6C Control of Blood Glucose Concentration Flashcards
Normal blood glucose concentration
90mg per 100cm3
How do hormones travel round the body
Via the bloodstream to target cells
What type of cells secrete insulin
beta cells
What is the bundle of cells that secrete hormones in the pancreas
islets of Langerhans
What type of cells secrete glucagon
alpha cells
How does insulin lower blood glucose
Insulin binds to specific receptors on the cell membranes of liver and muscle cells
It increase the permeability of the muscle cell membrane to glucose so cells take up more glucose this involves increasing the number of channel proteins in the cell membrane
Enzymes in the liver are activated and muscle cells that convert glucose into glycogen
The cells are able to store glucose in their cytoplasm as an energy source
Insulin increases rate of respiration of glucose
Define glycogenesis
Forming glycogen from glucose
How does glucagon raise blood glucose
Glucagon binds to specific receptors on the cell membranes of liver cells
Enzymes in the liver are activated that convert glycogen into glucose
Glucagon also activates enzymes that are involved in the formation of glucose from glycerol
Glucagon decreases rate of respiration of glucose
Define glycogenolysis
the formation of glucose from non carbohydrates
How does negative feedback raise blood glucose
Pancreas detects blood glucose is too low
a cells secrete glucagon
b cells stop producing insulin
glucagon binds to receptors on liver cells
glycogenolysis and gluconeogenesis is activated cells respire less glucose
cells release glucose into blood
How does negative feedback lower blood glucose
Pancreas detects blood glucose is too high
b cells secrete insulin
a cells stop secreting glucagon
insulin binds to receptors on muscle liver cells
cells take up more glucose
cells respire more glucose
glycogenesis is activated
How does insulin make more glucose transporters available for facilitated diffusion
Skeletal and cardiac muscle cells contain a glucose transporter channel protein called GLUT4
When insulin levels are low GLUT4 is stored in the vesicles in the cytoplasm of cells
When insulin binds to receptors on the cell surface membrane it triggers the movement of GLUT4 to the membrane
Glucose can then be transported into the cell through the GLUT4 protein by facilitated diffusion
How does adrenaline increase blood glucose concentration
Adrenaline secreted by adrenal glands
Its secreted when there is a low blood glucose concentration when you are stressed or exercising
Adrenaline binds to receptors on liver cells
It activates glycogenolysis
It inhibits glycogenesis
It also activates glucagon secretion and inhibits insulin secretion
Adrenaline gets the body ready for action by making more glucose available for muscle cells to respire
How do adrenaline and glucagon act as second messengers
The receptors for adrenaline and glucagon have specific tertiary structures that make them complementary in shape to their respective hormones.
Adrenaline and glucagon bind to their receptors an activate adenylate cyclase
Adenylate cyclase converts ATP into a second messenger called cyclic AMP
cAMP activates an enzyme called protein kinase A which then activates a cascade that breaks down glycogen into glucose
Describe type 1 diabetes
the immune system attacks the b cells in the isles of Langerhans so they can’t produce any insulin
Cause not know but some people can have a predisposition to type 1 diabetes and people may believe that it develops from a viral infection
How is type 1 diabetes treated
insulin therapy and regular insulin injections insulin therapy has to be carefully controlled as too much can cause hypoglycaemia
How can type 1 diabetes be managed
eating regularly and controlling simple carb intake
Describe type 2 diabetes
usually acquired later on in life
Often linked with obesity and is more likely in people with a family history
Other risk factors include, lack of exercise, age and poor diet
What causes Type 2 diabetes
when b cells don’t produce enough insulin or when cells don’t respond properly to insulin because the insulin receptors on their membranes don’t work so the cells don’t take up enough glucose, so the blood glucose is higher than normal
How can type 2 diabetes be treated
eating a healthy, balanced diet, losing weight and regular exercise. Glucose lowering medication may be used and insulin injections may be needed
Why are cases of type 2 diabetes on the rise
increasing obesity, more unhealthy diets and low levels of physical activity
What additional problems can type 2 diabetes cause
visual impairment and kidney failure
How to reduce the risk of developing type 2 diabetes
eat a balanced diet, take regular exercise and lose weight if necessary
How have food companies responded to criticism
by making food healthier by using sugar alternatives and reducing the sugar, salt and fat content
How to use colourimetry to determine the concentration of a glucose solution
By making five serial dilutions with a dilution starting with an initial glucose concentration of 4 mM
How to make a calibration curve with glucose solutions
due a quantitate Benedict’s test on each solution plus a negative control
Use a colorimeter to measure the absorbance of Benedict’s solution remaining in each tube
Using results to make the calibration curve with absorbance against glucose concentration
