Homeostasis Flashcards
What is homeostasis?
Maintains constant internal environment within restricted limits by a physiological control system
Use an example and explain why homeostasis is important
- Temperature and pH needs to be kept at an optimum.
- Blood glucose concentration as glucose needs to be available as a respiratory substrate
What is meant by negative feedback and why is it important?
A change to the normal level initiates a response which reduces the effect of the change
So restores system back to original level or prevents continuation of behaviour
What is meant by positive feedback?
A change to the normal level initiates a response which causes additional change in the sane direction
Thing produces thing which causes more production of thing which causes more of other thing
What does physiological mean?
Mechanism within the body
What is thermoregulation?
It’s the regulation of body temperature effecting temperature and Ph levels
What is endotherm?
Mammals, birds and some fish maintain body temperature by both physiological and behavioural means
What are ectotherms?
In all other animals except mammal some fish and birds by maintaining body temperature by behavioural means only such as exposing themselves to the Sun,taking shelter or gaining warmth from the ground
What gland is blood glucose concentration controlled by?
Pancreas, which has glucose receptor cells which monitor the concentration of blood glucose and endocrine cells which secrete hormones
What are the two endocrine cells that secrete hormones in the pancreas?
Alpha cells = secrete the hormone glucagon
Beta cells = Secrete the hormone insulin
Aim of insulin
This is secreted by beta cells in the pancreas and its aim is to reduce blood glucose levels to the normal range
Describe the action of insulin
Insulin binds to complement receptors on cell surface membrane of target cells
This controls the uptake of glucose
And it also activates enzymes that stimulate glucose into glycogen which would decreases blood glucose
What is it called when you activate enzymes from glucose to glycogen?
Glycogenesis
Aim of glucagon
Secreted by Alpha cells in the pancreas and its aim is to increase blood glucose levels to normal range
Describe the action of glucagon
Glucagon binds to receptors on cell surface membrane of target cells
Activate enzymes involved in the hydrolysis of glycogen into glucose
Activates enzymes involved in conversion of glycerol and amino acids into glucose
What is it called when you Hydrolyse glycogen into glucose?
Glycogenolysis
Describe the response to higher than normal glucose concentration
- Increase in glucose detected by hypothalamus and beta cells in the pancreas.
- Beta cells secrete insulin by exocytosis
- Insulin binds to complementary receptor on cell surface membrane of target liver or muscle cells
- Activate enzymes involved in glycogenesis which is the conversion of glucose into glycogen
Maintains concentration gradient of glucose or glucose continuous to diffuse into cell from blood
Causes more carrier and channel proteins complementary to glucose to move to cell surface membrane of target cells
Increased permeability to glucose so glucose enters by facilitated diffusion for lower blood plasma glucose concentration
Describe the response to a lower than normal blood glucose concentration?
- Decrease in glucose detected by hypothalamus and alpha cells in pancreas
- Alpha cell secrete glucagon by exocytosis
- Glucagon bias to complementary receptor protein found on river muscle cells which are target cells
- They activate enzymes involved in glycogen analysis, which is the hydrolysis of glycogen to release glucose and activate enzymes involved in conversion of glycerol and fatty acids and amino acids to glucose
Glucose leaves cell into blood by facilitated diffusion so increases blood plasma glucose concentration
