the autonomic nervous system Flashcards

1
Q

what processes happen in our bodies when we sleep

A

-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

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2
Q

what are the major components of the nervous system

A

-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

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3
Q

what does the sympathetic nervous system entail of

A

-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

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4
Q

what does the parasympathetic nervous system entail of

A

-rest and digest
-activated when digesting, defecation, and diuresis (excess of urine)
-activated by functions in a discrete, organ specific manner

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5
Q

examples of sympathetic stimulation

A

-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

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6
Q

examples of parasympathetic stimulation

A

-eyes: pupils constrict
-heart: decreases heartrate
-gastrointestinal tract: activated
-bladder: contraction of bladder wall and relaxation of urinal sphincta

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7
Q

is there a good balance between sympathetic and parasympathetic nervous systems

A

-yes
- they work synergistically together allowing rapid and precise control of tissue function

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8
Q

what is mainly sympathetic innervation

A

-sweat glands, hair follicles, blood vessel smooth muscle and adrenal medulla= all sympathetic

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9
Q

what’s the general organisation of the ANS

A

-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

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10
Q

what are preganglionic neurons

A

-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

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11
Q

what is the sympathetic pathway

A

-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)

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12
Q

why is the adrenal medulla an exception to the anatomical organisation

A

-chromaffin cells function similar to postganglionic neurons but release mainly adrenaline
-target tissues expresses alpha and beta adrenergic receptors

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13
Q

what’s the parasympathetic pathway

A

-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)

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14
Q

what are the essential central components of the ANS

A

-spinal chord: mediates autonomic reflexes, receives sensory afferent brainstem input
-brainstem: mediate autonomic reflexes

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15
Q

what does the integration and co-ordination by the hypothalamus control

A

-feeding
-thermoregulation
-circadian rhythms
-water balance
-sex drive
-reproduction

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16
Q

what else regulates ANS output

A

-forebrain: minimal conscious cortical control but cortical processes do regulate autonomic output e.g. anxiety leading to GI disturbance
-visceral afferents: sensory input from visceral afferent neurons takes priority over cortical functions e.g. bladder distension