Endocrine System (humans and plants)

  • Created by: ADS4222
  • Created on: 28-09-19 11:47

The Endocrine System

Made up of glands that secrete hormones into the blood

Hormones carried in blood to specific target organ where they have a specific effect

Compared to the nervous system effects of endocrine system are slower but longer lasting

Pituitary gland in brain secretes a variety of hormones into the blood depending specific body conditions, some of these stimulate other glands to secret hormones

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Adrenaline and Thyroxine (Higher only)

Adrenaline

Produced on adrenal glands

Released at times of fear/stress and prepares body for fight or flight response

Increases heart rate to boost oxygen and glucose delivery to the muscles and brain

Thyroxine

Produced in thyroid gland

Increases metabolic rate

Controls growth and developement in young animals

Controlled by negative feedback

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Control of Blood Glucose

Monitored and controled by panceas

If blood glucose concentration is too high then the pancreas secretes more isulin, insulin causes glucose to move from the blood into cells, this glucose is stored in the liver and muscle cells,  excess glucose  is converted to its insoluble storage form, glycogen.

(higher only):

If the blood glucose concentration is too low then the pancreas secretes glucagon, this stimulate glycogen to be broken back down into glucose and then released into the blood.

This is an example of negative feedback 

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Why Does Blood Glucose Concentration Have to be Co

If blood glucose levels get to high then theblood will have a more dillute concentration of water in it than the cells. This concentration gradient will casue water to leave the cells through osmosis causes them to shrivel up. The opposite occurs when blood glucose levels are too low, causong cells to take in water through osmosis and burst. This is why the glucose water solution in the blood must be isotonic to that in the cells, and so blood glucose levels must be controlled through negative feedback.

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Diabetes

Type 1:

Pancreas doesn't produce enough insulin

Causes high uncontrolled blood glucose levels

Normally treated with insulin injections, no cure so insulin injections must be taken everyday

Type 2:

Cells no longer respond to insulin

Has obesity as a risk factor as well as genetics

Treated with a carbohydrate-controlled diet and excersis, in extreme cases sometimes has to be treated with medication that either helps insulin work better on the body cells, helps the pancreas produce more insulin and/or reduce the amount of glucose absorbed by the gut.

If these medicaions don't work then insulin injections will probably be nesicary.

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Water Balance

Water leaves the body from he lungs when you breath, from the skin when you sweat and in urine (along with ions and urea)

If the concentration of the blood changes it will no longer be isotonic with the cells causing the same probelms as with blood glucose concentration being to high or to low

Ballance of water and ions in the body is regulated by the kidneys

Digesting protiens from foods resuls in excess amino acids, these are converted to amonia in the liver through deamination. 

Amonia is toxic so its immediately converted to urea which is transported to the kidneys and safely excreted.

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