ANS Flashcards
(46 cards)
Autonomic nervous system
- central nervous system
- peripheral nervous system
3a. autonomic nervous system
- visceral
- sympathetic
- parasympathetic
3b. somatic nervous system
- motor
- sensory
sympathetic nervous system
- nerves arise from thoracic and lumbar spinal cord
- ganglia close to CNS
- prepares body to cope with emergencies and intense muscular activity
parasympathetic nervous system
- maintenance function, conserves and stores energy
- nerves from brain
autonomic nervous systen function
maintain homeostasis
- operates via a 2 neuron system
1. preganglionic
2. post ganglionic
nerve conduction pathway
- resting state
- depolarisation phase
- repolarisation phase
- undershoot
- resting phase of nerve conduction
- 70mV
maintained by sodium potassium pump
all channels closed
- depolarisation phase of nerve conduction
Na channels open
K channels close
at peak depolarisation Na channels inactivated
- repolarisation phase of nerve conduction
K channels open
All Na channels inactivated
- undershoot phase of nerve conduction
K channels remain open Na channels closed
neurotransmitter for parasympathetic nervous system
acetylcholine
neurotransmitter for sympathetic nervous system
noradrenaline
physiological roles of the ANS
- regulation of the heart
- blood pressure, heart rate and contractility - regulation of secretary glands
- salivary, gastric, sweat and bronchiole - regulation of smooth muscles
sympathetic nervous system
activation of sympathetic NS results in
- fight or flight
- elevated levels of adrenaline
- dilation of pupils = far vision
- bronchodilation
- increased heart rate
- raised blood pressure
- elevated glucose levels
- increased energy consumption
activation of parasympathetic NS results in
- rest and digest
- pupil constriction
- reduction of heart rate
- reduction of blood pressure
- increased gut movement
- increased absorption of nutrients
- promotion of bladder and rectal emptying
receptors of the ANS
4 adrenergic receptors
- α1 – blood vessels, pupils, urinary bladder sphincter
– α2 ‐ pancreas
– β1 – heart
– β2 –bronchioles in lungs
2 cholinergic receptors
– Nicotinic – first synapse of both SNS and PNS
– Muscarinic – effector organ (heart, smooth muscle and gland)
mast cell activation during anaphylaxis
- release mediators (histamine, arachidonic acid, prostaglandins, cytokines)
- temporary constriction
- then vasodilation decreasing blood pressure
- contraction of smooth muscle cells in lung causing constriction of airways
signs and symptoms of anaphylaxis
- difficulty breathing
- gastrointestinal cramps
- drop in blood pressure
- itching
- swelling
why is there difficulty breathing during anaphylaxis
- bronchoconstriction
- increase in mucus production
why is there gastrointestinal cramps during anaphylaxis
- increased intestinal contraction
- vomiting
why is there a drop in blood pressure during anaphylaxis
- vasodilation
- peripheral pooling = dizziness
- decreased cardiac output
- relative hypovolaemia (increased capacity in blood vessels)
why use an epipen
contains adrenaline which activated the sympathetic nervous system
parasympathetic stimulation on eye
pupil constriction and close visionM3M2
- increased lacrimal gland secretion (tears) M3M2
- stimulate contraction of the iris circular resulting in constriction M3M2
- stimulate contraction of ciliary muscles enables lens to focus of close objects
sympathetic stimulation on eye
pupil dilation and allows far vision B2
- stimulate contraction of iris radial muscle = dilation A1
- beta receptor stimulation of ciliary body = increase production of aqueous humour B1B2
