adrenal glands + fight or flight response

How many adrenal glands do we have and where are they located

2 adrenal glands located above each kidney 

What 2 components does the adrenal gland consist of and state their function

Adrenal cortex = (outer layer of the gland) secretes steroid hormones 

Adrenal medulla = (inner layer of the gland) secretes nonsteroid hormones

What 3 groups of steroid hormones are produced by the adrenal cortex

Glucocorticoids 

Mineralocorticoids 

Androgens 

When does the adrenal cortex release these steroid hormones 

When stimulated by hormones from the pituitary gland 

What is the function of glucocorticoids

-regulate glucose and protein metabolism 

-regulate blood pressure

-suppressing/reducing inflammatory responses e.g. swelling, redness to an injury

What is the function of mineralocorticoids 

-maintain salt concentration to control blood pressure 

What is the function of androgens 

-regulatory sex hormones 

What 2 nonsteroid/peptide hormones are produced by adrenal medulla 

Adrenaline 

Noradrenaline 

What is the function of adrenaline 

Increases HR = (more blood flow, more o2 and glucose reaches muscles to produce atp, more muscle contraction),

Increases BGL 

What is the function of noradrenaline 

Dilate pupils = allows more light in 

Vasoconstriction of vessels in nonessential organs = blood is redirected which increases blood flow to essential organs e.g. muscles and brain

>> blood vessels in the muscles vasodilate allowing more blood and oxygen to reach them 

When does the adrenal medulla release these nonsteroid hormones 

When stimulated by sympathetic nervous system during a fight or flight response 

what is the fight or flight response and what two systems work together

stress response initiated when a threat is perceived

nervous system (specifically ANS) and endocrine system

outline the fight or flight response

1. stressor is perceived by sensory receptors and impulses are sent to hypothalamus

2. hypothalamus activates sympathetic branch of ANS causing body to change from parasympathetic to sympathetic state

3i. electrical impulses travel from brain along motor neurones to: skeletal muscles aswell as adrenal medulla stimulating release of adrenaline and noradrenaline (nonsteroid/ peptide hormones)

4i. adrenaline and noradrenaline are secreted into bloodstream which travel to target cells to cause instant physiological changes which triggers fight or flight response

3ii. hypothalamus releases hormone CRF which stimulates pituitary gland to secret ACTH (adrenocorticotropic hormone) into bloodstream which travels to adrenal cortex and stimulates it to release steroid hormones which travel to target cells

5. once threat has passed the parasympathetic branch of ANS works antagonistically, bringing body back to calm resting state

outline the action of adrenaline

1. adrenaline (acts as 1st messenger) binds to a specific complementary receptor on cell surface membrane of a liver cell

2. this receptor is part of of adenylyl cyclase enzyme, when adrenaline binds it activates adenylyl cyclase to convert ATP into cAMP (acts as 2nd messenger)

3. cAMP binds to protein kinases activating them

4. protein kinases are enzymes that work by phosphorylation, they add a phosphate group to other enzymes to activate those other enzymes e.g. enzymes that catalyse the breakdown of glycogen into glucose

5. glucose diffuses out liver cells via channel proteins into bloodstream which increases BGL so more glucose is delivered to body cells for respiration

why is the action of adrenaline refered to as a cascade effect and why is this useful

one single adrenaline > generates multiple cAMP > causes multiple protein kinase enzymes to be activated > actives many other enzymes with various actions

-at each stage the effect is more and more amplified = more molecules involved, this enables body to react very quickly e.g. to threats during fight or flight response