Lecture 17: GI Flashcards
What are the 7 functions of the GI system?
- Ingestion
- Mechanical processing
- Compaction
- Digestion
- Secretion
- Absorption
- Excretion
What is Ingestion?
Food and liquid intake (oral cavity)
What is Mechanical processing?
Swirling, mixing, churning, propulsive motions in tract
What is Compaction?
Dehydration of undigested material and waste into feces (colon to anus)
What is Motility?
The movement of things that are ingested throughout the tube
What are the two methods of Motility?
Mechanical processing and Compaction
What is Secretion?
Adding acids, enzymes and buffers by accessory organs
What is Absorption?
Movement of molecules, electrolytes, vitamins and water into interstitial fluid to the rest of the body
What is Excretion?
Elimination of undigested residue and waste products
What is Secretion needed for in the GI tract?
For food to be able to move and to breakdown food in order to be able to absorb it
After being absorbed into the blood from the GI tube, where do the absorptions go?
To the liver
What does the liver decide?
What is allowed into the body and what is excreted
Where does the liver send nutrients?
To the heart to add oxygen to the nutrient rich blood
What are the Accessory Organs of the GI tract?
- Salivary glands
- Liver
- Gallbladder
- Pancreas
What is the order of parts of the Gastrointestinal Tract?
Oral Cavity ➡️ Pharynx ➡️ Esophagus ➡️ Stomach ➡️ Duodenum ➡️ Jejunum & Ileum ➡️ Large intestine ➡️ Anus
What are the parts of the large intestine in order?
Cecum ➡️ ascending ➡️ transverse ➡️ descending ➡️ sigmoid colon ➡️ rectum
What are the parts of the Small intestine in order?
Duodenum, Jejunum, Ileum
Why is the Lumen of the GI tract extremely filled with lymphatic tissue?
Because it protects the body from what comes inside the tube
Why are the accessory organs considered accessory?
Because they dump into the tube but they do not directly contact ito contents
Which two systems are mixed in the Pharynx?
The Gastrointestinal and Respiratory system
Where does the Esophagus end?
The stomach in the abdominal cavity
Where do the Liver in Pancreas release their secretions?
The duodenum of the small intestines
Which accessory organs are released into the Duodenum of the small intestine?
The liver and the pancreas
Why is the Gallbladder not considered a Gland?
Because it is just a pouch that stores bile
Where does the majority of absorption occur?
The jejunum and the ileum
What are the 4 basic layers of the Gastrointestinal tube?
- Mucosa
- Submucosa
- Muscular externis layer
- Serosa
What is the first layer at the lumen of the Gastrointestinal tube?
The Mucosa
What is the outermost layer of the GI tube?
The Serosa
What does the Serous membrane (Serosa) of the GI tube do?
Help lubricate and produce water and fluid and prevent friction
What tissue are glands made of?
Epithelium
What do Exocrine glands secrete into in term of the the GI system?
The GI tube
What do the Endocrine glands secrete into in terms of the GI system?
Into surrounding CT
How are the Liver and Pancreas associated with the blood?
They produce hormones that are secreted into the circulatory system
What tissues are is the Mucosa made of of the GI tube made of?
Epithelium
Lamina propria (CT)
Muscularis Mucosa
How does the Epithelium of the mucosa of the GI tract vary?
It can vary between stratified and or simple depending on the portion of the GI tract
When is the Epithelium of the Mucosa of the GI tract stratified epithelium?
At the beginning and the end of the tube because these are high stress areas
When is the Epithelium of the Mucosa of the GI tract simple epithelium and why?
In the inner parts to absorb as much as possible
What connective tissue is associated with the mucosa epithelium of the GI tube?
Lamina Propria
What is the function Lamina Propria of the mucosa?
Contain lymphatics and glands
What do the Glands of the Lamina Propria of the Mucosa do?
Fill with mucus to help with motility of food as it move down
What is the layer of muscle found in the Mucosa known as?
Muscularis Mucosa
What is the function of the Muscularis Mucosa of the Mucosa of the GI tube?
Squish anything that needs to go into the lumen, like the mucus found in glands
What is the name of the second layer of the GI tube
Submucosa
What kind of tissue is the Submucosa of the GI tube made of?
Connective Tissue
What is the function of the Submucosa of the GI tube?
•It serves as a conduit for vasculatures, nerves, lymphatics
What is contain in the Submucosa of the GI tube?
- Immune cells
- Exocrine glands,
- Submucosal plexus
Which layer of the GI tube is the submucosal plexus found?
The Submucosa
What is the function of the Submucosa Plexus?
Controls everything found in the submucosa layer (glands)
What is the third layer of the GI tube?
The muscularis externis
What kind of muscle is the Muscularis Externis of the GI tube made of?
Smooth muscle
What is the orientation of the inner smooth muscle of the Muscularis externis?
Circular
What is the orientation of the outer smooth muscle of the Muscularis externis?
Longitudinal
What is the orientation of the Muscularis Externis smooth muscle in the stomach?
It has a third layer of Oblique smooth muscle
What is unique about the Muscular Externis at the beginning and end of the GI tube?
It is no longer smooth muscle it it skeletal (somatic) muscle
What are the layers of the Muscularis Externis of the GI tube?
Inner circular smooth muscle and outer longitudinal smooth muscle
What plexus is found in the Muscularis Externis of the GI tube?
The Myenteric Plexus
Where is the Myenteric Plexus found?
In the Muscularis Externis of the GI tract
What does the Myenteric Plexus control?
The two layers of the Muscularis Externis
What is the fourth layer of the GI tube called?
The Serosa
What is the Serosa made of?
Simple squamous epithelium and connective tissue
What is the function of the Serosa?
Produces watery fluid that lubricates the peritoneal surfaces
How many layers of Serosa are there?
Two
What is the Mesentery of the Serosa?
The two layers of the Serosa that form a sandwich overtop of vessels and allow them to pass through
Where is the Oral Cavity located?
The head
How are the Oral cavity and Respiratory system connected?
Through the Pharynx
Why is the Esophagus important?
- Ensures everything that is ingested is brought to the stomach
- Transitions between skeletal to smooth muscle
What is the transition from skeletal to smooth muscle in the GI system?
The Esophagus
What is the Position of the Esophagus as you go down?
It is initially posterior behind the trachea but sits right beside the Aorta but hits the front once it gets to the diaphragm
Why is the Aorta in the back?
Because when the diaphragm contracts it closes off the inferior vena cava and the esophagus but we don’t want that to happen to the Aorta
What is the color of the Gallbladder?
Green
Where do the Abdominal quadrant lines intersect?
The umbilicus (belly button)
What is found in the RUQ?
- Liver
- Gallbladder
- Duodenum
- Right kidney
What is found in the LUQ?
- Stomach
- Spleen
- Left kidney
- Body and tail of pancreas
What is found in the RLQ?
- Appendix
- Cecum
- Ascending colon
- Ileum
What is found in the LLQ?
- Ileum
* Descending & sigmoid colon
Which organ is found in both the RUQ and LUQ?
Pancreas
Which organ is found in both the RLQ and LLQ?
Ileum
What are the 3 planes of the Abdominal region?
- Midclavicular plane
- Subcostal plane
- Intertubercular plane
What are the 3 middle abdominal regions created by the planes from top to bottom?
- Epigastric Region
- Umbilical region
- Pubic region
What are the 3 middle regions separated by planes in the abdomen associated with?
Vasculature and innervation referred in that area
What is the Peritoneum?
Serous membrane lining the peritoneal (abdominal) body wall and organs
What does the Parietal Peritoneum line?
The entire peritoneal cavity (body wall)
What does the Visceral Peritoneum line?
The peritoneal organs (viscera)
What is the Mesentery (Proper)?
A sandwich of visceral peritoneum that serves as a conduit for vessels and also anchors organs to the body wall
What anchors organs to the body wall?
The Mesentery Proper
What is the Greater Omentum?
The mesentery from the greater curvature of the stomach to transverse colon (apron-like)
What is Lesser Omentum?
The mesentery from the lesser curvature of the stomach to the liver
Which organ in the abdominal cavity is not surrounded by visceral peritoneum?
The pancreas
What is the meaning of Intraperitoneal?
Everything inside the peritoneal cavity and surrounded by visceral peritoneum
What is the meaning of Retroperitoneum?
Everything not surrounded by visceral peritoneum or tacked to the body wall is retroperitoneal
Which organs are Intraperitoneal?
Most of the gut tube and liver
What is characteristic of Intraperitoneal organs?
They are surrounded by visceral peritoneum and has a mesentery
What Peritoneum is are retroperitoneal organs surrounded by?
Parietal peritoneum
Which organs are Retroperitoneal?
- Blood vessels
- Anything not associated with the GI system
- Kidneys and adrenal glands
- Pancreas
- Duodenum
- Ascending and Descending colon
What is the general rule for organs that are Retroperitoneal?
Anything that is not associated with the gut tube itself
Which parts of the tube are Retroperitoneal?
The duodenum, the ascending and descending colon and the rectum
What three regions is the gut split into based on the vasculature?
- Foregut
- Midgut
- Hindgut
Where does the Foregut span?
Abdominal esophagus to descending part of the duodenum
Where does the Midgut span?
From the descending part of the duodenum to the left clic flexure of the transverse colon
Where does the Hindgut span?
From the left colic flexure of the transverse colon to rectum
What is the vasculature and innervation for the Foregut done by?
The celiac trunk
What is the vasculature and innervation for the Midgut done by?
Superior Mesenteric artery
What is the vasculature and innervation for the Hindgut done by?
Inferior mesenteric artery
What is the Renal Artery associated with?
The urinary system
What is the Gonadal artery associated with?
Reproductive system
What it the difference in arteries and veins of the GI tract?
There is no Celiac vein only a splenic vein instead
Where do all the veins from the GI tube go?
To the liver via the Portal Vein
What is the composition of the Portal Vein?
Non-oxygenated but nutrient rich blood
Where does everything in the abdomen that is not the GI empty blood into?
The inferior vena cava
