Homeostasis: blood glucose concentration

Question 1

Homeostasis definitoin:

Answer 1

maintenance of a stable internal environment

Question 2

regulation of body temp in exotherms: too low

too high

Answer 2

thermoreceptors in hypothalamus detect decreased temperature of blood and send less impulses heat loss centre, sends less impulses to skin
shivering: contractions produce metabolic heat
raising of hair: thicker insulative layer of still air
increased metabolic rate: respiration produces heat
decrease in sweating

thermoreceptors in hypothalamus detect increased temperature of blood and send more impulses heat loss centre, sends impulses to skin
vasoconstriction: diameter of arterioles near the skin are made smaller. This reduces the volume of blood reaching skin through capillaries, less heat loss.

vasodilation: diameter of arterioles near skin made large, allows warm blood to pass to skin and give off heat

Question 3

Blood sugar levels too high: what happens

how is the blood glucose conc lowered?

Answer 3

1) Beta cells in Islet of Langerhans in the pancreas detect high blood glucose concentration and secrete insulin into blood plasma
2) Insulin binds to complementary receptor molecules- changes tertiary structure of glucose transport carrier proteins making them open
3) glucose enters by facilitated diffusion
4) increase in number of glucose transport carrier proteins.
5) glycogenesis occurs: glucose converted into glycogen by activation of enzymes.

increased rate of absorption
increase in respiratory rate of cells
increase in glycogenesis

Question 4

Blood Sugar levels too low- resting

Answer 4

Alpha cells in the Islet of Langerhans detect fall in blood sugar concentration- secrete Glucagon into blood
Glucagon bind to specific protein receptors on the liver- causes it to change shape
Stimulates adenylate cyclase enzyme to convert ATP to cAMP
cAMP binds to protein kinase which catalyses glycogenolysis- glycogen- glucose

also stimulates enzymes which hydrolyse gluconeogenesis

Question 5

Blood Sugar levels too low- stress

Answer 5

adrenaline bind to specific protein receptors on the liver- causes it to change shape
Stimulates adenylate cyclase enzyme to convert ATP to cAMP
cAMP binds to protein kinase which catalyses glycogenolysis- glycogen- glucose

Question 6

Type 1 diabetes causes:

how is this controlled?

Answer 6

body unable to produce insulin
may be an auto immune response

injections of insulin- cannot be eaten as its a protein that would be digested.
blood glucose conc monitored by biosensors
manage carbohydrate intake and exercise carefully

Question 7

Type 2 diabetes: what is the cause?

how is it controlled?

Answer 7

glycoprotein receptors lose responsiveness to insulin, or inadequate supply of insulin from pancreas.
obesity and poor diet
regulating diet and carbohydrate intake