6.4.2 Control of blood glucose concentration

Question 1

why would blood glucose increase?

Answer 1

following food or drink containing carbohydrates

Question 2

why would blood glucose decrease?

Answer 2

exercise or if you have not eaten

Question 3

what detects changes in blood glucose levels?

Answer 3

the pancreas

Question 4

what releases insulin and glucagon?

Answer 4

endocrine cells in the islets of langerhan

Question 5

what releases adrenaline?

Answer 5

adrenal glands

Question 6

what is the role of adrenaline in regulating blood glucose levels?

Answer 6

results in more glycogen being converted to glucose in the liver

Question 7

what detects an INcrease in blood glucose levels?

Answer 7

beta cells in the Islets of Langerhan

Question 8

what do the beta cells do when they detect high glucose levels?

Answer 8

release insulin

Question 9

what does the release of insulin cause?

Answer 9

• liver cells to become more permeable to glucose
• activates enzymes to convert glucose to glycogen

Question 10

how is glucose removed from the blood?

Answer 10

stored a glycogen in liver cells

Question 11

what detects a DEcrease in glucose levels?

Answer 11

alpha cells in the Islets of Langerhan

Question 12

what happens once a decrease in glucose has been detected?

Answer 12

• alpha cells release glucagon
• adrenal glands release adrenaline

Question 13

what happens once glucagon and adrenaline have been secreted?

Answer 13

second messenger model occurs to activate enzymes to hydrolyse glucagon

Question 14

what happens after the second messenger model occurs?

Answer 14

glycogen is hydrolysed to glucose and more glucose is released into the blood

Question 15

what is glycogenesis?

Answer 15

the process of excess glucose being converted to glycogen when blood glucose is higher that normal -> mainly occurs in the liver

Question 16

what is glycogenolysis?

Answer 16

the hydrolysis of glycogen back into glucose

Question 17

What is gluconeogenesis?

Answer 17

the process of creating glucose from non-carbohydrate stores in the liver

Question 18

what is the first way that insulin can decrease blood glucose?

Answer 18

• 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.

Question 19

what is the second way insulin can decrease blood glucose?

Answer 19

• more protein channels are incorporated into cell membranes
• so that more glucose is absorbed from the blood into the cells

Question 20

what is the third way insulin can decrease blood glucose?

Answer 20

• activating enzymes involved in the conversion of glucose -> glycogen
• results in glycogenesis in the liver

Question 21

first way glucagon can increase blood glucose?

Answer 21

attaching to receptors on the surface of target cells (liver cells)

Question 22

second way glucagon can increase blood glucose?

Answer 22

• 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

Question 23

third way glucagon can increase blood glucose?

Answer 23

• activating enzymes involved in the conversion of glycogen and amino acids into glucose

Question 24

explain the second messenger model:

Answer 24

• 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

Question 25

how does adrenaline increase blood glucose?

Answer 25

- 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

Question 26

what is diabetes?

Answer 26

when blood glucose cannot be controlled

Question 27

what is type 1 diabetes?

Answer 27

- when the body is unable to produce insulin - treatment involves injection of insulin

Question 28

what is type 2 diabtes?

Answer 28

- when receptors on the target cells lose their responsiveness to insulin - usually develops due to obesity and poor diet

Question 29

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)

Answer 29

High concentration of glucose in blood - Reabsorbed by facilitated diffusion / active transport - requires proteins/carriers - these are saturated - not all glucose is reabsorbed

Question 30

The urine of a non-diabetic person does not contain glucose. Explain why. (2)

Answer 30

- Leaves the blood at kidney - reabsorbed into blood from kidney tubule

Question 31

The scientists repeated the investigation using much higher doses of STZ. This led to destruction of pancreatic cells. The scientists concluded that these rats would not be suitable for studying type II diabetes. Give two reasons why the scientists made this conclusion.

Answer 31

Type II) still produce/release insulin; (Type II) cells/receptors less/not responsive/sensitive to insulin;      Pancreatic cells not destroyed in (type II diabetes)     Damage to pancreatic cells may affect processes/reactions (in t

Question 32

 Using your knowledge of the kidney, explain why glucose is found in the urine of a person with untreated diabetes.

Answer 32

High concentration of glucose in blood/filtrate; Accept tubule for filtrate. 2.      Not all the glucose is (re)absorbed at the proximal convoluted tubule; Reject no glucose is (re)absorbed. 3.      Carrier/co-transport proteins are working at maximum rate OR Carrier/co-transport proteins/ are saturated;

Question 33

 Describe the role of glucagon in gluconeogenesis. Do not include in your answer details on the second messenger model of glucagon action.

Answer 33

(Attaches to receptors on target cells and) activates/stimulates enzymes; Reject ‘produces enzymes’. 2.   Glycerol/amino acids/fatty acids into glucose;

Question 34

Metformin is a drug commonly used to treat type II diabetes. Metformin’s ability to lower the blood glucose concentration involves a number of mechanisms including: *   increasing a cell’s sensitivity to insulin *   inhibiting adenylate cyclase. (c)  Explain how increasing a cell’s sensitivity to insulin will lower the blood glucose concentration.

Answer 34

  (More) insulin binds to receptors; 2.   (Stimulates) uptake of glucose by channel/transport proteins OR Activates enzymes which convert glucose to glycogen;

Question 35

Explain how inhibiting adenylate cyclase may help to lower the blood glucose concentration.

Answer 35

Less/no ATP is converted to cyclic AMP/cAMP; 2.   Less/no kinase is activated; 3.   Less/no glycogen is converted to glucose OR Less/no glycogenolysis;

Question 36

The acidic pH conditions created by osteoclasts cause the inactive form of the protein osteocalcin to change into the active form of osteocalcin.

Answer 36

  (Change in pH) changes / breaks ionic / hydrogen bonds; 2.      Changes tertiary structure;

Question 37

 Binding of insulin leads to an increase in the rate of respiration in cells such as osteoblasts. Explain how.

Answer 37

nsulin) leads to more transport proteins / channel (proteins) / carrier (proteins) for glucose; Ignore references to opening channels Accept co-transport / GLUT 1 or 4 protein 2.      More glucose (for respiration / glycolysis) enters cell;

Question 38

   Each year, a few people with type I diabetes are given a pancreas transplant. Pancreas transplants are not used to treat people with type II diabetes. Give two reasons why pancreas transplants are not used for the treatment of type II diabetes.

Answer 38

(Usually)Type II produce insulin; 2.      Cells / receptors less sensitive / responsive (to insulin) OR Faulty (insulin) receptors; 3.      (Treated / controlled by) diet / exercise;