Digestive System

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Digestion:
The breakdown of large food particles into their component parts producing molecules small enough to be absorbed into circulation.
What are the 2 processes by which digestion is achieved?
-Mechanical
-Chemical
Mechanical Digestion:
Process through which large particles are broken down into smaller particles via mastication and mixing food (Physical Grinding)
Chemical Digestion:
Process in which chemical enzymes act on the smaller molecules rendering them readily absorbable
Where does digestion take place?
Throughout a long tube known as the GI tract along with the help of accessory glands and organs
The Gastrointestinal (GI) tract is also known as:
-Alimentary Canal
-Digestive Tract
Where does the GI tract start and end?
Starts in the oral cavity and ends at the anus
What are the components of the digestive tract?
-Oral Cavity
-Pharynx
-Esophagus
-Stomach
-Small Intestine
-Large Intestine
-Anus
What are the accessory organs or glands of the digestive tract?
-Salivary Glands (Parotid, submandibular and sublingual)
-Liver
-Gallbladder
-Pancreas
What is the main function of the GI System?
Digestion and Absorption
What happens in the oral cavity?
-Bolus gets formed
-Mastication takes place
What are the two boundaries of the superior portion of the oral cavity contain?
-Hard Palate (Superiorly)
-Soft Palate (Superiorly)
What is the inferior protrusion of the soft palate?
The uvula
What is the inferior boundary of the oral cavity? (floor)
Muscles of tongue
What is the anterior boundary of the oral cavity?
Lips
What are the lateral boundaries of the oral cavity?
Cheeks
What is the posterior boundary of the oral cavity?
Fauces (Throat/opening into pharynx)
What are the 3 parts of the pharynx?
-Nasopharynx (Air)
-Oropharynx (Food, Fluids, Air)
-Laryngopharynx (Food, Fluids, Air)
What is the location of the nasopharynx?
-Posterior to the nasal cavity
-Superior to the oropharynx
What is the location of the Oropharynx?
-Posterior to the oral cavity
-Inferior to the nasopharynx
-Superior to the laryngopharnx
What is the location of the laryngopharynx?
-Posterior to the larynx (voice box)
-Inferior to the Oropharynx
What parts of the pharynx aid in respiration?
-Nasopharynx (air)
-Oropharynx (food, fluids, air)
-Laryngopharynx (food, fluids, air)
What parts of the pharynx aid in digestion?
-Oropharynx (food, fluids, air)
-Laryngopharynx (food, fluids, air)
What is the uvula?
The flap (superiorly) that closes the nasopharynx while swallowing to prevent food from entering the nasal cavity
What is the epiglottis?
The flap (inferiorly) that folds over the larynx to prevent food and fluids from entering the respiratory tract while swallowing
The larynx is the passage way for what?
Air
What is the esophagus?
A muscular tube which carries food and liquids from the throat to the stomach for digestion.(neck->thorax->diaphragm->stomach)
What is the location of the esophagus?
Anterior to the vertebrae within the mediastinum and posterior to the trachea from C6 vertebra to T11 abdomen.
The esophagus extends from:
-The C6 Vertebrae to the Abdomen (From the pharynx to the stomach)
What 2 regions does the diaphragm separate?
-Thoracic Region
-Abdominal Region
The esophagus passes through:
The diaphragm at T10
How many sphincters does the esophagus have?
-2, an upper and a lower
What are the sphincters in the esophagus used for?
To prevent back flow of food
What is the esophageal hiatus?
A hole in the diaphragm which the esophagus and vagus nerve run through.
Where is the esophageal hiatus located?
At the T10 Vertebrae
What is the Greater Omentum?
A fold lining the abdominal cavity that prevents the spread of infection and stores fat.
What does the Greater Omentum do?
-Superficial layer of mesentery (Fatty Apron that connects organ to organ)
-Moves around when it finds an inflammed organ
-Adheres to it and protects the rest of the abdomin from the spread of infection
Where does the greater omentum attach?
Attaches from the greater curvature of the stomach to the transverse colon
Does the greater omentum cover the small and large intestine?
Yes
What are the 4 quadrants of the abdomen?
-RUQ: Right Upper Quadrant
-LUQ: Left Upper Quadrant
-RLQ: Right Lower Quadrant
-LLQ: Left Lower Quadrant
In which quadrant is the appendix located?
Right lower quadrant
In which quadrant is the cecum located?
Right lower quadrant
In which quadrant is the ascending colon located?
-Right upper quadrant
-Right lower quadrant
In which quadrant is the descending colon located?
-Left upper quadrant
-Left lower quadrant
Where does the esophagus meet the stomach?
Cardiac region
The stomach:
-J shaped muscular organ
-Located just inferior to the diaphragm in the left part of the abdominal cavity (Upper Left Quadrant)
-Located between the esophagus and the duodenum
-Creates chyme
What is the junction (sphincter) that connects the esophagus to the stomach?
Gastroesophageal (Junction) Sphinter
-Prevents backflow of the stomach into the esophagus
The fundus of the stomach:
Is a domed shape region to the left of the cardiac region and superior to the body
The body of the stomach:
Forms the central and largest region of the stomach.
The Pylorus of the stomach is:
-Inferior to the body, funnel shaped region
-Thick musculature at the part of the stomach in closest proximity to the duodenum, connects the stomach to the duodenum (region closest to the small intestine)
-Contains the pyloric sphincter.
The greater curvature of the stomach:
Extends from the fundus to the pyloric region
The lesser curvature of the stomach:
Extends between the cardiac and pyloric region
What attaches the greater curvature of the stomach?
Greater omentum
What attaches to the lesser curvature of the stomach?
Lesser omentum
What is the largest internal organ located inferior to the diaphragm?
Liver
What ligament separates the anatomical right and left lobes of the liver? And attaches the liver to the posterior aspect of the anterior abdominal wall?
Falciform ligament
What are the 2 anatomical lobes of the liver?
-Right
-Left
What 2 lobes are found in the inferior aspect of the liver?
-Caudate (Close to the inferior vena cava)
-Quadrate (Close to the gallbladder)
What does the liver produce and secrete?
Bile (Can go directly to the small intestine or to the gallbladder)
Which duct has a bi-directional flow of bile from and to the gallbladder?
Cystic Duct
-Lies between the gallbladder and the common bile duct
What two ducts form the common hepatic duct?
Right and left hepatic ducts
-Drains bile away from the right and left lobes of the liver
What do the cystic duct and and the common hepatic duct form?
Common bile duct
-Bile flows into the head of the pancreas
-Opens into the duodenum
Where does the pancreatic duct open into?
Dumps into the 2nd part of the duodenum
What stores the bile?
The gallbladder
What is the Fundus of the gallbladder?
Most distal portion of the gallbladder from the cystic duct
What do the pancreas produce and secrete?
Pancreatic juice
-Contains enzymes that are secreted into the duodenum along with bile coming from the common bile duct
Where do the common hepatic duct which drains into common bile duct unite with the pancreatic duct?
Hepatopancreatic ampulla
The hepatopancreatic ampulla opens into the duodenum at?
Major duodenal papilla
The biliary system and the pancreas work together for?
Digestion
The head of the pancreas is located close to?
Right part of the duodenum
The tail of the pancreas is located close to?
The Spleen
What are the three parts of the small intestine?
-Duodenum (C-Shaped 1st part)
-Jejunum (Middle, Thicker than the Ileum)
-Ileum (Last Part)
Where does most of the absorption and digestion occur?
Small intestine (Proximal regions Duodenum and Jejunum)
What are the parts of the large intestine?
-Cecum (1st part of the large intestine)
-Colon
-Rectum
-Anal Canal
What are the parts of the colon of the large intestine?
-Ascending colon (Up)
-Transverse colon (Across)
-Descending colon (Down towards anus)
-Sigmoid colon
Where does the ileum meet with the large intestine?
The cecum (AKA Ileocecal Valve)
What flexure is found on the right side of the ascending colon and transverse colon?
Right hepatic flexure OR Right colic flexure (close to the liver)
What flexure is found of the left side of the transverse colon and descending colon?
Left splenic flexure OR Left colic flexure (close to the spleen)
What is the band of the large intestine?
Teniae Coli
-Layers of longitudinal smooth muscle
Contraction of the Teniae Coli causes the formation of?
The haustra
-Pouches that run along the large intestine
What are the fat deposits of the colon called?
Epiploic appendages
What is the appendix?
-A wormlike sac attached to the cecum
-Located in the RLQ
-Composed of lymphatic tissue
Do we need an appendix to survive?
No
What is the common position of the appendix?
-Seen in numerous positions but the most common is Retrocecal position (behind the cecum)
What is McBurney's point? What is this used for?
1/3 the distance up a line joining umbilicus and Anterior superior iliac spine ASIS (point of maximum tenderness and rebound tenderness)
-To confirm appendicitis (Inflammation of the appendix)