By: M.H..D. as a h s ti t Lec e t c u t re r e 1

Transcription

1 By: M.H.Dashti Lecture 1

2 To Provide: Water & electrolytes Energy needs of body from nutrients Carbohydrates Lipids Proteins Essential Elements Some amino acids which can t be synthesized in the body _valine, methionine, leucine Vitamins Trace elements and salts

3 Daily use of Calories is 30-40X BW in Kg. So a 75 Kg woman burns 2250 to 3000 Calories/ day (about enough to run a small car for 1.5 Km) 1 calorie is the amount of energy require to raise the temperature of a ml of water 1 degree C. Food and Energy : Carbohydrates -- 4 Cal/gram Proteins -- 4 Calories/gram Fats -- 9 Calories/gram

4 Sitting 1.7 Calories/min Walking 3.8 Calories/min Biking 7 Calories/min Rowing 11 Calories/minute

5 The alimentary canal or gastrointestinal tract (GIT) consists of : Main digestive organs: mouth, pharynx, esophagus, stomach, small intestine, and large intestine Accessory digestive organs : teeth, tongue, salivary glands, liver, gallbladder and pancreas

6 1. Mucosal layer 2. Submucosal layer 3. Muscularis layer 4. Serosa layer

7 Circular folds or valvula connlvents 3x surface area Villi (~mm) 10x surface Microvilli (~nic) 20x surface

8 sub mucosal or Meissner s plexus Myenteric or Auerbach s plexus Produce Reflex Arches Sensors (stretch,chemo or osmo receptors) Afferent neurons Integrating center Efferent neurons Effectors( smooth muscle or epithelial cells) ENS

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10 parasympathetic Vagal nuclei sacral spinal cord Vagal nerves Extrinsic Neuronal Pathways To GIT sympathetic Central Nervous system preganglionic fibers sympathetic ganglion pelvic nerves Enteric Nervous System Myenteric plexus Meissner s plexus postganglionic fibers smooth muscle cells Secretory cells Endocrine cells Blood vessel's

11 Pre,v,g CNS EFECTOR stimuli Sensory receptor Local / Enteric Reflex EFECTOR ENS Sensory receptor stimuli Short / Prevertebral Reflex EFECTOR ENS Sensory receptor stimuli Long / Central Reflex

12 Functions of the Digestive System Ingestion Transport (propulsion) via GI motility ) Digestion: mechanical_ via GI motility Chemical secretion by GIT Bacterial_ by GIT flora storage Absorption Defecation Bacterial Digestion

13 Activity of single unit smooth muscles in GIT

14 oral Law of the gut anal

15 Myenteric plexus CGRP S.L.N relaxation L.L.N contraction Muscularis externa oral lumen Contraction by Sp/Ach Stretch Receptor bolus NO/VIP/ATP SP/5HT Direction of propulsion Aboral 5-HT= serotonin, Ach= acetylcholine; NO= nitric oxide; SP= substance P; VIP= vasoactive intestinal polypeptide, CGRP= calcitonin gene-related peptide

16 Exocrine Secretion of Water and Electrolytes Enterocyte Na + H 2 O Na + Cl - 2Cl - K + 3Na + 2K + K + Enterocyte Tight Junction

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18 vasodilator substances are: Endocrine secretion of cholecystokinin, vasoactive intestinal peptide, gastrin, and secretin. Paracrine secretion of kinins such as kallidin and bradykinin, Direct effect of decreased oxygen concentration and via increase of adenosine

19 By: M.H.Dashti Lecture 2

20 Motility :ingestion (voluntary, CN VII),mastication & buccal swallowing (voluntary) Secretion _saliva Chemical digestion amylase (ptyalin) begins starch digestion at ph of 6.5 or 7.0 found in mouth lingual lipase begins breakdown of triglycerides into fatty acids and glycerol Absorption Lipid soluble subs. ( alcohol )

21 Feeding center control of food intake satiety center in the ventromedial controls the feeding center in in lateral hypothalamus Decrease Feeding (Anorexigenic) a- Melanocyte-stimulating hormone (a-msh) from proopipmelanocortin ( POM C ) neurons Cocaine- and amphetamine-regulated transcript (CART) Leptin Serotonin Norepinephrine Corticotropin -releasing hormone Insulin Cholecystokinin (CCK) Glucagon -like peptide (GLP) Peptide YY (PYY) Increase Feeding (Orexigenic) Neuropeptide Y (NPY) Agouti-related protein (AGRP) Melanin-concentrating hormone (MCH) Orexins A and B Endorphins Galanin (GAL) Amino acids (glutamate and g-aminobutyric acid) Cortisol Ghrelin

22 2 Golgi-tendon apparatus Successi ve _ GTA + Stretch Sensory & Inverse S.R receptor Trigemin stretch s nuclei Reflexes Are Masticator Mandibular fallow muscle Muscle One branch Sensory & motor spindle Neurons and Extrafusal another Muscle spindle Of CN V integrating center & Is of Golgi- Mandibular Intrafusal fibers branch fibers Tendon Of Trigeminal nerve

23 Three pairs of produces1-1.5 L Saliva/ day. Parotid (25%) serous Submandibular (70%) seromucous Sublingual (5%) mucous

24 , Anxie Or IP 3 via Ach & SP

25 eptors and pressoreceptors thought smell sound sight CN IX CN IX from CN VII, V CN VII from Inferio superior salivary r S.L & S.M nuclei Parotid salivar glands glandsy

26 Sympathetic Norepinephrine R. _ C AMP R._ IP 3 Parasympathetic via IP 3 Ach SP

27 The effect of parasympathetic innervations on blood flow to the salivary glands. Cellular mechanisms of nearly isoosmotic electrolyte secretion by serou s cells H 2 O

28 An isoosmotic solution containing Electrolytes Na +, K +, Cl, PO 42, Alkaline HCO 3 Digestive enzymes Metabolic wastes acid urea and uric Protective agents Mucous (alkaline mucin),lysozyme, thiocyanate, proline rich protein, leukoferin & IgA Xerostomea & tooth decay K

29 Cellular mechanisms of salivary modification in salivary striated and excretory ducts In the salivary ducts Na + & cl - are reabsorbed and K + & HCO 3- are secreted ISF ATP K + Na +

30 Normal value

31 Buccal phase Pharyngeal phase Coordination of numerous actions by CN V, vii, IX,X, XI & XII esophageal phase

32 voluntary: tongue pushes food to back of oral cavity against the soft palate Once food contacts touch receptors in the pharynx & Pharyngeal Tonsils next phase starts

33 Involuntary : 1-Tongue lift against hard palate to close the mouth 2-soft palate are lifted to close off nasopharynx 3-breathing stops & airways are closed because: a-vocal cords close b-epiglottis is bent over airway as larynx is lifted 4-Upper esophageal sphincter relaxes Epiglottis closes Upper esophageal Sphincter relaxes 5-Pharyngeal folds pulled away to form swallowing groove on the pharyngeal roof 6-A peristaltic wave passes the bolus to the esophagus

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