Block 3 Flashcards
(34 cards)
Stomach functions
1) Store move
2) Mix contents and secretions to form chyme
3) Gastric emptying into duodenum. Controls rate of chyme entering the duodenum
4) Acidi environemnt kills bacteria and parasites
5) Begins protein breakdown process via breakdown of colagen
2 ESSENTIAL small intestine functions
1) Mixing: ontraction of circular muscle = sausage like intestine allowing for mixing and breaking of contents
2) move contents ]3-5 hours from duodenum to ileocecal valve
BOTH ARE VIA MYENTERIC PLEXIS
Small intestine MIXING
Involved contractio nof smooth muscle
SEGMENTATION = short distance mixing
contraction is via MYENTERIC PLEXUS (SUBSTANCE P AND ACH)
Whereas movement invovles both contraction and relaxation
Defecation reflex
1) Enteric NS (weak reflex): stimulates the descending colon and sigmoid to have more mass movements
Inhibits internal anal sphincter (relaxation) via NO and VIP
2) Paraysmpathetic = STRONG REFLEX: further amplifies the efefect of mass movements from descending colon and sigmoid INTO THE RECTUM
inhibits the iNTERNAL ANAL SPHCINTER (RELAXATION via NO and VIP)
What are the causes of constipation
1) Narcotic use
2) Colon cancer
3) Hormones
4) Hirsprungs (intrinsic motility)
5) Extrinsic innervation
Hirsprungs
Cause of constipation. Loss of nerve cells that enable motility in the colon
Factors affecting glandular secretion
1) Tactile stimulation
2) Enteric NS (Tactile stim, gut distension, chemical irritation)
3) PNS (Increases secretion)
4) Symapthetic is net decrease in secretion via decreasing blood flow (constriction)
Most intestinal juices are
BASIC
With exception of gastric (acidic)pH 1-3.5
Salivary glands produce 2 kinds of proteins
1) Ptyalin
2) Mucus
Ileocecal valve control
1) Pressure or irritation at the distal small intestine (ileum) will cause relaxation of spchinter to allow emptying from the small intestine into the cecum (first part of colon)
(pressure in ileum ==> increases peristalsis
2) More fluidity of contents promotes emptying into colon
3) Pressure or irritation in the cecum ==> inhibits peristalsis (pressure in spchinter increases to prevent things from being dumped into the cecum from the ileum)
eg appendicitis
Salivary gland 3 types of glands
1) Parotid
2) Submandibular
3) Sublingual
Parotid is ONLY SEROUS (AMYLASE)
SUBmandi and SUBlinguial are BOTH amylase and MUCUS secretions
Describe the structure of salivary gland
Acinar cells branching from DUCTS
Acinar cells produce
1) Ptyalin (amylase)
2) Mucus
3) Extracellular fluid
Ducts have active NaCl absorption and K/HCO3 secretion
What happens to salivary secretions as they move down the ducts
Active NaCl absoprtion and active KHCO3 secretion
Therefore at the end of the duct saliva is HIGH IN KHCO3 and low in NaCl
WHAT IS CONTAINED IN SALIVA
PTALIN (Aamylase) or MUCUS
Which substance does saliva start to braekdown
carbohydrates
Esophagus
Only produces MUCUS
Gastric secretion
Mucus
ALso what is made by Oxyntic gland
Where are oxyntic glands
PROXIMAL STOMACH
Compsoed of 3 cell types
1) Parietal cells
2) Chief cells
3) Enterochromaffin cells
2 factors that affect gastric secretion
1) Enteric NS via distension of small intestnie, irritation, and acidity in duodenum inhibit gastric secretion
2) Fats+protein breakdown + altered osmolality in duodenum ==> release of secretin –> decreases GASTRIC SECRETION
What activates pepsinogen secretion
1) ACh via PNS or ENS
2) HCL
PEPTIC ULCER DISEASE
2/3 duodenum
1/3 gastric
2 main causes of peptic ulcer disease
H. pylori infection + NSAID use comprise over 95% of cause in duodenal cases
H. pylori is the MAIN cause
Causes of peptic ulcer disease
1) H. pyloi
2) NSAIDs: advil, aleve, aspirin
3) Gastrinoma: gastrin secreting tumor. Too much acid secretion from parietal cells
4) viral infection
5) smoking
6) Crohns Disease
7) Lymphoma
Peptic ulcer disease
Gastric: Most common cause is H. pylori. other cause is NSAID
Duodenal: most . common cause is H pylori
other cause: Zollinger Ellison syndrome
Occurs with hypertrophy of Brunner glands
