Question

Please solve all of them. After 30 minutes I will be sitting for my tution teat. Please be fast. It is urgent.

Answer 1

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Ans 1 ) Red cells contain a special protein called hemoglobin, which helps carryoxygen from the lungs to the rest of the body and then returns carbon dioxide from the body to the lungs so it can be exhaled. Blood appears red because of the large number of red blood cells, which get their color from the hemoglobin.

Ans 2) There are several differences between heart muscle and the skeletal muscles of the body that mean that heart muscle should never build up lactic acid and feel fatigued. The reason for this is that the heart has to beat continuously for sometimes 100 years or more without a rest. When a muscle works anaerobically and builds up an oxygen debt it needs time to rest to recover but the heart is unable to do this.

The heart has the best supply of oxygen rich blood of any organ in the body. But the heart does not get its oxygen from the blood as it enters and leaves the heart during the beating cycle. The heart has its own circulation provided by the coronary arteries and veins. The coronary arteries start as a branch from the aorta, the main artery leaving the left side of the heart. Therefore, the heart has a plentiful supply of oxygen rich blood. The second main difference is in the number of mitochondria in the muscle. Glycolysis, the anaerobic stage of respiration, takes place in the cytoplasm of the cell, requires no oxygen (hence anaerobic), and produces small quantities of ATP. To generate more ATP the products from glycolysis move into the mitochondria and in the presence of oxygen are broken down to produce many molecules of ATP. Some skeletal muscles, especially very fast muscle, have very few or no mitochondria so all there respiration is anaerobic as this is the most efficient way to get fast short bursts of work from the muscle. The heart has lots of oxygen and lots of mitochondria so is able to continue working away day after day without building up an oxygen debt.

There is just one exception.. A 'heart attack' is caused by one or more of the arteries supplying the heart with oxygenated blood becoming blocked. Therefore, a region of the heart will not receive a plentiful supply of oxygen and so this region will start to produce lactic acid. This situation cannot be sustained for a long time, it can cause severe damage to the tissue that is not receiving sufficient oxygen, and this is what causes the pain. This demonstrates how important it is that cardiac muscle does not generate lactic acid under physiological conditions.

Ans 3) Platelets are small cell fragments without nucleus, disc-shaped and without colour, found in large numbers in the blood. They are also known as Thrombocytes. ... The normal plateletcount in humans, per microlitre ofblood is 150,000 to 350,000.

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