15 March 2014

#102 Control of blood glucose content

The control of glucose concentration in the blood is a very important part of homeostasis. 

Two hormones insulin and glucagon control blood glucose levels. 

Both hormones are secreted by the pancreas and are transported to the liver in the bloodstream.

When blood glucose levels get too high or too low, a person may:

- lose consciousness
- fall into a coma
- die

Too little glucose ---> Cells can not release enough energy they need. Brain cells are especially dependent on glucose for respiration, and die quite quickly if they are deprived of it. 

Too much glucose in the blood ---> water moves out of cells and into the blood by osmosis ---> Cell has too little water to carry out normal metabolic process.

The control of blood glucose concentration is carried out by the pancreas and the liver. 

Pancreas secretes insulin and glucagon: 2 hormones that work side-by-side.

Left-side: When glucose levels drop below normal, glycogen is broken down to glucose, which is released into the bloodstream. 

             glucagon: glycogen ---> glucose

Right-side: Excess glucose is stored in the liver and muscles as the polysaccharide glycogen (animal starch).

                 insulin:          glucose       ---> glycogen 
                                       ↑ respiration rates ---> cells consume more glucose 


    Try this

    Copy and complete the paragraph using some of the words in the list below.

    excretion    glucose   glycogen   insulin   liver    oestrogen   pancreas   secretion   starch   stomach   sucrose

    The bloodstream transports a sugar called __________ . The blood sugar level has to be kept constant in the body. If this level falls below normal, a hormone called glucagon is released into the blood by an endocrine organ called the ______ . The release of a substance from a gland is called ____. Glucagon promotes the breakdown of ­_______ to increase the blood sugar level. If the blood sugar level gets too high, the endocrine organ secretes another hormone called __________ into the blood. This hormone promotes the removal of sugar from the blood and its conversion to glycogen in the ________            [6 marks].


    glucose , pancreas, secretion, glycogen, insulin, liver. 


    1. Thank you SO much for this! It's so much better than the textbook :)

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