Homeostatis Flashcards
Coordinator
Formulates a response to a stimulus
Effector
Muscle or gland that produces the response
Homeostatis
The maintenance of a stable internal envrionment
Negative feedback
When there is an increase/decrease from set point opposite effect is instigated
Producing a response that returns the value to the norm
Positive feedback
Occurs when a deviation from an optimum causes greater deviation from the normal
Thermoregulation
Regulation of body temperature
If body temp to low lack of Ke so slower enzyme controlled reactions less successful collisions and less esc formed per second
If body temp to high enzymes denature (breaking of hydrogen and ionic bonds in 3* between R groups)
If blood pH changes enzymes+ other proteins denature
(Hb antibodies plasma proteins)
Endotherms + examples
Mammals+ some birds+ fish
Maintain body temp through physiological and behavioural means
Ectotherms + examples
All other animals (reptiles,amphibians)
Maintain body temp through behavioural means only such as
Exposing themselves to the sun
Taking shelter
Gaining warm from the ground
What is low levels of glucose known as
Hypoglycaemia
High levels of glucose known as
Hyperglycaemia
What is insulin secreted by And where
Describe Process to
Secretes by beta cells in the pancreas
Reduces blood glucose levels
Insulin binds to complementary receptors on target cells
Controls the uptake of glucose carrier proteins of target cells
(Striated muscle+ adipose tissue)
Insulin activates enzymes which converts glucose to glycogen (glycogenesis) reducing blood glucose
What is glucagon secreted by and where
Process to
Glucagon secreted by alpha cells in the pancreas
Glucagon binds to complementary receptors on target cells
Activates enzymes which hydrolyse glycogen into glucose (glycogenolysis)
Activates enzymes which convert glycerol and amino acids into glucose (gluconeogenesis
Describe the role of glycogen formation and its role in lowering blood glucose levels
Glucose concentration in liver falls
Higher concentration in the blood
Glucose concentration gradient creates
Glucose leaves the blood by facilitated diffusion via channel protein
What is adrenaline secretes by
What does it do
Secretes by adrenal glands (above kidney)
Increases blood glucose levels
Second messenger mode
Adrenaline+glucagon both bind to specifically complementary transmembrane protein receptors of target cells - first messenger
Hormone-receptor complex formed (receptor 3* shape changes)
Activates adenylate cyclase which converts atp into cAMP
cAMP activates protein kinase which hydrolyses glycogen into glucose
So gluconeogenesis occurs
Factors affecting blood glucose concentration
Diet- glucose from hydrolysis of starch,maltose,sucrose,lactose
Glycogenolysis
Gluconeogeneis
Type 1 diabetes
Insulin dependent diabetes
Insulin deficiency due to autoimmune killing of beta cells
(Due to virus or faulty gene)
Type 2 diabetes
Non-insulin-dependent diabetes
Insulin produced but insulin receptors on target cells are unresponsive so insulin has no effect
Symptoms of diabetes
High thirst due to osmosis of water from cells to the blood which has a low water potential
Large volumes of urine production due to excess water in blood
Poor vision due to osmotic loss of water from eye lens
Tiredness due to loss of glucose in urine and poir uptake of glucose by liver and muscle cels
How is urea from the blood
High hydrostatic pressure
Causes ultrafiltration at glomeruli
Through basement membrane
Enabled by small size of urea molecule
Describe how ultrafiltration produces glomerular filtrate
Higher than normal hydrostatic pressure
Glucose,urea mineral ions
Pass through basement membrane
Protein too large to go through
Presence of podocytes
Presence of pores
How is the high hydrostatic pressure in the glomerulus produced
Afferent arteriole is wider in diameter than the efferent arteriole that exists
Causing high hydrostatic pressure
