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What is coordinated response
A way in which the body responds to changes in its external/internal environment through both the endocrine and nervous system
What is the fight or flight response
A coordinated response between the nervous and endocrine system that occurs when a mammal is presented with a potentially dangerous situation
Aim of the fight or flight response
To create a series of physical responses which intend to help Mammals survive by either running or fighting
What happens once a threat is detected by the autonomic system
The hypothalamus communicates with the sympathetic NS and the adrenal-cortical system
Difference in action between the sympathetic NS and the adrenal-cortical systemSNS uses neural pathways to initiate body reactions, whereas the adrenal-cortical system uses hormones in the blood stream
Pathway of hypothalamus (SNS) (3)
-Activates SNS
-activates adrenal medulla and impulses activate glands and smooth muscle
-adrenal medulla releases adrenaline and noradrenaline into the bloodstream
Pathway of hypothalamus (A-CS) (3)
activates adrenal-cortical system by releasing CRF
-pituitary gland secretes ACTH
-ACTH arrives at adrenal cortex and causes the release of hormones e.g cortisol
Physiological responses of fight/flight and why? (4)
-HR increases- more oxygenated blood pumped around bod
-pupils dilate- more light taken into eyes for better vision
-vascular shunting- blood redistributed to vital organs, away from non-vital
- increased glycogenolysis/gluconeogenesis- increases glucose available for respiration to provide more ATP for muscle contraction
-vasoconstriction
-smooth muscles relax
digestive system shuts down (peristalsis stops)
salivary glands stop working
What is the main function of adrenaline
To trigger liver cells to undergo glycogenolysis so that glucose is released into the blood stream
What is glycogenolysis
breakdown of glycogen to glucose
What type of hormone is adrenaline? hence what is its mode of action
Non-steroid hydrophilic
Because it is hydrophilic and is repelled by the hydrophobic core of the phospholipid bilayer
- therefore it binds to receptors on the surface of liver cell membranes, and triggers reactions in the cell
Action of adrenaline at liver cells (3)
1. Adrenaline approaches receptor site
2. Adrenaline fuses to receptor site (forming adrenaline-receptor complex), and in doing so activates adenylyl cyclase inside the membrane
3. Adenylyl cyclase converts ATP to cAMP, which acts as a secondary messenger that activates protein kinases, which trigger enzymes that convert glycogen to glucose
What enzyme is activated by the formation of an adrenaline-receptor complex
Adenylyl cyclase
What does adenylyl cyclase do
Triggers the conversion of ATP into cyclic adenosine monopsohphate (cAMP)
What do protein kinases do
phosphorylate other enzymes
Why are protein kinases important in liver cells
The phosphorylate/activate the enzymes that trigger the conversion of glycogen to glucose
What are the components In the second messenger model
-the hormone (adrenaline) is the first messenger
-cAMP is the secondary messenger
What is the cascade effect
One hormone molecule can cause many cAMP molecules to be formed
- e.g. 1 hormone can make 2 cAMP, which can trigger 8 enzymes
Why is the enzyme cascade effect important
shows how the body can react very quickly to a stressful situation
