Organisms Respond to Change - Blood Glucose Flashcards
define homeostasis
maintenance of a constant internal environment within a living organism
what is maintained in homeostasis?
blood pH
core termperature
blood glucose concentration
water potential of blood
why is it important to regulate blood pH?
so enzymes can work at optimum activity
maintaining the shape of proteins
why is it important to regulate the water potential of blood?
so body cells don’t shrink or burst due to osmosis
why is it important to regulate blood glucose concentration?
to regulate water potential
provide a steady source of energy for respiration
why is it important to maintain a core temperature?
for optimum enzyne activity
which systems carry out homeostasis?
nervous system
endocrine system
what is the optimum point?
point at which the system operates best
what is a stimulus?
deviation from the optimum
what is a feedback mechanism?
mechanism where a receptor responds to a stimulus created by a change to the system from the effector
what is negative feedback?
change in conditions are reversed and returned to a set point to maintain optimum conditions
what is positive feedback?
change detected is further increased away from optimum conditions
what are the 3 ways hormones interact with cells?
affects permeability of cell membranes
causes release of second messenger inside cells
diffuse into cell and promote/inhibit transcription
what detects changes in blood glucose?
cells in the islets of langerhans
why is it important to regulate blood glucose?
hypo/hyperglycaemia can kill cells due to affecting water potential
glucose required for respiration
what detects low blood glucose?
alpha cells in islets of langerhans
what detects high blood glucose?
beta cells in islets of langerhans
what happens when high blood glucose is detected?
beta cells secrete insulin
insulin binds to receptors on surface of muscle and liver cells
in liver - glycogenesis
in muscle - increases uptake of glucose into the cells
excess converted into fat
what happens when low blood glucose is detected?
alpha cells secrete glucagon
glucagon binds to receptors on muscle + liver cells
in liver - glycogenolysis and gluconeogenesis
in muscle - gluconeogenesis
what is glycogenesis?
synthesis of glycogen from glucose
what is glycogenolysis?
breakdown of glycogen into glucose
what is gluconeogenesis?
synthesis of glucose from lipids and amino acids
what factors can affect blood glucose concentration?
glucose directly gained through diet
glycogenolysis/gluconeogenesis
what are the types of diabetes?
type 1 - insulin dependent
type 2 - insulin independent
what is type 1 diabetes?
where the body is unable to produce insulin
usually develops in childhood
what causes type 1 diabetes?
usually due to an autoummine response
immune system attacks beta cells of islets of langerhans
what are the signs of type 1 diabetes?
frequent urination
glucose in urine
weight loss
tiredness
what is type 2 diabetes?
insulin receptors lose receptiveness or are lost completely
usually older people, but increased in obese adolescents
what are the signs of type 2 diabetes?
same as type 1 but less severe
how is type 2 diabetes treated?
injections of insulin that are matched to glucose intake
regulation of glucose intake
how is type 1 diabetes treated?
insulin injections matched to glucose intake
why can’t insulin be ingested in treatment of diabetes?
it would be digested
describe the second messenger model
adrenaline binds to transmembrane protein receptor on liver cell
protein changes shape and activates adenyl cyclase to form cyclic AMP from ATP
cAMP binds to protein kinase, changing its shape and activating it
protein kinase catalyses conversion of glycogen to glucose which leaves the cell
