Diana's Diahorrea Flashcards
Where does the inferior mesenteric artery arise?
At L3
What are the tributaries of the inferior vena cava?
From inferior to superior they are: median sacral vein, right and left internal and external iliac veins forming common iliac vein, iliolumbar and adcending lumbar veins, testicular/ovarian veins, right and left renal and suprarenal veins, inferior phrenic veins, right, left and middle hepatic veins
What gives the jejunum it’s distinct, floccular appearance on a contrast X-ray (barium follow through) compared to ileum?
The great numbers of plicae circulares which are few in number and smaller in the ileum
What are the attachments of psoas major?
Arises from lumbar transverse process and lumbar vertebral bodies and attaches onto lesser trochanter of femur with the iliacus muscle.
Where is the lesser omenteum?
Stretched between liver and gallbladder to stomach
Where is the appendix in relation to the caecum?
On its posterio-medial wall
Where are the Na/KATPase pumps on luminal intestinal cells?
On basal and lateral sides
Which organs lie on the posterior abdominal wall (and are therefore retroperitoneal)?
Kidneys, suprarenal glands, duodenum, pancreas, ascending and descending colon
What is the defecation reflex?
1) rectal contraction
2) contraction of external sphincter, relaxation of internal sphincter
3) reflex relaxation of external sphincter, can be inhibited by voluntary striated muscle contraction
What does the colon do?
Reabsorbs water and some electrolytes from chyme, compacts dehydrated chyme into faeces, mass peristaltic movements to move faeces to rectum
What is the lower part of the rectum called?
Rectal ampulla
What are epiploic appendages?
Fat-filled extensions of serosa in colon
Which arteries supply proctodaeum?
Inferior rectal arteries
What are crypts?
Columner absorption focused epithelial cells and mucus secreting goblet cells
What are the branches of the sigmoid arteries?
Superior sigmoid branch joins left colic and inferior sigmoid branch joins superior rectal
Where is the ligament of Treitz?
It is the suspensory ligament of the duodenum
What are the parietal branches of the abdominal aorta?
Left and right inferior phrenic arteries, four paired lumbar arteries and the median sacral artery
Which arteries supply thoracic foregut?
External carotid and oesophageal
How do osmotic laxatives like lactulose work?
Stimulate the myenteric plexuses to increase peristalsis and reduce salt and water absorption to increase faecal volume, may inhibit Na+ pump, cAMP and prostaglandins adding to this effect
What are the anatomical folds of the duodenum called?
Plicae circularis
What type of epithelium does colon have?
Simple columnar with prominent glands
Which muscle marks the beginning of the anarectal junction and what does it do?
Puborectalis (part of levator ani) forms a sling around the rectum, pulling it forward and helping control defecation
Name the parts of the stomach and where they are
Cardia: where oesophagus enters
Fundus: top part mainly air filled
Antrum: bottom of stomach
Pylorus: where stomach meets duodenum
How does the duodenum produce CCK?
Via vasoactive intestinal peptide (VIP)
What is the average epithelial cell turnover in the small intestine?
6 days
How are the inferior and superior vena cava linked?
Lumbar veins drain to the IVC, azygos veins drain to the SVC. These two are continuous with one another in the posterior mediastinum so that if the IVC or SVC is blocked, blood will be rerouted via this system
What is the cloaca?
The terminal end of the hindgut in the embryo
What kind of epithelium does the upper half of the anal canal have?
Plum-red mucosa (due to internal rectal venous plexuses)
Where is the rectouterine pouch?
Fold of peritoneum between rectum and uterus in females
How do crypts aid water reabsorption?
They suck faeces into them and dehydrate it by creating osmotic pressure across their walls which draws water into the crypt space and reabsorbs it
Where is the lumbar plexus located?
In the substance of psoas major
Where does the inferior mesenteric artery arise?
From descending abdominal aorta at the level of L3
What do lipases do?
Pancreatic enzymes that break down fats into monoglycerides and fatty acids
Where does the IVC leave the abdomen?
By piercing the central tendon of the diaphrag,m
Where is the lower end of the anal canal derived from embryologically?
Invagination of surface ectoderm
Which visceral branches of the abdominal aorta are paired?
Suprarenal, renal and testicular/ovarian
Which artery supplies hind gut?
Inferior mesenteric artery
Which artery supplies foregut?
Coeliac artery
What kind of epithelium does the lower half of the anal canal have?
Stratified, squamous, non keratinising
Describe the asymmetries of the inferior vena cava.
On the left the suprarenal vein and testicular/ovarian vein are tributaries of the renal vein, on the right they are direct tributaries of IVC. The middle hepatic vein is on the left and not the right.
Where does the coeliac artery arise?
At T12
How does paraffin oil work as a laxative?
It blocks the crypt lumens so they cannot suck fluid out of faeces
What are the branches of the inferior mesenteric artery?
Left colic artery, sigmoid arteries, superior rectal artery
Where do superior and inferior pancreaticodudodenal arteries anastomose?
At the point of entry of bile duct into duodenum, and point of foregut becoming midgut
Where is the duodenum roughly?
To the right of L1-L3 in the umbilicus region
What are teteiae coli?
Strips of longitudinal muscle which contract to produce haustra
Which branches of the superior mesenteric artery anastomose with one another?
Right colic and ileocolic anastomose. Middle colic and right colic anastomose.
What forms the roof of the abdominal cavity and the upper part of posterior abdominal wall?
The diaphragm
Where does the inferior vena cava begin?
At L5
Where does the aorta enter the abdomen?
Under the median arcuate ligament at T12
What are Peyer’s patches?
Aggregated lymph follicles in the mucus membrane of ileum
Where is the greater omenteum?
Stretched below stomach across intestines
Where does the aorta end, and how?
At L4 it splits into common iliac arteries
What are the right and left paracolic gutters?
Trench formed by peritoneum on the lateral side of the ascending colon and descending colon respectively
How are vitamins A and E transported around the body?
In chylomicrons in lymph
Describe the neural control of defecation.
Rectum senses fullness, internal anal sphincter is inhibited as is voluntary sphincter and puborectalis muscle (ano-rectal angle can become more obtuse). Pre-synaptic sacral parasympathetic outflow causes contraction hindgut. The external anal sphincter is held under voluntary tonic control until point of defecation.
What are the symptoms of malabsorption?
Steathorrea, diarrhoea, nutritional deficiency, muscle weakness,sensory loss, malaise, low bone mass
What is arterial supply of anal canal above the pectinate line?
Inferior mesenteric artery
Where is the major site of iron absorption in the small intestine?
Duodenum
What are taeniae coli?
3 longitudinal strips of muscle which maintain muscle tone of colon and produce haustra (sac like divisions)
Where do testicular/ovarian arteries arise?
At L2
Which at artery supplies mid gut?
Superior mesenteric artery
What are the names of the salivary glands?
Parotid, submandibular, sublingual
What is venous drainage of anal canal below the pectinate line?
Inferior rectal veins
Where does the superior mesenteric artery arise?
From descending abdominal aorta at the level of L1
What are the general layers of the GI tract?
1) Mucosal (epithelial) layer
2) Lamina propria (connective tissue) layer
3) Muscularis mucosa (SM)
4) Submucosa (connective tissue)
5) Muscularis externa (SM)
6) Serosa (squamous mesothelial layer)
What inhibits voluntary sphincter and puborectalis muscle?
Pudendal nerves (S2-S4)
Where do renal arteries arise?
At L1/2
Where is McBurnley’s point?
2/3 of the way down a line drawn from umbilicus to right anterior superior iliac spine
What is the upper half of the second part of the duodenum in relation with?
At the upper half of the second part of the duodenum, it is sandwiched between right kidney and ureter (behind) and beginning of transverse colon (in front)
Irritation of which organs may cause spasm of psoas major, leading to pain and flexed hip?
Kidneys, pancreas, dudodenum, ureters, caecum, appendix and sigmoid colon
Where does most of the jejunum lie?
In the umbilical region of abdomen
Which third of the rectum is covered in front and sides by peritoneum?
Upper third
Where does the rectum begin and end?
Begins at S3 and ends at the pelvic floor
What are plicae transversalis recti?
AKA rectal valves of Houston. Semi circular folds in wall of rectum which zig zag the course of the rectum and slow the passage of faecal material
Where do suprarenal arteries arise?
At L1
How are proteins broken down in the small intestine? By which enzymes?
Proteases break down polypeptides into shorter chains by trypsin and chymotrypsin then they are broken down into single amino acids by carboxylpeptidase and aminopeptidase
Where does the superior rectal artery supply?
The rectum and upper half of the anal canal
Which artery joins superior and inferior mesenteric systems?
Marginal artery of Drummond
What are the branches of the left colic artery?
Has an ascending branch which joins the middle colic and a descending branch which joins the highest sigmoid branch
What are omental appendages?
Fatty tags on surface of colon
What are the branches of the ileocolic artery?
Has a superior branch that joins the right colic artery, anterior and posterior caecal branches, ascending branch which joins ascending branch of left colic artery
Describe the spread of pain in appendicitis.
From the region of umbilicus to McBurnley’s point
What are the branches of the middle colic artery?
Has right branch and left branch which joins ascending branch of left colic artery
Where does the hindgut receive blood supply from?
Inferior mesenteric artery
Name 5 sympathetic nerves that supply the gut.
Greater, lesser and least thoracic splanchnic nerves, lumbar splanchnic nerves and gray rami communicantes
How can diarrhoea be classified by time?
Acute: 2 weeks
Persistent: 2-4 weeks
Chronic: over 4 weeks
What is in the midgut?
Duodenum up to 2/3 through traverse colon
What is the sphincteric action of the ileocaecal junction?
There is a pair of lips which act as a form of valve to prevent relflux and overfilling of caecum but no true sphincter
Where is the caecum?
In the right iliac fossa
Where will lymph drain below the pectinate line?
To superficial inguinal nodes
How do long chain fatty acids enter the blood from the GI tract?
By firstly being absorbed into lymph by lacteals in the small intestine then entering blood stream via thoracic duct
What is the innervation of psoas major?
L1, 2 and 3 and femoral nerve (iliacus)
What forms the conjoint longitudinal coat for the anal canal?
Fusion of pubococcygeal fibres of levator ani and longitudinal smooth muscle coat of rectum
What is the cysterna chyli?
A large lymph sac near the aortic opening in diaphragm between L1-2where most lymph from abdomen drains to via para aortic nodes
What inhibits the internal anal sphincter?
Sympathetic stimulation from L1/2
What is nervous supply of anal canal above the pectinate line?
Insensitive to pain. Sensory nerve supply via parasympathetic nerves.
What are the parts of the colon?
Caecum with it’s vermiform appendix, ascending colon which becomes transverse colon at hepatic flexture (on the right) then the transverse colon becomes descending colon at the splenic flexture (left) and then finally sigmoid colon
What are the sensory nerves of the rectum that sense fullness?
S2-4 parasympathetic afferents
What activates Na+/H+, Na+/K+ATPase and Cl-/HCO3- channels?
Ca2+
How will the ileum appear radiologically?
Solid
What is the blood supply of the appendix?
Appendicular artery, a branch of the superior mesenteric
What kind of muscle is the external sphincter made of?
Skeletal
What stimulates pancreatic secretions?
CCK and vagus nerve activity
What muscle layers do anal canal and rectum have?
Complete layers of longitudinal and circular muscle. Longitudinal muscle is continuous with anal skin and causes puckering. Circular muscle forms internal anal sphincter
What is the mesentery of the appendix called?
Mesoappendix
Which nerve is cranial nerve X?
The vagus nerve
Which third of the rectum is devoid of peritoneum?
Lower third
What is the gastro-colic reflex?
Defecation often follows a meal, so sigmoid mass movement may be caused by gastrin
Which part of the duodenum crosses aorta and IVC?
The third part
What is the cephalic stage of gastrin secretion?
Pre-stomach. The sight smell and taste of food stimulates acetylcholine and gastrin release which stimulate histamine to activate parietal cells to secrete HCL
Which organs have some lymph which goes back through right and left bronchomediastinal lymph trunks?
Liver and stomach
Where does the superior mesenteric artery arise?
At L1
Which nerve supplies hindgut parasympatheticly?
Pelvic splanchnic nerve
Which nerve is cranial nerve IX?
Glossopharygenal
Which visceral branches of the abdominal aorta are unpaired?
Coeliac, superior and inferior mesenteric
Which plexus supplies posterior abdominal wall?
Lumbar plexus
What is the vitelline duct?
The diverticulum which connects the dorsal part of the yolk sac with the remnant yolk sac at the front
Which parts of colon are mobile and which are fixed?
Transverse and sigmoid are intraperitoneal so mobile and the rest is retroperitoneal therefore fixed, though caecum sometimes has a mesentery
Where is the major site of folate absorption in the small intestine?
Jejunum
What makes up the foregut?
Everything in the GI superior to the amputer of Vater entry into the duodenum
What makes up the hind gut?
Last 1/3 of transverse colon up to 1/2 down the anal canal
Which abdominal organs are retroperitoneal?
Rectum, ascending and descending colon and duodenum
Where will lymph drain above the pectinate line?
To inferior mesenteric pre-aortic nodes or some directly to internal iliac nodes
Where is the rectovesical pouch?
Fold of peritoneum between rectum and bladder in males
Which parts of small intestine are intraperitoneal and which are retroperitoneal?
Duodenum is largely retroperitoneal, jejunum and ileum are intraperitoneal
Where is foregut pain felt?
Epigastric
Which artery crosses duodenum anteriorly?
Superior mesenteric artery
Which nerves trigger peristalsis mass movements of smooth muscle of rectal wall and hindgut on defecation?
Parasympathetic efferents (S2-4)
What are diverticula?
Pathological out pouchings of gut wall
Where do inferior internal arteries arise from?
Paired pudendal arteries which arise from internal iliac arteries
What surface feature indicates transition of sigmoid colon to rectum?
Termination of taeniae coli
What are the mucosal glands of the duodenum called?
Glands of Brunner
How do inferior pancreaticoduodenal branches run?
Anastomose with superior pancreaticoduodenal from coeliac trunk to supply pancreas and duodenum
Where is hindgut pain felt?
Hypogastrium
What are the root values of iliohypogastric, ilioinguinal and genitofemoral nerves?
Iliohypogastric and ilioinguinal arise from L1, genitofemoral from L1-2
Why is the jejunum pinker in colour than the ileum?
It has thinner mesentery with less fat and a richer blood supply
What are the branches of the right colic artery?
Has a descending branch to join the superior branch of the ileocolic artery and an ascending branch that joins the right branch of the middle colic
Which third of the rectum is covered in front by peritoneum?
Middle third
What is the pectinate line?
The 6/7 anal columns which are linked by anal valves in the upper half of the anal canal. These are situated opposite the anal canal.
What activates Cl- channels?
cAMP
What are the attachments of quadratus lumborum?
Arises from iliac crest and is attached to lumbar transverse process and attaches superiorly onto 12th rib
How does lymph reach pre aortic nodes?
Follows pattern of arteries to the nodes located near coeliac trunk and SMA and IMA
How can you tell the difference between rectum and sigmoid colon?
The disappearance of mesentery, haustrae, taeniae coli and appendages epiploicae
What is the yolk sac?
Provides nutrients for foetus before placenta
How are ions and water reabsorbed in the large intestines?
By Na+/K+ATPase pump generating osmotic gradient where cellular Na+ is low so Na+ moves down gradient from lumen into cell, water follows
Name 3 parasympathetic nerves that supply the gut.
Anterior and posterior vagal trunk and pelvic splanchnic nerve
Which is the medial muscle of the posterior abdominal wall?
Psoas major
Where is the major site of B12 and bile salt absorption in the small intestine?
Ileum
What are haustra?
Sac like divisions of the colon
How much chyme enters colon per day?
Approx 1.5 L
What are the boundaries of the ischioanal fossa?
Anteriorly: perineal membrane, urogenital diaphragm, superficial and deep transverse perineal membrane
Posteriorly: gluteus maximus muscle and sacrotuberous ligament
Base: skin
Medial wall: levator ani, external anal sphincter and anal canal
Lateral wall: obturator internus muscle overlying ischium
Apex (superior): levator ani meeting obturator fascia
What is venous drainage of anal canal above the pectinate line?
Hepatic portal system
Where is midgut pain felt?
Umbilical
Where are Peyer’s patches found?
The ilieum only
What is McBurnley’s point?
Where the base of the appendix is and where maximal pain is felt during appendicitis
What kind of blood supply does the jejunum have?
Less complex than ileum, with long vasa recta (straight arteries) that reach the gut wall. These are anatomical end arteries.
What is the blood supply of the ileum like?
The ileal branches of superior mesenteric artery divide and reunite to form a complex series of arches and arcades so the vasa recta here are short, but still anatomical end arteries
Which abdominal organs are intraperitoneal?
Transverse and sigmoid colon, caecum, jejunum and ileum
Where is the appendix?
Attached to the caecum
Where does most of ileum lie?
In the pubic and right inguinal regions of abdomen
What is arterial supply of anal canal below the pectinate line?
Inferior rectal arteries
Which muscle lies most laterally on the posterior abdominal wall?
Quadratus lumborum
Which nerve supplies foregut and midgut parasympatheticly?
Anterior and posterior vagi
Which organ is duodenum most closely related to?
Pancreas
What are the main three laxative types and examples of each?
1) bulk forming (fibre)
2) stimulating (castor oil)
3) osmotic (lacultose)
When are gastric inhibitory peptide and CCK secreted? What do they do?
When there is fat in the duodenal chyme. Both inhibit gastrin and acid release and stimulate pepsinogen release from chief cells
What is nervous supply of anal canal below the pectinate line?
Very sensitive to pain. Nerve supply is somatic via pudendal nerves.
Describe the layers of the external anal sphincter.
Subcutaneous, superficial and deep from inferior to superior
What are the branches of the superior mesenteric artery?
Inferior pancreaticoduodenal branches, jejunal and ileal branches, ileocolic artery, right colic artery, middle colic artery
Which hormone controls the sphincter of Oddi?
Cholecysokinin (CCK)
How is HCL formed in parietal cells?
Exchange of H+ for K+ and then Cl- for K+ so there is HCL outside the cell and K+ remains in the cell.
Why does the duodenum have such a large surface area?
Villi, microvilli and circular folds in mucous membrane known as plicae circularis
What is contained in the ischioanal fossa?
Fat, vessels and nerves. Pudendal arteries and veins and the pudendal nerve (S2-4)
