homeostasis Flashcards
Describe how glucagon helps in the process of gluconeogenesis
-glucagon binds to complementary receptor of target cells
-activates enzymes that can convert glycerol/amino acids/fatty acids in glucose
what is the name of the region of the pancreas that helps control the blood glucose levels
islets of Langerhan
what is homeostasis
Internal environment is maintained within set limits around an optimum
what is positive feedback
a fluctuation that triggers changes which results in an even greater deviation from the average level
what is negative feedback
self-regulatory mechanisms that return internal environment back to the optimum when there is a fluctuation.
describe the stages involved in negative feedback
-receptors detect deviation/change
-travels to intermediate/co-ordinator
-corrective mechanism by effector
-receptors detect that the levels have returned to normal
suggest why intermediate neurones/co-ordinators analyse inputs from several receptors before sending an impulse to effectors?
-receptors may send conflicting information
-optimum response may require multiple types of effector
suggest why separate negative feedback mechanisms control mechanisms in different directions
-provides more control
-especially in cases of overcorrection, which would lead to deviation in the opposite direction to the original one
why is there a time lag between hormone production and response by an effector
-it takes time to:
-produce hormone
-transport hormone along bloodstream
-cause required change to target protein
name the factors that affect blood-glucose concentration
-amount of carbs in diet
-rate of glycogenolysis
-rate of gluconeogenesis
define glycogenesis, glycogenolysis and gluconeogenesis
-glycogenesis, liver converts glucose into glycogen stores
-glycogenolysis, liver hydrolyses glycogen into glucose, can diffuse into blood
-gluconeogenesis, liver converts glycerol and amino acids into glucose
describe and explain the role of insulin when blood-glucose levels are too high.
-β-cells in the islets of Langerhan detect increase in blood-glucose and secrete insulin
-insulin binds to surface receptors on target cells
-increases cellular glucose uptake
-activate enzymes for glycogenesis
-stimulate adipose tissue to synthesise fat
EQ: Using your knowledge of the kidney, explain why glucose is found in the
urine of a person with untreated diabetes
-High CONCENTRATION of glucose present in the filtrate as the damaged β-cells can’t produce insulin
-not all the glucose is selectively re-absorbed at the PROXIMAL CONVOLUTED TUBULE
-CO-TRANSPORT PROTEINS are working at maximum rate
How does insulin cause cells to become more permeable to glucose
-increases number of glucose carrier proteins
-triggers conformational change that opens glucose carrier proteins
describe the two types of diabetes mellitus
Type-one diabetes:
-autoimmune response attacks β-cells so no insulin produced
-treat with injections of insulin
Type-two diabetes:
-glycoprotein receptors damaged/less responsive to insulin
-strong correlation to obesity/poor diet
-controlled with exercise and diet
