human anatomy and physiology - digestive system

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  • Created by: aarafa11
  • Created on: 08-04-20 22:29
what is part of the enteric (GI) system
Mouth to anus; Long tube with different structures and functions
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what are the accessory found in the enteric (GI) system
Teeth; Tongue; Salivary glands; Liver; Gallbladder; Pancreas
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wha are the basic function of the enteric (GI) system
Ingestion; Secretion; Mixing and propulsion; Digestion; Absorption; Defecation
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what happens when you smell food
Salivary glands enzyme; Stomach begins to churn (muscles) and acid & enzymes are released; Pancreas and gall bladder activate; These are controlled by the CNS
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what enzymes do the Salivary glands produce
Serous and mucous fluid (mucins); Amylase – breaks down carbohydrates; Lipase – lipid digestion; Immunoglobulin A (IgA)
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what happens when you have the first taste of food
Salivary glands release serous and mucous fluid; Digestion begins; Chewing (mastication) and mixing of food with tongue; Stomach muscles contract, acid and enzymes released
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when happens when you swallow food
Tongue helps move food bolus to the oropharynx (mouth); Skeletal muscles in the pharynx move food to esophagus; Oesophagus = a conduit to stomach; Muscles contract to allow peristalsis
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what is the function of the stomach
Storage of food; Mixing via muscle contractions; Parietal cells secrete HCl (Kills bacteria Degrades foods = chyme); Chief cells release pepsinogen – a zymogen; Pepsinogen combines with hydrochloric acid to form pepsin – cleaves proteins
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what are the types of cells found int he stomach
parietal cells; chief cells; Enteroendocrine cells; G cells
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what is parietal cells
Hydrochloric acid and intrinsic factor (needed for B12 absorption)
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what does chief cells do
Release pepsinogen
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what do Enteroendocrine cell do
Release regulatory hormones
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what does G cell do
Release gastrin
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what happens to food in the small intestine
Acidic Fluids flow into the small intestine; Digestion accelerates and pH neutralized to pH ~ 7; Absorption of building blocks through enterocytes to the liver via the portal blood system ;Undigested material remains
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what are the Acidic Fluids that flows into the small intestine
digestive enzymes and bicarbonate (HCO3-) added from Pancreas; Liver makes bile for lipid absorption; Water added and reabsorbed
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what are the division of the small intestines
duodenum; jejunum; ileum; large intestine; rectum
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what happens to the food in the large intestine
Dehydration of indigestible material; Compaction of indigestible material; Elimination of undigested material; Houses bacteria
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what are the accessory glands do in the digestive system
salivary glands; pacrease; liver; gallbladder
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what does the salivary gland do in the digestive system
Moistening/lubricating fluid with enzymes; Amylase helps break down starch; lipase - lipids
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what does the pancrease do in the digestive system
Release of digestive enzymes; Release of bicarbonate (HCO3- ) solution; Endocrine functions = insulin & glucagon
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what does the liver do in the digestive system
Makes bile -- helps dissolve fats; Receives and stores building blocks (aa, CHO, etc.) from intestine; Makes blood proteins; Detoxifies drugs
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what does the gallbladder do in the digestive system
Stores and concentrates bile (from liver
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what does the tongue do
mechanical processing, moistening, and mixing with salivary secretions
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what does the pharynox do
Muscular propulsion of materials into the esophagus
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what does the esophagus do
Conduit to the stomach
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what is digestion
Break down of foodstuffs to basic building blocks (aa, sugars, fats, nucleotides)
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what is absorption
Passage of building blocks from intestine via portal system to the liver
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what is elimination
Release of waste products and recovery of fluids
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what is absorbed into the epeithelial cells
Carbohydrate – glucose, fructose and galactose; Fat – free fatty acids, glycerol and monoglycerides; Protein – single AAs, dipeptides and tripeptides (90% in small intestine)
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what is the small intestine lined with
with columnar epithelial cells that contain microvilli
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what is the function of microvilli
Increase the surface area of the small intestine allowing more area for nutrients to be absorbed
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how are nutrients absorbed
villus has a network of capillaries and fine lymphatic vessels called lacteals. The epithelial cells of the villi transport nutrients from the lumen of the intestine into these capillaries ( amino acids and carbohydrates) and lacteals (lipids)
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what is the Celiac Disease
Autoimmune disease of the small intestine which leads to inflammation so less nutrients absorbed
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how does the celiac disease effect a person
Exposure to gliadin leads to an inflammatory response in the villi, which reduces the surface area available for nutrient absorption and can cause damage to the intestinal lining
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where to find gliadin protein
(component of gluten), a protein present in wheat barley and rye
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what does GI stand for
Gastrointestinal
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what are the layers of wall found in the lower oesophagus to the anus (GI tract)
Mucosa ;Submucosa; Muscularis; Serosa/ adventitia
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what is contained in the Mucosa wall
Muscularis mucosae; Lamina propria; epithelial
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what is contained in the Submucosa wall
Submucosal nerve plexus
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what is contained in the Muscularis wall
Inner circular layer; Myenteric nerve plexus; Outer longitudinal layer
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what is contained in the Serosa/ adventitia wall
(a) Tunics
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what are the control mechanism for digestion
neuronal and hormonal
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what are the types neuronal (neurocrine) mechanism in degestion
Short/ Intrinsic Reflex; Long /Extrinsic Reflex
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what is the Short/ Intrinsic Reflex mechanism
Neurons within the GI system (ENS = enteric nervous system); Signal from the lumen to the ENS and back; The only organ system capable of using a reflex response without the CNS
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what is the Long /Extrinsic Reflex mechanism
Neurons in the CNS – (outside the ENS); Signal from the lumen to the CNS and back to the GI tract
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what is the hormonal mechanism for digestion
enteroendocrine cells in the GI epithelium and endocrine glands
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what nervous system does extrinsic use
CNS
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what nervous system does intrinsic use
PNS = ENS (enteric)
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how does the intrinsic/ short reflex work
Sensory neurons receive signals from the lumen; Signals go to intrinsic Parasympathetic neurons; Sympathetic fibers – shut enteric system down;Interneurons important for local reflexes; Motor neurons drive smooth muscle
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what does the sensory neuron contain in the intrinsic/ short reflex
Mechanoreceptors - for stretch; Chemoreceptors - pH, osmolarity, food breakdown products
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what happens when Signals go to intrinsic Parasympathetic neuron in the intrinsic/ short reflex
Cause cell/gland secretions and muscle contractions
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what do the sympathetic fibres do in the intrinsic/ short reflex
Mostly inhibit parasympathetic neurons; Control blood flow
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what happes when there is an input from the 5 senses in the CNS signal to the GI system
Starts gland and cell secretions in mouth and stomach; Starts muscle contractions in stomach
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what happes when there Signals in GI are sent to the CNS
Sensory information(from GI) =afferent to CNS and response = efferent back to GI system = REFLEX;
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what signals will the CNS give to the enteric neurons when there Signals in GI are sent to the CNS
controls GI gland and cell secretions; controls GI muscle contractions– indirectly through ENS
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what influences can the CNS modify in the ANS(autanomic) when there Signals in GI are sent to the CNS
Parasympathetic and sympathetic
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what emotions can cause the CNS to effect the enteric system
Butterflies when flying 1st time; Talking in front of a class – mouth is dry; Really scared – urination or diarrhea
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what are the types of Hormonal Signaling Mechanisms
1)Autocrine – signal goes back to cell of origin 2) Paracrine – signal goes short distance to nearby cells. 3) endocrine mechanism
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what do Enteroendocrine cells do (hormonal mechanism)
‘ taste’ chemicals in the lumen
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what does Enteroendocrine cells release (hormonal mechanism)
peptide hormones released into the blood; Function via paracrine & endocrine mechanisms; Controls secretion of gland cells & enhance or inhibit muscle contraction; Influence intrinsic and extrinsic nervous system input
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what are the endocrine hormones (hormonal mechanism)
insulin; glucagon
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what do exocrine glands release products through
duct system
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what do endocrine glands release products through
circulation (blood vessels) to circulate to target cells; enteroendocrine cells secrete peptides; GI is the largest endocrine gland –
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what do Enteroendocrine cells respond to (taste buds of the gut)
mechanical/chemical events in the lumen; Secrete peptides – paracrine & endocrine (into the circulation); Some also respond to CNS neural inputs
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examples of Enteroendocrine cells secreting peptides
Example: G cells release gastrin – a peptide; Gastrin – to near cells and enters into blood vessels and controls (Cell secretion, Muscle motility)
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what do the exocrine glands do
Salivary glands make H20 and enzymes; Liver makes bile; Pancreas makes digestive enzymes and bicarbonate (HCO3-); Duodenal glands make bicarbonate (HCO3-) to neutralize HCl
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what do the skeletal muscle do
Voluntary control from CNS; Tongue and pharynx; Upper 2/3 esophagus; Anal region sphincter
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how does the intrinsic muscle control the smooth muscle
from enteric parasympathetic neurons on:
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what are the enteric parasympathetic neurons that the intrinsic control (smooth muscle)
Muscularis mucosa: smooth muscle; Muscularis externa: inner circular and outer longitudinal bands
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how does the extrinsic muscle control the smooth muscle
from the CNS neurons CNS neurons stimulate ENS parasympathetic neurons; Control muscles in the enteric nervous system; Modified by sympathetic neurons
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what are the Necessary functions of smooth muscle motility
Mixing of food, acid and enzymes in the stomach; Slow release of chyme into the small intestine; Controls movement through small intestine and thus rate of digestion; Movement and removal of indigestible material
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what are the structure of smooth muscle cells (smooth muscle motility)
Closely positioned elongated cells w/o direct synapses; Gap junctions allow synchronous contractions of many cells
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what are the causing agents of smooth muscle motility
Release of neurotransmitter from ENS neurons; Signal molecules (e.g. histamine)
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Card 2

Front

what are the accessory found in the enteric (GI) system

Back

Teeth; Tongue; Salivary glands; Liver; Gallbladder; Pancreas

Card 3

Front

wha are the basic function of the enteric (GI) system

Back

Preview of the front of card 3

Card 4

Front

what happens when you smell food

Back

Preview of the front of card 4

Card 5

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what enzymes do the Salivary glands produce

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