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8 Cards in this Set

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what are the functions of the ANS

Regulates function of involuntary organs including heart, blood vessels, the exocrine glands and thevisceral organs. In some organs ANS acts along with circulating endocrine hormones and locally producedchemical mediators.




Homeostatic control e.g. BP, temperature, blood glucose...


Regulates metabolism and coordinates body’s response to exercise and stress


Important in communication using unconscious expression of emotion (fear, anger, laughter etc) Mediates between brain and immune system to modulate immune responsiveness Assist endocrine system to regulate reproduction

What are the divisions of the ANS how they work together

symapthetic and parasympathetic .


Most regions supplied by both divisions. Often work reciprocally (e,g, Heart SNS ↑HR,PSNS ↓HR)


Sometimes work synergistically e.g In Gut SNS ↑ mucus , PSNS ↑ enzymes.


Some organs (skin and blood vessels) receive only SNS inputs -> regulation by variation in baseline firing rate of sympathetic nerves.

describe the sympathetic ANS

consists of two neuron efferent pathway originates from ganglia either side of thoracic/lumbar (thoracolumbar). NS – ganglia close to spinal cord – “long” post-ganglionic fibres project to effector.


Is "adrenergic".


Involved in utilisation of metabolic resources and emergency responses of the body. (fight and flight).

describe the parasympathetic ANS

consists of two neuron efferent pathway originates from nuclei in brainstem and caudal part of the spinal cord (craniosacral). ganglia are within / close to organs they innervate with “long” pre-ganglionic fibres (e.g. vagus).


Is "chlorenergic".


Involved in the restoration and buildup of the body's reverse and elimination of waste products. (rest and digest).




ANS also has sensory (afferent) component. Information in visceral afferents originates from visceral receptors including chemoreceptors, osmoreceptors, baroreceptors, temperature and painreceptors and can evoke autonomic reflex responses. They enter the CNS via dorsal root ganglia inparallel with somatic afferents. Information may or may not reach consciousness. Autonomicreflexes may be invoked by somatic as well as visceral afferents e.g. HR responses to pain.

describe what happens at the terminals of the postganglionic axons

Postganglionic axons terminate in varicosities (swellings containing vesicles) which release neurotransmitter into the extracellular space around effector cells. ANS activity originates in some of the effector cells then propagates to the remainder via gap junctions.

What are the neurotransmitters used by the ANS

acetylcholine


norepinephrine/noradrenaline


other neurotransmitters (co- released) neuropeptide Y with NE by vasoconstrictive nerves, vasoactive intestinal peptide and calcitonin-gene-related peptide with ACH in sweat glands. And NO by nonadrenergic non chloronergic autonomic nerve endings.

Acetylcholine receptors in ANS

at ganignial of both SNS and PNS are nicotinic receptors fos ACh and post ganglionic PSNS muscarinci and at postganglionic SNS to sweat glands and some blood vessels in muscle.


Action of Each on receptors terminated by acetylcholinesterase.

norepinephrine/noradreniline receptors in ANS

located at postganglionic SNS neuron terminal. activate by NE/NAdr from adrenal medulla.




Action of NE determined by receptor subtype (alphtypes 1 and 2 of beta types 1 2 and 3) receptors are defined by there response to agonists e.g. propanol acts as an agonist at beta but not alpha.




GPCR


action of NE terminated by diffusion away from synapse and reuptake into terminal