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35 Cards in this Set
- Front
- Back
What can be defined by nausea?
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Subjective unpleasant sensation
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How nausea happens?
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Stimulation of the medullary (brain stem) vomiting center
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Nausea is preceded by?
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Anorexia - due to;
- Lack of desire to eat despite physiologic stimuli that normally produce hunger - Some stimuli (e.g. foods and drugs) |
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In what aspects nausea is accompanied by autonomic responses?
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- Salivation
- Peripheral vasoconstriction with pallor - Sweating - Tachycardia |
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Nausea can be an early warning signal of pathology to?
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- GIT
- Pulmonary - Hepatic - Renal - CNS |
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How vomiting can act as basic physiologic protective mechanism?
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Limits possibility of damage from ingested noxious agents - By emptying the contents of the stomach and upper part of small intestine
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How vomiting can represent total-body response to many factors influencing functional state of stomach?
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- Directly affect vomiting center / chemoreceptor trigger zone in brain stem
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Where can we find chemoreceptor trigger zone?
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Area postrema, floor of fourth ventricle
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How chemoreceptor trigger zone is activated?
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By reaction to input of emetogenic (emesis = vomiting) substances from blood / CSF
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Where is vomiting center?
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Dorsal part of reticular formation
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Vomiting center gets info from?
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Emetogenic signals from;
-Chemoreceptor zone - Vestibular system - Hypothalamus - Thalamus - Psychic stimuli (Emotions, Stress) - Peripheral signals from GIT |
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How peripheral signals come from GIT?
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Via vagus nerve, CN X
Via splachnic nerves From stomach, upper intestine |
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How efferent signal activate vomiting?
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- CN VII
- CN IX - CN X - CN XII - Spinal cord (diaphragm, abdominal wall) |
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What are neuromediators of vomiting?
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- Dopamine
- Serotonin |
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Two types of stimuli that can lead to vomiting?
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- Peripheral stimuli (from GIT)
- Central stimuli |
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Where peripheral stimuli influence directly?
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On center within CNS
- Chemoreceptor zone - Vomiting center |
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Meaning of central vomiting?
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Complications of some other primary pathological process
- Can be warning for early diagnostics / intervention of pathological CNS process |
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Peripheral vomiting is due to?
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- Mechanical stimuli
- Chemical stimuli - Ischemia / hypoxia of stomach - Signals from inflammation |
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How is mechanical stimuli causing peripheral vomiting?
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- Distension of stomach
- Distension of duodenum - Mechanical influence of solar plexus - 3rd trimester of pregnancy - Renal-gastric reflex |
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Why stomach is distended?
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- Overeating
- Upper ileus |
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Why duodenum is distended?
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- Dumping sy
- Ileus |
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Why 3rd trimester pregnancy can cause peripheral vomiting?
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Enlarged uterus compresses stomach
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How renal-gastric reflex can cause peripheral vomiting?
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Obstruction of ureter by stone
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Why chemical stimuli is important to cause vomiting?
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Prevent toxin absorption
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But, some toxins are not recognized. Examples?
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Phalloidin from toxic mushroom Amanita phalloides (hepatotoxic)
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So, how can we eliminate Phalloidin toxin?
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Evoke vomiting
- By oral intake of hypertonic solution of NaCl - By gastric suction |
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What can cause massive bleeding to esophagus / stomach?
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- Esophageal varices in portal hypertension
- Peptic ulcers |
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How bleeding can cause vomiting?
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Blood irritate chemical stimuli
- Cause vomiting of blood (hematemesis) |
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Why ischemia / hypoxia of stomach is dangerous?
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Because digestion is energetically demanding
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What can cause ischemia / hypoxia of stomach?
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- Extreme physical activity
- Stress - Circulatory shock - Heart failure - Respiratory failure - Drugs causing gastric vasoconstriction (also caffeine) |
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Why extreme physical activity can cause ischemia / hypoxia of stomach?
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Redistribution of blood to muscles
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How stress, circulatory shock, heart failure can cause ischemia / hypoxia of stomach?
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Centralization of circulation to vital organs
- By activating sympathetic activity - Causing vasoconstriction in splachnic area |
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Example of respiratory failure that can cause peripheral vomiting?
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Pneumonia in children
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Where can we get signals from inflammations that cause peripheral vomiting?
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- GIT
- Urinary system |
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Central vomiting is caused by?
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1. Chemical stimuli
2. Physical stimuli 3. Increased activation of stato-kinetic apparatus 4. Emotional reactions 5. Bad smell 6. Psychic disorders |