OCR Biology A-Level Endocrine System Summary

Protein Hormone Cascade :
↳ Adrenaline :



1 .
Adrenaline binds to cen surface receptors
Adrenaline
adenyl cyclase enzyme
2 .

activate
3 .



Adeny cyclase/ converts ATP to Cyclic Amp
(Secondary Messenger
4 CAMP activates Linases
protein
.




3 Protein linases
phosphorylate and activate other
encymes
.




Pancreas :




Produces digestive enzymes Amylase protease lipase :
, ,
-> Acinar cells

Produce insulin
Is let of Langerhans Alpha sens Produce
Glucagon Beta caus :
:
:




islet of Langerhans
Acinar ceus


blood
Increasing glucose concentration :

Diet Eat
· :


carbohydrate rich foods

Glycogenolysis Glycogen is broken down into
glucose
· :




·Gluconeogenesis formation of from non-carbohydrate sources
glucose
:




Decreasing blood glucose concentration :


Respiration Glucose is used to make
energy
·
:




Glycogenesis
:
formation
guycogen of
Role of of glycogenesis
insulin :
Increasing the rate
of
Increasing rate
glucose absorption Increasing glucose <
fat conversion
.




·
Increasing respiratory rate
Inhibiting the release of glucagon
Role of
glucagon Reducing amount of glucose absorbed
by hepatocytes
:




Glycogenolysis Increasing gluconeogenesis
Control of insulin Secretion :

: Normal blood Potassium channels K diffuses B cell
glucose open out -70mv
:
are s is
,




2
blood Glucose
High glucose enters the sel
by glucose transporter
.

a
:




.
3 Glucose is metabolised
by the mitochondria -> ATP produced
4 .
ATP closes the potassium Channels -
Depolarisation potential difference of
,
-30mv


voltage gated
.
3 Depolarisation opens the calcium channels

6 Calcium enters resides to release insulin via
.




causing exocytosis