Homeostasis The control of blood sugar levels (The Regulation of Glucose in the blood)

HomeostasisHomeostasis

The control of blood sugar The control of blood sugar levelslevels

(The Regulation of Glucose in (The Regulation of Glucose in the blood)the blood)

The Regulation of Glucose The Regulation of Glucose in the Bloodin the Blood

Normal glucose level is about 5 to 5.5 mmol dmNormal glucose level is about 5 to 5.5 mmol dm--

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If this level rises too high it would affect the If this level rises too high it would affect the water content of the body.water content of the body.

If glucose appears in the urine (If glucose appears in the urine (glycosuria)glycosuria) water reabsorbtion in the kidney will be water reabsorbtion in the kidney will be reduced.reduced.

If glucose level in the tissue fluid is high water If glucose level in the tissue fluid is high water will be lost from cells by osmosiswill be lost from cells by osmosis..


If levels fall below 3 mmol dmIf levels fall below 3 mmol dm-3-3 ((hypoglycaemia)hypoglycaemia) this would lead to this would lead to a loss of consciousness (coma).a loss of consciousness (coma).

If level goes above 10 mmol dmIf level goes above 10 mmol dm-3-3 ((hyperglycaemiahyperglycaemia) glucose will ) glucose will appear in the urine, the pH of the appear in the urine, the pH of the blood would fall and this also leads blood would fall and this also leads to coma.to coma.

Both conditions are a feature of Both conditions are a feature of diabetes mellitusdiabetes mellitus..

Insulin is the “key” that Insulin is the “key” that allows special “gates” for allows special “gates” for

sugar transport across cell sugar transport across cell membranes to be opened membranes to be opened


If insulin can not be made the glucose is If insulin can not be made the glucose is not removed from the blood and glycogen not removed from the blood and glycogen is broken down into sugar resulting in high is broken down into sugar resulting in high blood sugar levels. This is blood sugar levels. This is Type 1Type 1 or or insulin-dependent diabetesinsulin-dependent diabetes..

Possibly caused by the destruction of beta-Possibly caused by the destruction of beta-cells due to viral infection. cells due to viral infection.

It seems the immune system makes a It seems the immune system makes a mistake and cells that normally protect you mistake and cells that normally protect you from germs attack your beta cells insteadfrom germs attack your beta cells instead


Type II (insulin-independent Type II (insulin-independent diabetes)diabetes) is linked to the ageing is linked to the ageing process and obesity – often process and obesity – often controlled by controlling the diet.controlled by controlling the diet.

Normal blood sugar level



If blood sugar risesThis could be theResult of ingestion of Food or release ofGlucose from the liver





Detector – the alpha and beta cells of the Islets of langerhans. The alpha cells stop secreting glucagon and the beta cells secrete insulin







Effector – liver cells stop breaking glycogen down due to drop in glucagon; most body cells increase uptake and use of glucose due to rise in insulin




Effector – liver cells stop breaking glycogen down due to drop in glucagon; most body cells increase uptake and use of glucose due to rise in insulin




Effector – liver cells stop breaking glycogen down due to drop in glucagon; most body cells increase uptake and use of glucose due to rise in insulinBlood glucose

stabilised




Effector – liver cells stop breaking glycogen down due to drop in glucagon; most body cells increase uptake and use of glucose due to rise in insulinBlood glucose

stabilised

negative feedback

control loop




If blood glucose falls

This could be the result of a high rate of cellular uptake and use of glucose or failure to ingest carbohydrate foods





Detector – alpha and beta cells of the Islets of Langerhans. The alpha cells secrete glucagon and the beta cells stop secreting insulin











Effector – liver cells break down glycogen into glucose due to rise in glucagon: most body cells decrease uptake and use of glucose due to fall in insulin











Blood glucose stabilised






Blood glucose stabilised

negative feedback

control loop

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Homeostasis The control of blood sugar levels (The Regulation of Glucose in the blood)