Topic 6- Glucagon Flashcards
How do hormones cause the conversion of glucose to other chemicals (or the opposite)?
By activating enzymes
Define glycogenolysis
Breaking down of glycogne into glucose
Define glycogenesis
Formation of glycogen from glucose
What is glucongenesis?
Glcycerol/ amino acids converted into glucose
Where does glucongenesis take place?
In the liver
Why do muscle and liver cells store glucose as glycogen?
-Glucose is soluble so glucse would lower water potential of the cell as water would move into cellls by osmosis causing lysis of cells /(glycogen insoluble, water potential not affected, no osmosis or lysis of cells)
-Glucose concentration in cell low which maintains the concentration gradient of glucose so more glucose can move into the cell
What type of molecules are glucagon and insulin?
Hormones
What type of molecule is glycogen?
A polysacharide (acts as a storage molecule)
What type of molecule is glucose?
A monomer
Explain how glucose is regulated in blood when levels are increased?
-Glucose increases due to ingesting carbohydrates
-Islet cells (recptors) in the pancreas (an endocrine gland) detect a rise
-Beta cells release insulin
-More glucose is moved from blood into cells (liver, muscle and adipose)
-Glucose is converted into glycogen (glycogenesis)-(converted 1st as it is a short term store)
-Glucose converted into lipids/fats (stored in adipose tissue)- (long term store, occurs when yoyuhave too much glucose)
-Glucose decreases
Explain how glucose is regulated when levels are decreased
-Glucose decreases due to more respiration during respiration
-Islet cells (receptors) in the pancreas detect the fall
-Alpha cells release glucagon
-Glycogen converted into glucose (Glycogenolysis)
-Gluconogeneosis in liver (glycerol/amino acids converted into glucose)
-Glucose released into the bloodstream
-Glucose increases
What is the function of an endocrine gland?
-Hormones are released directly into capilaries (bloodtsream)
Which hormone activates glycgenosis?
Insulin
Which hormone is responsible for glycogenolysis, conversion of glcycerol to glucsoe and amino acids to glucose ?
Glucagon
Which hormone is responsible for glycogenolysis?
Adreneline
When glucose is converted into glycogen cells in the liver, it increases the rate that glucose diffusses from the blood into the cells. Explain why.
The conversion decreases the glucose concentration in liver cells therefore maintaining a high concentration gradient between blood and liver cells
How do hormones actually activated enzymes which catalyse glycogenesis, glycogenolysis and glucageneosis?
-Insulin,glucagon and adreeneline attach to specific receptors on the surface of target cells
What is the rate of uptake of glucose limited by?
The number of channel proteins
Explain insulin increases the rate of uptake of glucose in muscle and adipose cells
-Insulin binds to the receptor which causes the vesicle to fuse
-Vesicles inside muscle and adipose cells fuse with membranes so there are more channel proteins in the membrane
-This is increases the surface area
-So more facillitated diffussion of glucose into cells at a faster rate
-More glucose taken into the cell + higher glucose level in the blood
Features of receptors
-Complementary structure
-Specific
-Due to tieratry structrure (as it is a protein)
At what concentration is glucose released at?
Low
What factors affect the rate of facilitated diffusion?
-Concentration gradient
-SA (due to microvill/ number of carrier proteins available)
-Temperature (does not affect constant temperature organisms
Why is the rate of uptake of glucose in liver cells not limited by the number of channel proteins?
They have a very large number of glucose channel proteins
How does insulin increase the rate of uptake of glucose by liver cells
-The conversion of glucose to glycogen decreases the glucose concentration in the liver cells, thereofe increasing the concentration gradient (between blood and liver cells)
-This is how a high concentration gradient is maintained
Which cells act as the effectors in response to insulin?
-Muscle
-Liver
-Fat cells
