3. The white-blooded icefish lives in the Antarctic seas where the water tempera

Question

3. The white-blooded icefish lives in the Antarctic seas where the water temperature is around -1°C. It is the only vertebrate that doesn't have any hemoglobin in its body. Instead, oxygen dissolves directly into the blood (which lacks red blood cells entirely), rather than binding to chemicals in the blood. Let's analyze some features of this fish's survival strategy A Estimate the approximate concentration of oxygen that can be dissolved in the icefish's blood, approximating its composition to be the same as that of seawater. Compare this to the oxygen-carrying content of a "normal" active fish By what factor is it lower? B To make up for the lower oxygen content, the icefish must circulate a larger flow rate of blood through its circulatory system. Assuming that the circulatory system is identical in design to other fish, and that the animal maintains the same metabolic rate as a hemoglobin-carrying fish of the same size would use, by what factor must it increase its blood pressure? And by what factor must it increase the power output of its heart? Don't forget to consider the difference in viscosity between regular blood and "icefish blood". C The icefish actually cannot increase its blood pressure beyond a hemoglobin-carrying fish's blood pressure, due to structural limitations in the strength of the blood vessels. So it must produce a higher flow rate by lowering the resistance to flow. Partly this is accomplished by the lower viscosity of the blood, and partly by having wider vessels throughput the body. Assume now that the icefish has half the metabolic rate of a similar hemoglobin-carrying fish (reducing the needed flow rate), and that its blood pressure is the same as the red-blooded fish. Estimate by what factor the diameter of the varyious arteries and veins will be increased

Explanation / Answer

A).Effect of cold on oxygen:

The cold temperature compensate to a small degree, since oxygen is more solution in cold water than it is in warm water( solids salt and dissolved better in warm water , but gases are different). This is not not enough especially as oxygen must enter and move around inside a muscle cell by cell by diffusion and diffusion is slower in the cold cold. In fact really matters is the permeability of tissues to oxygen and permeability =rate of diffusion × solubility and the increased solubility of oxygen in cold water actually compensate for the slower rate of diffusion of oxygen in cold water.

IAntartic icefish of the family channichthyidae one the only vertebrate animal that as adults do not express the circulatory oxygen binding protein haemoglobin. Icefish also have lack the intercellular oxygen binding protein myoglobin(Mb) in the ventricle of their herat and lack myoglobin in oxidative skeletal muscles.

B. Metabolism of icefish: Metabolism of icefish mainly regards to the aerobic generation of ATP.

Studies of the glycolytic system were carried out on the heart muscles and brain, but not in liver specimen handled . To enhance oxygen diffusion heart icefish have a greater surface area compare with red blood species . Icefish heart also have a greater capacity for aerobic Metabolism capacity is not compromise d by the lack of haemoglobin.

Viscosity of Icefish blood: Icefish blood has lacks of red blood cells ,an adaptation that reduce it's viscosity.

C) . Carrying more oxygen without haemoglobin:

If Icefish blood can only 10% of the oxygen per miligram of blood that a red blooded fish can, carry then one solution is to have more blood . The blood volume of the icefish is large at about 2-4 times larger than for a red blooded fish to the sMe size. The alone means that 10% become 20-40% . Additionally icefish have more blood capillaries in the skin and find which can absorb oxygen direct from the sea water.About 30-40% of the oxygen is absorb ed across the skin which , making it thin to allow oxygen to diffuse across it more easily. The gills absorb the rest and are of a normal surface area. Most of this extra blood must be suppressed in the capillaries , delivering this blood require a large pump and the heart has very large stroke volume 6-15 times higher than for a red blooded fish of similar size. ThE icefish heart has a capacity similar to that of a vertebrate heart. The heart only beats 15 times a minute and does not have beat very hard as the blood pressure is low the viscosity blood slips easily through the unusually large capillaries which are actually more than double the normal diameter . The blood vessels in the gills are also large so blood flows rapidly through the gills so that more oxygen is picked up.

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