Basic Science VI

42

Have you ever seen slogans like these anywhere?Why do we say 'Blood donation is life donation'.What are the occasions blood needs to be donated?

Do you know what your blood group is? Ask your friends abouttheir blood group.

Occasions where blood is donated

Blood DonationA healthy man can donate blood once in six months. Thedonated blood is chilled and kept in the blood bank.Blood of a particular donor does not match with all kindsof blood. It is due to the differences in certain constituentsof blood. Based on these constituents grouping of bloodis done.

BloodThe major constituents of blood are its fluidpart called plasma, Red Blood Cells (RBC),White Blood Cells (WBC) and platelets. Bloodis essential for the sustenance of life. A healthyperson has 5 to 6 litres of blood in the body.This may vary according to the height andweight of the person. Red colour of the bloodis due to the presence of a protein calledhaemoglobin. Iron is the major constituent of haemoglobin. Bloodcarries nutrients and oxygen to the cells of the body.

red blood cells

white blood cells

platelets

plasma

‘Blood donation is life donation’‘Donate blood:

Save precious life’

WHEN THE HEART BEATS…5

43

Basic Science VI

What are the different organs that help blood toreach all parts of the body?

Let’s Observe the Blood VesselsHold your fist tight and look at the outer part.What do you see? Examine the inner side the lowereyelid of your friend. Do you see blood vesselsthere? Is there any difference in them from theblood vessels you have already observed. Lookat the inner side of your lower lip using a mirror.Are the colour and size of the blood vessels youhave observed alike?

Record the differences you have observed.

Blood vesselsThe blood vessels that carry blood from the heart todifferent parts of the body are the arteries. Veinscarry blood from different parts of the body to theheart. The minute blood vessels that connect arteriesand veins are the capillaries. The organ systemwhich consists of heart, blood vessels and bloodtogether constitute the circulatory system.

Basic Science VI

44

Where else on your body can you feel pulse?

Examine the heartbeat of your friends using a stethoscope.How many times does the heart beat in a minute?

Rhythm of the heartWhy do doctors examine the patients byfeeling their wrist?Hold your own hand or your friend'shand as shown in the picture.What do you feel?

StethoscopeHeart pumps blood to different parts of the body.Contraction and relaxation of heart makes aheartbeat. Stethoscope is an instrument used tomeasure heartbeat. A doctor places the stethoscopeon different parts of the body of a patient andidentifies the nature of heartbeat by the vibrationof the diaphragm of the stethoscope.

Y tube

plastictube

plastic tube

diaphragm

Can you make a stethoscope using plastic tubes,funnel, balloon and a ‘Y’ tube?Examine the heartbeat of the members of yourfamily using this stethoscope?HeartHeart is one of the vital organs of our body. Whathappens if the functioning of the heart stops?

What I have understood about thefunctioning of the heart.

45

Basic Science VI

While fryingTake a piece of banana chips and burn it in a candle flame.What do you see?

Repeat the experiment using other fried food items.What I want to say to the ones who eat fried food items excessively.

WastesBlood plays a major role in transporting oxygen and nutrients todifferent parts of the body. As a result of various life activities certainunwanted substances are also formed in our body. These unwantedsubstances are also carried by the blood itself.

Does the changing food habits harmfully affect the health of the heart?Discuss and find out.

Health of heart and food habits

Heart related disorders are common in thosewho consume fatty food regularly. Free flow ofblood through the blood vessels is blocked bythe deposition of fat molecules at the inner wallof the blood vessels. Doctors often suggest regularexercises and less fatty food to maintain thehealth of the heart. Over intake of salt also is notgood for the health of the heart.

Basic Science VI

46

What happens when both the kidneys fail to function?

kidney

u r i n a r ybladder

ureter

veinartery

nephron

The Sieve in our Body

Kidneys are the bean shaped darkred organs seen in the abdominalcavity on either side of thevertebral column. Kidneys act asa sieve that filters waste from theblood. The minute sieves callednephrons seen in the kidneys helpin this process. The materials thusfiltered are excreted along withurine. Urea, salts and water are themajor constituents of urine. Anadult man excretes an average of1.5 liters of urine a day. Manydiseases can be detected by urinetest.

How are these wastes removed from the blood?

It becomes impossible toeliminate wastes from theblood when both the kidneysfail to function properly. Thenthe blood is to be purified byusing certain devices(artificial kidney). Thisprocess is called dialysis. Theblood of a patient is allowedto pass through the dializer.After filtering out the wastes,pure blood is transferred backto the body of the patient.

Dialysis

47

Basic Science VI

Does sweating help us?

What I have understood about the functioning of certain organs inmy body?

Are there any other organs that help our body to expel wastes? Notedown.

Heart

Blood vessels

Kidneys

Skin

Organ Function(s)

Sweat and skinWon’t you feel cold when windblows over your sweat body? Bodytemperature is to be kept constant forthe proper functioning of lifeactivities. The body maintains aconstant temperature throughsweating and by the evaporation ofsweat. Sweat is the mixture of water,urea, sodium chloride and othersalts. Skin plays a major role in theexcretion of these wastes from thebody. Skin is the largest organ in ourbody.

Basic Science VI

48

Transplantation of body organsThe failure in the functioning of vital organs like heart,kidneys, liver etc. may be fatal. On such occasionsorgan transplantation is the only remedial measureto save a life. You may have come across news reportson transplantation of organs like heart, kidneys, liveretc. from those who are confirmed 'brain dead' to thepatients who are in need of them. There areindividuals who are willing to donate their organsafter their death.

Can we make such great life saving endeavours a business? What isthe difference between donation of organs and sale of organs?Collect articles, news and pictures related to organ transplantationand prepare an album on this.What measures are to be taken into account for the proper functioningof the heart and kidneys?

For the health of kidneys For the health of heart