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