2. Controlling blood glucose concentration

Question 1

define glucagon

Answer 1

a hormone produced by a cells at the islets of Langerhans in the pancreas, which increases blood glucose

Question 2

define gluconeogenesis

Answer 2

conversion of carbohydrates into glucose, when glycogen supply is exhausted

Question 3

define glycogenesis

Answer 3

conversion of glucose into glycogen

Question 4

define glycogenolysis

Answer 4

hydrolysis of glycogen, happens when blood glucose levels are lower

Question 5

factors that increase blood glucose in the body when

Answer 5

• carbohydrates are broken down into monosaccharides
• glycogen stores in the liver are broken down to release glucose
• when substances are converted into glucose

Question 6

why does blood glucose decrease in the body

Answer 6

• during exercise
• glycogenesis
• drinking alcohol can prevent the lover from producing glucose

Question 7

define endocrine glands (islets of Langerhans)

Answer 7

glands which secrete hormones, without ducts

Question 8

what are exocrine glands

Answer 8

glands which secrete hormones with glands

Question 9

what does the pancreas contain

Answer 9

exocrine and endocrine tissue

Question 10

outline the islets of langerhans

Answer 10

• alpha cells which secrete glucagon
• beta cells that secrete insulin

Question 11

what do alpha cells secrete?

Answer 11

glucagon

Question 12

what do beta cells secrete?

Answer 12

insulin

Question 13

what hormone is released when blood glucose is too high

Answer 13

insulin

Question 14

what hormone is released when blood glucose is too low

Answer 14

glucagon

Question 15

outline the action of insulin when blood glucose concentration is too high

Answer 15

• B-cells detect the increase in blood glucose concentration
• glucose moves into B-cells via facilitated diffusion
• causes insulin containing vesicles to move towards the cell surface membrane where they release insulin into the capillaries
• insulins binds to specific receptors on membranes of target cells (liver, muscle cells)
• insulin binding activates more glucose transporter proteins to their cell surface membrane
• increases the permeability of cells to glucose
• increase of facilitated diffusion of glucose into cells
• lowers the blood glucose concentration
• insulin binding to liver receptors, increases uptake of glucose in the liver, stimulating glycogenesis, converting glucose to glycogen
• helps lower blood-glucose concentration gradient between the capillaries and liver cells

Question 16

outline the action of glucagon when blood concentration is too low

Answer 16

• a and b cells in the islet of langerhand detect blood glucose concentration change
• b cells respond by stopping the secretion of insulin
• reducing the use of glucose by liver and muscle cells
• a cells respond by secreting glucagon, which binds to receptors in the cell surface of membranes of liver cells
• glucagon binding activates enzymes involved in glycogenolysis and gluconeogenesis
• glucose is released from the liver and blood glucose concentration increases