Relationship between diet, blood pressure, blood cholersterol and circulatory disease.

We are all aware that a diet high in saturated fat can have huge implications on our overall health. There are strong links between high blood pressure, high cholersterol and heart disease.
Decades of research have shown that if we alter our lifestyles by reducing risk factors for heart disease, we stay healthier for longer. - http://www.diet-and-health.net/
When our diet consists of high saturated fats it results in our bodies becoming overweight and obese. These are the most common risk factors for heart disease.

Over time the heart and the surrounding arteries become lined in a build up of fatty deposits. The heart then has to work harder to meet the demands of the body. This constant demand causes the pressure of the blood leaving the heart to rise. This pressure overtime results in the arteries becoming thicker, causing them to narrow and eventually may lead to a total blockage, resulting in a heart attack or stoke.

                                                                   

 Cholesterol is transported around your body attached to a protein in your blood. This combination of fat and protein is called a lipoprotein. There are different types of lipoprotein, depending on how much fat there is in relation to protein. Cholersterol is an essential fat to our diets. It is needed for the digestion of fats. When you ingest fat, your liver converts it to a lipoprotein, which is carried through the body by low density lipoprotein's (LDL). Although it is necessary for your body to function, LDL has the reputation of being "bad" cholesterol. When you eat high-fat animal products, it raises your levels of LDL cholesterol, and too much LDL can stick to the sides of blood vessels causing plaque buildup, which can clog the arteries in vital organs. -www.ehow.com

About two in three adults have a cholesterol level that is higher than recommended. Having high cholesterol affects your heart and blood vessels and increases your risk of developing cardiovascular disease (CVD). In time, the blood vessels supplying your heart may become so narrow that they can't deliver enough oxygen to the heart muscle, particularly when you're exerting yourself. This can cause you to feel chest pain (angina). If a fatty plaque breaks off, it may cause a blood clot which can block blood flow to your heart (heart attack) or brain (stroke). - High cholesterol-information (Bupa)

By making small changes to the way we eat and look after our bodies we really could make a huge difference to our overall health and improve it for many years to come.

Smoking and its relationship with coronary heart disease

Smoking is one of the major causes of cardio-vascular disease. Smoking damages the heart by damaging the lining of the arteries leading to a build up of fatty deposits, reducing the space for blood to flow.
Nicotine a substance found in tobacco smoke stimulates the body to produce adrenaline. This increases the heart rate, blood pressure and results in heart having to work harder.
Carbon monoxide in cigarette smoke reduces the amount of oxygen that blood can carry to the heart and the rest of the body.
All these factors increase the risk of developing coronary heart disease and having a heart attack or stroke.
Over time the ateries become so narrow that they cant deliver enough oxygen to the heart. This leads to a condition known as angina. Angina is a crushing chest pain that if left untreated causes heart cells to die.
A heart attack can occur if a fatty deposit that has formed in the artery detatches and forms into a blood clot. It is this that starves the heart of blood and oxygen.
A stroke can occur if the artery becomes so blocked that no oxygenated blood can reach the brain.-www.bhf.org.uk


 


 Another disease which is directly linked to smoking is COPD. COPD is caused by noxious particles or gas, most commonly from tobacco smoking, which triggers an abnormal inflammatory response in the lung. The inflammatory response in the larger airways is known as chronic bronchitis, which is diagnosed clinically when people regularly cough up sputum. In the alveoli, the inflammatory response causes destruction of the tissues of the lung, a process known as emphysema. This is a progressive disease that can eventually lead to total heart faliure.

Smoking and its relationship to cancer

Cancer is a class of diseases characterized by out-of-control cell growth, and lung cancer occurs when this uncontrolled cell growth begins in one or both lungs. Rather than developing into healthy, normal lung tissue, these abnormal cells continue dividing and form lumps or masses of tissue called tumors. Tumors interfere with the main function of the lung, which is to provide the bloodstream with oxygen to be carried to the entire body.

The most common cause of lung cancer is long term exposure to tobacco smoke. Lung cancer is the second most common cancer in the uk.

Effects of smoking on body systems

Nicotine is the addictive drug in tobacco smoke that causes smokers to continue smoking. Along with nicotine there are over 4000 other chemicals that activate and trigger profound and damaging effects on the human body.

Tar – this is the collective term for all the various particles suspended in tobacco smoke. The particles contain chemicals including several cancer-causing substances. Tar is sticky and brown and stains teeth, fingernails and lung tissue. Tar contains the carcinogen benzo(a)pyrene that is known to trigger tumour development (cancer).


Carbon monoxide – this odourless gas is fatal in large doses because it takes the place of oxygen in the blood. Each red blood cell contains a protein called haemoglobin – oxygen molecules are transported around the body by binding to, or hanging onto, this protein. However, carbon monoxide binds to haemoglobin better than oxygen. This means that less oxygen reaches the brain, heart, muscles and other organs.

Hydrogen cyanide – the lungs contain tiny hairs (cilia) that help to clean the lungs by moving foreign substances out. Hydrogen cyanide stops this lung clearance system from working properly, which means the poisonous chemicals in tobacco smoke can build up inside the lungs. Other chemicals in smoke that damage the lungs include hydrocarbons, nitrous oxides, organic acids, phenols and oxidising agents.

Free radicals – these highly reactive chemicals can damage the heart muscles and blood vessels. They react with cholesterol, leading to the build-up of fatty material on artery walls. Their actions lead to heart disease, stroke and blood vessel disease.

Metals – tobacco smoke contains dangerous metals including arsenic, cadmium and lead. Several of these metals are carcinogenic.

Radioactive compounds – tobacco smoke contains radioactive compounds, which are known to be carcinogenic. - http://www.betterhealth.vic.gov/

The chemicals in nicotine cause many effects on the bodies systems, these can include:

Respiratory system                Irritation to trachea and larynx
                                                 Reduced lung function
                                                 Increased risk of lung infection
                                                 Permenant damage to lungs (air sacs)

Circulatory system                  Raised blood pressure and heart rate
                                                 Tightening of blood vessels
                                                  Less oxygen carried by blood
                                                 'Stickier' blood more prone to clotting
                                                  Damage to lining of arteries
                                                  Reduced blood flow to fingers and toes
                                                  Increased risk of stroke and heart attack due to blockages in blood flow

Immune system                       More prone to infections as system does not function as well
                                                 More prone to pneumonia and influenza
                                                 Body takes longer to recover from illness
                                                 Lower levels of antioxidants

Musculoskeletal system         Tightening of certain muscles
                                                  Reduced bone density

Other effects                            Irritation and inflamtion of stomach and intestines
                                                  Increased risk of ulcers in digestive tract
                                                  Reduced ability to smell and taste
                                                  Premature wrinkling of skin
                                                  Higher risk of blindness
                                                  Gum disease (periodontis)

                                                   

The process of redistributing blood during excercise

When we exercise it causes an increase in the heart rate. This creates a change in the concentration of O2 and CO2 in the blood and the respiratory system is able to detect this change and increase the rate in which we breathe.
The intercostal muscles of the diaphragm allow the thoraxic cavity to expand, enabling more air to be drawn in. This allows the diffusion of gases to be more efficient and the transportation of gases increases due to increased blood flow.

During exercise the heart rate increases rapidly. This provides the muscles with the necessary oxygen and nutrients to provide the muscles with energy. During exercise, cardiac output is increased.

During exercise stroke volume increases because, more blood is being sent back to the heart due to the muscles squeezing blood in the veins. The heart fills up with more blood and it stretches. This stretching allows the muscle fibres to contract more strongly and therefore more blood is being pumped out.

The transportation of oxygen and carbon dioxide in the blood

The exchange of gases between the atmosphere, blood and cell is called respiration which has several meaning in physiological terms :


1.External respiration (pulmonary). This kind of respiration includes exchange of gases between blood and lungs . Oxygen from the lungs diffuse into the blood and carbon dioxide diffuse out to the lungs from the blood.

2. Internal respiration (tissue). This is a process of exchange of gases in the body tissues. CO2 from the cells of the body is exchanged from the blood for oxygen.

3. Cellular respiration. It is a cellular process where oxygen is utilized as a fuel to release energy. Thus it is the total biochemical process in a cell for release of energy.

In contrast to these physiological processes, there occurs a mechanical process in higher animals called breathing. It enables us to exchange air in and out of our lungs. Also called ventilation.

Cardiac output

Cardiac output is the amount of blood pumped out by each side of the heart (each ventricle) in one minute. It is the combination of heart rate (HR) and the stroke volume (SV). Stroke volume is the volume of blood pumped out by each ventricle with each heartbeat.

A normal adult blood volume is about 5000ml and the entire blood supply passes through the body once each minute. Cardiac output varies with the demands of the body. It rises when when the heart beats faster or stroke volume is increased and it drops when either or both factors decrease.

By using normal resting heart rate (75 beats per minute) and stroke volume (70ml per beat) we can work out the average adult cardiac output.

      CO = HR (75beats/min) X SV (70ml/beat)

      CO = 5250 ml/min

Assessment of the cardiac output is important in determining the work that the heart is actually performing with respect to the rest of the cardiovascular system. If the cardiac output is too low, then the body is not being properly supplied with blood (heart failure), which can and will lead to life threatening problems if left unchecked.

Electrical activity of the heart during a beat

The heart has its own natural pacemaker that regulates the rate of the heart. It is situated in the upper portion of the right atrium, and is a collection of special cells known as the sinus or sino-atrial node. These are able to generate a number of sparks per minute and each spark travels across a specialised electrical pathway to stimulate the muscle walls if the four chambers. This enables the heart to contract and empty in a certain pattern. The upper chambers are stimulated first, followed by aslight delay to allow the two atria to empty then the two ventricles are stimulated in the same way. www.heartsite.com

Cardiac Cycle

A normal healthy heart beats approximately 75 times per minute. The heart contracts then begins to relax, during the relaxation period the ventricles begin to contract. This is known as systole and diastole which means heart contraction and relaxation respectively.

Cardiac cycle is the term used to refere to both these events, which complete a heart beat. The complete cardiac cycle is a term of events that occur during a three stage event.

1. Mid-to-late diastole

This is when the heart is in complete relaxation. The pressure in the heart is low. The semi lunar valves are closed and the atrio-ventricular (AV) valves are open. The atria contracts and forces any remaining blood in their chambers back into the ventricles.

2. Ventricular systole

This stage is when the pressure within the ventricles increase rapidly, closing the AV valves. When the intraventricular pressure is higher than that in the large arteries leaving the heart the semi lunar valves are forced open and blood rushes through them out of the ventricles. During ventricular systole the atria are relaxed and their chambers are filling with blood.

3. Early diastole

This is the end of diastole, the ventricles are relaxed, semi lunar valves snap shut to prevent back flow and for a moment the ventricles are completely closed chambers. During this time the intraventricular pressure drops. As it drops lower than the pressure in the atria, the AV valves are forced open again, begin to fill rapidly with blood and complete the cycle.
Essentials of Human Anatomy and Physiology(Elaine N Marieb)

The structure of the Heart

The heart is a powerful muscle known as the Myocardium. The heart has two separate pumps that continuously send blood throughout the body carrying nutrients, oxygen and removing harmful wastes.
The right hand side of the heart receives blood low in oxygen and the left side receives blood that has been oxygenated by the lungs.

Right Atrium

The right atrium is larger than the left side as it receives blood back from all the other parts of the body. The walls of the right atrium are thinner than the left as the blood it receives is under less pressure. It has two main veins that return the blood, theses are known as the superior vena cava and the inferior vena cava. The superior vein returns deoxygenated blood from the top half of the body and the inferior returns deoxygenated blood from the lower half of the body.
The right atrium also receives blood back from the heart itself. When blood is collected in the right atrium, it is pumped into the right ventricle through the tricuspid valve.

Left Atrium

The left atrium receives blood from four pulmonary veins. The blood has been oxygenated by the lungs. This blood is then pumped into the into the left ventricle through the bicuspid valve.

Right Ventricle

The right ventricle recieves blood from the right atrium. As the heart contracts blood is forced out through the pulmonary semilunar valve into the pulmonary artery.

Left Ventricle

The walls of the left ventricle are four times thicker than the right hand side. This is because the oxygenated blood it receives needs to be pumped to the rest of the body. When the heart contracts blood is forced through the aortic semilunar valve and into the aorta.

Aorta

The aorta is the largest vessel in the body. It carries oxygenated blood to every part of the body. It receives blood from the left ventricle.

Superior Vena Cava

This is one of the largest veins in the body. It returns deoxygenated blood to the right atrium from the upper parts of the body.

Inferior Vena Cava

This returns deoxygenated blood from the lower parts of the body to the right atrium.

Pulmonary Arteries

These carry blood from right ventricle to both of the lungs, where it is oxygenated and sent back to the left atrium of the heart.

Pulmonary Veins

These carry oxygenated blood back to left atrium in the heart.

Mechanisms for regulating ventilation and pulse rates

To breath is a completely mechanical process. A rule to remember about the mechanics: Volume changes lead to pressure changes, which lead to the flow of gases to equalise the pressure. The mechanical process depends on the volume changes in the thoracic cavity. - Essentials of Human Anatomy and Physiology (Elaine N Marieb).


The rate at which we inhale and exhale is controlled by the respiratory centre, within the Medulla Oblongata in the brain. Inspiration occurs due to increased firing of inspiratory nerves and so the increased recruitment of motor units within the intercostals and diaphragm. Exhalation occurs due to a sudden stop in impulses along the inspiratory nerves.

The diaphragm flattens and moves downwards and the intercostal muscles move the rib cage upwards and out. This increase in size decreases the internal air pressure and so air from the outside (at a now higher pressure that inside the thorax) rushes into the lungs to equalise the pressures.


When we exhale the diaphragm and intercostal muscles relax and return to their resting positions. This reduces the size of the thoracic cavity, thereby increasing the pressure and forcing air out of the lungs.

The breathing rate is all controlled by chemoreceptors within the main arteries which monitor the levels of Oxygen and Carbon Dioxide within the blood. If oxygen saturation falls, ventilation accelerates to increase the volume of Oxygen inspired.


Arteries have the ability to constict or dilate rapidly during excercise to ensure blood flow demands are met. During this time the arteries dilate in the muscles so that blood flow can increase to the capillaries. This increase in blood flow allows the muscles to increase in the exchange of oxygen, the release of heat and the removal of waste products such as lactic acid and carbon dioxide. If levels of Carbon Dioxide do increase a substance known as carbonic acid is released into the blood which causes Hydrogen ions (H+) to be formed. An increased concentration of H+ in the blood stimulates increased ventilation rates.