Summary AQA a-level Biology: The Endocrine System Revision Notes

, The Endocrine System


Positive & Negative Feedback




Positive :
Negative
:




memorise these
graphs




Vasodilation to decrease temperature
0
0
Vasoconstric tion to increase temperature



n ote :
thermoreceptors a re found in the
hypothalamus .




input receptor Coordinator effector response

skin receptor smooth muscle
temp to o
thermo in ar teries and
vasoconstric tion
cold
receptor hypothalamus ar terioles



skin receptor smooth muscle
temp too
thermo in ar teries and
not receptor hypothalamus ar terioles vasodilation




example of positive feedback :
depolarization



of negative feedback potential
:
example action




The Pancreas




endocrine system endocrine t i ss u e (excretion eg . hor mones)


Islet of Langerhans ( tissue)


✗ cells to blood
produce glucagon increase glucose



B ce lls
produce insulin to decrease blood glucose



ATP,
lower blood glucose Leads to decreased respiration , decreased leading to an
energy deficit .


Hypoglycaemia .




higher blood glucose Leads to an increase in wa te r
moving into blood
by osmosis because wa te r potential in blood i s lower so




cells
dehydrate .
Hyperglycemic .




I
insulin
tuecagon