The GI Tract / Digestive System Flashcards
What are the 2 groups of organs that make up the digestive system?
GI tract & Accessory digestive organs.
What are the Accessory Digestive organs?
Teeth, tongue, Salivary glands, Liver, Gallbladder, Lips and Pancreas.
What are the functions of the Digestive system?
Ingestion, Secretion, Mixing and Propulsion, Digestion, Absorption and Deification.
What are the layers of the GI tract?
Mucosa, Sub Mucosa, Musculairs, Serosa.
What is the layer of the GI tract “Mucosa”?
Composed of a layer of “Epithelium” in direct contact with the contents of the GI Tract.
A layer of connective tissue called “Lamina Propria”.
And a thin layer of smooth mm.
What is the layer of the GI tract “Sub Mucosa”?
Consist of CT that binds it to the Muscularis Mucosa.
Contains many Blood and Lymph vessels that receive absorbed food molecules.
What is the layer of the GI tract “Muscularis”?
Muscularis of the (Mouth, Pharynx and superior and middle parts of the esophagus contains skeletal mm that produces Voluntary swallowing.
Thought the rest of the Tract this layer is found in 2 sheets: an inner sheet of circular fibers and an outer sheet of longitudinal fibers.
What is the layer of GI tract “Serosa”?
It is a serous membrane composed of Areolar CT and simple Squamous Epithelium.
What is the Neural innervation of the GI tract?
Regulated by an Intrinsic set of nn’s AKA the “Enteric” nn’s.
Also by an Extensive set of nn’s that are also apart of the Autonomic Nervous system.
What is the Deepest layer of the GI tract?
Mucosa
What is the most superficial layer of the GI tract?
Serosa
What does involuntary contractions of smooth mm in the GI tract help do?
This helps move, digest and break down food.
What are the GI tract Reflexes?
Many neurones of the ENS are components of the GI Reflex pathways that regulate GI Secretion and Motility in response to stimuli present in the lumen of the GI tract.
What is the Peritoneum?
Largest Serous membrane in the body.
Divided into the Parietal Peritoneum and the Visceral Peritoneum.
What are the 5 major portions / Folds of the Peritoneum?
Greater Omentum, Falciform Ligament, Lesser Omentum, Mesentery, Mesocolen.
What is the Greater Omentum?
The largest Fold, drapes over the Transverse colon and coils of the small intestine.
Normally contains a lot of Adipose tissue.
What is the Falciform Ligament?
Attaches the Liver to the Anterior Abdominal Wall and Diaphragm.
What is the Lesser Omentum?
It is the Pathway for BV’s entering the Liver and contains: the Hepatic portal Vein, common hepatic artery, common bile duct.
What is the Mesentery?
Extends from the Posterior abdominal wall to wrap around the small intestine and then returns to its origin.
What is the Mesocolon?
2 separate folds, Bind the Transverse colon and Sigmoid colon of the large intestine to the posterior abdominal wall.
What is the only Digestive Organ attached to the Anterior Abdominal Wall?
The Liver.
What is the Hard palate of the Mouth?
The Anterior portion of the roof of the mouth, It is formed by the Maxillae and Palatine bones.
Forms a bone partition between the Oral and Nasal cavity.
What is the Soft Palate of the Mouth?
Posterior portion of the roof of the mouth, is arch shaped muscular partition between the Oropharynx and Nasopharynx.
What are the Salivary glands?
Most saliva is secreted by the Major Salivary glands that lay beyond the Oral Mucosa, into ducts that lead to the Oral Cavity.
What are the Major Salivary Glands?
Parotid, Submandibular, Sublinginul.
What does the Tongue consist of?
Divided into halves by a Median Septum.
There are Intrinsic and Extrinsic mm’s.
What do Intrinsic mm’s of the Tongue do?
The alter shape of the Tongue for speech and Swallowing.
What do Extrinsic mm’s of the Tongue do?
They help move food for chewing.
What do the Teeth consist of?
The typical tooth has 3 Major External regions, The Crown, Root & Neck.
What is the Crown of a Tooth’s External Layer?
This is the Visible portion above the gums.
What is the Root of a Tooth’s External Layer?
Embedded in the socket where the Tooth sits are 1-3 Roots.
What is the Neck of a Tooth’s External layer?
The Neck is the constricted junction of the crown and Root near the Gum line.
What forms the Majority of the Tooth?
Internally Dentin forms the majority of the Tooth.
Dentin of the Crown is covered in Enamel.
Dentin of the Root is covered by Cementum.
What are the 2 Enzymes in the mouth that help with Chemical digestion?
Salivary Amylase & Lingual Lipase.
What does the Pharynx consist of?
A funnel shaped tube that extends from internal nares to the Esophagus posteriorly and to the Larynx Anteriorly.
When food is first swallowed where does it go?
Composed of skeletal mm and lined by mucus membrane and is divided into 3 parts:
Nasopharynx, Oropharynx and Larnyngopharynx.
What does the Esophagus consist of?
The Esophagus begins at the inferior end of the Laryngopharynx, Passes through the inferior aspect of the of the neck and enters the Mediastinum anterior to the vertebral column.
After this it pierces through the Diaphragm through an opening called the Esophageal hiatus.
What is at the End of each part of the Esophagus?
At each end “Muscularis” becomes slightly more prominent and forms 2 Sphincters.
The “Upper Esophageal Sphincter” (UES) & “Lower Esophageal Sphincter” (LES).
What Esophageal Sphincter is Skeletal mm and what one is Smooth mm?
The (UES) is Skeletal mm and the (LES) is Smooth mm.
What is the function of the UES?
Regulates movement of food from pharynx into the Esophagus.
What is the Function of the LES?
Regulates movement from Esophagus into stomach.
What is Deglutition?
The movement of food from Mouth to stomach.
Occurs in 3 stages.
What are the 3 stages of Deglutition?
1: Voluntary
2: Pharyngeal stage
3: Esophageal stage
What does Deglutition involve anatomically?
Facilitated by secretion of Saliva, and mucus and involves the mouth, Pharynx and Esophagus.
During Deglutition what does the Bolus do?
Stimulating receptors in the Oropharynx which sends impulses to the Deglutition enter of the medulla and lower parts of the brain.
The returning impulses causes the soft palate and uvula to move upward to close off the Nasopharynx.
In addition the epiglottis closes off the opening to the Larynx.
What does the Stomach connect the Esophagus to?
It connects the Esophagus to the Duodenum, The first part of the small intestine.
What are the main regions of the Stomach?
The 4 main regions: Cardia, Fundus, Body, and Pyloric part.
Where is the Cardia of the Stomach located?
Surrounds the superior opening of the Stomach.
Where is the Fundus portion of the Stomach located?
The Rounded portion superior and to the left of the Cardia is the Fundus.