the autonomic nervous system Flashcards
what processes happen in our bodies when we sleep
-we metabolise things in our body
-we breathe
-temperature and heartbeat is regulated
-blood still reaches various organs
-nutrients absorbed
-sweat
-our autonomic nervous system ensures we survive despite a lack of conscious, cortical input
what are the major components of the nervous system
-somatic nervous system- muscles and temperature
-visceral nerves- gastrointestinal e.g. needing toilet
-these are both the sensory part of the peripheral nervous system
-somatic nervous system is voluntary (muscle contraction, aware you’re doing it
-autonomic nervous system is involuntary (motor part of peripheral nervous system)
-somatic = skeletal muscles
-autonomic= smooth muscle, cardiac muscle and glands (digestive ones)
-ANS receives sensory information about the state of the body and makes any required changes to maintain a steady state
what does the sympathetic nervous system entail of
-fight or flight
-activated during exercise, excitement, emergency, embarrassment
-can be organ specific or not
-activated by co-ordination, a whole body response or discrete and organ specific
what does the parasympathetic nervous system entail of
-rest and digest
-activated when digesting, defecation, and diuresis (excess of urine)
-activated by functions in a discrete, organ specific manner
examples of sympathetic stimulation
-eyes: pupillary dilation, eyelid contracts to lift
-heart: increases heart rate and force of contraction
-blood vessels: can restrict or dilate depending on what’s needed
-lungs: increasing diameter of airways- more O2 in and more CO2 out
-liver: creates glucose for more energy
-bladder: innovation of bladder as you don’t want to urinate during fight or flight
-adrenal medulla: produces more adrenaline
-discrete functions include reproductive systems for an orgasm
examples of parasympathetic stimulation
-eyes: pupils constrict
-heart: decreases heartrate
-gastrointestinal tract: activated
-bladder: contraction of bladder wall and relaxation of urinal sphincta
is there a good balance between sympathetic and parasympathetic nervous systems
-yes
- they work synergistically together allowing rapid and precise control of tissue function
what is mainly sympathetic innervation
-sweat glands, hair follicles, blood vessel smooth muscle and adrenal medulla= all sympathetic
what’s the general organisation of the ANS
-centrals nervous system first has the preganglionic neuron
-after this the peripheral ganglion (group of neurone clustered together) has the postganglionic neuron
-this then reaches the target cell
what are preganglionic neurons
-always cholinergic fibres e.g. ACh
-ACh activates nicotinic ACh receptors on the postsynaptic cell
-fires action potentials and these reach presynaptic terminal and release ACh into synaptic cleft
what is the sympathetic pathway
-in spinal chord
-short, cholinergic preganglionic neurone from thoracic and lumbar spinal chord
-long adrenergic postganglionic neurons
-target tissue expresses alpha and beta adrenergic receptors (G protein receptors)
why is the adrenal medulla an exception to the anatomical organisation
-chromaffin cells function similar to postganglionic neurons but release mainly adrenaline
-target tissues expresses alpha and beta adrenergic receptors
what’s the parasympathetic pathway
-long cholinergic preganglionic neurons from brainstem and sacral spinal chord
-short cholinergic postganglionic neurons
-target tissue expresses muscarinic ACh receptors (another G protein coupled receptor)
what are the essential central components of the ANS
-spinal chord: mediates autonomic reflexes, receives sensory afferent brainstem input
-brainstem: mediate autonomic reflexes
what does the integration and co-ordination by the hypothalamus control
-feeding
-thermoregulation
-circadian rhythms
-water balance
-sex drive
-reproduction