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
What is the effect of the parasympathetic system on the heart?
Activates muscrainic receptors on pacemaker cells
-Decreases HR
Little effect on myocytes
-Little effect on strength of contraction
What is the effect of the sympathetic nervous system on the lungs?
Activates b2 receptors on smooth muscle of airways
-Makes smooth muscle relax and dilates airways
What is the effect of the parasympathetic nervous system on the lungs?
Activates muscarinic receptors
-Makes smooth muscle contract and constric airways
What is the effect of the sympathetic nervous system on blood vessels?
Activates a1 receptors on smooth muscle of vessels
-Smooth muscle contracts and blood flow decreases to thet area
Activates b2 receptors on smooth muscle of vessels:
-Smooth muscle relaxes and blood flow increases to that area
Effect depends on what receptor different tissues express
What is the effect of the parasympathetic nervous system on blood vessels?
Usually no effect
What is the effect of the sympathetic nervous sysetm on the gut?
Activated a/b receptors on smooth muscle of gut
-decreases gut motility
Activates a receptors in pancreas
-Inhibits secretion of enzymes
What is the effect of the parasympathetic system on the gut?
Activates muscarinic receptors on smooth muscle of the gut
-Increases gut motility
Activates muscarinic receptors in the pancreas
-Increases secretion
What is the effect of the sympathetic nervous system on energy stores?
Activates a/b receptors on hepatocytes
-Stimulates glygogenolysis and gluconeogenesis
Actovates a/b receptors on lipocytes
-Increases lipolysis
What is the effect of the parasympathetic nervous system on energy stores?
No effect
What is the effect of the sympathetic system on salivary glands?
Activates b receptors
-Stimulates thick secretion rich in enzymes
What is the effect of the parasympathetic system on salivary glands?
Activates muscarinic receptors
-Stimulates profuse watery secretion
What is the effect of the sympathetic system on the bladder?
Activates b2 receptors on smooth muscle of bladder wall
-Reduces pressure
Activates a1 receptors on smooth muscle of sphincter
-Contracts smooth muscle and stops urination
What is the effect of the parasympathetic nervous system on the bladder?
Activates muscarinic receptors on bladder wall
-Increases pressure
Activates muscarinic receptors on sphincter
-Relaxes smooth musce and causes urination
What is the effect of the sympathetic system on the reproductive tract?
Activates a1 receptors on smooth muscle of urethra
-Contracts smooth muscel and causes ejactulation
What is the effect of the parasympathetic system on the reproductive tract?
Activates muscrainic receptors on smooth muscle of corpus cavernosum
-Relaxes smooth muscle and causes erection
