14.5 Fight Or Flight Response Flashcards
What is the fight or flight response
An instinct that all mammals posses. It gets automatically triggered if a potentially stressful and dangerous situation is detected. This response triggers a series of physical responses. These responses help the mammals by either preparing them to run or fight.
What happens once the threat is detected by autonomic nervous system?
The hypothalamus communicates with the sympathetic nervous system and the adrenal cortical system. The sympathetic pathway uses neuronal pathways to initiate body reactions whereas the adrenal cortical system uses hormones in the blood stream, the combined effects of these two systems result in the fight or flight response
How does the sympathetic nervous system work?
Sends impulses to glands and smooth muscles and tells the adrenal medulla to release adrenaline and noadrenaline into the bloodstream. These ‘stress hormones’ cause several changes in the body, including increased heart rate
How does the adrenal cortical system work
The release of other stress hormones that have longer term action from the adrenal cortex is controlled by hormones produced from the pituitary gland. Hypothalamus stimulates pituitary gland to release ACTH, which travels via the blood stream to the adrenal cortex, where it activates many other hormones to deal with a threat
Is adrenaline hydrophilic or hydrophobic and why is this important
It is hydrophilic, therefore it can’t pass through cell membranes. So it binds with receptors on cell surface of liver cells and triggers a chain reaction inside the cell.
What is the chain of reactions for adrenaline
Adrenaline binds to receptor and the enzyme adenylyl cyclase is activated
Adenylyl cyclase then triggers the conversion of ATP to cyclic adenosine mono-phosphate (cAMP) on the inner surface of the cell membrane in the cytoplasm
The increase in cAMP activates specific enzymes called protein kinases which phosphorylate and activate other enzymes. I.e. enzymes are activated that trigger the conversion of glycogen to glucose
What is adrenaline an example of
Secondary messenger model. Hormone is first messenger, cAMP in secondary messenger. At each stage, the number of molecules involved increases so the process is said to have a cascade effect
