6.4.2 Control of blood glucose concentration Flashcards
why would blood glucose increase?
following food or drink containing carbohydrates
why would blood glucose decrease?
exercise or if you have not eaten
what detects changes in blood glucose levels?
the pancreas
what releases insulin and glucagon?
endocrine cells in the islets of langerhan
what releases adrenaline?
adrenal glands
what is the role of adrenaline in regulating blood glucose levels?
results in more glycogen being converted to glucose in the liver
what detects an INcrease in blood glucose levels?
beta cells in the Islets of Langerhan
what do the beta cells do when they detect high glucose levels?
release insulin
what does the release of insulin cause?
- liver cells to become more permeable to glucose
- activates enzymes to convert glucose to glycogen
how is glucose removed from the blood?
stored a glycogen in liver cells
what detects a DEcrease in glucose levels?
alpha cells in the Islets of Langerhan
what happens once a decrease in glucose has been detected?
- alpha cells release glucagon
- adrenal glands release adrenaline
what happens once glucagon and adrenaline have been secreted?
second messenger model occurs to activate enzymes to hydrolyse glucagon
what happens after the second messenger model occurs?
glycogen is hydrolysed to glucose and more glucose is released into the blood
what is glycogenesis?
the process of excess glucose being converted to glycogen when blood glucose is higher that normal -> mainly occurs in the liver
what is glycogenolysis?
the hydrolysis of glycogen back into glucose
What is gluconeogenesis?
the process of creating glucose from non-carbohydrate stores in the liver
what is the first way that insulin can decrease blood glucose?
- attaching to receptors on the surface of target cells
- this changes the tertiary structure of the channel proteins
- resulting in more glucose being absorbed by facilitated diffusion.
what is the second way insulin can decrease blood glucose?
- more protein channels are incorporated into cell membranes
- so that more glucose is absorbed from the blood into the cells
what is the third way insulin can decrease blood glucose?
- activating enzymes involved in the conversion of glucose -> glycogen
- results in glycogenesis in the liver
first way glucagon can increase blood glucose?
attaching to receptors on the surface of target cells (liver cells)
second way glucagon can increase blood glucose?
- when bound, it causes a proteins to be activated into adenylate cyclase
- and to convert ATP into cyclic AMP (cAMP)
- which activates protein kinase which can hydrolyse glycogen into glucose
third way glucagon can increase blood glucose?
- activating enzymes involved in the conversion of glycogen and amino acids into glucose
explain the second messenger model:
- glucagon binds to glucagon receptors on liver cells
- once bound it causes a change in the shape to the enzyme adenyl cyclase, which activates it
- activated adenyl cyclase enzymes converts ATP into cyclic AMP
how does adrenaline increase blood glucose?
- attaches to receptors on the surface of target cells
- causing a protein to be activated to convert ATP -> cAMP
- cAMP activates an enzyme that can hydrolyse glycogen into glucose
what is diabetes?
when blood glucose cannot be controlled
what is type 1 diabetes?
- when the body is unable to produce insulin
- treatment involves injection of insulin
what is type 2 diabtes?
- when receptors on the target cells lose their responsiveness to insulin
- usually develops due to obesity and poor diet
Some people who have diabetes do not secrete insulin. Explain how a lack of insulin affects reabsorption of glucose in the kidneys of a person who does not secrete insulin. (4)
High concentration of glucose in blood
- Reabsorbed by facilitated diffusion / active transport
- requires proteins/carriers
- these are saturated
- not all glucose is reabsorbed
The urine of a non-diabetic person does not contain glucose. Explain why. (2)
- Leaves the blood at kidney
- reabsorbed into blood from kidney tubule
