14.5 coordinated responses

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 system

SNS 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