The human blood

The human blood consist of a 55% of fluid called plasma and other 45% is cellular components consist of red blood cells, white blood cells and platelets. 

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Plasma is yellow liquid in our blood. 90% of plasma is water. The rest are dissolved substances which include nutrients such as glucose, amino acid and vitamins, proteins like antibody, hormones, enzymes, albumins and fibrinogen and inorganic ions such as sodium, calcium, chlorides and phosphates. Main function of plasma are to transport nutrients to tissue, to remove waste products from tissues, to distribute hormone, enzymes, antibodies and other proteins and to distribute heat energy from the liver and muscles to all other part of the body.

Red blood cell (erythrocytes) transport oxygen from the lungs to all parts of the body. They contain a red pigment called haemoglobin which combines with oxygen molecules to form oxyhaemoglobin. They also carry carbon dioxide from our body cells to our lungs. Red blood cells are made in the bone marrow. The lifespan of red blood cells is about 120 days. When red blood cells are worn out, they are destroyed in the liver and spleen.

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White blood cells (leucocytes) are much larger than red blood cells and they each have a nucleus. They are usually irregular in shape, colourless and do not contain haemoglobin. There are several types of white blood cells. White blood cells are formed from bone marrow cells. The lifespan of white blood cells depends on the type of white blood cells. It varies from a few hours to a few months. They play a vital role in the body’s defence against diseases. Unlike red blood cells, white blood cells can squeeze through the walls of the blood capillaries into the space among the cells to destroy the bacteria.

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Platelets are cells fragments produced by large cells in the bone marrow. Under a high-powered microscope, they appear as under tiny oval-shape structures without nucleus. They play an importance role in blood clotting. When a blood vessel breaks, the platelets release clotting factors.

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The blood vessels

There are three types of blood vessels; arteries, veins and capillaries. Arteries are blood vessels which carry blood away from the heart. Arteries deliver oxygenated blood except the pulmonary artery. The walls of arteries are much thicker and stronger than those of veins because they have to withstand the high pressure of blood coming from the heart. Veins are blood vessels which carry blood back to the heart. Veins deliver deoxygenated blood except pulmonary veins. Veins are thinner walls than arteries because blood pressure in the veins is much lower than in the arteries. Since the blood in the veins may be moving against gravity, they contain valve to prevent the blood from flowing back. Capillaries are tiny blood vessels which connect arteries and veins. They have walls which are only one cell thick. Oxygen and nutrients move from the blood through the capillary walls into the body cells. At the same time, carbon dioxide and other waste products move from the cells into the blood.

Source: http://academic.kellogg.edu/herbrandsonc/bio201_mckinley/f23-1_walls_of_an_arter_c.jpg

Structure of the human heart

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The function of the heart is to pump the blood to all parts of body. The heart is made up of two pumps located side by side. The right side of the heart pumps deoxygenated blood it receives from the tissue to the lungs. Carbon dioxide is removed in the lungs. The left side of the heart pumps oxygenated blood it receives from the lungs to the rest of the body. Oxygen is removed in the tissue for respiration.

The Transport System in Human

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The transport system in human is called circulatory system. The human circulatory system is a called double circulatory system because the blood flows through the heart twice in a complete circuit. The human double circulatory system consists of the pulmonary circulation which transports blood between the heart and the lungs and the systemic circulation which transports blood between the heart and all other parts of the body.

A circulatory system has four basic characteristics, Circulating fluid, pumping device, blood vessel and valves. The circulating fluid is called blood which transports useful and waste materials. Pumping device is the heart; blood is moved through the body by muscular contractions of the heart. Blood vessels are a complex network of blood vessel carries materials to the tissue and back to the heart. There are three main types of blood vessels; arteries, veins and capillaries. Valves are present in some blood vessels to prevent backflow and ensure that bloods flows in one direction only.

The Importance of a Healthy Respiratory System

Air pollutant	Harmful substances	Effect on respiratory system
Cigarette smoke	Nicotine, Tar	Nicotine is the drug that causes addiction to cigarette smoking. Nicotine cause rapid heartbeat, increased blood pressure and rapid breathing. The diseases related to nicotine include emphysema, hear disease and stroke Tar contains carcinogens (substances that cause cancer). It also irritates the respiratory tract, causing ‘smoker’s cough’
Gases from factories	Sulphur dioxide, nitrogen dioxide	Sulphur dioxide can cause irritation of the respiratory system. It can cause both temporary and permanent damage to the lungs.
Exhaust fumes	Carbon monoxide	Carbon monoxide combines with haemoglobin in the blood faster than oxygen can hence it is a poisonous gas which cause suffocation. Low concentration of carbon monoxide can cause dizziness, headaches and fatigue whereas high concentrations can be fatal.
Haze	Smoke, dust	Continuous exposure to particulate matter cause coughing, nasal congestion, watery nose, constant sneezing and chest pain. Those who are very likely to be affected by haze are children, the elderly and people with illnesses like asthma, bronchitis and pneumonia.

Diseases of the respiratory system

Asthma is caused by the narrowing of the fine airways (bronchi and bronchioles) due to the contraction of muscles in their walls. This is perhaps because of sensitivity to air pollutants including smoke. A patient will find it difficult to breathe, wheezing and feeling tightness in the chest.

Bronchitis is caused by the inflammation of the lining of the bronchioles. This may be due to infection by bacteria or viruses or chemicals such as those found in tobacco smoke. 'Smoker's cough' is an early sign of chronic bronchitis. In several cases, the patient may turn blue which is especially noticeable at the lips and fingers due to poor oxygenation of blood.

Lung Cancer is cause by change in the cells inside the lung such that they divide out of control and produce lumps of cells (tumours) which interfere with the normal functions of the lungs. This diseases may not have any symptoms. When it is detected, the cancer cells may have spread from the lung to other organs.

Emphysema is a condition in which the structure of the alveoli is broken down by coughing. This reduces the surface area for gas exchange. The patient cannot take in enough oxygen and become very short of breath

Heart disease caused by nicotine that raises the blood pressure and increases the level of 'bad' cholesterol in the blood. This makes a smoker more likely to suffer from a stroke or a heart attack 

The Transport of Oxygen in The Human Body

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During inhalation, air is taken into the lungs through the nasal cavity, passing through the trachea, bronchi, bronchioles and finally alveoli. The air reaches the alveoli is rich in oxygen and poor in carbon dioxide. The blood from the heart that reaches the capillaries surrounding the alveoli is poor in oxygen and rich in carbon dioxide.

Oxygen diffuses from the alveoli into the red blood cells in the capillaries. At the same time , the red blood cells in the capillaries release carbon dioxide which diffuses into the alveoli.

Red blood cells contain the red pigment called Haemoglobin. Haemoglobin combine with oxygen to form oxyhaemoglobin. Oxyhaemoglobin from the lung is flow to the heart.

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When the oxyhaemoglobin from the heart reaches to the body tissue cell, oxygen has a higher concentration in the capillaries than in the body cells. So, oxyhaemoglobin releases oxygen which diffuses into the body cells. At the same time, carbon dioxide has higher concentration in the body cells than in the capillaries. So, carbon dioxide diffuses into the blood capillaries. Blood contain carbon dioxide next flow into the heart.

 

Source : http://www.tutorvista.com/content/biology/biology-ii/respiration/human-beings-gaseous-exchange.php

A Model of The Human Respiratory System

 

Glass tube ---> Trachea
Ballons ---> Lung
Bell jar ---> Thoracic Cavity
Rubber sheet ---> Diaphragma
Y-tube ---> Bronchus

1. When the rubber sheet is pulled down, the pressure inside the bell jar decreases. Air from outside enter the balloons
2. When the rubber sheet is pushed up, the pressure inside the bell jar increases. Air is forced out of the balloons

Mechanisms of Inhalation and Exhalation

Inhalation Mechanisms

1. Diaphragm muscles contract and flattens out
2. Volume of thoracic cavity increases
3. Air pressure inside thoracic cavity decreases
4. Air flow into lung
5. Ribcage move forward and upward

Exhalation Mechanisms

1. Diaphragm relax and arches upwards
2. Volume of thoracic cavity decreases
3. Air pressure inside thoracic cavity inrcreases
4. Air flow out of the lung
5. Ribcage move downward and inward