Chapter 6 life process class 10

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 Transportation

Body of unicellular organism such as Amoeba is in direct contact with the environment. They can take the required substances such as oxygen, food, etc. Directly from the environment by the process of diffusion through the body surface.

Transports of oxygen, minerals, etc. to all the cells/tissues and waste products like carbon dioxide, urea, etc. from the cells/tissues to the excretory organs for their removal from the body. This takes place by different methods in plants and animals called transport system.

Transportation in Human Beings

In humans, substance like oxygen and minerals are transported to the body cells and metabolic wastes such as carbon dioxide are removed from cells by extracellular fluids. 
These fluids keep on circulating in the body and helps in transportation of various substances. 
This flow of extracellular fluid in the body is called circulation

Circulatory system or transport system in human consists of : 
• circulatory medium-- Blood and lymph
• system of blood vessels-- Arteries, veins and capillaries
• central pumping organ-- Heart

1. Circulatory Medium-- Blood

Blood is a red- coloured liquid which circulates in our body. Blood is red due to the presence of a red pigment called haemoglobin in its cells.
Blood consists of:
1. Plasma 
2. Red blood corpuscles (red blood cells)
3. White blood corpuscles ( white blood cells)
4. Platelets 


• plasma 
The liquid part of blood is called plasma. Plasma is a colourless liquid which mainly consists of water 90% with many substances dissolved in it

Functions of plasma 

• Transportation of digested food 
• Transportation of oxygen
• Transportation of carbon dioxide
• Transportation of metabolic wastes 
• Transportation of hormones 
• Transportation of heat
• Homeostasis 
 

• Red blood cells 

Red blood cells are red in colour due to the presence of red pigment called haemoglobin. Red blood cells are the carries of oxygen beacause haemoglobin has the ability to combine readily with oxygen to form oxyhaemoglobin which readily gives up oxygen to the needy tissues.


Functions of red blood cells
• Transportation of oxygen 
• Transportation of carbon dioxide

• white blood cells 

White blood cells fight against infection and protect us from diseases. Some white blood cells can eat up the disease causing germs. Some white blood cells produce 'antibodies' to fight against infection.
White blood cells are called soldiers of the body because they protect the body from the attack of disease causing germs germs and other harmful foreign substances.


Types of white blood cells
• Agranular white blood cells
• Granular white blood cells

Functions of white blood cells
• phagocytosis:  The engulfing of the particles like solid substances such as bacteria, worn out tissues.
• Formation of Antibodies and Antitoxins
• Immunity

Blood platelets

They are the smallest corpuscles . They are denucleated. They are produced in bone marrow by fragmentation of some giant cells called megakaryocytes. Their life span is about 3-5 days and are mainly destroyed in the spleen.

Functions of platelets
Blood platelets are responsible for coagulation     ( clotting) of blood in a wound or cut. 

Functions of blood 
•Transport of substances like respiratory gases, oxygen, and carbon dioxide; digested food or nutrients; waste products; hormones; enzymes from one part of the body to the other.
• protection against diseases.
• Regulation of body temperature.

Blood clotting
If a person gets injured, then the blood vessels in his body parts may get ruptured. Due to rupture of blood vessels, blood escapes from the cut. Our body has its own mechanism of preventing the loss of too much blood from a cut or wound by forming a 'blood clot'.

 2.System of Blood vessels

• Arteries  They carry blood away from the heart for distribution to the various organs of the body. Except for pulmonary artery, all the arteries contain oxygenated blood. Due to considerable pressure of the blood flowing in them , they have thick and elastic walls. They have narrow lumen and are deep - seated. 
• veins  They bring blood from the body organs back to the heart. Except the pulmonary vein, they contain deoxygenated blood. Since the blood flows through them at low pressure, they are thin walled. They are provided with valves to prevent back flow of blood. They have wide lumen and are superficially situated and can be seen from the surface of skin.


• capillaries  smallest vessels whose cell walls are only one -cell thick are called capillaries.
They join the arteries and veins. Arteries divides and redivides to form capillaries. These capillaries have very thin walls which help in exchange of respiratory gases, food products, excretory products, etc. 

3. Central pumping organ-- Heart

• Structure.  The heart acts like a pumping station that pushes out the blood with great force into the blood vessels. The blood vessels form an extensive network of transport pathways along which the blood flows.
Heart is surrounded by double membranes called pericardium. The narrow space between the two membranes called pericardial cavity is filled with a fluid called pericardial fluid.


• Working of heart.  The heart beats all the time throughout one's life. Heart beat is due to rhythmic contraction and relaxation of heart muscles. When the atria are relaxed , the blood from large veins are called vena cava flows into the right atrium. The oxygenated blood present in the left ventricle is distributed to all the parts of the body through largest artery called aorta. From right ventricle, deoxygenated blood flows to the lungs and comes back to the heart. Int his way , blood flows twice through the heart in each cycle. This is called double circulation. 


• Blood pressure.  The hydrostatic pressure exerted by blood on the walls of blood vessels is known as blood pressure. It is much greater in arteries than in veins. 
It is of two types:
1. Systolic pressure:   It is the pressure of blood inside the artery during ventricular systole. The normal systolic pressure is 120 mm of Hg. 

2. Diastolic pressure:  It is pressure in artery during ventricular diastole. The normal diastolic pressure is 80 mm og Hg.

The average blood pressure is expressed as 120/80 mm of Hg. The 
Difference between the systolic and diastolic pressure is called pulse pressure. It averages 40mm of Hg and provides information about the condition of arteries.

The blood pressure is measured with the help of an instrument called sphygmomanometer. The process of measuring blood pressure

High blood pressure with systolic more than 140mm of Hg and diastolic more than 90mm of H g I'd called hypertension.



• Heart beat.   A complete contraction and relaxation of the heart is called heart Beat.
Usually, the heart beats about to 70 to 72 times per minute. A doctor listens to our heart beat with the help of an apparatus called stethoscope.
The number of heart beats of a person of a person increases after a physical exercise or when a person is heart beats of a person increases after a physical exercise or when a person is excited. 




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