Autonomic NS 2: Adrenaline/epinephrine Flashcards
Chemistry of Adrenaline
- Alkaloid obtained from suprarenal medulla
- Catecholamine; with L-isomer 20x D-isomer
Adrenaline is formed from the amino acid—-
Tyrosine
Oxidation of Adrenaline forms—-
adrenochrome
toxic pink Hallucinogen
Oral absorption of adrenaline
ineffective, due to:
* Gastric enzymes
* rapid metabolism by liver
* cause VC of mucous membrane (through A1) leading to poor absorption
Subcutaneous absorption of Adrenaline
causes VC, leading to:
* slow absorption
* long duration
why it’s given with Local anesthesia for prolonged action
Intravenous adminstration of adrenaline
FATAL;
causes Ventricular fibrilation
due to most of the dosage directly affecting the heart
Intracardiac Adminstration of Adrenaline is used for
Cardiac resuscitation
Adrenaline inhilation is used for
Bronchial Asthma
effect of Adrenaline adminstration on CNS
Catecholamines don’t pass blood brain barrier
Effect of Adrenaline on the heart
Increase all Cardiac properties:
* Positive Ionotropic
* Postive Chronotropic
* Positive dromotropic
It increases total cardiac output
excessive Adrenaline effect on the heart causes
- first: arrhythmia
- then, Ventricular fibrilation
effect of adrenaline on BV
- through Alpha1 : General VC (skin & mucous membrane)
- Through Beta2: VD of Coronary & skeletal BVs
Explain why adrenaline is not useful in angina
It increases Cardiac work, which is theoretically impaired by the presence of the Angina (ischemia)
Describe the effect of Adrenaline on Blood pressure
- Systolic pressure depends on Cardiac output (& a little on Peripheral resistance)
- Diastolic pressure depends mainly on Peripheral resistance
- Since Adrenaline increases Cardiac output
- It increases Systolic Blood pressure
- With slight variation in disatolic Blood pressure
- As a result: pulse pressure increases
pressor (vasoconstrictor) effect of adrenaline can be reversed by
Alpha blocker
acts on Alpha 1 (which causes decrease general VC)