Chapter 28 Flashcards
Hormones
> endocrine system–from glands
secreted through blood
only deliver messages; which cause a biochemical response in target cell.
Messenger molecules
Hormones or neurotransmitters
>bind to a specific receptor protein in membrane of target cell.
>non covalent interactions (irreversible)
Neurotransmitters
> nervous system–from nerves
Amino acid derivatives
hormone
> Synthesized from a standard AA by loss of Carb. acid
Polypeptide
Hormone
>largest class of hormones >most varied in size & complexity Examples--insulin, glucagon,endorphins,FSH,TSH
Second messengers
> Activate or inactivate other enzymes by addition or removal of phosphate.
cAMP–most common,phosphodiester
How hormones work:
Adrenaline is an emergency hormone that excited nerves and causes energy boost, causes the synthesis of cAMP in cells >
>binding adrenaline to its receptor protein causes a shape change& activates G protein> G moves until it binds to adenylate cyclase > AC synthesize cAMP> activates protein kinase> provide a response signal to adrenaline
Removing the messenger:
> cAMP is destroyed by phosphodiesterase
>adrenaline is destroyed by mono amine oxidase(MAO)
Steroid
Hormone
> hydrophobic
all have similar structure
–cause cross reactivity of hormones
Receptor protein mechanisms:
Direct action: no secondary messenger;receptor is the ion channel
Indirect action: a secondary messenger(cAMP)
Removal of message:
Neurotransmitter
1) enzymatic destruction
2) reuptake (recycle)
Acetylcholinesterase
Destroys ester
>direct action
>inhibition of acetylcholine nerve recharging causes muscle paralysis
Termination of message
Both messenger& secondary messenger are removed
>primary by: re uptake or oxidation
>secondary by:hydrolysis
MAOIs
Block the oxidation of monoamines
“Block the destruction”
-result in increase of messenger concentration
Histamine
>Mono amine >responsible for symptoms of allergies >2 receptors: -h1 receptors-respiratory tract -h2 receptors-stomach
