Homeostasis Glucose scenario

Question 1

Describe 5 actions of insulin

Answer 1

1. accelerates facilitated diffusion of glucose into cells
2. Accelerates conversion of glucose into glycogen (glycogenesis)
3. Increases synthesis of protein and fatty acids (lipogenesis)
4. Slows conversion of glycogen to glucose (glycogenolysis)
5. Slows formation of glucose from lactic acid, amino acids and glycerol (gluconeogenesis)

Question 2

With the high level of glucose in the blood (20mmol/L) would you expect a change in the composition and volume of urine? Explain

Answer 2

Glucose levels exceed renal threshold (9mmol/L) so the renal tubules will not be able to reabsorb all the glucose. Glucose will be lost in the urine and water follows by osmosis so volume of urine will increase

Question 3

Explain what is happening to the blood osmolality, will the patient be more or less thirsty?

Answer 3

Blood osmolality will be increased due to excessive urine output causing dehydration. Thirst centre in hypothalamus will activate and patient will want to drink more as they will be thirsty.

Question 4

Name and describe two metabolic reactions that will provide glucose to cells

Answer 4

Glycogenolysis - breakdown of glycogen to form glucose

Gluconeogenesis - synthesis of glucose from amino acids, lactic acid and glycerol

Question 5

Lipolysis will also occur, this breakdown in fat has led to an overproduction of ketone bodies causing ketoacidosis. What does this mean for pH and H+ concentration

Answer 5

pH will lower in response to increase in H+ ions

Question 6

Explain how the respiratory system will compensate for the change in pH including location and type of receptors, control centre and response. How will this effect pH?

Answer 6

Blood gas indicates a metabolic acidosis. Chemoreceptors in the aortic arch and carotid sinus will detect the change and send signals to control centre in medulla oblongata and pons. Respiratory (control) centre will send signals to increase the rate and depth of breathing to expel more CO2 lowering the number of H+ ions and raising pH

Question 7

Name the hormone produced in response to LOW BGL and describe 2 ways it will increase BGL

Answer 7

Glucagon
Stimulates liver cells to breakdown glycogen (glycogenolysis)
Formation of glucose from lactic acid and amino acid (gluconeogenesis)

Question 8

Name 3 other hormones that would help increase BGL, explain what causes the release of each and describe 1 action for each to restore glucose homeostasis

Answer 8

Adrenaline - stimulated by sympathetic nervous system and causes rapid glycogenolysis
Cortisol - released under stress and causes gluconeogenesis by liver cells
Growth hormone - hypothalamus detects low BGL and tells anterior pituitary to release growth hormone which stimulates the breakdown of triglycerides into fatty acids and glycerol
Thyroxine - Stimulates protein synthesis and use of glucose and fatty acids for ATP production