Autonomic Physiology Flashcards
What does the autonomic nervous system do?
Controls the things you dont want to think about
How does the autonomic nervous system fit into the grand scheme of the nervous system?
Afferent and Efferent nervous system
Efferent nervous system can be divided into:
- Somatic nervous system
- Autonomic nervous system
How does the autonomic nervous system differ from the somatic nervous system in terms of peripheral synapses?
Somatic doesnt synapse before target in peripheral nervous system
Autonomic synapses in autonomic ganglia
How does the autonomic nervous system differ from the somatic nervous system in terms of synapsing at junction?
Somatic nervous system:
- Specialised NMJ
- Ionotropic receptors
- Always excites target
Autonomic nervous system
- Less specialised junction
- Metabotropic receptors
- May excite or inhibit target
How does the sympathetic and parasympathetic differ in terms of exit from spinal cord?
Sympathetic:
- Thoracic (T1-12)
- Lumbar (L1-2)
Parasympathetic:
- Cranial (III, VII, IX and X)
- Sacral (S2-4)
How does location of ganglia differ between sympathetic and parasympathetic nervous system?
Ganglia lie close to spinal cord in sympathetic trunk (paravertebral ganglia), or in collateral ganglia (prevertebral ganglia = celiac, mesenteric)
Parasympathetic ganglia = close to or inside target organ
Name the autonomic neurotransmitters
Acetylcholine:
- Acts on cholinergic receptors
- –Nicotinic receptors
- –Muscarinic receptors
Noradrenaline (and adrenaline):
- Acts on adrenergic receptors
- –a receptors
- –b receptors
What are the neurotransmitters of the sympathetic system?
Preganglionic fibres release acetylcholine
-Acts on nicotinic cholinergic receptors
Postganglionic fibres release noradrenaline
-Acts on a or b adrenergic receptors
Postganglionic cells of the adrenal medulla have no axons, but release adrenaline and noradrenaline into the blood
What are the neurotransmitters of the parasympathetic nervous system?
Preganglionic fibres release acetylcholine
-Acts on nicotinic cholinergic receptors
Postganglionic fibres release acetylcholine:
-Acts on muscarinic cholinergic receptors
How do some sympathetic and parasympathetic fibres bend the rules?
Sympathetic cholinergic fibres innervate sweat glands
Some postganglionic fibres release non-adrenergic non-cholinergic (NANC) transmitters
-e.g. peptides or NO
What are the overall effects of the Sympathetic nervous system?
- Airways dilate
- Heart beats stronger and faster
- Blood diverts to muscle
- Gut motility decreases
- Ezyme secretion in gut generally inhibited
- Stored energy is released
- Pupils dilate
- Eye focus far away
- Hair stand on end
- Mouth gets dry
What is the overall effects of the parasympathetic nervous system?
- Airways constrict
- Heart beats slower and weaker
- Blood diverts to gut
- Gut motility increases
- Enzyme secretion in gut generally stimulated
- Energy is stored
- Pupils sonctrict
- Eye focus close up
- Hair lies flat
- Mouth starts drooling
What is the effect of the sympathetic system on the eye?
Activates b2 receptors on ciliary muscle around lens
-Eye focus far away
Activates a1 receptors on radial muscle of iris
-Radial muscle contracts an makes pupil larger
What is the effect of the parasympathetic system on the eye?
Activates muscarinic receptors on ciliary muscle
-Ciliary muscle contracts and eye focus close up
Activates muscarinic receptors on sphinter muscle
-Contracts sphincter muscle and makes pupil smaller
What is the effect of the sympathetic system on the heart?
Activates b1 receptors on pacemaker cells
-Increases heart rate
Activates (mainly) b1 receptors on myocytes
-Increases strength of contraction
