The respiratory system is the human body’s system that is responsible for breathing, both mechanical through the chest wall; and physiological, through the alveoli. The circulatory system assists in gaseous exchange, in the alveoli, and circulation of oxygen to all parts of the body, as well as, removal of carbon dioxide from the parts of the body. The two systems work together to facilitate gaseous exchange. This paper seeks to the role played by the two systems in gaseous exchange and transportation to and from the body tissues. To effectively discuss the relation of the systems and their role, the paper is divided into sections, each discussing a particular aspect.

1.1. Structure of the Respiratory System:

The respiratory system is divided into the upper and the lower respiratory tract. The part that is upper respiratory tube is composed of the structures that pick up air and direct it into the lower structures. These include: the nose, the mouth and a section that has the beginning of the trachea.

The lower respiratory tract includes the trachea, the two bronchi, the branches of the bronchi called bronchioles, and the lungs. The lungs are two in number; one lung is on the left; the other on the right. The chest cavity holds the structures of the lower respiratory tract. Sternum, chest muscles and the rib cage offers mechanical protection to them.

Trachea is a tube that starts from a point below the nose, and divides into two branches called bronchi. The division of the bronchi into smaller branches gives out bronchioles. These divide further when they get into the alveoli lungs. The lungs consist of the alveoli-small air sacs where gaseous exchange takes place. The alveoli are rich in blood vessels to facilitate gaseous exchange. The walls making up the alveoli are only one cell thick to give the molecules entering and leaving them a short distance to travel. To ensure that the rate of exchange is maximum, the alveoli are supplied with a rich blood supply. The alveoli are also very many, in millions, to give a large surface area for gaseous exchange.

1.2. Mechanism of breathing and gaseous exchange:

Breathing involves two steps; inhalation (breathing in) and exhalation-breathing out. The process is aided by two sets of muscles (diaphragm and rib cage) which contract and relax to decrease and increase the volume of the chest cavity.

Inhalation –the muscles are contracted, it flattens causing the chest cavity to increase in volume. Contraction of the rib cage causes it to rise. This creates low pressure in the lungs. Air enters the lungs from the high pressure outside.

Exhalation happens with the muscles relaxed. The diaphragm rises and becomes dome-shaped. The rib cage moves inwards. Volume in chest decreases and pressure increases. This makes the air with more carbon dioxideto be expelled out of the atmosphere.

Gaseous exchange is a function that is aided by a concentration gradient. Air entering the alveoli of the lungs is more concentrated in oxygen. The air in the alveoli is more concentrated in carbon dioxide. The countercurrent flow system of the alveoli also helps increase the concentration gradient. Because of the gradient, air with more oxygen crosses the epithelial lining of the cells of the alveoli into the blood vessels. While this happens, carbon dioxide comes out of the capillaries where it is more concentrated to the alveolar space where it is less concentrated. It is expelled out through the process of exhalation.

1.3. Regulation of breathing:

It is vital to note that; the main purpose of the respiratory system is to distribute oxygen to the tissues as per the demand, and to remove carbon dioxide as it is produced by tissues. The body has a mechanism of regulating breathing through sensing the levels of carbon dioxide (Holmgren and Nilsson 1994 P.59). Carbon dioxide dissolves in water to produce hydrogen ions and hydrogen carbonate ions. The brain has central chemoreceptors, which sense rising levels of hydrogen carbonate ions.When the levels of carbon dioxide rise, it initiates a response through breathing. The peripheral chemoreceptors located at the base of the aorta sense the rising levels of hydrogen ions. They send messages to the brain to stimulate breathing. When the levels of these ions are low, less stimulation is initiated.

1.4.(A). Asthma

Asthma is considered a chronic disease of the respiratory system whose main symptom is difficulty in breathing (WHO 2008). a patient suffering from asthma experiences attacks of breathlessness referred to as Asthmatic attacks.

Among the causes of asthma are allergens like dust and pollen, chemical irritants, tobacco smoke and air pollution.

The main symptoms during the attack are breathlessness, fatigue, and reduced activity levels.

Curing asthma is difficult. Management involves controlling the disease and symptomatic management. Medications that are short term are used to relieve the symptoms and also to reduce exacerbations. Preventing the patient from allergens is a very effective method of management. It is one disease condition that leads to chronic obstructive pulmonary disease. Failing to take the medications can lead to death (WHO 2008).

(B) Emphysema

Emphysema is a respiratory system disorder that results from the destruction of the air sacs. It also constitutes the chronic obstructive pulmonary disease. Among the main causes are marijuana smoke, tobacco smoke, air pollution and silica (WHO 2008).

The main symptom of emphysema is a difficulty in breathing that start slowly. This is also accompanied by fatigue, mental alertness, fast heart rate and cyanosis (Mayo Clinic 2014).

Treatment for emphysema involves oxygen supplementation and pulmonary rehabilitation. Medications are also used. Such medications include antibiotics, pulmonary steroids, bronchodilators, and smoking cessation drugs like Chantix. Counselling people to leave a lifestyle that increases risks is also a rationale used in the management of the disease.

Emphysema can also bring complications to the body. These complications include a collapsed lung which is referred to as a pneumothorax, heart problems like purmonale, and giant bullae that refers to having empty spaces in the lungs (WHO 2008).

2.1. Composition and Functions of Blood Cells:

The blood, which is the liquid part of the body, consists of the plasma and the blood cells. The blood cells consist of three types; the red blood cells also known as the erythrocytes; the white blood cells which are also called leucocytes; and the platelets also known as the thrombocytes (Reiss and Givens 2002).

The red blood cells have no nucleus inside the cell. They contain a component known as the hemoglobin that gives them the red color. The cells are biconcave shaped as an adaptation to carry maximum oxygen. One cell is capable of carrying four molecules of oxygen. Their function is to carry oxygen in the body.

The white blood cells are many per milliliter of blood, and their function is to fight diseases from attacking the body. They are of two types: the phagocytes and the lymphocytes. The phagocytes provide protection by ingesting micro-organisms. The lymphocytes provide protection by the production of antibodies against the antigens that invade the body (Reiss and Givens 2002).

The function of platelets is clotting of blood. They perform this function through production of fibrin fibers that thread and harden to form a scar. This way, they prevent the body from losing blood when a compromise in the integrity of the skin occurs.

The plasma part of the blood is the liquid part of blood which contains and houses the blood cells.

2.2. Composition and Functions of the Heart and the Blood Vessels:

The heart is described as a muscular pump. It consists of chambers that hold blood and blood vessels in a form of tubes that transport blood to all the parts of the body. A special, unique muscle makes up the heart, and it contracts continuously without fatigue.

The chambers of the heart are four in number. The lower vessels are referred to as ventricles. The upper chambers are referred to as auricles. Lower chambers receive blood while the upper chambers pump blood out of the heart.

The blood vessels of the heart consist of two main types; the artery system and the venous system. Thicker walls are found in the arteries than in the veins. The main artery that leaves the heart is called the aorta. It divides to form branches that supply the main parts of the body like the head and the legs. Divisions of major arteries after they enter the organs are referred to as the arterioles. Arterioles divide further to form the capillaries. Capillaries are in contact with the tissues, and they form the exchange system of materials with the tissues. Arteries have a major function in supplying the body tissues with oxygenated blood. However, the exception has been found in the pulmonary artery, because it carries de-oxygenated blood from the lungs (Reiss and Givens 2002).

The venous system consists of the venules that leave the tissues with de-oxygenated blood and join main veins. The major vein entering the heart is referred to as the venacava and it enters the the heart through the left auricle.

The main function of the heart and the blood vessels involves carrying blood to the body tissues and carrying it back to the heart. The heart, through the pulmonary vein, gets oxygenated blood from the lungs and distributes it to the body through the arterial system. Blood rich in carbon dioxide gets to the heart through the venous system. It is transported to the heart for oxygenation through the pulmonary artery.

2.3. Disorders of the circulatory system:

(A). Hypertension.

Hypertension, which has a feature of high blood pressure, refers to a circulatory system condition which pressure of this blood in almost all the vessels is higher than the normal. This can lead to adverse effects including a disease of the heart. The volume of blood pumped by the heart, and the amount of resistance offered by the blood vessels, determines the blood pressure. If arteries are narrow, and the heart pumps more blood, the blood pressure increases.

The causes of hypertension are divided into two: essential hypertension and secondary hypertension. Primary or essential hypertension has no identifiable cause. The cause is described as idiopathic (Reiss and Givens 2002). Among the causes of secondary hypertension are tumors of the adrenal gland, disease of the kidney, congenital diseases, some drugs like cocaine, and some medications like contraceptive pills and decongestants.

Symptoms do not occur in some people. Those that experience symptoms present with a dizzy feeling, dull headaches and nose bleeds.

There are any risks that are associated with blood pressure. Older people are more predisposed to blood pressure than younger people. The black people have been known to develop hypertension more than the other races. If one has a family history of blood pressure, the chances of getting it are higher. Being obese or overweight is also a risk factor to developing hypertension. Smoking is also another risk of developing hypertension. Too much intake of salt is also a risk. Other risk factors include stress, having very little potassium in the diet, drinking a lot of alcohol, and some chronic conditions like disease of the kidney (WHO 2008).

There are several strategies through which the treatment of blood pressure is targeted. The first means is through medications. There are some types of medicines that can be used to treat blood pressure. Knowing the exact cause of blood pressure enables the practitioner to choose which medication to use in a particular case. These medications include thiazide diuretics, beta blockers, and calcium channel blockers.

Another treatment model for hypertension is changing one’s lifestyle. For example, a person can abstain from alcohol or smoking in order to reduce the risk of getting the disease. Another form of lifestyle change is by adopting a diet that does not increase the chances of getting blood pressure.

Among the complications of blood pressure that does not heal mostly affects the heart. They can lead to a heart attack. Heart’s failure or aneurysm can also occur. The eye’s blood vessels may become torn. The patient later shows trouble with memory and understanding.

(B). Varicose veins:

Varicose veins refer to enlarged, twisted veins close to the surface of the skin. They are found mostly on the ankles and the legs. They may heal with time, or may complicate to bring about serious problems.

The condition is commonly caused by weak veins and valves on the legs or the areas in which they occur. The events leading to causation come about when veins become incompetent. Competent veins allow blood to flow back to the heart from the extremities and prevent it from flowing back. When the incompetent veins are unable to prevent blood from flowing back, blood collects in the extremities. After sometime, pressure builds up in the affected limbs. This is what causes the veins to enlarge, become twisted, and weak (Larckome 2002).

Some predisposing factors to varicose veins include age, and a family history of the condition.

The manifestations of the malady when it is on serious stages are, thin-dry skin, color changes, scaling, inflammation and leg swelling. Sometimes bleeding or open sores occur. Caution is encouraged because the varicose veins can occur as a sign of deep vein thrombosis (Larckom 2002).

The diagnosis of the condition involves inspecting or looking for the symptoms in the legs.

Treatment involves easing the symptoms by propping up the legs, wearing of stockings, doing exercises, and avoiding standing or sitting down for long.

Some other complex forms of treatment include: sclerotherapy that stands for closing off the vein; destruction of the vein through laser treatment; removing or tying up the vein through surgery and closing the vein through radiofrequency.

REFERENCES

Holmgren and Nilsson. 1994. Comparative physiology and evolution of the autonomic nervous system. London: Harwood Academic Publishers.

Mayo Clinic. 2014. Diseases and conditions: Emphysema. Retrieved online from http://www.mayoclinic.org

Reiss, M. & Givens, P. 2002. Human biology and health studies. Cheltenham, UK: Thomas Nelson and Sons.

Larckom, E. 2002. Biology with the human body. Cheltenham, UK: Thomas Nelson and Sons.

World Health Organization (WHO). 2008. Chronic respiratory diseases: Asthma. Retrieved online from the WHO website at http://www.who.int/respiratory/asthma/