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26 Cards in this Set
- Front
- Back
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What is the structure-function relationship in the G.I. tract?
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Length and complexity of gut determined by ease of digestibility and processing of food
Short, simple gut = fast processing (carnivore) |
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What processes are under control in the digestive system?
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Mechanical processing (smooth muscle contraction)
Secretion of gastric juices Enzymatic breakdown Absorption |
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What are the 2 ways in which digestion is controlled?
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Neural and hormonal influences
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Which parts of the nervous system control the digestive system?
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Autonomic and enteric
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Give some examples of digestive hormones
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CCK, gastrin, histamine
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What is the sympathetic nervous system responsible for?
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Fight or flight response
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Which parts of the autonomic nervous system correspond to the intrinsic and extrinsic parts of the gut?
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Intrinsic - enteric NS
Extrinsic - Parasympathetic and sympathetic |
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Which part of the nervous system can reach the G.I. tract without communicating with the enteric NS?
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Sympathetic NS
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Which nerve connects the parasympathetic NS to the ENS?
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Vagus (oesophagus to small intestine) and pelvic (large intestine)
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What are pre-ganglionic fibres in the sympathetic nervous system?
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Fibres from CNS to prevertebral ganglia (where synapse occurs e.g. coeliac ganglia)
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What are post-ganglionic fibres in the sympathetic nervous system?
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Fibres between prevertebral ganglia to effector organ
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What are the neurotransmitters in the pre-ganglionic and post-ganglionic fibres?
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Pre-ganglionic - acetylcholine
Post-ganglionic - noradrenaline |
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What is the difference between post-ganglionic fibres in the sympathetic and parasympathetic nervous systems?
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Post-ganglionic fibres in the parasympathetic NS are enteric neurones because pre-ganglionic fibres synapse in the enteric NS
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Where do pre-ganglionic fibres of the vagus nerve and the pelvic nerve arise from, respectively?
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Vagus nerve - medulla
Pelvic nerve - S2 - S4 |
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In the parasympathetic NS, which fibres are excitatory and inhibitory?
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Pre-ganglionic - excitatory
Post-ganglionic - excitatory or inhibitory |
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What is the neurotransmitter of pre-ganglionic fibres of parasympathetic NS?
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Acetylcholine
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Which parts of the digestive system are innervated somatically?
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Pharynx/oesophagus
External anal sphincter For swallowing and defaecating |
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Which nerves control swallowing and defaecating?
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Swallowing - vagus nerve
Defaecating - pudendal nerve |
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Does the enteric NS need CNS control?
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Reflexes can operate independently of CNS
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What does the enteric NS control?
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Motility, fluid movement and blood flow
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Where is the myenteric plexus found?
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Between the outer longitudinal muscle and the inner circular muscle of muscularis propria layer
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What are the 3 types of neurone found in the enteric NS?
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Motor
Sensory Interneurone |
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What is an interneurone?
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The connection between motor and sensory neurones
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Name 4 enteric neurotransmitters
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Vasoactive intestinal peptide
Acetylcholine Substance P Nitric oxide |
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Can more than one neurotransmitter be found in a neurone?
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Yes (record is 7)
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Where is the submucous plexus found?
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Between inner circular muscle and submucosa
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