Digestive System Flashcards
Where does the digestive system start and end?
Oral cavity
Anal opening
What are the main functions of the digestive system?
- breakdown of ingested food and fluid
- absorption of required nutrients and water
- waste removal system
Where does the system pass through in the body?
Head, neck, thorax, abdomen and pelvis
What are the abdominal sections split into based on the blood supply?
foregut, midgut and hindgut
What suplies the foregut?
Branches from the celiac axis
What supplies the midgut?
Branches from the superior mesenteric arteries
What supplies the hindgut?
Branches from the inferior mesenteric arteries
What occurs in the oral cavity?
teeth break down food, tongue helps form a bolus which can be swallowed
What do the salivery glands release?
Amylase to begin the breakdown of starch
Whats the role of the pharynx?
Collects the bolus and funnels it towards the oesophagus
How and where does the oesphagus push food down its tube?
Muscular tube from inferior constrictor of the pharynx (C6 level in the neck)
Through the thoracic inlet and into the posterior mediastinum of the thorax
Passes through the oesphageal opening of the diaphragm at T10 vertebral level
Small intra-abdominal section before joining the stomach
What are the structures within the foregut?
Distal oesophagus, stomach, liver, gall bladder, spleen, proximal duodenum, pancreas
What parts of the foregut are involved in the digestive system and why?
Proximal duodenum and part of pancreas as they both get supply from the celiac axis and the superior mesenteric arteries
Where does the celiac axis originate from?
Anterior surface of the abdominal aorta and vertebral level T12
What does the celiac axis split into?
The left gastric and hepatic splenic arteries
Where does blood from the foregut drain into?
Portal system and eventually into the hepatic portal vein
From there into the liver to have any toxins removed
Where does the liver drain blood directly?
Inferior vena cava via hepatic veins
Name the 3 parts of the stomach
Fundus, body and pyloric canal
There is a lesser curvature and a greater curvature in the stomach. What is the lessure curvature also called?
Angular incisure
What are the folds within the stomach called?
Rugae
How many layers does the stomach have?
3
What is the function of the stomach?
Churns food with digestive acid to crete chyme which is passed into the duodernum via the pyloric valve
Where does the oesophagus pass through the stomach?
The fundis
What can patients be given in order for thier soft tissue to be seen in an X-ray?
Barium meal
What is the role of the lesser omentum?
Carries the hepatic portal vein to the liver
How is the gretaer omentum moved?
Situated under the greater curvature of the stomach
By the intestines
What does the greater omentum do when the intestines are infected?
Moves and adheres to the area of infection and tries to localise any infections within the area?
Where is the liver located?
Very large organ under right hemisphere-diaphragm, also protected by the lower ribs and crosses the midline
What is located between the left and right node on the anterior view of the liver?
Falciform ligament
Where is the gall bladder located on the liver?
Beneath the right lobe
What 4 lobes are seen on the poster-inferior view of the liver?
Left lobe
Right lobe
Quadrate lobe
Caudate lobe
Where does blood drain to from the liver?
Into the inferior vena cava via hepatic veins
What occurs in the porta hepatic of the liver?
Blood is carried to the liver via hepatic aretry and portal vein
Bile is carried away from the liver by the bile duct
What is the use of bile in the liver?
Emulsify fats
What does the gall bladder do?
Stores bile and releases it into the duodenum via the cystic and bile ducts
How to gallstones form?
As the bile concentrates- removing water but forming āstonesā made of salts, bile pigments and cholesterol
Where is the spleen located and what is it protected by?
Small organ posterior and lateral to the stomach
Protected by left ribs 9,10,11
What is the purpose of the spleen?
Breaks down old red blood cells, naiive T and B immune cells are exposed to antigens
Describe the duodenum
āCā shaped tube passing between the pyloric valve of the stomach and the jejunum
What is the 1st, 2nd, 3rd and 4th part of the duodenum?
1st- Duodenel cap attached to the pyloric valve
2nd- Loop around head of pancreas, duodenal papilla (Ampulla of Vater) entrance of bile duct and pancreatic duct
3rd- Transverse crossed by superior mesenteric vessels
4th- Ascending to join jejunum
Where does the duodenum recieve blood from?
Branches of the celiac axis and branches of the superior mesenteric arteries
What type of organ is the pancreas?
Endorine and Exocrine
insulin and digestive enzyme
Where is the head and tail of the pancreas located?
Head - Loop of the duodenum
Tail- Extends to abut on the spleen
What does the main pancreatic duct do?
Empties digestive enzymes into the duodenum
What runs along the posterior/superior surface of the pancreas?
Spenic artery and vein
Where does the midgut pass?
Passes from the distal duodenum to 2/3rds along the transverse colon
What does the midgut contain?
Small and large intestine
Where does the midgut recieve and drain blood?
Receives- branches of the superior mesenteric artery
Drains- to the hepatic portal vein (portal vein made by union of superior mesenteric vein and splenic vein)
What does the peritoneum do?
Lines the abdominal cavity
Creates a smooth environment for the soft, delicate organs
Holds organs to the abdominal wall
What does the mesentery do on the small intestine?
Carries blood vessels, autonomic nerves and lymphatic vessels
What does the greater and lesser omentum do?
Greater- overlies the intestines
Lesser- carries structures to/from the portal hepatis
Where does the jujunum and ileum extend to?
Jejunum- passes from the distal duodenum to the ileum
Ileum- Passes from the jejunum to the caecum at iliocaecal junction
What is the Caecum?
First part of the large intestine
Swollen sac at the proximal end of the ascending colon, and has a small outgrowth called the appendix
What is the appendix?
Blind-ended tube that may have immune function
Where does the ascending colon lie?
Between the caecum and the transverse colon
Passes on the right side of the abdominal cavity and ends at the hepatic flexure
What does the ascending colon do?
Absorption of nutrients and water
What is the hausfrau, tenaie coli and appendices epiplocae?
Sacculations
Longitudinal muscle band
Fatty tags
Where does the transverse colon start and end from?
Start- hepatic flexure
End- Splenic flexure
What does habitus mean?
Affect of body shape
Where is the hingut located?
Between the splenic flexure and the anal canal
What is within the hindgut?
Distal transverse colon, descending colon, sigmoid colon, rectum and anal canal
Where does the hindgut receive and drain blood?
Receive- Branches of the inferior mesenteric artery (aorta L3)
Drains- To portal vein until mid-rectum, distal rectum drains to inferior vena cava
Where does the decending colon lie?
Between the splenic flexure and the sigmoid colon
Passes down the left side of the abdominal cavity
Describe the anal canal
Smooth muscle and skeletal sphincters
Where do the different arteries supply?
Coeliac axis- T12 (foregut)
Superior mesenteric artery- L1
Inferior mesenteric artery- L3
Why is it called hepatic portal vein?
Takes blood to the liver
What is the hepatic portal vein a union of?
Spenic and superior mesenteric veins
