Physiology Flashcards
What 3 nervous systems control the gut
Sympathetic, parasympathetic and enteric
What are the 2 plexuses in the enteric nervous system
Myenteric and submucosal
Where is the gut wall is the submucosal plexus found
Between the muscular layer and mucosa
Where in the gut wall is the myenteric plexus found
Between the 2 muscle layers
Which 3 nerves coming from the sympathetic nervous system control the gut
Greater, lesser and least splanchnic nerves
True or false: the sympathetic nervous system shuts off blood supply to the lungs
True - shutting off GI functions
What nerves from the parasympathetic nervous system control the GI
Vagus nerve and pelvic splanchnic nerve
True or false: the parasympathetic nervous system shuts off blood supply to the GI
False - it increases blood supply
What hormones are produced in the GI tract
Gastrin, CCK, secretin, GIP
What does gastrin do
Causes gastric acids secretion
What cells produce gastrin
G CELLS
What does CCK do
Stimulates secretions from pancreas and gallbladder
Where is CCK secreted
Duodenum and jejunum
What does secretin do
Causes an increase in bicarbonate production
What does GIP stand for
Gastrin inhibitory polypeptide
What is peristalsis
Muscular contractions to propel the bolus of food
True or false: the muscle behind the bolus relax during peristalsis
False - they contract, the muscles in front relax
What is segmentation
Contraction of the smooth muscle to split up the bolus
Why does segmentation occur
To increase the SA of the food and the epithelium
Which NS (sympathetic or parasympathetic) increases motility of the GI tract
Parasympathetic
Why do you get central abdominal pain first in appendicitis
The appendix inflames and irritates the visceral membrane which hasn’t got its only nerve supply. The region covering the appendix is supplied by the lesser splanchic nerve which comes from T10. Therefore, the body presumes the pain is coming from the T10 dermatome which covers the umbilicus giving pain in this area
Why do you get lower right abdominal pain following central pain in appendicitis
The appendix inflames so much that it now touches the parietal membrane which has different mesoderm derivative from visceral so gives localised pain
What structures give back pain
Retroperitoneal structures are they irritate nerve plexuses in the back
what are the 4 layers of the gut
mucosa
submucosa
muscle layer
serosa
what are the 3 layers in the mucosa
epithelia
lamina properia
muscularis externa
what type of epithelia lines the GI tract
simple squamous in the oesophagus and rectum
simple columnar everywhere else
what is found in the lamina properia
lymphoid tissue
what is found in the submucosa
lymphoid tisse, glands, submucosal plexus, blood vessels, dense CT
how many muscle layers are there in the external muscle layer
2 (circular and longitudinal)
however, there is a 3rd oblique layer in the stomach
irritation of the visceral peritoneum from structures arising from the foregut gives pain where
epigastric region
irritation of the visceral peritoneum from structures arising from the midgut gives pain where
periumbilical region
irritation of the visceral peritoneum from structures arising from the hindgut gives pain where
suprapubic region
which sphincter is the only one under voluntary control
external anal
what are enterocytes
the epithelia lining the GI tract - they allow for absorption
what are goblet cells
mucus producing cells
what is the difference between goblet cells and gastric mucous cells
gastric mucus cells are found in the stomach and produce a more bicarbonate rich mucus
what are the permeant folds in the intestines called
pliace circulares
what are the temporary folds in the stomach called
folds of rugae
what do the folds of rugae allow
expansion the stomach to hold food, without increasing in pressure
what are paneth cells
cells found in crypts which secrete antibacterial proteins to protect stem cells
why are there stem cells found in crypts
to allow regeneration of the epithelia due to the acidic environment
what is the rectus sheath
the sheet of tendons from the muscles external oblique, internal oblique and transverse abdominis. this sheet envelops the rectus abdominis muscle
what is the arcuate line
where there is a change in the rectus sheath as all the muscle tendons now pass over rectus abdominis covering it anteriorly only, instead of both anteriorly and posteriorly
where is the arcuate line found
half way between the umbilicus and pubic symphysis
what are peritoneal ligaments
double folding of peritoneum that links 2 organs together or links the abdominal wall to a organ
what does the gastrocolic ligament connect
stomach and transverse colon
what does the gastrosplenic ligament connect
stomach to the spleen
what does the falciform ligament connect
liver to abdominal wall
what does the triangular ligament connect
liver to diaphragm
what is the arterial blood supply to the GI
coeliac trunk for the foregut
superior mesenteric artery for the midgut
inferior mesenteric artery for the hingut
what is the venous drainage of the GI
all veins from the GI tract enter the liver via the portal vein, where it is then drained into the hepatic vein into the IVC
what structures are a part of the foregut
oesophagus, stomach, pancreas, liver, gall bladder, duodenum
what structures are a part of the midgut
jejunum, ileum, caecum, ascending colon, proximal ⅔ transverse colon
what structures are a part of the hindgut
distal ⅓ transverse colon, descending colon, sigmoid colon, rectum, upper anal canal
