The autonomic nervous system (physiology) Flashcards
Three functions of the ANS
Integration of visceral functions
Maintenance of homeostasis
Integration of stress response
What are the two efferent neurons of the autonomic pathways
Preganglionic neuron
Postganglionic neuron
What is a ganglion?
A cluster of neuronal cell bodies outside the CNS.
What are the responses towards increased sympathetic activity. (5)
Vasocontriction
Pupil dilation
Increased heart rate and blood pressure.
Activation of sweat glands
Increased metabolic rate
At which vertebral level do we find the preganglionic fibers of the SNS?
T1 and L2
What is the structural difference btwn the preganglionic neurons of the SNS and PSNS?
SNS-They are short
PSNS-They are long
Where do we find the preganglionic fibres of the PSNS?
Cranial nerves:3,7,9,10 and S2-S4
Which neurotransmitter is released by the preganglionic neuron of the SNS and in which receptor does it bind to?
Acetylcholine, binds to nicotinic receptors.
Which neurotransmitter is released by the postganglionic neuron of the SNS and to which receptor does it bind to?
Noradrenaline, binds to adrenergic receptors.
To which effector organ does the postganglionic neuron of the SNS release Acetylcholine?
To sweat glands
What enzyme metabolizes noradrenaline during the synaptic transmission?
Monoamine oxidase (MAO)
Which hormones stimulates the sympathetic nervous system?
Noradrenaline and adrenaline
During sympathetic stimulation, to which receptors does:
A. Adrenaline binds to?
B. Noradrenaline binds to?
A. Both the alpha and beta receptors
B. Alpha receptors
What type of receptors are the alpha and beta receptors?
G-protein coupled receptors
Which receptor is found in smooth muscle cells and is excitatory?
Alpha-1 receptor
Which receptor is found in the preganglionic sympathetic neurons and is inhibitory?
Alpha-2 receptor
Which receptors are found in the membranes of cells in skeletal muscles, lungs, heart, liver etc and triggers metabolic changes?
Beta receptors
What role does the adrenal medulla play in the ANS?
Secretes neurotransmitters into general circulation.
What are the major effects of PSNS? (5)
-Vasodilation
-Pupil constriction
-Reduction in heart rate and blood pressure
- Secretion by digestive glands
-Constriction of respiratory passageways.
Which activities are controlled by the ANsS?
Emotional stages, heart activity and blood pressure, body temp, water balance, endocrine activity, ‘fight or flight’.
