The Digestive System Flashcards
GI Tract
Long Tube equaling 25 feet
How long is the GI Tract in a Cadaver?
30 feet
The GI Tract is open at both ends for what reason?
The Transit of food during procession
Structures of the GI Tract
Mouth, Pharynx, Esophagus, Stomach, Small Intestine, Large Intestine, Rectum, and Anal Canal
The Small Intestine is how long?
20 feet
The Large Intestine is how long?
5 Feet
Small vs. Large is assigned based on what?
Diameter NOT length
Accessory Structures of the GI Tract
Teeth, Tongue, Salivary Glands, Liver, Gallbladder, and Pancreas
Digestion begins where?
Teeth, Tongue, and Salivary Glands
What are the Six Basic Processes?
Ingestion, Secretion, Mixing and Propulsion, Digestion, Absorption, and Defecation
Ingestion
Taking food into the mouth (eating)
Secretion
Release of water, acid, buffers, and enzymes into the Lumen of the Tract
How is secretion accomplished?
Cells of the GI Tract and Accessory Organs
Mixing and Propulsion
Result of alternating contraction and relaxation of the Smooth Muscles within the walls of the GI Tract
Mechanical Digestion
Movements of the GI Tract aid in breaking food into smaller pieces
There is no what in Mechanical Digestion?
Chemical change in food particles
Chemical Digestion
Series of catabolic reactions that break down large carbohydrates, lipids, and protein food molecules into smaller molecules usable by the body cells
Absorption
Passage of digested molecules from the Lumen of the GI Tract across the wall of the GI Tract, and into underlying Blood or Lymph’s for distribution to the cells throughout the body
Deification
Emptying of the rectum to eliminate indigestible substances from the GI Tract
Layers of the GI Tract
Mucosa, Submucosa, Muscularis, and Serosa
Mucosa of the Stomach and Intestines is needed for what?
Secretion and absorption
The Mucosa of the Stomach and Intestines is lined with what?
Simple Columnar Epithelium
Mucosa of the GI Tract consists of what?
Epithelium, which contains the Lamina Propria and the Muscularis Mucosa
Epithelium of the Mucosa
Direct contact with the contents of the GI Tract
In the Epithelium of the Mucosa, from the Mouth to the Esophagus it is lined with what?
Non-Keratinized Stratified Squamous Cells for protection
In the Epithelium of the Mucosa, there is what?
Lamina Propria
Lamina Propria are found in what?
Lymph and Blood Vessels, Nerves and some CT
Type of Lamina Propria
MALT
What does MALT stand for?
Mucosa-Associated Lymph Tissue
What is MALT?
Part of the Lymphatic System that monitors and produces an immune response against pathogens passing with food through the GI Tract
Muscularis Mucosa
Allows for local movements of the Mucosal layer that is independent of the other layers of the GI Tract Wall
Contraction of Smooth Muscle in the Muscularis Mucosa aids in what?
Rugae and Plicae
Rugae
Temporary folds that are only evident when that organ or tissue is deflated or relaxed
Example of Rugae
Gastric Rugae
Plicae
Folds that remain folded regardless of distension or relaxation
Plicae are what?
Permanent folds
Example of Plicae
Small Intestine Plicae
Submucosa of the GI Tract
Loose CT with a large number of Blood and Lymph Vesselsq
The Submucosa binds what to what?
Mucosa to the Muscularis
The Submucosa contains the what?
Submucosal Plexus
Submucosal Plexus
Controls secretions of the GI Tract and contains the Network of neurons that makes up the ENS
Muscularis of the mouth, pharynx, and upper part of the Esophagus is what?
Skeletal muscle tissue, meaning it is voluntary
Skeletal muscle also forms what?
External and Internal Sphincter
In the Muscularis, the rest of the tract consists of what?
Smooth muscle in an inner sheet of Circular fibers and an Outer sheet of Longitudinal fibers
The Inner Circular Fibers and Outer Longitudinal Fibers produce what 2 distinct waves?
Peristalsis and Segmentation
Peristalsis
Results in the food bolus progressing forward through the GI Tract from one section to the next
During Peristalsis, Contractions occur how?
Directly behind the bolus, forcing it into the next relaxed section of the tract
After the food bolus is forced into the relaxed section of the tract, what happens?
Smooth muscle of the relaxed section contracts and propels the bolus forward towards to the Rectum
Peristalsis is created by what?
Coordinating muscular contractions
Peristalsis is governed by what?
Both Hormonal and Neuronal control
Segmentation
Stationary, oscillatory waves that aid in mixing food with the Digestive Enzymes that have been secreted
Segmentation also does what?
Increases contact between the food bolus and the Mucosa
Segmentation increasing the contact between the food bolus and Mucosa is necessary for what?
Absorption
Segmentation is basically carried out by what?
Alternating contractions and relaxations of the Circular layer of the Muscularis
What is between the Inner and Outer Longitudinal layers in the Muscularis?
Myenteric Plexus
Myenteric Plexus
Controls the strengths and frequency of the muscular contractions within the GI Tract
Control GI Tract Motility
The Myenteric Plexus along with the Submucosal Plexus makes up the what?
Neural Network of the ENS
Serosa
Serous Membrane and most superficial of the GI Tract
What does the Serosa secrete?
Slippery, watery (serous) fluid
If the Serosa is inferior to the Diaphragm, what is it?
Visceral Peritoneum
Peritoneum
Serous Membrane in the Abdominal cavity
The Peritoneum is the largest what?
Serous Membrane in the body
Parietal Peritneum
Portion of the Peritoneum that lines the wall of the abdominal cavity
Visceral Peritoneum
Covers the organs and constitutes the Serosa
What is the name of the space between the Parietal and Visceral Peritoneum?
Peritoneal Cavity
Peritoneal Cavity
Contains small amount of Serous fluid secreted by the Peritoneum
Peritoneal Folds
Contains large folds that weave between the Viscera
What do Peritoneal Folds do?
Support Organs and house Blood Vessels, Lymphatic Vessels, and Nerves of the Abdominal Organs
What are the extensions of the Peritoneal Folds?
Greater Omentum, Lesser Omentum, Falciform Ligament, Mesentery, and the Mesocolon
Greater Omentum (apron-like)
Extends from the Greater Curvature of the Stomach and drapes over the anterior of the Small Intestine, then doubles itself to ascend and attach to the transverse Colon
The Greater Omentum is the what?
First structure observed when the Abdominal Cavity is open
Lesser Omentum
Extends from the Liver to Lesser Curvature of the Stomach
Falciform Ligament
Attaches the Liver to the Anterior Body wall and separates the left lobe from the right lobe
Mesentery
Attaches the small Intestine to the Posterior wall of the Abdomen
Mesocolon
Attaches the Colon to the Posterior wall
Peritnoitis
Acute inflammation of the Peritoneum
Symptoms of Peritonitis
Abdominal pain, tenderness, bloating, fatigue, and satiety
Retroperitoneal
Region posterior to the Abdominal Peritoneum
Retroperitoneal Organs
Kidneys, Pancreas, and portions of the Large Intestines
Where do Retroperitoneal Organs lie?
Against the Posterior Abdominal wall behind the Peritoneum
What do Salivary Glands secrete?
Saliva
Salivary Glands pour their contents into what?
The ducts that empty into the Oral Cavity
3 Pairs of Extrinsic Salivary Glands
Parotid, Submandibular, and Sublingual
Parotid Salivary Glands
Secrete Serous Fluid
Submandibular Salivary Glands
Secrete both Serous and Mucus
Sublingual Salivary Glands
Secrete Mucus
Salivary Glands are controlled by the what?
P-ANS
With the Salivary Glands, the P-ANS stimulates what?
Release of Enzymes into the Saliva for digestion
Saliva resulting from the S-ANS is what?
Thicker and contains more mucus with less digestive enzymes
Mumps
Inflammation and enlargement of the Parotid Salivary Glands caused by the infection, Mumps Virus
Symptoms of Mumps
Fever, Malaise, pain, and swelling of one or both glands
If an adult male beyond puberty contracts Mumps, what will he experience?
Inflammation of the Testes that can occasionally result in infertility
Digestion begins in the mouth with what?
Chemical digestion from Enzymes found in the Saliva
Through mastication (chewing), food is mixed with Saliva and what happens?
The food is shaped into a bolus that can be easily swallowed
The only chemical digestion occurring in the mouth is from what?
The enzymes found in Saliva
Salivary Amylase
Begins the breakdown of starch by breaking particular chemical bonds between the Glucose subunits and continues to work for an hour until it becomes inactivated by the Stomach Acids
Pharynx
Funnel-Shaped tube that extends from the Internal Nares to the Larynx and Esophagus
The Pharynx is composed of what?
Skeletal muscle that’s lined by Mucous Membrane
Nasopharynx
Functions ONLY in Respiration
GI Tract is covered with what?
Stratified Squamous Epithelium from the Mouth down to the Stomach
From the Mouth to the Stomach, the GI Tract is lined with Stratified Squamous Epithelium, what is it lined with after the Stomach?
Columnar Epithelium
Oropharynx
Digestive and Respiratory Functions
Laryngopharynx
Digestive and Respiratory Functions
The tongue is composed of what?
Skeletal Muscle
Esophagus
Collapsible, Muscular tube that lies Posterior to the Trachea and connects the Pharynx to the Stomach
Why is the muscular portion of the Esophagus unique?
It contains both Skeletal and Smooth muscle
Upper 1/3 of the Esophagus
Skeletal Muscle meaning it’s voluntary
Middle 1/3 of the Esophagus
Skeletal and Smooth Muscle
Lower 1/3 of the Esophagus
Smooth Muscle
Muscularis at either end of Esophagus forms what 2 sphincters
Upper Esophageal Sphincter and Lower Esophageal Sphincter
Both the UES and LES are used to regulate what?
Passage of food further down the GI Tract
What does GERD Stand for?
Gastroesophageal Reflux Disease
What is GERD a result of?
Dysfunctional LES
The Esophagus secretes only what?
Mucus
The Esophagus has no what?
Digestion, meaning there is no absorption
Swallowing involves the what?
Mouth, Pharynx, and Esophagus
Swallowing is aided by the what?
Mucus and Saliva
What are the 3 Stages of Swallowing
Voluntary, Pharyngeal, and Esophageal
Voluntary Swallowing
Tongue helps force the food bolus into the Oropharynx
Pharyngeal Swallowing
Breathing is temporarily interrupted as food is passing through the Oropharynx and into the Esophagus
What helps prevent food from going down the wrong pipe?
Soft Palate and Uvula, Epiglottis, and the Vocal Cords
Soft Palate and Uvula
Move upward to close of the Nasopharynx
Epiglottis
Closes off the Larynx as it elevates
Vocal Cords
Come together to close the entry into the Trachea
Esophageal Swallowing
Food Bolus is passed through the Esophagus into the Stomach by Peristalsis
In Esophageal Swallowing, what is the first step of Peristalsis?
Circular fibers above the bolus squeeze the bolus downward
In Esophageal Swallowing, what is the second step of Peristalsis?
Longitudinal fibers around the bottom of the bolus contract and therefore shorten and widen the Lumen of the Esophagus at the particular region in which the bolus is entering
In Esophageal swallowing, what is the third step of Peristalsis?
After the bolus moves into the new section of the Esophagus, Circular Muscles above it contract and the cycle repeats
Difference between Peristalsis and Segmentation
Peristalsis is created by coordinating muscular contractions and Segmentation is carried out by alternating contractions and relaxations of the circular layer of the muscularis
Mucosa of the Stomach lines the surface with what?
Simple Columnar Epithelium Cells
Simple Columnar Epithelium Cells are called what?
Surface Mucous Cells
The Surface Epithelium have numerous what?
Invaginations into the Lamina Propria
The numerous invaginations of the Surface Epithelium into the Lamina Propria are called what?
Gastric Pits
What does Surface Mucous Cells produce?
Cloudy, viscous, and Alkaline Mucus that forms thick, gel-like juices to protect it from abrasions and prevent Gastric Juices from destroying underlying tissue layers
Gastric Pits open up into what?
Gastric Glands
Why do Gastric Pits open up into Gastric Glands?
The pores open into the Lumens of the Stomach that lead to Glands
Exocrine
Glands that secrete their products through ducts opening into an Epithelium rather than directly into the Bloodstream (outside world)
Exocrine Gland Secretions
Mucous Neck Cells, Chief Cells, and Parietal Cells
Exocrine secretions from the three Exocrine Cells are collectively called what?
Gastric Juices
Mucous Neck Cells
Secrete Mucus, which lines and protects the Stomach
Chief Cells
Secrete Pepsinogen and Gastric Lipase
Pepsinogen2
Precursor of Pepsin
pepsin is active at a pH of what?
2
Gastric Lipase works at a pH of what?
3-6
Parietal Cells
Secrete HCl and Intrinsic Factor
HCl
Lowers the pH in the Stomach, neutralizes Chyme, and converts Pepsinogen to Pepsin
Intrinsic Factor
Necessary for the absorption of B12 in the Small Intestine
Inadequate Production of Intrinsic Factor results in what?
Pernicious Anemia
Endocrine
Glands that secrete Hormones or other products directly into the Blood stream
Endocrine secretions are NOT a part of the what?
Gastric Juice because the products are released into the bloodstream, Not the Stomach lumen
Endocrine Gland Secretion
Gastrin
Gastrin
Secreted by G Cells
What does gastrin do?
Stimulate Chief, parietal, and Paracrine Cells, relaxes the Pyloric and Ileocecal Sphincters, and promotes the mass movement of food through the GI Tract
G Cells
Enteroendocrine Cells meaning they are hormone-secreting cells in the GI Tract
Paracrine
Relating to, promoted by, or being a substance secreted by a cell and acting on adjacent cells
Paracrine Secretion
Paracrine Cells
Paracrine Cells
Secrete Histamine
Histamine stimulates what?
Secretion of HCl from Parietal Cells
Autocrine
Relating to, promoted by, or being a substance secreted by a cells and acting on surface receptors of the same cells
Chemical Digestion in the Stomach is primarily by what?
Pepsin
Pepsin
Enzyme that breaks down Peptide bonds
pepsin is the only major what?
Digestive enzyme effective in strongly acidic environment, like the stomach
Stomach
J-Shaped enlargement of the GI Tract that begins at the distal aspect of the Esophagus and ends at the pyloric sphincter
Stomach serves as a what?
Mixing and holding area for food, continues digestions, and converts the food bolus to a liquid called Chyme
Subdivisions of the Stomach
Cardia, Fundus, and Pylorus
Gastric Rugae
When the stomach is empty, the luminal aspect of the stomach exhibits temporary folds, which are the gastric Rugae
When are Gastric Rugae formed?
During the contractions of the Muscularis Mucosae
As the Stomach fills, what happens to the gastric Rugae?
They disappear and form Smooth Mucosa
What are the 3 layers of the Smooth Muscle in the muscularis of the Stomach
Longitudinal, Circular, and an Inner Oblique Layer
With the Lesser Curvature, the Visceral Peritoneum becomes the what?
Lesser Omentum
With the Greater Curvature, the Visceral Peritoneum becomes the what?
Greater Omentum
The Stomach is what to most substances?
Impermeable
What are some thing that the Stomach is permeable to?
Water, Electrolytes, Aspirin and Alcohol
Aspirin and Alcohol disrupt the Gastric Mucous Barrier, which does what?
Contributes to the development of or worsening of Gastric Ulcers
Peptic ulcer Diseases (PUD)
Umbrella condition that includes both Gastric and Duodenal Ulcers
Divisions of the Pancreas
Head, Body, and Tail
The Pancreas connects to the Duodenum via the what?
Pancreatic Duct and Accessory Duct
The Pancreatic Duct and Common Bile Duct join at the what?
Ampulla of Vater
Release of fluid from the Ampulla of Vater is controlled by the what?
Sphincter of Oddi
Endocrine Pancreas Cells constitute what percentage of the Pancreatic Cells
1 percent
Cells within the Pancreatic Iselts of the Endocrine Pancreas
Alpha, Beta, and Delta Cells
Alpha Cells
Secrete Glucagon
Glucagon
increases Blood Glucose
Beta Cells
Secrete Insulin
Insulin
Decreases Blood Glucose
Delta Cells
Secrete Somatostatin
Somatostatin
Maintains Homeostasis of hormones
The Exocrine Pancreas constitutes what percentage of Pancreatic Cells
99 percent
Exocrine Pancreas Cells secrete what?
Mixture of Sodium Bicarbonate and Digestive Enzymes
Sodium Bicarb and Digestive Enzymes make up what?
Pancreatic Juices
Digestive Enzymes
Secreted from Pancreatic Acinar Cells in response to the hormone CCK
Digestive Enzymes function best at what?
An Alkaline pH
Pancreatic Amylase
Digests Starch
Pancreatic Proteases
Digests Protein
Pancreatic Lipase
Digests lipids
Pancreatic and Gastric Lipase both work to digest Lipids, but do what differently?
Have slightly different mechanisms of action and function at different pH levels
Pancreatic Lipase is the more what?
Significant player
Pancreatic Nucleases
Digest Nucleic acids
Sodium Bicarbonate
Secreted from Pancreatic Duct Epithelial cells in response to Secretin
Sodium Bicarbonate does what?
Converts acidic Chyme to alkaline, halts the activity of Pepsin and gastric lipase, and promotes the activity of Pancreatic Enzymes because they function best as Alkaline
Secretion of Sodium Bicarb and Digestive enzymes is under control of what 2 horomones?
CCK and Secretin, which allows for separate control mechanisms
CCK
Secreted by the Duodenum and stimulates the release of enzymes from the Pancreatic Acinar Cells
Secretin
Secreted by the Duodenum and stimulates the release of Sodium Bicarb from the Pancreatic Duct Epithelial Cells which causes the Pancreas to do its job
Hepatic Lobule is the what?
Functional unit of the liver
In the Hepatic Lobule, the several Hepatic Sinusoids radiating out from the Central vein are going towards what?
Portal Triads
What is the basic function of the Hepatocyte?
To produce Bile
Bile
Bitter-tasting, dark green to yellowish-brown fluid
Humans make roughly how much Bile a day?
500ml
What is the purpose of Bile?
Detergent action on particles of dietary fat, causing fat globules to break apart into minute, microscopic fat droplets
the 3 basic components of Bile
Bile Salts, Bilirubin and Cholesterol
Bile Salts
Aid in the emulsification and assembly of Micelles
what percentage of Bile Salts are reabsorbed?
95 percent
What percent of bile Salts are excreted in the feces?
5 percent
Bile Salts that are reabsorbed is done so by how?
Terminal ileum and returned to the Liver via the Hepatic Portal System for reuse
The pathway of which takes reabsorbed Bile Salts via the Terminal Ileum and returned to the Liver by the Hepatic Portal System is called the what?
Enterohepatic Circulation
Bilirubin
Derived from Heme when Fixed Macrophages in the Spleen and Liver remove RBC’s from circulation
Bilirubin is the principal what?
Pigment found in Bile
In the process of making Bilirubin, what is the first step?
RBC’s are broken down into their Heme and Globin parts
In the process of making Bilirubin, what happens when the Globin portion is broken down?
The Globin is broken down into AA’s and reused to create other proteins
In the Process of making bilirubin, what happens when the Heme portion is broken down?
The Heme is broken down and the iron is removed to be stored for later use during Erythopoiesis
The non-iron portion of Heme is converted to what?
Biliverdin and then to Bilirubin
Bilirubin enters the blood and is then what?
Transported to the liver where its stored and releases by Hepatocytes as part of Bile
Cholesterol
Created by the Liver and/or consumed in the diet
Bile is synthesized where?
Hepatocytes
How is Bile Transported?
By a Duct System either to the Duodenum for immediate use or the Gallbladder for concentration and temporary storage
With the transportation of Bile, the Duct System begins with what?
Bile Cannaliculi
Bile Cannaliculi
Small ducts wedged between hepatocytes that collect Bile as it is being produced
Bile flows from the Cannaliculi to where?
Bile ducts and then to the R/L Hepatic Ducts
From the R/L Hepatic Ducts, where does Bile go to next?
The Common Hepatic Duct and then to the Common Bile Duct
From the Common Bile Duct, where does Bile go to next?
Through the Ampulla of Vater, out the Sphincter of Oddi and into the Duodenum
When the Sphincter of Oddi is closed due to there being no food in the Duodenum in need of digestion, what happens to the Bile?
It backs up into the Cystic Duct and into the Gallbladder to be concentrated and stored for future use
A Portal Triad consists of what?
Bile Duct, Branch of the Hepatic Artery, and a branch of the Hepatic Portal Vein
Function of the Liver in Digestion
Create Bile
Function of the Liver in Immunity
Kupffer Cells
Function of the Liver in Carbohydrate Metabolism
Stores Glycogen, which releases Glucose as needed and helps maintain blood glucose levels
3 sections of the Small Intestine
Duodenum, Jejunum, and Ileum
How long is the Duodenum?
1 foot
How long is the Jejunum?
8 feet
How long is the Ileum
10 feet
Absorption occurs how?
Osmosis, Simple Diffusion, Facilitated Diffusion, and Active transport
What percentage of absorption takes place in the Small Intestine?
90 percent
what percentage of absorption happens in the Stomach and Large Intestine?
10 percent
All water absorption in the GI Tract occurs how?
Osmosis from the Lumen of the Intestines through Mucosal Epithelium Cells and into the Blood Capillaries
Absorption of water in the Small Intestine depends on what?
The absorption of electrolytes and nutrients to maintain an Osmotic balance within the Blood
Absorption of Monosaccharides
Essentially all carbohydrates are absorbed as monosaccharides
What does carbohydrates being absorbed as monosaccharides mean?
They absorbed into the Blood capillaries of the Villi
Most proteins are absorbed how?
Into Enterocytes in the form of AA’s, Dipeptides, or Tripeptides
Inside Enterocytes, what happens?
Dipeptides and Tripeptides are digested into single AA’s
After Dipeptides and Tripeptides are digested within Enterocytes, what happens to the AA’s?
Then absorbed into Blood Capillaries of the Villi
Triglycerides are composed of what?
Glycerol plus 3 fatty acids
Fatty acids can be what?
Short, medium, or long chain
Lipids cannot be absorbed as what?
one molecule, rather their components are absorbed as either monoglycerides or free FA’s
What are Micelles composed of?
Long-Chain FA’s, Monosaccharides, Cholesterol, Vitamins DAKE, and other dietary lipids
Bile salts keep Micelles what?
Soluble until they can e transported into the Absorptive Cells
Chylomicrons are the largest what?
Particles with a protein coat and the largest Lipoprotein
Chylomicrons are exocytosed through the what?
Basal Aspect of the Absorptive Cell and transported into the Lacteals
Chylomicrons carry what away?
Long-Chain Fatty Acids
Some Lipids are what?
Insoluble in water and body fluid
In order to be transported within the blood and utilized by body cells, Lipids need to be what?
Combined with protein transporters to be made soluble
Types of Lipoproteins
Chylomicrons and LDL
Chylomicrons do what?
Transport exogenous Lipids
LDL (Low Density Lipoprotein)
“Lousy Cholesterol”
What are the ideal lab values for LDL?
Low labs
HDL’s are able to do what?
Remove Cholesterol from buildup within the Arterial Wall
When Chyme reaches the Ileum, most Bile Salts are what?
Reabsorbed and transported back to the Liver via Enterohepatic Circulation
After Bile salts are reabsorbed and transported back to the Liver in Enterohepatic Circulation, Bilirubin is excreted as what?
Waste
Absorption of Fat-Soluble Vitamins
Included in the Micelles
Fat-Soluble Vitamins
DAKE
Absorption of Water-Soluble Vitamins
Absorbed via Simple Diffusion into the Blood Stream
Water-Soluble Vitamins
B and C
The Mucosal wall of the Small Intestine is made up of what?
Villi
The Villi of the Mucosal Wall in the Small Intestine does what?
Increases Surface Area
The Surface area of the Absorptive Cells is made up of what?
Microvilli (Brush Border)
Where are the Digestive Enzymes found?
Brush Border (Microvilli)
What are the Digestive Enzymes found on the Brush Border?
Maltase, Lactase, and Sucrase
Absorptive Cells function primarily in what?
Ion and Water absorption
Goblet Cells
Mucus secreting Cells and are single-celled exocrine glands
Enteroendocrine Cells
CCK Cells, S Cells, and K Cells
The Lamina Propria contain Lacteals embedded within each what?
Villus
Lacteals
Lymphatic capillary of the Small Intestine
The Lamina Propria also have what embedded within that extend into the Submucosal layer?
Peyer’s Patches
Peyer’s patches
Specific type of MALT
First step following a meal in Mechanical Digestion
Segmentation occurs
Second Step following a meal in Mechanical Digestion
After most of the food is absorbed, segmentation ceases and Peristalsis begins, traveling in waves across the successfully digested parts of the Small Intestine
Third Step following a meal in Mechanical Digestion
The Peristalsis waves propel Chyme onward throuhg the Intestinal Tract, sweeping undigested parts of the stomach and Small Intestine towards the Terminal Ileum
The third step of mechanical digestion following a meal is what a phenomenon of what?
The ENS
Motilin modifies what?
Activity of Peristalsis wave patterns
First step of Chemical digestion in the Small Intestine
Chyme enters the Small Intestine containing partially digested carbs and proteins
Second Step of Chemical digestion in the Small intestine
Completion of digestion in the Small Intestine is a collective effort of Bile, Pancreatic Juice, Intestinal Juice and the Brush Border Enzymes
Third step of Chemical digestion in the Small Intestine
The final products of digestion are ready for absorption from the Lumen across the Mucosa and into the Blood capillaries or in some cases, the Lymphatic Capillaries
Ions and Water absorb into the Blood by what?
Osmosis
Monosaccharides, Simple AA’s, Dipeptides, Tripeptides, and Short-Medium Chain FA’s absorb in the small Intestine by what?
Simple Diffusion
Long-Chain FA’s are emulsified by what into what?
Bile Salts into Micelles
Micelles can be more easily what?
Transported into absorptive cells
Micelles are converted into what?
Chylomicrons in the Cells
Chylomicrons are transported into the what?
Lacteals
Mucosa of the Large Intestine does not have what?
Villi
In the Large Intestine, most of the Intestinal Glands only secrete what?
Mucus
The Longitudinal Muscles of the Muscularis have what?
3 bands called Taenia Coli
Absorption in the Large Intestine is primarily what?
Water, electrolytes and vitamins
Deification reflex is primarily under what control?
P-ANS
Deification is aided by what?
Voluntary contractions of the diaphragm and abdominal muscles
The what can be voluntarily controlled, except in infants
External Anal Sphincter
Cephalic Phase Triggers
Smells, sights, or thoughts of food activates the Sensory Receptors
Cephalic Phase Effects
Stimulates Salivary and Gastric secretions, and Motility
Gastric Phase Triggers
Begins with either: Stomach walls are distended or pH increase
With the Gastric Phase Trigger where the Stomach walls are distended, what does that activate?
Stretch receptors
With the Gastric Phase trigger where the pH increases, what does that activate?
Chemoreceptors that cause the pH to increase when proteins enter the Stomach and buffer some of the Stomach acid
Gastric Phase Effects
Results in waves of Peristalsis and continual flow of Gastric Juices, as well as relaxes the Pyloric Sphincter
What do the inhibitory effects do in the Intestinal Phase?
Slows the exit of Chyme from the Stomach and prevents overloading of the Duodenum with more Chyme than it can handle
In the Intestinal Phase, what is the response to the inhibitory effects?
The promotion of continued digestion of foods that reached the Small Intestine
Intestinal Phase Triggers
Food enters the Duodenum
Intestinal Phase Effects
Regulation by both the Neural and Hormonal Component
Intestinal Phase Effects by the Neural Component
Stimulated by the distension of the Duodenum
What does the Neural regulation of the Intestinal phase trigger?
The Enterogastric reflex which inhibits Gastric Emptying
Intestinal Phase Effects by the Hormonal Component
Stimulated by components of the Chyme entering the Intestine
What does the Hormonal regulation of the Intestinal phase trigger when it is Chyme with AA or FA?
Stimulates the release of CCK
What does the Hormonal regulation of the Intestinal phase trigger when it is Chyme with the acidic component?
Stimulates the release of Secretin
Gastric Emptying
Process by which the contents of the stomach are moved into the Duodenum
The Enteric Nervous System (ENS) is what?
Intrinsic
The Autonomic NS (SANS and PANS) is what?
Extrinsic
S
Suprarenal (Adrenal) Gland
A
Aorta/IVC
D
Duodenum (2nd and 3rd parts)
P
Pancreas (except the tail)
U
Ureters
C
Colon (ascending and descending)
K
Kidneys
E
Esophagus
R
Rectum
