Imbalances of the Cardiovascular System
The heart continuously pumps at around 70-75 beats per minute, sending out 5.25 Litres of blood (stroke volume) around the body. Oxygenated blood will also contain the essential nutrients required to support the body's metabolism. Stroke volume will change dependent upon age, gender, body temperature, emotions and activity level.
There are three types of blood cells;
Red blood cells, erythrocytes, which carry oxygen around the body.
White blood cells, leucocytes, which are part of the immune system.
Platelets, thrombocytes, which help blood to clot and prevent blood loss after injury.
This enables the body to carry out a number of functions;
- To deliver oxygen and nutrients to the tissues.
- To deliver cell waste to excretory organs including carbon dioxide to be excreted by the lungs.
- To deliver hormones to their target receptors and antibodies to the site of infection.
- To provide heat and help maintain homoeostasis.
- To provide clotting factors that promote blood clots when required.
Blood also contains plasma. The contents of plasma include; Albumin, which helps maintain osmotic pressure, Carrier molecules for lipids and steroid hormones, Globulins which transport antibodies, and Lipoproteins which carry triglycerides and cholesterol.
Erythrocytes contain haemoglobin which enables it to carry oxygen. It requires B12, folic acid, and haem (iron). Red blood cell numbers need to be controlled to a certain constant. The lifespan of a red blood cell is 120 days, When old or damaged, they are removed from the circulation by the spleen and broken down in the liver. Haemoglobin is broken down into Haem and Globin. The Globin is further broken down into amino acids. The Haem is broken down into iron and bilirubin. The iron can be stored by the liver and then transported to the bone marrow where new haemoglobin is produced. The bilirubin is transported to the gall bladder where it forms bile, and is eventually excreted in the faeces.
In situations of hypoxia (low oxygen levels in the blood), the kidneys release Erythropoietin which stimulates the production of new red blood cells in the bone marrow. Excess Carbon Dioxide will increase the sympathetic nervous system response, resulting in more rapid breathing as the body responds to eliminate the excess carbon Dioxide produced.
Leucocytes are important in protecting the body from any foreign invasions that may cause damage. They are specialised cells that have different functions which enables them to deal with microbes, parasites, and fungi. Some patrol the body within the blood responding to cytokines (chemical messengers) produced by distressed cells of the body, as a result of damage or infection. They also have the ability to learn from the experience of the infection and produce antibodies to that threat, which will respond quicker the next time it encounters the same pathogen. They also help to remove damaged or infected cells.
Platelets also responds to damaged cells and tissue. They produce blood clots that stops bleeding and helps to fix the damage.
An important measure of the heart's functioning is its blood pressure. If too high, blood vessels may be damaged causing clots or bleeding from the site of rupture. If it is too low, blood flow would be inadequate for the essential organs to function as they are not receiving sufficient quantities of blood to work effectively. Therefore blood pressure is constantly monitored. Hypertension is when there is an increase in blood pressure, often from an unknown cause. However there are identifiable risk factors, such as; Family history, smoking, sedentary lifestyle, high intake of salt or alcohol, stress, and obesity. Hypertension can also be due to kidney disease resulting in water and salt retention, or as a result of an endocrine disorder, again leading to the retention of excess sodium and water.
Hypotension, low blood pressure, which usually occurs as a complication of other conditions, for example, shock or Addison's disease. This may lead to in an inadequate blood supply to the brain causing fainting or longer states of unconsciousness.
The control of blood pressure is achieved through; changing the blood volume by urine water retention using the Renin Angiotensin system. Altering cardio output, that is stroke volume. Or by changing the resistance to blood-flow that is by altering blood and or blood vessel characteristics.
While structural and hereditary conditions plays a role within the functioning of the Cardiovascular system, nutrition can have a significant impact. Cardiovascular disease is the most frequent cause of death in the European Union and the USA. Hypertension being the most important and modifiable, risk factor. Diet and exercise, along with controlling stress levels can contribute to providing a healthy balance.
Complications of hypertension include; haemorrhages due to a thickening and thereby narrowing of the walls of blood vessels leading to the rupture of the wall of the vessel. Fat deposits may lead to embolisms resulting in a stroke.
Kidney disease may occur as a result of the damage done to arteries within the kidneys.
Another area within the cardiovascular system where nutrition has an important role to play is in preventing Anaemias.
Iron Deficiency Anaemia
Iron deficiency anaemia is due to a shortage of iron which leads to a reduction in the level of haemoglobin produced. Excess iron is toxic, therefore the assimilation of iron is usually sufficient for the body’s needs, the rest is excreted. Women need more iron than men to make up for the amount they loose during their menstrual period. Around 1 mg of iron is lost for every day of bleeding during menstruation. In pregnancy the need for iron increases to meet the needs of the developing foetus. Increased demand also occurs during periods of rapid growth, as in adolescence. It is estimated that around 1 in 5 women are affected by iron deficiency anaemia. There are a number of causes which can result in a deficiency. As has been implied a deficiency can result due to insufficient levels of iron in the diet or due to excess demand at a particular moment in time.
Is found in every cell of the body combined with protein. 60 to 70% is contained within haemoglobin. Due to a lack of iron the body will produce less haemoglobin. Iron is stored in the liver, spleen and bone marrow and is drawn on when needed. 5% is found in myoglobin (muscle oxygenating protein).
Iron is poorly absorbed, in particular non-heme (that is iron found in vegetables). Phytates found in whole grain and oxalates found in certain vegetables bind to some of the iron and make it unabsorbable. Vitamin C converts ferric iron to ferrous which is better absorbed. This is then bound to the protein transferrin and travels to the bone marrow to produce red blood cells. Some goes to the liver and spleen. The body conserves iron well, but there is a risk of toxicity as a result of oxidation, therefore the body will absorb enough dependent upon requirements. Due to menstruation Women need more iron intake than men.
Citrus fruits that contains vitamins C help with iron absorption. Copper (also helps form haemoglobin). Cobalt, and Manganese, also improves iron absorption. Iron is required for some of the important enzymes involved in energy production and protein metabolism. Iron absorption is compromised by low stomach acid, phosphates, oxalates, and phytates. Caffeine, and tea can also reduce iron absorption. Some studied have suggested that excess Calcium intake may also interfere with Iron absorption.
Deficiency signs and symptoms. Anaemia, pallor, dry skin, poorly formed upturned nails, brittle hair, easily tired, weak, lack of energy, increased susceptibility to infection, learning disabilities, cold sensitivity, constipation, poor appetite, and sore inflamed tongue.
When taken in excess Iron can cause symptoms of; fatigue, headaches, pallor, pulse, and rapid increase in respiration.
In Pernicious anaemia - Vitamin B12 deficiency (megaloblastic anaemia) results from a deficit in Folic acid or Vitamin B12. While reduced Folic acid levels are diet related, a lack of B12 may also be as a result of poor absorption (which is the most common cause). Vitamin B12 is dependent upon Intrinsic Factor for absorption. It is produced by the gastric cells of the stomach. Autoantibodies can lead to the destruction of Intrinsic factor and also a reduction in hydrochloric acid. The reduction of hydrochloric acid will also result in a decrease in the absorption of iron and in the digestion of protein. In this condition iron deficiency anaemia may also be present. Stomach acid declines with age.
As a result of this deficiency, maturation of erythrocytes is impaired and they become enlarged and subsequently destroyed. Vitamin B12 deficiency may lead to nerve damage which can cause tingling and numbness in the hands and feet, muscle weakness, and loss of reflexes. Other symptoms of vitamin B12 deficiency include; nausea and vomiting, heartburn, abdominal bloating and gas, constipation or diarrhoea, loss of appetite, and weight loss. A smooth, thick, red tongue is also a sign of vitamin B12 deficiency and pernicious anaemia.
B12 also contains Cobalt. It requires intrinsic factor produced in the stomach for its absorption. The thyroid hormone also facilitates absorption. Excess calcium intake may interfere with B12 absorption. The body can store B12 but for a limited amount of time. It is necessary for the health of the nervous system and for folic acid metabolism, and plays a role in reducing homocysteine levels which are associated with cardio-vascular disease. High alcohol and caffeine intake, oral contraception, chronic digestive disorders, hyperthyroidism, can interfere with B12 absorption.
Functions; Maintenance of the nervous system, metabolism and formation of red blood cells, and the maintenance of growth. Also required for the metabolism of fats, protein and carbohydrates. It is essential for the integrity of cell membranes, and the production of epithelial cells. Increases energy, and is required to process folic acid
Folic acid, Vitamin B9
Acts as a coenzyme for a multitude of functions. Vitamin B12 is required to convert Folic acid into an active form, however Folic acid can mask B12 deficiencies. Aids in red blood cell production by carrying the carbon molecule to the larger heme molecule. It is central to all rapidly dividing cells. With B12 and vitamin C it helps in the breakdown and utilisation of protein and many amino acid conversions. Used in the formation of nucleic acids for RNA and DNA. Required for the proper balancing of the brain's neurotransmitter levels of catecholamines like epinephrine and norepinephrine. Plays a critical role in the development of the infant nervous system. Reduces high levels of homocysteine. A high level of homocysteine can contribute to arterial damage and blood clots in blood vessels.
Levels can be reduced through; Cigarette smoking, deficiency in B12 and Vitamin C, alcohol, and oral contraceptives.
Aplastic anaemia is when the body doesn't produce enough red blood cells. Sometimes the cause is unknown. The condition can be as a result of an infection, certain medicines including radiation therapy, autoimmune diseases, and exposure to toxic chemicals. As it is a failure of production within the bone marrow itself there will also be a decrease in the production of leucocytes (white blood cells) and platelets. As well as the usual signs and symptoms of anaemia other symptoms are observed, which include; frequent or prolonged infections, being more easily bruised, nosebleeds and bleeding gums, and prolonged bleeding from cuts.
Haemolytic anaemias is as a result of the excessive destruction of erythrocytes. Causes include; an over proactive spleen, genetic defects, immune reactions, toxins, infections such as malaria, and transfusion reactions. One example is Sickle cell anaemia which leads to the abnormal formation of haemoglobin, resulting in the changed shape of the erythrocyte from a disk to a sickle shape. The change of shape results in a shorter life span of the cells, from 120 days to only 20. This will lead to a lower erythrocyte level within the blood.
The reduced flexibility of the cell potentially leads to an obstruction within the small blood vessels. Symptoms include; fatigue, pain crises, dactylics (swelling and inflammation of the hands and/or feet), arthritis, bacterial infections, sudden pooling of blood in the spleen, liver congestion, lung and heart injury, and leg ulcers.
Haemolytic disease of newborn is when the mother makes antibodies to the baby’s red blood cells ‘rhesus factor’. Being given an incompatible blood type during a transfusion can also lead to difficulties for similar reasons.
A genetic condition resulting in an abnormality in the production of haemoglobin, thereby reducing the amount of haemoglobin synthesised and the number of erythrocytes. One type predominantly affects people from Greece and Italy while another affects mainly those from Southeast Asian. Signs and symptoms are dependent upon the type and severity of the condition and includes; weakness, pale or yellowish skin, facial bone deformities, slow growth, fatigue, abdominal swelling, and dark urine.
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