PHS233 GI Introduction PDF

01 02 03 The gastrointestinal tract takes in food, digests it to extract and absorb metabolites for the growth and energy needs of the body plus fluid and electrolytes to replace losses, and expel the remaining waste. The gastrointestinal system consists of:...

01 02 03 The gastrointestinal tract takes in food, digests it to extract and absorb metabolites for the growth and energy needs of the body plus fluid and electrolytes to replace losses, and expel the remaining waste. The gastrointestinal system consists of: A long epithelium lined tube With functional sections separated by sphincters Connected to accessory exocrine glands. AKA the hepatopancreatic sphincter  Waha Paeoro (Larynx) Te pūnaha nakunaku kai Kōpani (epiglottis / lid) Pūkai Puku Kiripuku (stomach lining) Kōpiro nui Kōpiro iti Tero (used for rectum and anus) General principals of Regulation General principals of Regulation General principals of Regulation - Phases Cephalic phase Gastric Phase Intestinal Phase Preparative Digestive Controlled release Why phasic regulation? We will learn more about these phases and how they are regulated in later motility lectures and the gastric secretion lectures.  Starting from the lumen, which order for the four major layers that make up the wall of the intestines is CORRECT? muscularis externa : microvilli : somatic mucosa : villi : epithelium : neurons : sub-mucosa : mucosa : sub-mucosa : muscularis externa : muscularis externa : plicae muscularis : serosa serosa serosa serosa  Lecture 25 - Gut 2 FOCUS BREAK AstraZeneca – Envy. Opioid-induced constipation (OIC) awareness add : https://adage.com/videos/astrazeneca-envy/682  NEURAL REGULATION OF THE GI TRACT  The autonomic (parasympathetic, sympathetic,) NS Neurons include both motor (efferent) & Sensory (Afferent) neurons. They provide a route for interaction between CNS and ENS. They are not part of the ENS We learn that adrenaline from the sympathetic NS is inhibitory, but it needs an intermediary in the ENS! In neural regulation of the GI tract by the CNS: 1. The long reflex pathway generates a response to internal stimuli (GI lumen contents). 2. The sympathetic NS is usually stimulates GI function. 3. The parasympathetic NS usually inhibits GI function. 4. The Enteric nervous system is not involved in the response. Images show examples of enteroendocrine cells  AND A BRIEF DISCUSSION ON THE IMMUNE SYSTEM REGULATION OF THE GI TRACT WHAT DOES IT DO? Barrier function Active immune response Modulator of GI tract (and systemic) Physiology RESPONDS TO Food antigens, pathogens, commensal/mutualistic bacteria Releases inflammatory and other mediators that modulate GI function Histamine, prostaglandins, leukotrines, cytokines THE BARRIER FUNCTION OF THE GUT EPITHELIA Immune System Specific Structures Mesenteric lymph nodes and Peyers patches housing a range of immune cells. Immune cells : Intraepithelial lymphocytes, B cells, T cells, mast cells, macrophages, eosinophils. Compare and contrast general regulation of the GI tract by the ENS, the CNS, and hormones. Consider the duration of the response and the advantages and disadvantages of each. We will go over some answers briefly at the start of the next lecture and that will serve as a lecture summary. Note: while there are no mini essays for 233 this year, writing this type of mini essay is a good way to revise a lecture.