Body fluids and Circulation 1 Flashcards
why do we need transport system
You have learnt that all living cells have to be provided with nutrients, O2
and other essential substances. Also, the waste or harmful substances
produced, have to be removed continuously for healthy functioning of
tissues. It is therefore, essential to have efficient mechanisms for the
movement of these substances to the cells and from the cells. Different
groups of animals have evolved different methods for this transport. Simple
organisms like sponges and coelenterates circulate water from their
surroundings through their body cavities to facilitate the cells to exchange
these substances. More complex organisms use special fluids within their
bodies to transport such materials.
explain what is plasma made up of
Plasma is a straw coloured, viscous fluid constituting nearly 55 per cent of
the blood. 90-92 per cent of plasma is water and proteins contribute 6-8
per cent of it. Fibrinogen, globulins and albumins are the major proteins.
explain the funtions of things in the plasma
Fibrinogens are needed for clotting or coagulation of blood. Globulins
primarly are involved in defense mechanisms of the body and the albumins
help in osmotic balance. Plasma also contains small amounts of minerals
like Na+
, Ca++, Mg++, HCO3
–
, Cl–
, etc. (to maintain isotoonic nature. if too concentrated or dilute, then cellsmay shrink or swell)Glucose, amino acids, lipids, etc., are
also present in the plasma as they are always in transit in the body. Factors
for coagulation or clotting of blood are also present in the plasma in an
inactive form. Plasma without the clotting factors is called serum.
what are formed elements
Erythrocytes, leucocytes and platelets are collectively called formed
elements (Figure 18.1) and they constitute nearly 45 per cent of the blood.
what are rbcs
Erythrocytes or red blood cells (RBC) are the most abundant of all
the cells in blood. A healthy adult man has, on an average, 5 millions to
5.5 millions of RBCs mm–3 of blood. RBCs are formed in the red bone
marrow in the adults. RBCs are devoid of nucleus in most of the mammals
and are biconcave in shape. They have a red coloured, iron containing
complex protein called haemoglobin, hence the colour and name of these
cells. A healthy individual has 12-16 gms of haemoglobin in every
100 ml of blood. These molecules play a significant role in transport of
respiratory gases. RBCs have an average life span of 120 days after which
they are destroyed in the spleen (graveyard of RBCs).
what are platelets
Platelets also called thrombocytes, are cell fragments produced from
megakaryocytes (special cells in the bone marrow). Blood normally
contains 1,500,00-3,500,00 platelets mm–3. Platelets can release a variety
of substances most of which are involved in the coagulation or clotting of
blood. A reduction in their number can lead to clotting disorders which
will lead to excessive loss of blood from the body
what are the common features of white blood cells
Leucocytes are also known as white blood cells (WBC) as they are
colourless due to the lack of haemoglobin. They are nucleated and are
relatively lesser in number which averages 6000-8000 mm–3 of blood.
Leucocytes are generally short lived.
what are the 2 main categoriesof wbcs
We have two main categories of WBCs
– granulocytes and agranulocytes. Neutrophils, eosinophils and basophils
are different types of granulocytes, while lymphocytes and monocytes
are the agranulocytes. Neutrophils are the most abundant cells (60-65
per cent) of the total WBCs and basophils are the least (0.5-1 per cent)
among them.
explain the functions of various leucocytes
Neutrophils and monocytes (6-8 per cent) are phagocytic
cells which destroy foreign organisms entering the body.
Basophils secrete
histamine(vasodilator), serotonin(vasoconstrictor), heparin(anticoagulant), etc., and are involved in inflammatory
reactions.
Eosinophils (2-3 per cent) resist infections and are also associated with allergic reactions.
Lymphocytes (20-25 per cent) are of
two major types – ‘B’ and ‘T’ forms. Both B and T lymphocytes are
responsible for immune responses of the body.
what is the basis of blood grouping
ABO grouping is based on the presence or absence of two surface antigens
(chemicals that can induce immune response) on the RBCs namely A
and B. Similarly, the plasma of different individuals contain two natural
antibodies (proteins produced in response to antigens). The distribution
of antigens and antibodies in the four groups of blood, A, B, AB and O
what is the distrubution of antigens and antibodies in diff blood grps
blood grp
A- has A antigen/ anti-B in plasma/ Donor may be A or O
B- has B antigen/ anti A in plasma/ Donor may be B, O
AB- has A and B antigen/ no antibodies/ Donor may be A,B,AB,O
O- has no antigen/ has anti-b and anti a/ only O
who are the universal donors
t that group ‘O’ blood can
be donated to persons with any other blood group and hence ‘O’ group
individuals are called ‘universal donors’.
who are universal acceptor
Persons with ‘AB’ group can
accept blood from persons with AB as well as the other groups of blood.
Therefore, such persons are called ‘universal recipients’.
what is the rh group
Another antigen, the Rh antigen similar to one present in Rhesus monkeys
(hence Rh), is also observed on the surface of RBCs of majority (nearly 80
per cent) of humans. Such individuals are called Rh positive (Rh+ve)
and those in whom this antigen is absent are called Rh negative (Rh-ve).
An Rh-ve person, if exposed to Rh+ve blood, will form specific antibodies
against the Rh antigens. Therefore, Rh group should also be matched
before transfusions
what is erythroblastosis foetalis
. A special case of Rh incompatibility (mismatching)
has been observed between the Rh-ve blood of a pregnant mother with
Rh+ve blood of the foetus. Rh antigens of the foetus do not get exposed to
the Rh-ve blood of the mother in the first pregnancy as the two bloods are
well separated by the placenta. However, during the delivery of the first
child, there is a possibility of exposure of the maternal blood to small
amounts of the Rh+ve blood from the foetus. In such cases, the mother
starts preparing antibodies against Rh antigen in her blood. In case of
her subsequent pregnancies, the Rh antibodies from the mother (Rh-ve)
can leak into the blood of the foetus (Rh+ve) and destroy the foetal RBCs.
This could be fatal to the foetus or could cause severe anaemia and
jaundice to the baby. This condition is called erythroblastosis foetalis.
This can be avoided by administering anti-Rh antibodies to the mother
immediately after the delivery of the first child.
