Fight or flight response revision flashcards. OCR A: A level biology revision notes. Module 5: Communication, Homeostasis and Energy. A* biology student's notes. Summary of key content to be memorised. Process that needs to be memorised from specification.
Fight or Flight Response: Fight or Flight Response:
Stimuli is likely auditory or visual.
The cerebral understanding of a threat activates
the hypothalamus.
This increases activity in the sympathetic nervous
system.
Adrenaline is released from the adrenal medulla
of the adrenal gland.
The hypothalamus also releases corticotropin-
releasing hormone (CRH) & thyrotropin-
stimulating hormone (TSH) which stimulate the
anterior pituitary gland to release hormones.
The anterior pituitary gland releases adreno-
corticotropic hormone (ACTH).
This stimulates the production of cortisol & many
other hormones in the adrenal cortex.
Cortisol sustains energy (releasing glucose), but it
also curbs the surge of adrenaline & turns off CRH.
Effects of The Fight or Flight Response: Effects of The Fight or Flight
Response:
Pupils dilate to let in more light (irises contract).
Arterioles in the skin contract & arterioles to
major muscle groups dilate to increase blood flow
to major muscle groups.
Blood glucose levels increase through triggering of
glycogenolysis, the glucose can be used in
respiration.
Smooth muscles of the airways relax, to allow
more air into the lungs.
Peristalsis shuts down so resources can solely be
focused on emergency functions.
Erector pili muscles in skin contract making the
hairs stand on end.
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