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  • 1. Accessory glands
    Salivary glands, liver and pancreas produce secretion that discharged into the lumen of GI tract
    Salivary glands: Produce saliva that moistens ingested food, cleanses and protect the mouth
  • 2. Pancreas
    • Mixed gland that has both exocrine and endocrine functions
    • 3. The exocrine secretions are the digestive juices
    • 4. Acinar cells produce the juices and ducts carry them to the small intestine
    • 5. Endocrine products of pancreas
    • 6. Insulin
    • 7. Glucagon
    Slide 14.38
  • 8. Liver
    • Largest gland in the body
    • 9. Located on the right side of the body under the diaphragm
    • 10. The major function is production of bile
    • 11. Connected to the gall bladder via the common hepatic duct
  • Bile
    Slide 14.40
  • 18. Gall Bladder
    • Hollow organ, divided into fundus, body and neck
    • 19. Stores bile from the liver by way of the cystic duct
    • 20. Bile is introduced into the duodenum in the presence of fatty food
    Slide 14.41
  • 21. Control of the digestive system
    The autonomic nervous system, hormones and other chemical messengers control motility and secretion in the gastrointestinal system to maximize digestion and absorption
  • 22. Control of the GI Tract depends on the location of food
    Control of the digestive system progresses from the head to the stomach to the small intestine as foods moves through GI tract
    Cephalic
    Gastric
    Intestinal
  • 23. During the cephalic phase receptors for sight, smell and taste initiate reflexes that caused salivation, production of gastric juice and gastric contraction
    These responses are mediated by Vagus nerve and prepare the GI system for the arrival of the meal
  • 24. During the gastric phase, the meal in the stomach
    The stomach content and volume initiate reflexes that cause production of gastric secretion and motility
  • 25. During intestinal phase of control, the intestinal content and volume initiate reflexes that caused secretion of digestive enzyme, bile and bicarbonate and begin contraction
    The phases of control occur in sequence only at the beginning of the meal. Once the meal is underway the phases are simultaneous
  • 26. Parasympathetic and Sympathetic Nerves
    Parasympathetic and sympathetic divisions of the autonomic nervous system regulate the digestive tract
  • 27. Somatic VS Autonomic
    Voluntary
    Skeletal muscle
    Single efferent neuron
    Axon terminate release acetylcholine
    Involuntary
    Smooth, cardiac muscles, glands
    Multiple efferent neuron
    Axon terminates release acetylcholine or norepinephrine
  • 28. Comparison of Autonomic and Somatic Motor Systems
    Autonomic nervous system
    Chain of two motor neurons
    Preganglionic neuron
    Postganglionic neuron
    Pre-ganglionic
    Post-ganglionic
    Ganglion
  • 29. Autonomic and Somatic Motor Systems
  • 30.
  • 31. Divisions of the Autonomic Nervous System
    Sympathetic and parasympathetic divisions
    Innervate mostly the same structures
    Cause opposite effects
    Parasympathetic impulses promote digestive processes and sympathetic impulses depress digestive activity
    In the digestive tract autonomic fiber contact neurons in independent nervous system called the enteric nervous system (ENS). Consider the third division of the (ANS)
  • 32. The enteric nervous system
    The submucosal and myenteric plexuses comprise of the (ENS)
    There are many sensory neurons and motor neurons in this complex
    Thus, ENS can independently carry out many digestive functions (e.g. peristalsis)
  • 33. Reflexes coordinate digestive activity
    Stimuli from the GI tract are sent to CNS for processing. Responses generated from the CNS and converted to the gut are called long reflexes
    Stimuli in one part of the GI tract is processed in the ENS and produces an effect in another part of the tract. These called short reflexes
  • 34. The volume (heavy meal produces stronger contractions compared to light meal) and content (Fat meal empties more slowly from the stomach than a high carbohydrate meal) of a meal initiate reflexes that modulate motility and secretion of the GI system
    Reflexes coordinate digestive activity
  • 35. Stressors such as strong emotion, worry and anxiety affect digestive activity. Signals from the central neuron system override the auto regulatory control of the digestive system and caused upsets like stomachaches, constipation or diarrhea.
    Reflexes coordinate digestive activity