ANS introduction Flashcards
Targets of the AUTONOMIC nervous system (4)
Exocrine glands, smooth muscle, cardiac muscle, metabolism host defence
Targets of the SOMATIC nervous system (2)
Skeletal muscle (diaphragm and respiratory muscle)
Targets of the NEUROENDOCRINE system (6)
Growth, metabolism, reproduction, development, salt/water balance, host defence
Components of the autonomic nervous system
Sympathetic (fight or flight) and Parasympathetic (rest and digest)
Actions controlled by the autonomic system
Pupillary constriction Cephalic (secretions) & Gastric (motility/secretions) phases of gastric secretions Basal control of heart rate
Effects of sympathetic activation (eye, trachea, heart, gastrointestinal, blood vessels, adipose, ureter/bladder, skin)
Eye = pupil dilation
Trachea = dilation Liver = glycogenolysis/gluconeogenesis
Heart = ↑ rate and contractility
Gastrointestinal = ↓ motility and tone/ sphincter contraction
Blood vessels = skeletal muscle dilation, skin/mucous membranes/splanchnic area constriction
Adipose = lipolysis Kidney = ↑ renin secretion
Ureters/bladder = relax detrusor + contract trigone/sphincter
Skin = piloerection + ↑ sweating
Effects of parasympathetic activation (eye, trachea, ureter/bladder, heart, gastrointestinal)
Eye = pupil & ciliary muscle contraction
Trachea = Constriction
Ureter/bladder = detrusor (contract), trigone/sphincter (relaxation)
Heart = ↓ rate and contractility
Gastrointestinal = ↑ motility, tone and secretions
Outline the pre and postganglionic neurotransmitters of the autonomic nervous system
Outline the action of the enteric nervous system
Sensory neurone attached to mucosal chemoreceptors and stretch receptors => detect chemical substances/gut wall tension from food => information to submucosal and myenteric plexus via interneurons =>motor neurones contract/relax smooth muscle
Substances released by the motor neurones of the enteric nervous system and their effects
CONTRACT smooth muscle = acetylcholine + substance P
RELAX smooth muscle = vasoactive intestinal peptide + nitric oxide
Describe nicotinic receptors
> At all autonomic ganglia
> Stimulated by nicotine/Ach
> Type 1 Ionotropic
> Pre ganglionic
Describe muscarinic receptors
> At all effector organs innervated by postganglionic parasympathetic fibres
> Stimulated by muscarine/Ach
> Type 2 - G protein-coupled
State the muscarinic cholinoceptor sub-types
M1 = Neural (forebrain - learning & memory)
M2 = Cardiac (brain - inhibitory autoreceptors)
M3 = Exocrine & smooth muscles (Hypothalamus - food intake)
M4 = Periphery: perjunctional nerve endings (inhibitory)
M5 = striatal dopamine release
Describe the action of adrenoreceptors
> At all effector organs innervated by postganglionic sympathetic fibres
> Stimulated by noradrenaline/adrenaline
> Type 2 G protein coupled
What receptors are found on effector organs using noradrenaline and adrenaline
a1, a2, b1, b2
