Question 1. What is the importance of plasma proteins?
Answer: The major plasma proteins are; fibrinogen, globulins and
albumins. Fibrinogen play important role in blood coagulation. Globulins are
mainly involved in defense mechanism and albumins help in osmotic balance.
Question 2. Why do we consider blood as a connective tissue?
Answer: Blood is mesodermally derived; as other connective
tissues. Blood serves the purpose of connecting the body systems; by
transporting substances. Moreover, blood too has a matric; like other
connective tissues. Hence, blood is considered as a connective tissue.
Question 3. What is meant by double circulation? What is its
significance?
Answer: Complete double
circulation is present in birds and mammals. In this case, the oxygenated blood
is received by the left atrium and the deoxygenated blood is received by the
right atrium. The oxygenated blood is pumped out through the left ventricle,
while the deoxygenated blood is pumped out through the right ventricle. In
complete double circulation, there are two separate pathways for oxygenated and
deoxygenated bloods. There is complete separation of oxygenated and
deoxygenated blood in case of complete double circulation. This provides better
efficiency to the organism in terms of energy generation
Question Question 4. Describe the evolutionary change in the pattern of
heart among the vertebrates.
Answer: A muscular chambered heart is present in all
vertebrates. The fishes have a 2-chambered heart; with an atrium and a
ventricle. Amphibians and reptiles have a 3-chambered heart; with two atria and
one ventricle. But crocodiles have 4-chambered heart. Birds and mammals have
4-chambered heart; with two atria and two ventricles.
5. Write the differences between:
(a) Open and Closed system of circulation
Answer: The organs are directly bathed in blood in case of open
circulatory system. In case of closed circulatory system, the blood is channelized
through closed vessels.
(c) Systole and Diastole
Answer: Contraction of heart muscles is called systole, while dilatation is called diastole.
(d) P-wave and T wave :
Answer: P-wave marks the depolarization of atria, while T-wave marks the
return of ventricles to repolarised state
6. What is the significance of atrio-ventricular node and atrio-ventricular bundle in the functioning of heart?
Answer: AV Node and AV Bundles are responsible for conduction of heart beat to different parts of the heart after initiation in the SA node.
Question 7. Why do we call our heart myogenic?
Answer: Normal activities of the heart are intrinsically
regulated, i.e. auto regulated by the nodal tissues. Due to this, the heart is
called myogenic.
Question 8. Sino-atrial node is called the pacemaker of our
heart. Why?
Answer: The SA Node is responsible for initiating and
maintaining the rhythmic contractile activity or beating of the heart. Due to
this, the SA Node is called the pacemaker.
Question 9. Define a cardiac cycle and the cardiac output.
Answer: Cardiac Cycle: The sequential contraction and dilatation
of different chambers of heart in a cyclical manner is called cardiac cycle.
Cardiac Output: The volume
of blood pumped by the heart in one minute is called the cardiac output. The
average cardiac output is 5000 ml or 5 litre per minute
Question 10. Explain heart sounds.
Answer: Lub and Dub Sounds: Two prominent sounds are produced
during each cardiac cycle. These sounds can be easily heard through a
stethoscope. The first sound is called lub and is associated with the closure
of the tricuspid and bicuspid valves. The second sound is called dub and is
associated with the closure of the semi-lunar valves. These sounds are
important for clinical diagnosis.
Question 11. From a standard ECG and explain the different segments
in it.
Answer: Each peak in the ECG is identified with a letter from P
to T (PQSRT) which corresponds to a specific electrical activity of the heart.
The P-wave represents the electrical excitation or
depolarization of the atria. Depolarisation of atria leads to atricular
systole.
The QRS complex represents the depolarization of the ventricles
which initiates ventricular systole.
The T-wave represents the return of the ventricles from excited
to normal state (repolarisation). The end of T-wave marks the end of systole.
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