Pharmacology Of Autonomic Nervous System 17.11.23 Flashcards
Structure of autonomic nervous system
In the autonomic system, there are two nerves in series: pre and post-ganglionic fibres.
The parasympathetic ganglia are near their targets with short post-ganglionic nerves, whereas the sympathetic are near the spinal cord with longer post-ganglionic fibres
Structure of somatic nervous system
In the somatic NS, one neurone comes from the CNS to innervate muscle
Structure of parasympathetic nervous system
Cranial nerves like the oculomotor nerve, facial nerve and vagus nerve carry signals to the body
A further sacral outflow innervates the pelvis
Short post-synaptic nerve fibres reach the targets and release acetylcholine (ACh), which acts on muscarinic receptors of various subtypes
Structure of the sympathetic nervous system
Regulates the fight-and-flight response
Nerve fibres originating in the spinal cord terminate in ganglia near the cord, then send out long nerve fibres to blood vessels, muscles etc.
They release noradrenaline which activates adrenergic receptors, of which there are two main types (alpha/ beta) with subtypes
What chemical mediators are produced at synapses?
Parasympathetic and sympathetic fibres coming out of the CNS both release ACh, which acts on specific receptors called nicotinic receptors
The post-ganglionic parasympathetic fibres release more acetylcholine, this time acting on muscarinic receptors
The post-ganglionic sympathetic fibres release noradrenaline, acting on alpha and beta adrenoceptors
What are the 4 types of receptors in the sympathetic nervous system? With the functions of them?
Alpha 1 (postsynaptic) —> vasoconstriction
Alpha 2 (presynaptic) —> negative feedback (suppressed noradrenaline release)
Beta 1 —> increased h.r and contractility (ONE HEART)
Beta 2 —> brochodilation (TWO LUNGS)
What 3 factors determine your blood pressure?
Heart rate
Stroke volume
Systemic vascular resistance
How do alpha blockers affect the sympathetic nervous system?
They block the sympathetic nervous system on the blood vessels causing vasodilation
Which of the following are clinical uses for phenylephrine?
A) congestant nasal spray
B) Intra-penile injection for priaprism
C) During a C-section birth to manage hypotension
D) As a cream to treat haemorrhoids
E) All of the above
E) all of them
Which of the following drug - action pairings are correct?
A) Metaraminol - treats hypertension
B) Tamsulosin - treats Benign Prostatic Hyperplasia
C) Salbutamol - directly acts on beta 1 receptors
D) Carvedilol - safe for use in patients with asthma
E) Isoprenaline - reduces obesity
B) Tamsulosin - treats benign prostatic hyperplasia
Meaning of dyspnoea?
Shortness of breath
Meaning of miosis
Excessive constriction of pupil of the eye
Bradycardia meaning
Low heart rate
What are the 2 types of cholinergic receptors?
Nicotinic and muscarinic
Where are Nicotinic receptors present?
Pre-ganglionic, SNS and PNS
