week 4 autonomic nervous system Flashcards
what are the differences between the autonomic nervous system and the somatic nervous system
- the autonomic nervous system innervates stuff that you don’t think about e.g. smooth & cardiac muscle, glands, somatic innervates skeletal muscle
- there is a pre-ganglionic fibre and a post ganglionic fibre in the autonomic NS whereas in the somatic there is just one fibre
- in the somatic NS there is the NMJ which uses ionotropic receptors and always excites target, whereas in the autonomic it is a less specialised junction, uses metabotropic receptors and may excite or inhibit target
what are the two parts of the autonomic nervous system
Sympathetic
- fight or flight
Parasympathetic
- rest and digest
are the ganglion closer to the spinal cord or the target organ in the sympathetic nervous system
- in sympathetic the ganglion are close to the spinal cord
are the ganglion closer to the spinal cord or the target organ in parasympathetic nervous system
- closer to target organ
(think of it because fibres in parasympathetic only come from top and bottom of spine so why would they be close to the spinal cord)
what do you call outflow of parasympathetic nervous system
- cranio-sacral
what do you call sympathetic outflow
- thoracic-lumbar
- coming from all twelve thoracic regions and the first two lumbar regions
what are sympathetic paravetebral ganglia and collateral ganglia
- the paravertebral ganglia sit next to the spinal cord and look like a sort of ladder
- collateral ganglia are pre-vertebral ganglia (form a sympathetic chain)
what are the two autonomic nervous system neurotransmitters
- acetylcholine
- noradrenaline
what receptors does acetylcholine have in the autonomic nervous system
acts on cholinergic receptors
- nicotinic receptors (PREganglionic)
- muscarinic receptors (POSTganglionic)
what receptors does noradrenaline have in the autonomic nervous system
acts on adrenergic receptors
- alpha receptors
- beta receptors
what releases acetylcholine in the autonomic nervous system and what receptors does it act on
- both sympathetic and parasympathetic PRE-ganglionic fibres release acetylcholine
- this acts on nicotinic cholinergic receptors
what releases noradrenaline in the autonomic nervous system
- sympathetic POST-ganglionic cells of the adrenal medulla release adrenaline and noradrenaline into the blood which acts on alpha of beta receptors
so what are the steps in parasympathetic outflow
- pre-ganglionic fibres release acetylcholine which acts on nicotinic cholinergic receptors
- post-ganglionic fibres release acetylcholine which acts on muscarinic cholinergic receptors
what are the steps in sympathetic outflow
- PRE-ganglionic fibres release acetylcholine which acts on nicotinic cholinergic receptors
- POST- ganglionic fibres release noradrenaline which acts on alpha or beta adrenergic receptors
what is the sympathetic innervation of the eye
- alpha 1 receptors contract radial muscle of the eye = pupil dilates
- beta 2 receptors relax ciliary muscle
what is the parasympathetic innervation of the eye
- activates muscarinic receptors which contracts sphincter muscle of iris and pupil gets smaller
- muscarinic receptors contract ciliary muscle
what is the sympathetic innervation of the heart
- beta 1 receptors on pacemaker cells increase heart rate
- beta 1 receptors on myocytes increase strength of contraction
what is the parasympathetic innervation of the heart
- muscarinic receptors on pacemaker cells decrease heart rate
- little effect on myocytes, so parasympathetic has little effect on strength of contraction
what is the sympathetic innervation of the airways
- beta 2 receptors relax smooth muscle in airways and dilates the airways
what is the parasympathetic innervation of the airways
- muscarinic receptors make smooth muscle contract and constrict airways
what is the sympathetic innervations of the blood vessels
- depends on what receptors the tissues display
- beta 2 receptors in skeletal and cardiac muscle relax the smooth muscle of the vessels and increase blood flow (needed in these areas in fight or flight)
- alpha 1 receptors contracts smooth muscle of vessels elsewhere and restricts blood flow
what is the parasympathetic innervation of the blood vessels
- doesn’t innervate blood vessels except in the genitalia or the salivary glands
what is the sympathetic innervation of the salivary glands
- beta receptors stimulate thick secretion rich in enzymes
what is the parasympathetic innervation of salivary glands
- activate muscarinic receptors and stimulates profuse watery saliva
what is the sympathetic innervation of the bladder
- beta 2 receptors relax smooth muscle of bladder wall to decrease pressure (don’t want to pee in fight or flight)
- alpha 1 receptors contract sphincter to stop urination
what is the parasympathetic innervation of the bladder
- muscarinic receptors contract smooth muscle of bladder wall
- muscarinic receptors relax sphincter muscle and cause urination (diff. subtypes of muscarinic receptors)
what is the sympathetic and parasympathetic innervation of the reproductive tract
- sympathetic = alpha 1 receptors contract smooth muscle of urethra = ejaculation
- parasympathetic = muscarinic receptors relaxes smooth muscle of corpus cavernous = erection
