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List the functions of the Digestive System
- Ingestion
- Mechechincal Digestion
- Chemimal Diegestion Secretion
- Secretion
- Absorbtion
- Excretion
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What are the 4 layers of the digestive track?
- Serosa
- Muscularis Externa
- Submucosa
- Mucosa
- muscularis mucosa, lamina propria, epithelium linning
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Describe the Serosa:
Outer tough connective tissue membrane for PROTECTION
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Describe the Muscularis Externa:
Longitutdal & Circular muscle layers for CONTRACTION
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Describe the Submuscosa:
Loose connective tissue = blood vessels & glands for SECRECTION
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Describe the Mucosa:
- Made of three layers=
- Muscularis Mucosa (or Interna)
- Lamina Propria (connective tissue)
- Epithelium Linning (inner most)
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What does ENS stand for ?
Enteric Nervous System
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Describe the ENS / what special characteristic does it have ?
The G.I. Tract LITTLE BRAIN that functions independantly
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What are the functions of the Enteric Nervous System ?
- Sensory Neurons = montior GI tension, chemical & hormone levels.
- Monitor Interneuronal Circuts = controls GI muscles motility, blood flow & secretions
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What does the Enteric Nervous System consist of :
- Myenteric Plexus
- Submucosa Plexus
- Parasympathetic
- Symphathetic
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Describe the Myenteric Plexus of the ENS:
Linear chains of neorons located BETWEEN the Longitudal & Circular muscle layers
Control GI Muscels tone, contraction intensity, frequency & velocity
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Describe the Submucosal Plexus of the ENT:
nonlinear neurons SCATTERED in the submucosa
Controls intertinal secretions, digestion, and absorption
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What does the parasympethetic nervous system do to the ENS?
Activates ENS
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What does the sympethetic nervous system do to the ENS?
Inhibits the ENS
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________ are protien catalystis that speed up the digestion chemical reactions.
Protien Catalyistis
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Protien Catalyists speed up digestion @ _______ temperature.
Body temperature.
They are not altered during the reaction, but are SENSITIVE to changes in Temperature & pH
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Protien catalyists are _________ enzymes that use water to split food molecules.
Hydrolytic
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Mastication happens where? explain it.
- Mouth, is mechanical
- breaks down & lubicrates food for easy swallowing.
- increases surface area for enzyme action
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What chemical digestion happens in the mout?
Salivary Amylase tuens starch into Disaccharides
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Name the 3 types of salivary glands :
- Parotid
- Sublingual
- Submandibular
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Where are the Parotid Glands & what do they do?
- inferior to the zygomatic arch
- Serous Secretion + Amylase
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Where are the Sublingual Glands & what do they do?
- under the base of the tongue
- Mucous secretion only (mucins)
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Where are the Submandibular Glands & what do they do?
- on inner surface of the mandible
- Serous + Mucous + Amylase
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What are the phases of swallowing?
- 1. Buccal
- 2. Pharyngeal
- 3. Esophageal
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Describe the Buccal Phase of swallowing:
the tongue pushes the BOLUS of food from ORAL Cavity into the OROPHARYNX
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What is the only phase of swalling you conciouslucontrol?
Buccal phase
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Describe the Pharayngeal Phase of swallowing:
Soft Palate closes Nasopharynx & Epiglottis closes the Laryngopharynx
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Choking is most likly to occure during what phase?
- Pharayngeal phase
- getting stuck in the laryngopharynx
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Describe the Esophageal Phase of swallowing:
- A. Upper Esophageal spincter opens
- Peristalis propels bolus down esophagus
- B. Cardiac spincter opens & bolus enters stomach
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What layer does the Esophaghagus have instead of the sercosa?
Adventita
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What do the rugae do in the stomach?
allow it to contract when empty & expand when full
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Name the muscle layers of the stomach:
- Rugae
- Oblique (over mucosa)
- Circular
- Longitudal
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What are the 4 functions of the stomach?
- Storage
- Mechanical digestion
- Chemical digestion
- Absorbtion (of liquids &drugs)
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The ________ holds food during feeding.
Stomach
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_________ Digestion in the stomach makes liquid ______ and pushes it into the small intestine.
Mechanical digestion, grinding waves of the 3 muscle layers, make Chyme
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In chemicl digestion of the stomach, _____________ is protiens begin digestion.
Pepsin Protiens
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Absorbtion in the stomach is limited to what?
Water, Alcohol, & Drugs
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What are the 4 parts of the gastric gland?
- Mucous neck cells
- Parietal cells
- Chief cells
- G cells
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What do the mucous neck cells of the Gastric Gland do?
secrete protective mucous (mucins)
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What do Parietal Cells of the Gastric Gland do?
secrete Hydrochloric Acid & Intrinsic Factor
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What do the cheif cells of the gastric gland do?
secrete Pepsinogen & Gastric Lipase
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What do G-cells of the Gastric gland do?
secrete the hormone Gastrin which stimulates gastric secretion
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Pepsinogen is converted to the ative enzyme Pepsin in the stomach lumen by ________ ______ .
HCL = Hydrocloric Acid
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_______ digests protiens to small __________.
Pepsin digests PROTIENS into POLYPEPTIDES
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Gastric Lypase starts _________ digestion.
LIPID
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What are the layers of the Small Intestine?
- Serosa (bottom)
- Muscularis Externa
- Submucosa
- Mucosa
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What is the "modification" of the small intestine?
the mucosa layer has 4-5 million villi
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What are the villus of the small intestine covered with?
Columnar Epithelium & Goblet Cells
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What do the capillaries inside the villus do?
Absorbtion of Nutients
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Lymphadic Capillaries are also known as =
- Lacteal
- found in small intestine, inside the villi
- aide in lipid digestion product absorbtion
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What does an Absorptive cell do and where is it found?
epithelium cell of the villi = digestion & absorbtion
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What does a Goblet cell do and where is it found?
secrete mucous on villi
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What does an Endocrine cell do and where is it found?
Intestinal Hormones created locally on villi
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What does a Paneth cell do and where is it found?
Macrophage found in villi
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_______ propel chyme along the intestine.
Peristalsis
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________ moves chyme back and forth to it thoroughly with digestive enzymes.
Segmentation
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Enzymes from the ______ & ______ complete digestion of protien, starch, disaccharide sugars and fat.
Pancreas & Small Intestine
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Segmentation & Peristalsis are part of _______ digestion in the small intestine.
Mechanical
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Enzymes & Bile are part of _____ digestion in the small intestine.
Chemical
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The Gallbladder empties ______ into the small intestine to aide in fat digestion.
Bile
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Describe the Pancreas:
- 5 inch long extension from the Duodenum to the Spleen
- Consists of 4 parts (head, neck , bady, & tail)Describe the Pancreas:
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What cells are found in the Pancreas?
95-98% are EXocrine producing digestive enzymes
Some are ENDOcrine cells in pancreatic islets which produce hormones
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What are Acinar cells & where they found?
EXocrine cells that secrete digestive enzymes into the ducts of the Pancreas
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What are Ductal cells & where they found?
secrete a BICARBONATE Solution that neutralizes the acidic Chyme from the stomach and PROTECTS the mucosa of the Duodenum as the food moves from the stomach into the duodenum
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Protiens can only be absorbed as a _______ amino acid.
Single
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Pancreatic Juice is made of what?
Bicarbonate Solution & Digestive Enzymes
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Protiens are digested by what Pancreatic Enzyme & Where are they activated?
Proteolyic Enzymes = activated in the Duodenum
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The Proteytic Enzymes digest protiens & polypeptides into what?
- Tripeptides
- Dipeptides
- Single Amino Acids
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Starch is digested by what Panreactic Enzyme?
- Pancreatic Amylase
- it digested starch into disaccharides
- ** this is the sams as in the mouth **
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Fats are made of what?
Triglyceride
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What pancreatic enzyme digests fats?
Paancreatic Lipase Enzyme
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Digestion of each triglyceride yields what?
One Monoglyceride molecule & Two fatty acid molecules
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Bile from the _______ is required so that pancreatic lipase can digest ______ more effeciently.
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Bile flows from ______ to _____ to mix with & emulsify fats.
from the Gallblader, down the bile duct and into the Duodenum
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_________ is breaking fat drops into very small droplets for effecient enzyme action.
Emulsification.
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Bile aides in the ______________ of fats.
Absorbtion of digested fats
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Bile is a medium for _____ & ______ excretion by the liver.
Bilirubin & Cholesterol
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Name the 4 lobes of the Liver:
- Left
- Right
- Caudate
- Quadrate
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The liver lobes contain microscopic liver _______.
Lobules
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Liver Lobules consist of rows of liver ______ and rich blood supply.
Hepatocytes
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Blood is supplied to the liver by branches of the _________ & _________ at the six corners of each lobule.
Hepatic Artery & Portal Vein
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Blood flows toward the central vien of each liver lobule through the _________, which is surrounded by hepatocutes.
Sinusoids
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Liver macrophages are called ___________.
Kupffer Cells
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Kupffer cells take over ___________ in the liver, cleaning the blood.
microorganisms
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Bile Canaliculi are what?
bile ducts that collect bile from each hepatocyte and delivers it into the Billary system
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Bile flows from the liver through _______ ducts into the _________.
Hepatic ducts into the Gallbladder
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The common hepatic duct & the cystic duct from the gallbladder untie to form what?
The Common Bile Duct
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Common Bile duct unites with the _____ duct.
Pancreatic
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Bile & Pancreatic juices enter the _______ via the common bile duct.
Duodenum
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Functions of the Liver:
- Carbohydrate, Lipid, & Protein metabolism
- Storage of glycogen
- Removal of hormones, antibodies, & metabolic waste products
- Detoxification of drugs & toxins
- Phagocytosis by Kuffer Cells
- Plasma Protien Synthesis
- Bile synthesis & secretion
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______ are located on the microvillei of instestinal cells.
Brush-Border enzymes
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________ digests tri & depeptides into single amino acids.
Peptidases
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______ digests fats into glycerol and free fatty acids.
Intestinal Lipase
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Disaccharides digest disaccarides into individual _______.
Monosaccharides
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_____ digests Sucrose into Glucose & _______.
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_____ digests Maltose into Glucose & ________.
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_____ digests Lactose into Glucose & _______.
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Absorption is the transfer of substances into _______ and then into ________.
Absorptive cells then into Blood or Lymph capillaries
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Villi & Microvilli provide what of absorptive cells?
very large surface area for absorption
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Where are most foods, water, electrolytes and vitamins absorbed?
Small Intestine
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In Lacteal : fats & fat soluble vitamins in ______.
Chylomicrons
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Mucosa have no villi and are covered in what type of epithelium?
Simple Columnar epithelium
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Submucosa has deep _____ with intestinal glands that secrete _________.
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What are the layers of the Large Intestine?
- Serosa
- Muscularis Externa
- Submucosa
- Mucosa
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In the large instine, what happens to undigested food?
it is digested by bacteria
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What vitamins are formed in the large intestine? and by what?
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What is absorbed in the Large Intestine?
- Water
- Electrolytes
- Vitamins
- Bile Salts
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Feces is formed by what?
Bacterial Action
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What is Mass Movement?
Propelling of feces in the large intestine by contractions
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The Desire for defecation is initiated when?
When mass movement contractions in the colon push feces into the Rectum
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Tonic contractions of the _______ & ______ prevent actual defecation execept in ____.
- Internal & External Sphincters
- except in Babies
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The internal anal sphincter is made of what type of muscle?
Smooth = this makes it involuntary
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The internal anal spincter relexes by the parasympathetic ______ nerve stimulation.
Pelvic
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The internal spihncter tightens or constricts via stimulation from what nerve?
Hypogastric Nerve
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The external anal sphincter is made of what muscle type?
Skelatal, making it voluntary
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The external anal spincter is innervated by the ________ nerve and is under ________ control.
- Pudendal nerve
- Voluntary conscious control
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What are the 3 reflexes of Defecation?
- Intrinsic Reflex
- Parasympathetic Reflex
- Conscious Control
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The Intrisic Reflex includes what?
- Myenteric Plexus Reflex which triggers Peristalsis in the colon & Rectum
- Too weak to cause defication
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The parasympatheic reflex involves what?
transmission of signal to the spinal cord via the PELVIC Nerve & intesified Peristalsis
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Concous control includes what?
- relaxation of the external spincter
- contraction of abdominal muscles
- emptying of the deciending & sigmoid colon and rectum
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