L6 - Adrenal medulla Flashcards
function of adrenal medulla
synthesises catecholamines (Camines) and adr
what part of NS is adrenal medulla part of
ANS
is adrenal medulla essential for life and why
no because other parts of NS can produce things that is also produced by medulla
where does adrenal medulla originate from
primitive neural crest then to sympathetic ganglia and chromaffin cells
what are chromaffin cells
they are CC cells where it produces Camines like Nadr and adr
pathway of Camines synthesis
tyrosine>L-DOPA>dopamine>Nadr> Adr
what is the enzyme that converts N adr to Adr
PNMT
hwo are Camines stored
transported into vesicles > protects them from degradation
how are Camines regulated
High camines levels inhibit rate limiting step of tyrosine to LDOPA.
-but if there is high level of stimulation from the nerves, this overtakes the high Camines levels and stimulate tyrosine hydroxlase
pathway of adr secretion from the stimulus
stress(sstimulus)> hypothalamus> SNS activation > adr secretion
what other molecules can activate adr secretion
high levels of ACTH/cortisol due to stress can activate PNMT enzymes to convert Nadr to adr
ACTH/cortisol production has a negative feedback so does this have an effect on adr secretion
no
how can Camines be terminated
uptaken into nerve terminals to be metabolised and recycled
- inactivated in liver or kidney
pathway of metabolic degradation of adr to exretion in kidney
adr> metadr>VMA> excreted via kidney
how can be VMA be used as an indicator
to see how much adr in circulation
sensiitivirty of a and B receptors towards Nadr and Adr
a: A>NA
effects of adr on CVS
HR and force contraction increases
- vasodil of skeletalvessels
effects of adr on RS
bronchodilation
effects on CNS by adr
increases alterness, anxiety, muslce tremor
effects of adr on muscle
glycogen breakdown into glucose
effects of adr on liver
increases glycogenolysis or gluconeogenesis
effects of adr on adipose tissue
FAs mobilised to glucose
why is it useful to have medulla alongside with SNS
longer lasting effect, wide spread effect, has a diff effect to SNS activation
what is phaeochromocytoma
excess Camines produced due to tumour of chromaffion cells(oversecretion) or dramatic eps due to sudden stressors
