damage, pregnancy, cancer and hormonal therapy.

What symptoms are associated with an embolism?

As with the other blood-vessel problems, you may not experience symptoms immediately. Certainly any pain in the calf muscles of the legs that is not associated with recent excessive activity should be taken seriously.

If the embolism reaches the pulmonary artery you will experience a sharp, stabbing pain in the chest which becomes worse if you take a deep breath. You will be short of breath and feel as though you are having an anxiety attack. You may start to cough and sweat and finally pass out.

Seek medical attention immediately and as this can be difficult to diagnose, knowing the symptoms and being able to describe them will be vital to speedy treatment.

Coming up….

So that is the bad news but understanding how your body works and also fails is key if problems are to picked up early. The good news is coming next with foods that contain the nutrients that are essential to the maintenance of a healthy network and then a look at the blood that flows through the network keeping you alive.

Part one of this series is here.

©SallyCronin Just Food For Health 2009


Smorgasbord Health -The Circulatory System -60,000 mile long network.

As we get older our bodies require more and more maintenance to keep essential functions and systems working efficiently. What worked for us at 20, 30 and even 50 is not necessarily enough once we get over 60 or older. Our circulatory system is not an optional extra but a critical and essential pathway throughout our body that carries our lifeblood. Without that lifeblood our organs die and within a few minutes the core of our being.. the brain dies.  In this series of updated posts from 18 months ago I will be covering both the network and the blood that it carries.

Our blood is fascinating and whilst we only see with the naked eye, under a microscope it is teeming with life.. most of which is essential to our own.  But before moving onto the blogs about the blood that flows through our body, a couple of articles on the system that carries it.

We have all suffered from bruising at some point in our lives which is when damage occurs to the blood vessels closest to the skin, but damage can also occur deep inside our bodies that can be extremely serious. Today a look a the structures themselves and next time how these arteries and veins can be damaged.

Depending on our age, the average adult has between 60,000 and 100,000 miles of blood vessels should they be laid end to end. Enough to circle the world 7 times. Our blood will travel around our bodies and achieve around the 12,000 miles each day. That is 500 miles an hour. There are an average of 8 pints of blood or 4.7 litres in an adult and this has to carry all the nutrients and oxygen we need to live around the body to keep our major organs alive.

A blockage in this 60,000 plus miles of blood vessels can be catastrophic as even a few minutes of lack of oxygen to a vital organ such as the heart or brain will cause a heart attack or stroke.

I have covered the results of blockages in the blood flow on the brain and the heart in previous blogs, but we rarely consider this amazing system that feeds those organs unless we cut ourselves or notice a bruise.

Maintaining the health of our blood vessels is fundamental to our health and the network needs a combination of oxygen, specific nutrients and exercise to keep them flexible and clear of debris.

Today I will talk about the structural aspects of the system and then over the next few blogs I will cover the common health issues of the vessels and the nutrients needed to keep them healthy.

How does blood circulate?

There are really two circulatory systems working in the body, the pulmonary and the systemic. Apart from the major veins and arteries there are also millions of smaller blood-vessels that form an interconnecting pathway throughout the body.

In the diagram below the blue is oxygen poor blood and the red is the oxygen rich blood.

pul-circ no labels

In the pulmonary system de-oxygenated blood is taken from the heart to the lungs where it is replenished with oxygen before making the return journey back to the heart. The oxygenated blood leaves the heart in the systemic circulatory network and taken to every single part of the body.

Although the circulation in our bodies is a closed system, the blood in the circuit begins its journey around the body in the left ventricle of the heart into the aorta. The blood at this point is oxygen-rich and full of nutrients and hormones as well as other substances necessary for us to function.

The coronary arteries split off and the aorta passes upward before doubling back on itself in an arch. From this arch the two main arteries to the head split off (left and right carotid arteries) and the main arteries for the arms (brachial). The aorta descends down the chest and into the abdomen where it branches off to the liver, intestines, and each kidney before dividing into the left and right iliac arteries, which supply blood to the pelvis and the legs. From there the blood passes into the arterioles and capillaries to feed the interior of organs and outlying areas of the body and remove any waste.

After passing through these tiny blood-vessels the blood is passed into the veins starting its return journey in small vessels called venules which are similar in size to the arterioles. It then makes its way back to the heart via the veins, which are close to the skin and visible at most times to the naked eye. These are the veins that contain valves to ensure the blood travels in only one direction.

All the veins in the body eventually merge into two very large blood-vessels called the superior vena cava and the inferior vena cava. The first collects the blood from the head, arms and neck and the second the blood from the lower half of the body. This blood then passes back into the heart and out to the lungs where it is re-oxygenated and returned to the heart to begin the process all over again.

What is the structure of the different blood-vessels?

Arteries are subjected to enormous pressure with each strong heartbeat and they therefore have to be thick walled and muscular. The outer layer of the artery (tunica adventitia) is a loose fibrous sheath filled with tiny blood-vessels that supply nutrients to the artery walls. Beneath this is an elastic sheath covering the muscular layer (tunica media) that gives the artery its strength. There is an internal elastic area covering the lining (tunica intima) of the blood-vessel.

 Artery 1

The thick elastic and muscular walls are vital if the system is to work efficiently and the blood is to be pushed around the entire body.

When you take your own pulse you will be measuring the force of each heartbeat as it is transmitted through the arteries and it is a very useful diagnostic tool for a doctor when determining any heart or circulatory problems you might be experiencing.

Veins are similar to arteries in the way that they circulate and when they both service major organs they often run in parallel. The major differences in the two blood-vessels are structural to enable them to perform their own individual roles in the circulatory system.

Veins have much thinner and more flexible walls that can expand to hold large volumes of blood. The pressure of blood returning to the heart is much lower than that in the arteries and its movement requires the use of valves in the veins to prevent the blood going backwards in the system.

The smallest capillaries only measure about eight- thousandths of a millimetre and are barely wider than a single blood cell. These minute vessels are thin and porous allowing the nutrients, oxygen rich blood and waste to pass between the circulatory system and the cells freely.

Capillaries also have another vital role in the body and this is in their ability to help regulate our body temperature. When the body is hot the capillaries in the skin expand to allow more blood to reach the surface of the skin and be cooled. When we experience extreme cold our circulatory system closest to the skin will begin to shut down forcing our blood to the centre of our bodies to ensure that our hearts and lungs are protected.

The capillaries nearest the skin are the most vulnerable to cuts, and when we bruise it is the damage to these small blood-vessels just under the skin which cause the discolouration. During our lifetime, any damage is usually repaired but as we age this ability lessens and capillaries collapse and leave the purple patches behind that are commonly seen on the arms and legs of the very elderly.

After passing through the capillaries and having completed the job of providing oxygen and nutrients from the tips of our toes to the scalp tissues the blood returns to the heart in the veins.

Are there any interruptions to the smooth flow of blood in our system?


At some stage, food that we have consumed must be processed and the nutrients extracted and waste removed. Part of this process involves the intestines and the liver. When blood leaves the intestines it does not flow directly back to the heart but diverts into the liver or hepatic portal system of veins. Once in the liver this enriched blood passes through the liver cells in special capillaries called sinusoids before passing back into the veins which transport it to the inferior vena cava and then to the heart.

What if we suffer damage to one system or another?

As blood loss and loss of circulation to a part of the body can be fatal, we do have an emergency diversion system that takes over in some areas. In the arms and the legs for example, damage to one artery stimulates another in the same branch to widen to allow more blood to pass through it, maintaining circulation.

During the fight or flight response, when adrenaline has been released, during intense activity or after eating, other mechanisms come into play. If you suddenly become more active blood vessels in the leg will increase in size and those in the intestine shut down so that you get the power where you need it. When you eat a meal the reverse process occurs – with blood being directed to the intestines. This is why it is advisable not to exercise too soon after eating a large meal as you will interrupt this major part of the digestive process.

Is blood in equal amounts in the two systems?

The blood is not evenly distributed in the two systems. If you were to take a snapshot of the circulatory system you would find approximately 12% to 15% in the arteries and veins in and around the lungs. About 60% will be in the veins and 15% in the arteries with 5% in the capillaries and 10% in the heart. It will also be travelling at different speeds in the various parts of the system leaving the heart quickly at around 30 cm per second and slowing down considerably in the capillary system. It speeds up again in the veins until it reaches the heart travelling around 20 cm per second.

Where is our circulation controlled from?

There are a number of the systems governed by certain parts of the brain such as hypothalamus. In the case of our circulation there is a small area in the lower part of the brain which is in charge called the vasomotor centre. The vasomotor centre receives messages from the pressure sensitive nerves in the aorta and carotid arteries and if necessary the centre sends out messages to the arterioles that will expand or constrict to control and maintain correct levels.

Next time the damage that can occur in our blood vessels that can cause problems in the blood flow.

©sallycronin Just Food For Health 2009