blood glucose concentration

Question 1

Describe how hormones work

Answer 1

Hormones are:
- produced in endocrine glands and secreted directly into the blood

• carried in blood plasma to the target cells on which they act. Target cells have specific receptors complementary to the specific hormone
• effective in low concentrations but have long lasting, widespread effects

Question 2

Explain the second messenger model of hormone action

Answer 2

Second messenger model is used for non lipid soluble hormones in order to get their ‘message’ into the cell.

e.g.adrenaline in regulation of blood glucose concentration.

• adrenaline binds to complementary protein receptor spanning cell surface membrane of liver cell
• causes protein to change shape on inside of membrane
• change in protein shape leads to activation of enzyme adenyl cyclase
• activated adenyl cyclase converts ATP to cyclic AMP (cAMP)
• cAMP acts as second messenger binding to, changing the shape of and therefore activating protein kinase
• active protein kinase catalyses the conversion of glycogen to glucose which moves from the liver cell to the blood by facilitated diffusion

Question 3

what is the second messenger model used for?

Answer 3

Second messenger model is used for non lipid soluble hormones in order to get their ‘message’ into the cell.

Question 4

what cells in the Islets of Langerhans in the pancreas produce insulin

Answer 4

Beta cells in the Islets of Langerhans in the pancreas produce insulin

Question 5

what cells in the Islets of Langerhans in the pancreas produce glucagon

Answer 5

Alpha cells in the Islets of Langerhans in the pancreas produce glucagon

Question 6

define exocrine gland

Answer 6

secretes digestive enzymes into the pancreatic duct

secrete pancreatic juice into pancreatic duct (e.g: amylase, trysinogen, lipase)

Question 7

define endocrine gland

Answer 7

secretes hormones
insulin and glucagon in blood

hormones are secreted from the cells in the islets of Langherhans

Question 8

what hormone do alpha cells secrete

Answer 8

alpha cells manufacture and secretes glucagon

Question 9

what hormone do beta cells secrete

Answer 9

beta cells manufacture and secrete insulin

Question 10

explain what happens when you trigger fight or flight response and run

Answer 10

• adrenaline released
• increases heart rate, increases breathing rate
• glycogen hydrolyzed to glucose
• glucose used in aerobic respiration to provide energy for muscle contraction to run

Question 11

Describe the three processes that take place in the liver and
regulate blood sugar. (6 marks)

Answer 11

Glycogenesis: Glucose to glycogen

Glycogenolysis: Glycogen to glucose

Gluconeogenesis: Production of glucose from sources other
than carbohydrates

Question 12

what is the process that converts other substances to glucose

Answer 12

gluconeogenesis

Question 13

what process converts glucose to glycogen

Answer 13

glycogenesis

Question 14

what process converts glycogen to glucose

Answer 14

glycogenolysis

Question 15

describe the sources of blood glucose (3 marks)

Answer 15

• from diet
• glycogenolysis
• gluconeogenesis

Question 16

most body cells have glycoprotein receptors on their cell surface membrane

describe the results of insulin binding to these receptors (3 marks)

Answer 16

• tertiary structure of the glucose carrier proteins
  changes and causes them to open
• increased number of glucose carrier proteins in the cell surface membrane
• activation of enzymes that convert glucose to glycogen to fat

Question 17

describe ways blood glucose concentration is lowered (4 marks)

Answer 17

• increased rate of absorption of glucose into cells
• increases respiratory rate of cells
• increased glycogenesis
• increased rate of conversion of glucose to fat

Question 18

describe the actions of glucagon (4 marks)

Answer 18

• low concentration of glucose in the blood
• attachment to specific receptors on cell surface membrane of liver cells
• activate enzymes that convert glycogen to glucose
• activate enzymes involved in gluconeogenesis

Question 19

describe the role of adrenaline in regulating blood glucose level

Answer 19

• adrenaline raises blood glucose concentration
• adrenaline attaches to protein receptors on opposite side of cell surface membrane of target cells
• activate enzymes that cause breakdown of glycogen to glucose in the liver