Autonomic Nervous System Flashcards
What is the cardiac output?
Volume of blood per minute by each ventricle
How do you calculate cardiac output?
Stroke volume multiplied by heartbeat
How are heart rate and stroke volume regulated?
The autonomic nervous system
Are autonomic nerves voluntary or involuntary?
Involuntary, subconscious
How does the autonomic nervous system effect the blood vessels?
Tone of vascular smooth muscle
What does a reflex limb contain?
Afferent limb
A central component located in the spinal cord, brain stem, hypothalamus
Effector pathway
Where does sensory input come from in the case of the ANS?
Visceral organs
What are the two divisions of the autonomic nervous system?
Sympathetic
Parasympathetic
Where is the cardiac control centre in the brain?
The pons
What are the names given to the two efferent nerves in the autonomic nervous system?
Preganglionic neuron
Postganglionic neuron
Where is the cell body of the preganglionic neurons?
CNS
Where is the cell body of the postganglionic neurons?
Autonomic ganglion
Where do the preganglionic neurons of the sympathetic division originate?
T1 to L2 segments of the spinal cord
Where do the preganglionic neurons of the sympathetic division synapse?
Paravertebral ganglia
Prevertebral/collateral ganglia
Within adrenal medulla
Where do the paravertebral ganglia lie?
Either side of the spinal cord
Where do the prevertebral ganglia generally lie?
Abdominal cavity
What do the paravertebral ganglia form?
Sympathetic chain of ganglia
Where do preganglionic neurons of the parasympathetic division originate?
Brain and sacral level of the spinal column
Where are the terminal ganglia located?
Close to or within target organs
Which nerve originates from the sacral region of the spinal column?
Splanchnic nerve
What feature do postganglionic nerve fibres have?
Varicosities
What is synthesised and released from varicosities?
Neurtransmittors
What name is given to the sites of varicosities?
Neuroeffector junctions
What neurotransmitter does the sympathetic system releases?
Noradrenaline/Norepinephrine
What response is evoked from norepinephrine being received by organs?
Adrenergic response (after the receptors)
What are noradrenaline and adrenaline?
Catecholamines
What neurotransmitter may certain sympathetic nerves release?
Acetylcholine
What neurotransmitter does the parasympathetic nervous system release?
Acetylcholine
What is the name of the response when ACh binds to the organ?
Cholinergic response
Are receptor proteins specific or non-specific for neurotransmitters?
Specific
What does the activation of the receptors initiate?
Intracellular signalling cascade
What are the two main signalling cascades in the ANS?
Adenylyl cyclase - cAMP pathway
Phosphoinositide pathway
What is an agonist?
Activator of a receptor
What is the function of adenylyl cyclase do?
Convert ATP to cAMP
What can cAMP do?
Activate a kinase
What does the kinase do?
Phosphorylate cells initiating a cell response
What is the function of phospholipase C?
Acts on lipids on surrounding lipid bilayer breaking it down into inositol trisphosphate and diacylglyerol
What is the function of inositol trisphosphate?
Opens calcium channels in intracellular calcium stores affecting the response in the cell
What is the function of diacylglycerol?
Activates kinases
What receptors do noradrenaline bind to?
Adrenergic recptors
What are the 5 subtypes of adrenergic repsonses?
Alpha 1, alpha 2, beta 1, beta 2, beta 3
What do alpha adrenoceptors do?
Activate the phosphoinositide pathway and inhibit the cAMP cascade
What do beta adrenoceptors do?
Activate the cAMP cascade
What does acetylcholine bind to?
Cholinergic receptors - nicotinic and muscarinic receptors
Where are nicotinic receptors located in the ANS?
Synapses between the preganglionic and postganglionic neurons
Where are muscarinic receptors present in the ANS?
Binding site from parasympathetic postganglionic neurons
What are the five subtypes of muscarinic receptors?
M1-M5
What does atropine do?
Inhibit muscarinic receptors
What does the sympathetic effect do to the heart rate?
Increases it
What does the sympathetic effect do to the conduction of the heart?
Increased rate
What does the sympathetic effect do to the strength of the heart?
Increase it
What does the sympathetic effect do to the blood vessels?
Mostly constriction; affects all organs
What does the sympathetic effect do to the bronchioles?
Dilation
What does the sympathetic effect do to the mucous glands?
Inhibition of secretion
What does the parasympathetic effect do to the heart rate?
Decrease it
What does the parasympathetic effect do to the heart’s conduction?
Decreased rate
What does the parasympathetic effect do to the strength of the heart?
N/A
What does the parasympathetic effect do to the blood vessels?
Dilation in a few organs
What does the parasympathetic effect do to the bronchioles
Constriciton
What does the parasympathetic effect do to the mucous glands?
Stimulation of secretion
What name is given to the innermost area of the adrenal gland?
Adrenal medulla
What is the adrenal medulla?
Ganglion of sympathetic nervous system
What name is given to the postganglionic cells in the adrenal medulla?
Chromaffin cells
Why is this name given to the postganglionic cells in the adrenal medulla?
They stain brown with chromic acid
What will chromaffin cells do in response to activation by preganglionic cells?
increases synthesis and release of catecholamines
What is the only difference between adrenaline and noradrenaline?
Methyl group in adrenaline
What percentage released into circulation is adrenaline?
80%
What do noradrenaline and adrenaline act as?
hormones
What do noradrenaline and adrenaline act as?
hormones
What may cause a response in the sympathetic pathway?
Hypovolemia
Trauma
Pain
Hypoglycaemia
Hypothermia
Anxiety
What are the cardiovascular effects of adrenaline?
Increased heart rate
Increased cardiac output
Raised blood pressure
Vasodilation of skeletal muscle blood vessels
Vasoconstriction of gastrointestinal, renal and splenic beds
What receptors does adrenaline have a high affinity for?
Beta 2 adrenergic receptors
What do Beta 2 adrenergic receptors do?
Trigger smooth muscle relaxation
What adrenergic receptors are found on GI, renal and splenic beds?
Alpha 1 and alpha 2 adrenergic receptors
What do the alpha-adrenergic receptors do?
Trigger smooth muscle contraction
