Transportation in Human Beings
Human beings like other multicellular organism need regular supply of food, oxygen etc.
This function is performed by circulatory system.
→ The circulatory system in human beings consists of:
(i) Heart (pumping organ)
(ii) Arteries and Veins (Blood vessels)
(iii) Blood and lymph (Circulatory medium)
• Circulatory system in human beings
→ The lungs supply oxygen-rich blood to the the left atrium of the heart.
→ The left atrium relaxes when it is collecting the blood and contracts when blood is
transferred to the left ventricle. The left ventricle expands when it receives blood.
→ The blood is pumped out of the body when the muscles of left ventricle contracts.
→ De-oxygenated blood comes from the body to the upper chamber on the right i.e. the right
atrium when it expands.
→ The corresponding lower chamber i.e. the right ventricle expands when right atrium
contracts. It transfers the blood to the right ventricle which in turn pumps it to the lungs for
oxygenation.
→ Right ventricles have thicker muscular walls so that they pump blood into various organs.
→ Valves ensure that blood does not flow backwards when the atria or ventricles contract.
Blood circulation in human body
→ Double circulation: Blood travels twice through the heart in one complete cycle of the
body.
Direction of blood flow through human heart
→ Pulmonary Circulation: Blood moves from the heart to the lungs and back to the heart.
→ Systemic Circulation: Blood moves from the heart to rest of the body and back to the
heart.
Why is it necessary to separate the right side and left side of the heart?
The separation of the left and right sides of the heart in birds and mammal is necessary for
Efficient Oxygen Delivery to tissues and cells
Maintaining Body Temperature as mammals and birds are warm blooded
High Energy Needs for powering the increased metabolic activity required to
maintain their body temperature.
The separation is achieved by the atrial and ventricular septa,(Septum) which are muscular
walls that divide the heart into left and right sides.
Animals, like amphibians or many reptiles have three-chambered hearts, and
tolerate some mixing of the oxygenated and de-oxygenated blood streams as that do
not use energy for maintaining the body temperature, the body temperature depends on
the temperature in the environment.
Fishes, on the other hand, have only two chambers to their hearts, and the blood is
pumped to the gills, is oxygenated there, and passes directly to the rest of the body.
Thus, blood goes only once through the heart in the fish during one cycle of passage
through the body.
The force that blood exerts against the wall of a vessel is called blood pressure.
This pressure is much greater in arteries than in veins. The pressure of blood inside the artery
during ventricular systole (contraction) is called systolic pressure
and pressure in artery during ventricular diastole (relaxation) is called diastolic pressure.
The normal systolic pressure is about 120 mm of Hg and diastolic pressure is 80 mm of Hg.
Blood pressure is measured with an instrument called sphygmomanometer.
High blood pressure is also called hypertension and is caused by the constriction of
arterioles, which results in increased resistance to blood flow.
It can lead to the rupture of an artery and internal bleeding.
• Blood (The transporting medium)
Blood is connective tissue which is fluid in nature.
→ Solid components of blood (Blood corpuscles):
(i) RBC (Red blood cells): It carries O2 and CO2 and also contain Haemoglobin which impart
red colour to the blood.
(ii) WBC (White blood cells): It provides body defence by engulfing the germs and produces
antibodies.
(iii) Blood Platelets: It helps in blood clotting during injury.
The loss of blood from the system has to be minimized in case of injury. Leakage would
lead to a loss of pressure which would reduce the efficiency of the pumping system. To
avoid this, the blood has platelet cells which circulate around the body and plug these leaks
by helping to clot the blood at these points of injury.
→ Liquid components (Plasma): It is a yellow colour fluid which contain 90% water & 10%
organic substances. Plasma transports food, carbon dioxide and nitrogenous wastes in
dissolved form.
• Lymph
→ It is a yellowish fluid which escapes from the blood capillaries into the intercellular
spaces.
→ It contains less proteins than blood and no RBCs
→ It flows from the tissues to the heart which helps in transportation of materials and
destroying germs.
→ It carries digested and absorbed fat from intestine and drains excess fluid from extra
cellular space back into the blood.
• Types of Blood Vessels
There are two types of blood vessels
(i) Arteries
(ii) Veins
Arteries Veins
Carry oxygenated blood from heart to Carry deoxygenated blood from body parts
body parts except pulmonary artery. to heart except pulmonary vein.
Also called distributing vessel. Also called collecting vessel.
Thick and elastic. Thin and less elastic.
Superficial (near to the skin) as compared
Deepseated. (far from the skin) to arteries.
Transportation in Plants
There are two main conducting pathways in a plant.
(i) Xylem
(ii) Phloem
Xylem Phloem
Carries water & minerals from the roots to Carries product of photosynthesis from
other parts of the plant. leaves to the other parts of the plant.
In xylem tissue, vessels and tracheids of the
roots, stems and leaves are interconnected to . The translocation of food and other
form a continuous system of water- substances takes place in the sieve tubes
conducting channels reaching all parts of the with the help of adjacent companion cells
plant. both in upward and downward directions.
No energy is used. Energy is used from ATP.
Transpiration and its Functions
It is the process of loss of water as vapour from aerial parts of the plant.
Function :
(a) Absorption and upward movement of water and minerals by creating PULL.
(b) Helps in temperature regulation in plant.
Transport of food from leaves (food factory) to different part of the plant is
called Translocation.
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