GI tract and accessory organs Flashcards
label the 12 parts of the digestive system
- mouth
- salivary glands
- oesophagus
- stomach
- liver
- gallbladder
- pancreas
- large/small intesting
- appendix
- rectum
- anus
define body hiatus in terms of GI tract
Body habitus refers to the common variations in the shape of the human body, which in turn determines the position of internal viscera.
Body habitus indicates the body wall thickness and the placement of organs
what are the 3 types of body habitus/ physiques of the Gi tract
- hypersthenic
- sthenic
- hyposthenia/asthenic
describe a sthenic body habitus
average, mesomorphic. It is a moderately heavy build with the organs orientated as such:
heart - moderately transverse
lungs - moderate in length
diaphragm - moderately high
colon - spread evenly with a slight dip in the transverse colon
gallbladder - right upper abdomen
describe a hypersthenic body hiatus
Also known as endomorphic. It is a largerbuild with the organs orientated as such:
heart - axis is almost transverse
lungs - short apices lie near the clavicles
diaphragm - high
stomach - high transverse and in the middle
colon - around the periphery of the abdomen
gallbladder - high
describe a hyposthenic/asthenic body hiatus
Also known as very slender, ectomorphic. It is a frail build with the organs orientated as such:
heart - nearly vertical and in the midline
lungs - long apices above clavicles
may be broader above base
diaphragm - low
stomach - low near the midline
colon - low folds on itself
gallbladder - relatively lower close to the midline
what are the 3 salivary glands
- parotid salivary gland
- sublingual salivary gland
- submandibular salivary gland
what percentage of saliva do the parotid and submandibular gland produce
parotid = 25%
sub mandible = 70%
what are the 5 functions of saliva
- lubricates oral mucosa
- lubricates food during mastication
- initiates digestion of starches
- protective pellicle on teeth
- secrete proteins, enzymes, glycoproteins, antibacterial agents
what enzyme found in saliva breaks down starches
amylase
what examination is done to look into salivary glandds
sialography
- injection of small vol of contrast into salivary ducts of single gland then xray projection
the abdominal organs are derived primarily from where
endoderm, which forms the primitive gut tube
what 3 sections is the gut tube divided into
foregut
midgut
hindgut
what abdominal contents are found in the foregut
from abdominal oesophagus to 2nd part of duodenum
what does the midgut consist of
from the 2nd part of duodenum up to 2/3 along the transverse colon
what does the hindgut consist of
from 2/3 of transverse colon all the way to rectum
what vasculature supplies the foregut, midgut and hindgut
foregut = coeliac trunk
midgut = superior mesenteric trunk
hindgut = inferior mesenteric trunk
what are the 3 pre-aortic lymph nodes
- celiac node
- superior mesenteric node
- inferior mesenteric node
where is the start and end of the oesophagus (give landmarks)
- starts at inferior border of cricoid cartilage (c6)
- ends at t10/11 (cardiac orifice of stomach)
describe the structure of the oesophagus going into the abdomen
The oesophagus begins in the neck, at the level of C6. Here, it is continuous superiorly with the laryngeal part of the pharynx (the laryngopharynx).
It descends downward into the superior mediastinum of the thorax, positioned between the trachea and the vertebral bodies of T1 to T4. It then enters the abdomen via the oesophageal hiatus (an opening in the right crus of the diaphragm) at T10.
The abdominal portion of the oesophagus is approximately 1.25cm long – it terminates by joining the cardiac orifice of the stomach at level of T11.
at what landmark does the distal end of the oesophagus enter the abdomen thru the abdominal hiatus found in the diaphragm
t10
at what landmark does the abdominal oesophagus end as it joins with the cardiac orifice of the stomch
t11
what is UES and what is its purpose
upper esophageal sphincter
- high-pressure zone located in between the pharynx and the cervical esophagus.
- The physiological role of this sphincter is to protect against reflux of food into the airways as well as prevent entry of air into the digestive tract.
what is LES and its purpose
The lower esophageal sphincter (LES) is a high-pressure zone located where the esophagus meets the stomach and protects the esophagus from the reflux of gastric contents
what are the 3 layers of the stomach muscle
- longitudinal (outermost)
- circular
- oblique (innermost)
rugae is found on the inner wall of the stomach, what is this
a series of ridges produced by folding of the wall of an organ.
how many parts of the duodenum are there and what are tehy
4
1st (pylorus) (superior)
2nd (descending)
3rd (inferior)
4th (ascending)
what part of the gut comes after the 4th part of the duodenum
jejunum (middle part of small gut)
what vascualture supplies the first half and 2nd half of the duodenum
up to 2nd part = coeliac trunk
3rd and 4th part = superior mesenteric artery
what pH is the mouth
pH 5-7
what pH is the stomach
pH 1-3
what pH is the small intestine
pH 6-7.5
what pH is the large intestine / colon
pH 5-7
what is the transpyloric plane
imaginary horizontal plane located halfway between the suprasternal notch of manubrium and upper border of the pubic symphysis
what landmark is the pubic symphysis found
L1
is the pancreas found in the fore, mid or hind gut
foregut
what is unique about the blood supply to the pancreas despite it being located in the foregut
- has supply from both the coeliac trunk and superior mesenteric trunk
what part of the pancreatic structure is the connection to the coeliac and superior mesenteric supply found
at the uncinate process
- area of the pancreas that bends backwards and beneath the body of the pancreas.
describe the 5 structural components of the pancreas
- head
- neck
- body
- tail
- uncinate process
what structure does the head of pancreas sit in
- duodenum
what are the 2 main functions of the pan creas
- The exocrine pancreas produces enzymes that help to digest food, particularly protein
- secrets bicarbonate to neutralise stomach acid
what are the 2 ducts found in the pancreas and their roles
- Main pancreatic duct (of Wirsung)
- drains most of the pancreas, the uncinate process and caudal aspect of the head
- Accessory pancreatic duct (of Santorini)
- accessory duct typically communicates with the main duct and drains into the duodenum via the minor papilla
the common bile duct and main pancreatic duct of wirsung (pancreas) joins at which location/structure
hepatopancreatic ampulla
the connection of the bile duct and main pancreatic duct drain through which structure
draining into the ampulla of Vater through the Sphincter of Oddi. (tiny hole that connects to the duodenum)
what is the role of the illeocecal valve
separates the luminal environments of the small and large intestines as they have different pH and bacterial content
- stops reflex from large to small intestine
- helps regulate small intestinal tract
what are the 5 different positions the appendix can be found
- pre-ileal (over illeocecal valvue)
- post ileal (under illeoceacal valve)
- retro-cecal (behind caecum)
- subcaecal (below caecum)
- pelvis (towards pelvis)
what is the most common appendix position
retro-cecal
note the appendix is INTRAPERITONEAL
(within peritoneal cavity)
what are the 7 structures of the large intestine (not counting appendix)
- ascending colon
- right colic flexure
- transverse colon
- left colic flexurre
- descending colon
- sigmoid
- rectum
what is the taeniae coli found in the large intestine
3 smooth longitudinal muscles of the colon
what are hastura found in the large intestine
sacculations of colon wall between taeniae (bumpy/ lumps of colon wall)
what is the omental appendices of the large intestien
- pouches of peritoneum that are filled with fat
- They’re attached to the external surface of the large intestine, opposite the side that the mesentery arising from the posterior abdominal wall attaches to.
what feature of the large intestine allows back and forth movement of the food, enhancing mixing of food with mucus and enzymed
haustrations (segmentation of the large intestine)
compare what small and large bowel obstruction looks like on scan
small = stacks of pennies ( valvulae conniventes)
large = dilated transverse and sigmoid colon
what is the major muscle found in the anus
levator ani
what plexus is found to be innervating the entire gut
myenteric plexus
what additional plexus is found to be innervating the gut minus the oesophaus
submucosal plexus
note that we do not need para/sympathetic innervation to control gut motility but it can modify the frequencuy
which nerve leads to the myenteric and submucosal plexus
vagal/vagus nerve
how do vagus nerves help the GI tract
- helps control oesophageal propulsion
- gastric acid secrretion
- emptying bladder
- gallbladder contraction
how long is the long and small intestine
small = 6.5 m
large = 1.8 m
what prevents the intestines from tying into knots
they are held in place by the peritoneum
the abdomen is filled with metres of churning and peristaltic tubes with their own blood vessels, lymphatics and nerves
what is the peritoneal cavity
potential space between the parietal peritoneum and the abdominal wall and visceral peritoneum and the organ it covers
- space that lies between the parietal peritoneum and the visceral peritoneum
what sits within the peritoneal cavity and why
peritoneal fluid, lubricates the organs
what is parietal innervation
- detects pain/temp/chemical stimulations with pain localised to the precise area affected
(contains same sensory bodies found in skin)
what is visceral inneervation
- detects stretch or irritation but can only localise to rough area e.g foregut
what 9 Gi structures are retroperitoneal, use mnemonic SAD PUCKER
- suprarenal adrenal gland
- aorta
- duodenum
- pancreas (except tail)
- ureters
- colon (ascending and descending)
- kidneys
- esophagus
- rectum
what 10 GI structures are intraperitoneal, use mnemonic SALTDSPRSS
- stomach
- appendix
- liver
- transverse colon
- duodenum (1st part0
- small intestine (jejunum and ileum)
- pancreas (only tail)
- rectum (upper 3rd)
- spleen
- sigmoid colon
what 5 parts can the peritoneal cavity be split into
- right/ left subphrenic space
- sub hepatic space
- right/left infra-mesocolic space
be aware that the different spaces within the peritoneal cavity can accumulate fluid collections
what is the greater omentum
a large apron-like fold of visceral peritoneum that hangs down from the stomachs greater curvature
what is the lesser ommentum
the double layer of peritoneum that extends from the liver to the lesser curvature of the stomach, and to the first part of the duodenum.
the venous drainage unlike usual where they follow the arteries, travel through what
liver
the portal system (GI venous system) is the exception of rule that veins always follow arteries.
in the gut, all venous blood containing the nutrients, drugs etc get processed through the liver first
what is the portal system
carries all venous blood from the abdomen and GI tract to the liver for processing
where might metastases from colon cancer be found
liver , as all venous blood from GI tract and abdomen goes to the liver first
what ligament stops the liver from moving
falciform ligament
what is the difference between the diaphragmatic and visceral surface of the liver
Diaphragmatic surface – the anterosuperior surface of the liver.
It is smooth and convex, fitting snugly beneath the curvature of the diaphragm.
The posterior aspect of the diaphragmatic surface is not covered by visceral peritoneum and is in direct contact with the diaphragm itself (known as the ‘bare area’ of the liver)
Visceral surface – the posteroinferior surface of the liver.
With the exception of the fossa of the gallbladder and porta hepatis, it is covered with peritoneum.
It is moulded by the shape of the surrounding organs, making it irregular and flat.
It lies in contact with the right kidney, right adrenal gland, right colic flexure, transverse colon, first part of the duodenum, gallbladder, oesophagus and the stomach.
what percentage of arterial and venous blood reaches the liver and through what vessels
hepatic artery = 25% arteriole blood
hepatic portal vein = 75% venous blood
where is the arteriole blood reaching the liver from
coeliac trunk
where is the venous blood reaching the liver from and how does this allow liver to carry out its function
supplies the liver with partially deoxygenated blood from abdomen/GI tract, carrying nutrients absorbed from the small intestine.
This is the dominant blood supply to the liver parenchyma and allows the liver to perform its gut-related functions (such as detoxification).
understan the gallbladder structure
what is the main function of the gallbladder
concentrate and store bile which is produced by the liver.
describe the 3 sections of the gallbladder
fundus
body
neck
describe the billiary system and how it goes down to the duodenum
- cystic duct branches from gall bladder joins to the common hepatic duct from the liver
- as the cystic duct and common hepatic duct join, it forms the common bile duct
- towards the distal end, the pancreatic duct joins to the common bile duct forming the hepatopancreatic ampulla of vater
- it the enters the duodenum through the sphincter of oddi
describe the arterial supply of the gallbladder
- receives blood from the cystic artery (which is a branch of the right hepatic artery coming from the common hepatic artery as part of the coeliac trunk)
describe the venous drainage of the gallbladder
via the cystic veins, which drain directly into the portal vein. Venous drainage of the fundus and body of the gallbladder flows into the hepatic sinusoids.
describe the arterial supply of the pancreas
pancreatic branches of the splenic artery.
The head is additionally supplied by the superior and inferior pancreaticoduodenal arteries which are branches of the gastroduodenal (from coeliac trunk) and superior mesenteric arteries, respectively.
describe the venous system of pancreas
Venous drainage of the head of the pancreas is into the superior mesenteric branches of the hepatic portal vein. The pancreatic veins draining the rest of the pancreas do so via the splenic vein.
find image and understand all structures found in abdomen / GI tract
what is the left and right colic flexure of large intestine also known as
right hepatic flexure
left splenic flexure
