Evaluation of the effects of smoking on the body systems

Smoking has long been associated with the cause of lung cancer as tobacco is made up of cancer producing chemicals like carcinogens. However tobacco smoke also contributes to a number of other cancers which has a detrimental effect on the heart and the rest of the body. Lets face it if you keep putting a mixture of nicotine and carbon monoxide present in each cigarette (which will clog the lungs up like soot in a chimney) this is going to put tremendous strain on the heart and the blood vessels.

The costant inhalation of carbon monoxide will rob your brain, heart and muscles of much needed oxygen. This will cause the heart to work harder causing your airways to swell up and get blocked as smoking causes fatty deposits which narrow the blood vessels ultimately allowing less air into the lungs. This can cause not only heart attacks but strokes due to the strain being put on the heart.

Emphysema is an illness which is synonymous with smoking as it slowly rots your lungs. This is caused by the constant coughing that develops due to the sticky constituency of tar which stops the cilia on the mucucous membrane moving allowing a build up of mucus. This constant coughing damages the aveoli making breathing very difficult, allowing the lungs vunerable in contracting bronchitis and pneumonia.

The good news is that no matter what age or how many cigarettes one smokes, the health benefits of quitting is very quick. From the moment you quit your blood pressure and pulse rate return to normal and the carbon monoxide is being elimated from your body as your lungs are able to breath normally so improving circulation.

The changes in artery structure associated with circulatory disease

We can compare blood travelling through arteries to that of water being pumped through a hosepipe. Turn the tap up on the hosepipe and the pressure of the water coming out of the hose is greater, turn it down and so does the pressure. So if we liken that to the pressure of our blood in the arteries, if the blood flow is constant without any constrictions then a normal blood pressure reading is obtained. However if the arteries are blocked or if there is some kind of build up within the artery then the pressure must go up to force the blood around to the viatal organs.

The build up of fat or plaque is the main factor in high blood pressure and heart disease. With this build up of fat and plaque the whole structure of the artery changes. It goes from a very efficient system that is both strong and elastic to a system that has been narrowed and hardened making it more difficult for blood to flow through around the body. The main consequence of this is inadequate blood supply, tissue damage occurs, increased risk in a blood clot forming and worst case senario death. As you can expect with poor circulation oxygen rich blood has difficulty in reaching the heart, which can cause angina or a heart attack

Redistributing of blood during exercise

As we start to exercise our muscles require more energy, therefore we need more food and increased oxygen to produce this. This extra oxygen must be made available to our blood through increased breathing and depth of breathing to obtain this. Our blood cells also need to react to this extra oxygen as they need to deliver more oxygenated blood to the working muscles. When the ATP gets used up within the muscles, then the muslce starts to produce several metabolic byproducts in the biochemical process of energy transfer, ie. carbon dioxide, adenosine. When these byproducts leave the cells within the muscles this then enables the capillaries which have been previously closed to dilate. Along with the dilated arteries, this increased blood flow transports the oxygenated blood required to the working muscle.

There is also a bit of division going on as the blood flow is redistributed less to all other major organs apart from the brain and the heart where more blood flows to the working muscles. This is down to the sympathetic nervous system which stimulates the nerves to the heart and blood vessels. It is this nervous stimulation which cause the arteries and veins to either contract or constrict, so restricting blood flow to the tissues. So as the rest of the body starts to get the message to constrict the blood vessels and the muscles dilate their blood vessels. The blood flow from the say the stomach, kidneys etc is diverted to the working muscles.

Mechanisms of Ventilation and pulse rates

In my recent blogs I have explained about the respiratory system, blood and understanding the circulation and structure of blood as well as probably the most important muscle in our body the heart. So what makes all these complexities tick so to speak. How does it all happen and more important what makes our heart beat. It all comes down to one thing, the brain. Actually the cardiovascular part of the brain to be precise. Our brain is responsible for many things, therefore it has many parts to deal with these demands. The cardiovascular part is found within the medulla oblongata, which is located at the bottom of the brainstem. It is within the medulla oblongate that the motor nerves which are responsible for carrying action potentials from the brain to the heart is situated. It is these nerves that are connected to the Sinoatrial Node (SAN) and stimulate the SAN to either speed up or slow down depending on the body's needs.

The response of the medulla depends on the action potentials received by the SAN from baroreceptors. Situated within the aorta they are stimulated when the aorta wall is streched (increase output). So basically the SAN acts as the pacemaker by generating at regular intervals the electrical impulses of the heart beat so maintaining normal cardiac rhythm and pulse rates.

Cardiac Output

In my last blog I described the electical activity which results in a heart beat normally around 70 beats per minute. So how do we get this figure of 70 beats per minute and why is it important. Let us explore more!

Basically cardiac output is the measure of the volume of blood in milliliters per min (mL blood/min) ejected by the heart in one minute to establish the efficiency (or not) of the heart.

• Cardiac Output in mL/min = heart rate (beats/min) X stroke volume (mL/beat)

So if we look at an average persons heart rate at rest of 70 beats per minute, with a resting stroke volume of 70 mL/beat. Then the cardiac output would show:

• 70 (beats/min) X 70 (mL/beat) = 4900 mL/minute.

So why is this important? The heart rate and cardiac output have a direct relationship. As the heart rates increases therefore the cardiac output increases also. Monitoring of cardiac output gives doctors and clinicians the tools to be able to recognize, respond and understand many cardiac emergencies. A general rule of thumb is if a patient has a heart rate that is to fast or to slow then this requires urgent assessment as it could be a result of a blockage of the coronary arteriers which may cause a heart attack (myocardial infarction) or a fatal rhythm disturbance resulting in cardiac arrest.

Also people with heart disease usually have a weak blood supply, thus making their hearts beat slower due to poor electric conductivity. In all cases a electrocardiogram (EKG) is a noninvasive test that measures the electrical activity of the heart. This will detect many heart conditions as a result of high or slow cardiac output being detected in the first instance.

The electric heart

The heart has a natural pacemaker that regulates the rate and pace of the heart. This pacemaker sits on the upper portion of the right atrium and consists of a collection of special electrical cells known as the sinus or sino atrial (SA NODE). The SA node generates electricity which travels across a special pathway to stimulate the muscles of the four chambers of the heart to contract in a specific way.

The heart usually beats about 72 beats per minute on average at rest (normal activity) and is part of an intricate series of events that happen within your heart to produce a heartbeat. Each heartbeat consists of two parts.

• Diastole is where the atria and ventricles relax and fill with blood.



• Atrial is where the atria contracts and pumps blood into the ventricals. The atria relaxes so your ventricles can then contract pumping blood out of the heart.

As mentioned the electrical signal that sets the heart pumping begins with the SA node which then generates the two vena cavae to fill the hearts right atrium with blood from other parts of the body. This signal then spreads right across the cells of the heart to the right and left atria causing the atria to contract. This contraction then produces the action to push the blood through to the open valves from the atria into both the ventricles. The signal arrives at the AV node which sits near to the ventricles slows for an instant which allows the right and left ventricles of the heart to fill with blood. The signal is then released, moves along a pathway called the 'Bundle of His' (which is a collection of heart muscles cells specifically for the conduction of electrical activity which then transmits electical impluses from the AV node to the point of the apex of the fascicular branches) located within the walls of the ventricles.

From the 'Bundle of His' the signal fibers then divide to the right and left bundle branches through the Purkinje fibres which connect directly to the cells within the left and right ventricles. The signal then starts to spread acroos the these cells causing both ventricles to contract, which however doesn't happen at exactly the same time. This is because the left ventricle contracts an instant before the right one does. By doing this it pushes the blood through the pulmonary valve situated at the right ventricle to the lungs, then through the aortic valve for the left ventricle to the rest of the body.

As the signal passes the walls of the ventricles relax and await the next coming signal so the whole process continues over and over again.

Heart Structure and Cardia Cycle

The heart is an amazing powerful muscle which is a hollow upside down pear shaped shell, which consists of cardiac muscle fibres that contract and cause a wringing type of action. Located just to the left of the centre of the chest its size is a little larger than the size of your fist. The wall of the heart consists of three layers.

Epicardium, Myocardium and Endocardium

The epicardium is the thin outer layer that gives the heart the smooth slippery texture. The endocardium is the smooth inner lining with large blood vessels and the myocardium makes up the bulk of the heart. It is made up of strong cardiac muscle fibres and is in control of the pumping action.

The heart has two sides the right side being the one that pumps the deoxygenated blood to the lungs via the pulmonary artery and the left receives blood oxygenated by the lungs through the pulmonary vein. This forms a double circulation as the oxygenated blood gets pumped to the body in the aorta which then eventually returns back to the right hand side in the vena cava which enables this process to start all over again.

This double circulation which involves the contracting of the heart is called the cardiac cycle. This has two major phases the diastole and the systole. Diastole is the period between ventricular contractions where the right and left ventricles relax and fill. The systole phase occurs when the ventricles of the heart contract, this results in a high pressure within the systemic and pulmonary circulatory systems. These coordinated series of events takes place simultaneously on both the right pulmonary circuit and the left systemic circuit of the heart.

Blood Circulation - Structure of Arteries, Veins & Capillaries

Arteries are the blood vessels that carry the oxygenated blood away from the heart, they are also responsible in helping the push of the rapid flow of blood when both ventricles are relaxed and the heart is refilling. Varying in size which is depicted by how far away from the heart they are their structure consists of three layers of tissue.

1. Tunica Adventria - This is the strong outer covering consisting of fibrous tissue which allow the arteries and veins to stretch due to the pressure that is exerted on the walls by the blood flow.


2. Tunica Media - This is the middle layer of the walls of arteries and veins, composed of smooth muscle and elastic fibers which allows them to stretch more gentle each time the heart pumps blood into them, then return back to their original shape.


3. Tunica Intima - The inner most layer of the arteries and veins composed of an elastic membrane lining and smooth endothelium that is covered by elastic tissue.

Veins are the opposite to arteries whereby they carry the deoxygenated blood back to the heart. Although thinner than arteries they share the same composition with the same three layers with less muscle and elastic tissue in the tunica media. With some veins containing valves to make sure that the flow of blood travels to the heart not backwards, the pressure in a vein is less than that of an artery so no pulse can be found in a vein compared to that of an artery where a pulse can be obtained.

Capillaries are the smallest of the blood vessels within the body. Composed of a single layer of endothelial cells they operate as a link between arteries and veins where the exchange of blood and tissue takes place in the capillary bed.

Transportation of Oxygen in the blood

In my previous blog regarding red blood cells I gave an explaination of how they play a crucial part in the assistance of oxygen transportation throughout the body. This is carried out by haemoglobin pigment molecules which binds four oxygen molecules to form Oxyhaemoglobin. These are then transported to individual cells within the body's tissue where they are released.
The presence of carbon dioxide aides the release of oxygen from the haemoglobin, this is known as the Bohr effect. Appropriately named after a guy called Bohr it is the adaptation to release oxygen in the oxygen starved tissues in capillaries where respiratory carbon dioxide lowers blood ph. So this basically means if the ph in the blood decreases so does the ability of the haemoglobin to bind to oxygen decrease. As it is the haemoglobin primary function to carry oxygen from the lungs to the tissues at low ph the Bohr effect allows the blood to unload oxygen for use by the muscles, which is necessary for the body to function.

Red Blood Cells

Red blood cells make up around 40% of our bloods volume, also called 'erythrocytes' they contain hemoglobin which is a single protein of iron pigments when combined with oxygen gives our blood the distinctive red colour. Their apperance is unique looking very much like a doughnut with a thin centre that becomes thicker towards the edges.

Their role is to facilitate oxygen from the lungs through the gasious exchange carried out within the aveoli to our body tissue and also to take away the carbon dioxide from these tissues back to the aveoli within the brochial tree in the lungs.

They are made within the red bone marrow which is in the thoracic bones, vertebrae, craniel bone and the ends of the femur and humerus bones. Blood contains around 25 trillion red blood cells which has to be replaced at a rate of around 3 million per second. It is very important that we don't allow our red blood cell count to drop as this can lead to anemia which is a condition that is caused by our healthy red blood cells dropping to a level that causes stress on the body. Anemia can be a result from a inherited disorder, a lack of iron or vitamin deficiency due to poor diet, infections or some kind of cancers.

Blood - Plasma

Blood is the fluid for sustaining life. One can never under value the importance of this substance that helps provide growth, health and the fighting of disease by transporting essential elements to provide antibodies, that are used by the immune system to identify and neutralize foreign bacteria and viruses.



About 55% of blood volume is made up of plasma which is a straw coloured clear liquid in which red and white blood cells and platelets are suspended. It is about 95% water and as the heart pumps blood cells all over the body, it is plasma that nourishes them and removes any waste products. The main protein in plasma is albumin which helps keep fluid from seeping out of blood vessels and into tissues. There are other proteins in plasma that include antibodies which form part of our immune system in the body's fight against viruses, bacteria and clotting factors to aide control of bleeding. Plasma is the first source that acts as a reservoir to replenish water if required as well as aborbing surplus water from tissues. Plasma also helps to maintain the blood pressure and circulation throughout the body and it is this that plays a crucial role in regulating the body temperature by transmitting heat generated in the core body tissues through to the areas that can lose heat easily for instance the arms and legs.

Nervous system

It is fair to say that the nervous system is the master control unit inside your body. It has a huge responsibility for sending, receiving and processing nerve impluses throughout the body. For the facilitaion of this control unit there are sense organs that afford this information by means of sight, smell, hearing, taste, pressure and pain. There are nerves that are connected throughout the body to the brain which carry information by electrochemical signals called impluses. It is the aim of these impluses to travel from the brain and spinal cord to the nerves sited throughout the body.


The autonomic nervous system ensures that our unconscious breathing is carried out in a regular rate and pattern. Being part of the peripheral nervous system the brain stem or medulla is the centre where the nerve cells send simultaneous signals to the intercostal muscles (ribs & diaphragm) to contract and relax at regular intervals. The ANS controls the body's internal environment which also helps control the heart rate, blood pressure, digestion respiration.

Gaseous Exchange

Gaseous exchange is the movement of oxygen into the body and the expelling of carbon dioxide out of the body. This is facilitated by diffusion through the alveolar surface within the lungs. There are about 300 million alveoli in each lung which gives a substantial surface area for exchange to transpire over.

The surface of the alveoli is very thin and moist so enabling the gases to pass through or exchange quickly. Situated within the walls of each alveoli lies a network of capillaries. Oxygen gets passed from the alveoli into bloodstream, which is then used up by cells within the body where it is used for respiration. The blood then carries back the waste which is carbon dioxide back through the alveoli walls where it is breathed out as you exhale.

Respiratory System & the process of Ventilation

The primary funcion of the respiratory system is to supply the blood with oxygen from the air that is breathed in through our lungs. Pulmonary ventialtion (breathing) is a process that all of us do without even thinking about it of which is subsequently controled by the nerve cells situated within the medulla of the brain.

As the air is drawn in through pulmonary ventilation through the nase cavity it is warmed, moistened and cleaned by the paranasal sinuses. The air then passes through the pharynx then into the respiratory tract. This is the passageway that facilitates air into the bronchi within the lungs then sub divides into smaller passageways which are called secondary bronchi. The bronchi keep dividing to create an impressive tree with smaller brances that ends in clusters of tiny air sacs called alveoli. These series of air passages are lined by membranes that contain special cells that produce mucus which keep the lining moist as well as trapping dirt and dust.

Within our respiratory system there are structures which enable air to move in and out of the lungs. The diaphragm, ribcage and intercostal muscles form this structure for the efficient delivery of oxygen for life sustaining activities. The diaphragm is the most important muscle of the ventilation structure, made up of a large sheet of skeletal muscle which works with the intercostal muscles by contracting and relaxing forcing air in and out of the lungs.