Question

Give an account of the hearts in the circulatory system of pheretima?​

Answer 1

Answer:

The blood of Pheretima is red coloured due to the presence of a respiratory pigment haemoglobin in it. The haemoglobin is not contained in the corpuscles like the vertebrates but it is found dissolved in the plasma. The plasma also contains many corpuscles which are colourless and nucleated.

Answer 2

• The blood vascular system of Pheretima is of closed type. It consists of the blood vessels, hearts, loops, capillaries and the blood glands.

• The blood of Pheretima is red coloured due to the presence of a respiratory pigment haemoglobin in it. The haemoglobin is not contained in the corpuscles like the vertebrates but it is found dissolved in the plasma. The plasma also contains many corpuscles which are colourless and nucleated.

• The blood vessels are of two types collecting blood vessels and distributing blood vessels which are closed tubes with definite walls and they break up into capillaries to ramify in the different parts of the body. The arrangement of blood vessels in the anterior thirteen segments is somewhat different from that behind the thirteen segment, i.e., in the region of intestine.

• Therefore, for convenience the blood vessels can be described under the following two heads:

• A. Blood vessels and their arrangement in the segments behind 13th, i.e., intestinal region.

• B. Blood vessels and their arrangement in the anterior thirteen segments.

A. Blood Vessels and their Arrangement in the Segments behind 13th, i.e., Intestinal Region:

The blood vessels of this region include:

1. Median longitudinal blood vessels;

2. The intestinal blood plexus;

3. The commissural vessel;

4. The integumentary vessel; and

5. The nephridial vessels.

B. Blood Vessels and their Arrangement in the Anterior 13 Segments:

The blood vascular system in the first thirteen segments is modified considerably and differs markedly from that of the intestinal region.

It consists of the following:

1. Median longitudinal vessels;

2. Hearts and anterior loops;

3. Blood vessels of the gut.

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