ANS I Flashcards
The ANS controls […]
Visceral organs
What are the three major divisions of the ANS?
The sympathetic system, the parasympathetic system, and the enteric system.
What type of tissue does each division of the ANS innervate?
Sympathetic: cardiac and smooth muscle, glandular tissue
Parasympathetic: cardiac and smooth muscle, glandular tissue
Enteric: digestive tract
The sympathetic system is activated in […] reactions.
Emergency fight-or-flight
The parasympathetic system is activated in […] reactions.
Rest-and-digest
When are the sympathetic system and parasympathetic system active?
They are both active all the time, but in different proportions depending on the situation.
What are the two types of neurons present in the sympathetic system?
Preganglionic and postganglionic
The preganglionic cells in the sympathetic nervous system originate in the […]
Ventral roots of the thoracic and lumbar regions of the spinal cord
The postganglionic cells in the sympathetic nervous system originate in the […]
Sympathetic ganglia
What is the the sympathetic ganglia?
It is the chain that runs along either side of the spinal cord where the pre and postganglionic neurons synapse in the sympathetic nervous system.
Compare the structure of the preganglionic sympathetic neuron and the postganglionic sympathetic neuron.
Because the preganglionic sympathetic neuron synapses on the ganglia right outside of the spinal cord, its axons are quite short.
The postganglionic neuron has a long axon, because it must go from the ganglia all the way to the organ.
Sympathetic preganglionic neurons release […], which activates […] on […]
Acetylcholine, nicotinic acetylcholine receptors, postganglionic neurons
Sympathetic postganglionic neurons release […], which activates […] on […]
Norepinephrine, alpha and beta adrenergic receptors, target organs
Explain how beta blockers work.
Norepinephrine activates alpha and beta adrenergic receptors. Beta blockers for the heart prevent the sympathetic nervous system from increasing your heart rate by preventing the activation of beta adrenergic receptors.
What type of receptors are alpha and beta adrenergic?
Metabotropic receptors.
Explain how alpha and beta adrenergic receptors affect their target cells.
Alpha and beta adrenergic receptors are metabotropic. Therefore, what the norepinephrine does depends on the biochemical properties of the target organ and cell. For example, it might cause some blood vessels to dilate, but it might causes others to constrict.
The axons from parasympathetic preganglionic neurons emerge from […]
The brainstem - cranial nerves 3, 7, 9, 10 - the sacral spinal cord.
Compare the structure of the preganglionic parasympathetic neuron and the postganglionic parasympathetic neuron.
The preganglionic neurons have very long axons, as they extend all the way from the brainstem nearly to the target organ. The postganglionic neurons have very short axons that just reach to the organs.
Parasympathetic input to the visceral organs is provided by the […]
Vagus nerve (cranial nerve 10)
Parasympathetic input to the salivary glands is provided by the […]
Facial (cranial nerve 7) and glossopharyngeal nerves (cranial 9)
Parasympathetic input to the eye is provided by the […]
Oculomotor nerve (cranial nerve 3)
Parasympathetic input to the bladder, large intestine, and reproductive organs is provided by the […]
Sacral spinal cord
Preganglionic parasympathetic neurons release […], which activates […]
Acetylcholine, postsynaptic nicotinic acetylcholine receptors
Postganglionic parasympathetic neurons release […], which activates […]
Acetylcholine, muscarinic acetylcholine receptors on the target organ
What type of receptor is a muscarinic acetylcholine receptor?
It is a metabotropic receptor
Describe how the sympathetic and parasympathetic systems affect the heart.
Sympathetic: increases heart rate and the strength of heart contraction
Parasympathetic: decreases heart rate and contraction.
The human enteric system contains […] neurons. How does this compare to the spinal cord?
100 million. This is as many as the spinal cord.
Describe the relationship between the enteric system and the parasympathetic and sympathetic systems.
The enteric system receives input from those systems but can function normally without external input.
What are the two types of neurons in the enteric nervous system?
Cholinergic neurons and adrenergic neurons.
What do cholinergic neurons do in the enteric nervous system?
They activate peristaltic contractions of the gut.
What do adrenergic neurons do in the enteric nervous system?
They suppress gut peristalsis and neurons that release neuropeptides, ATP, and NO
