Blood Glucose Level Higher Human Biology

Regulation of Blood Glucose Level All living cells in human body require a continuous supply of energy This comes from the breakdown of glucose during respiration The body only obtains glucose when food is eaten

Negative feedback control regulates how much glucose is available to cells

Blood Glucose level normal Glucose content of the blood HIGH Glucose content of the blood LOW Meal eaten Between meals Pancreas produces GLUCAGON Liver breaks down GLYCOGEN Pancreas produces INSULIN Liver stores glucose As GLYCOGEN Glucagon travels to Liver Insulin travels to Liver

About 100g glucose is stored as GLYCOGEN in the liver This can be added to or removed depending on demand by the body

Insulin Rise in blood glucose (after meal) Detected by receptor cells in pancreas Cells produce insulin Insulin carried in bloodstream to liver Excess glucose absorbed by liver cells Enzyme is activated Glucose  Glycogen Decrease in blood glucose

Glucagon Blood glucose levels drop (between meals or during the night) Receptor cells in pancreas detect this Cells release GLUCAGON Transported to the liver in the bloodstream Activates an enzyme Glycogen  Glucose Glucose released from liver cells Blood glucose increases

Antagonistic Insulin and Glucagon act antagonistically They counteract each other/ act against each other

Epinephrine During exercise or ‘fight or flight’ the body requires additional supplies of glucose to provide energy quickly Adrenal glands secrete epinephrine (adrenaline) Overrides normal homeostatic control Inhibits secretion of insulin Promotes glycogen  glucose Once the crisis is over epinephrine is reduced to a minimum and negative feedback control returns blood glucose to normal level

Diabetes Condition in which sufferers are unable to control blood glucose level Normal blood glucose = 5mmol/l Untreated diabetes can rise to mmol/l 2 types – refer to table 13.6 (page 189)

Both types of diabetes, if untreated result in a rapid increase of blood glucose after a meal. Much of the glucose in an untreated diabetic is not reabsorbed in the kidneys – Passes out in urine Urine tests can be used as an indicator of diabetes

Blood glucose levels and vascular disease Normally blood plasma has 5 mmol/l glucose Diabetes sufferers have elevated levels (sometimes up to 30 mmol/l)

Endothelial cells absorb more glucose than normal Leads to damage to blood vessels and may in turn lead to Peripheral Vascular Disease, CVD or stroke

Microvascular (small vessels) disease Arterioles/ Venules When they take in more glucose than normal Basement membrane becomes thicker but weaker Affected blood vessel becomes thicker but more likely to burst and bleed into surrounding tissue

A tissue can be affected by either; – being flooded with leaked blood OR – Not receiving an adequate oxygen supply Retina – affecting vision Kidney – causing renal failure Nerves – peripheral nerve dysfunction

Glucose Tolerance Tests Glucose tolerance How well the body deals with ingested glucose Depends on adequate production of insulin Clinical test used to diagnose diabetes

Fast for 8 hours Blood glucose measured Consume a known mass of glucose (glucose load) Blood glucose monitored over 2 ½ hours and results plotted

Refer to Fig (page 190) Curve 1: Glucose rises to a max after 30 mins then quickly drops back to normal = normal insulin production Curve 2: Continues to rise for around 60 minutes before slowly returning to normal = mild type 2 diabetes Curve 3: After fasting, blood glucose still very high. Continues to rise after ingestion of glucose and fails to drop to initial level even after 2 ½ hours = Diabetes (probably type 1)

Complete your blank negative feedback control blood glucose level sheets Complete blood glucose table activity sheet Little AYK book – Page 45, Q7. Do these activities before you make any notes please!