2.1 Introduction to the Autonomic Nervous System Flashcards
What are the 3 sections of the autonomic nervous system
sympathetic, parasympathetic and enteric
What is the enteric nervous system
A self contained group of nerves surrounding the GI tract (receiving inputs from somatic and autonomic)
Give examples of the information sent from afferent nerves to the CNS in the autonomic reflex arc
blood pressure levels, blood volume, temperature, distension of hollow organs, arterial PO2 PCO2 and pH
Give examples of the effectors that the efferent nerves in the autonomic reflex arc target
smooth muscle, cardiac muscle and exocrine glands
What are the 3 central regulatory areas of the autonomic nervous system and what do they each regulate
- medulla oblongata regulates respiration, heart rate and blood pressure
- midbrain regulates visual
- hypothalamus regulates temperature and osmolarity
What are the 2 types of signals that can be sent to the effector in the ANS
a parasympathetic (”rest and digest”) or sympathetic (”fight or flight”) signal
Give a couple of examples of organs with their sympathetic and parasympathetic actions
*dont need to know all of them
Eye:
sympathetic - Dilation of pupil (smooth muscle relaxation)
parasympathetic - Constriction of pupil (smooth muscle contraction)
Airways:
sympathetic - Dilation (smooth muscle relaxation - β receptors)
parasympathetic - Constriction (smooth muscle contraction)
Heart:
sympathetic - Increased heart rate, increased contractility (strength of contraction)
parasympathetic - Decreased heart rate, decreased contractility
Blood:
sympathetic - Constriction (smooth muscle contraction - α receptors); increased blood pressure
parasympathetic - No major effect (decreased blood pressure by decreased sympathetic activity)
GI Tract:
sympathetic - Relaxation, decreased motility, decreased secretions
parasympathetic - Increased motility, increased secretions
Adrenal Medulla:
sympathetic - activation
parasympathetic - no effect
Bladder
sympathetic - Relaxation of walls, closing of sphincter
parasympathetic - Contraction of walls, opening of sphincter
Genetalia
sympathetic - ejaculation
parasympathetic - erection
Describe the lengths of the pre and post ganglionic neurons in sympathetic and parasympathetic neurons
sympathetic: short preganglionic neuron and long postganglionic neuron
parasympathetic: long preganglionic neurons and short postganglionic neuron
Describe the preganglionic and postganglionic neurotransmitters used in sympathetic and parasympathetic neurons
sympathetic: acetylcholine as the preganglionic neurotransmitter and noradrenaline as the postganglionic neurotransmitter
parasympathetic: acetylcholine as the preganglionic neurotransmitter and acetylcholine as the postganglionic neurotransmitter
Describe the myelination of pre and post ganglionic neurons
preganglionic neruons are myelinated but post ganglionic neurons are not
Describe the preganglionic and postganglionic neurotransmitter receptors used in sympathetic and parasympathetic neurons
In the sympathetic nervous system a nictonic receptor is used for the acetylcholine in the preganglionic and an adrenergic alpha/beta receptor is used for the noradrenaline in the postganglionic. but in the parasympathetic nervous system a nictonic receptor is used for the acetylcholine in the preganglionic and a muscarinic receptor is used for the acetylcholine in the postganglionic
Describe how innervation causes the release of adrenaline from the adrenal medulla
Preganglionic splanchnic nerves (either sympathetic or parasympathetic) innervate chromaffin cells in the adrenal medulla. These chromaffin cells are neuroendocrine and act as a combination of a sympathetic ganglion and a gland so that adrenaline (epinepherine) can then be released.
