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| REGULATION OF THE GI PROCESSES |
REGULATION of GI |
| What are examples of changes that would induce GI reflexes? |
Distension (volume), Osmolarity of chyme, acidity of chyme, chyme concetration of digestion products |
| What are nerual regulation reflexes mediated by? |
Short (enteric NS), and long (Afferent/Efferent) |
| What is the enetric nervous system/ |
GI nervous system |
| What kin do fneurons does it have? |
adrennergic and choleneric stimulation |
| What is the primary innervation in the GI system? |
MOTOR inntervation |
| HORMONAL REGULATION |
HORMONAL REGULATION |
| Stomach secretes: |
Gastrin |
| Small intestine secretes? |
Secretin, CCK (cholecystokinin), and GIP (glucose dependent insulinotropic hormone) |
| What are the three phases of GI regulation? |
Cephalic, gastric, and intestinal |
| What are stimuli in the cephalic stage? |
Receptors stimulated by seeing, chewing...etc. |
| What are stimuli in the gastric phase? |
Distension, decreased acidity, peptides formed in protein digestion |
| What are stimuli in the Intestinal? |
Stimuli in the intestinal tract (distention, acidity, osmolarity, digestive products) |
| CEPHALIC |
CEPHALIC |
| Chewing is AKA? |
Mastication |
| Is chewing essential for eventual digestion and absorption? |
Not really, but it helps in swallowing |
| What is the role of SLAIVA and how is it released? |
stimulated by food in the mouth via chemoreceptors and pressure receptors |
| What does sympathietic stimulation do to the saliva released? parasympathetic stimulation/ |
Both INCREASE saliva released |
| Where does the food go in swallowing? |
From phyrnx to the esophagus |
| How is food prevented from entering the trachea (windpipe)? |
Inhibition of respiration (nerual conrtrol) and closure of the glottis (by epiglottis) |
| As food is swallowed when moving into the esophagus, what happens? |
The upper esophageal sphingcter releazes and it then closes after food is swallowed to allow breathing |
| What esophageal remains open throughout swallowing? |
The LOWER esophageal sphincter |
| What is heartburn? |
When the lower sphincter is open when there's food in stomach |
| How many waves constitute the peristaltic swallowing wave? |
MANY waves, NOT JUST ONE |
| What is the role of gastrin? |
Hormone helps with breaking down food |
| What is responsible to secrete HCL by the stomach? |
Parietal cells |
| How many liters per day of HCl secreted by the stomach? |
2L |
| During meals, what happens to increase HCl? |
More parasympathetic activity |
| What is the role of cheif cells? |
Secrete pepsinogen |
| What kind of neural activity increases pepsinogen? |
Same parasympathetic one as for parietal cells and HCl |
| How does protein breakdown occur? Where does this take place? |
Via pepsinogen reakdown to pepsin. Takes place in stomach. |
| What does the increase in acidity during a meal potentially cause? |
Ulcer problem |
| So how do we cure this problem? |
Pepsin block histamine receptors via over the coutner "peptin" |
| Where is the strongest place in the stomach for peristalsis? |
Antrum |
| Through what and how much of the chlora is secreted into the small intestine? |
Small amount through the plyloric sphincter at a time |
| What does peristaltic wave frequency depend on? |
The APs of the slow waves |
| What is the frequency of the pacemaker cells i? |
3/min |
| What is the force of contraction determined by? |
neural and hormonal inputs to antral smooth muscle |
| What happens to osmolarity if you increase distention? |
Increase osmolarity |
| What happens to the gastric emptying as you distend the small intestine? |
INHIBIT gastric emptying |
| If you eat a really large meal, how fast does your stomach empty? |
Really fast |
| SECRETIONS |
SECRETIONS |
| Pretend you ate a meal, go through the steps that would occur regarding secretions (citing locations!!): Note that these events would prevent an ULCER. READY....GO! |
Increase acid from stomach, increase secretin by small intestine, increase bicarbonate secretion by pancreas, increase bicarbonates going into small intestine, and small itnestine neturalizes acid, so we've decreased acid in stomach and no ulcers |
| What is the role of trypsin? |
Activates other inactive enzymes |
| Stuff eneded by the small intestine is secreted by? |
By the pancreas |
| What is SECRETIN released in response to and by what? |
Secreted by the small intestine in response to increased luminal acidity to stimulate bicarbonate secretion |
| What is CCK released from in response to what and stimulates what? |
From the small intestine in response to fat and protein and stimulates pancreatic enzyme secretion |
| When is bile especially important (hence, it has a role with...??) |
After eating a fatty meal, hence its role in colestrol |
| What do bile salts undergo to replenish their supply of salts? |
Enterohepatic reciculation |
| What is the relationship b/w bile salt concentration and the rate of bile secretion? |
Direct; as one creases, the other does to |
| What is Billirubin? |
Breakdown product of hemoglobin absorbed from blood by liver and secreted into blood |
| What two elements help mediate teh amount of Bile stored in gall bladder? |
Absorption of salt and water |
| What does the release of CCK after a meal lead to? |
The gallbladder contracts and the Oddi releaxes, releasing bile |
| What does the small intestine digest? |
Polysachs and proteins |
| What is the releationship between osmolarity and digestion of polysachs and proteins in teh small intestine? |
Direct, the digestion of polysachs and proteins increases osmolarity--Water flow |
| How do sports drinks work then? |
They lack the osmolarity gradient--don't let water out |
| Okay, now we're moving toward the large intestine. Let's review. What did the small intestine do? |
Re-absorbved water and digested and broke stuff down |
| What is the migrating motility comples? |
Moving undigsted material into large intestine |
| What is the primary function of the LARGE intestine? |
Store and concetrate fecal matter before defacation |
| Water is absorbed from the ===== intestine ===== to the active absorption of sodium, leading to teh concetration of fecal matter. |
LARGE intestine; secondary to the active absorption-->more concentrated feces |
| What is flatus due to? |
Fermentation of bacteria |
| How does defecation work? |
Mechanoreceptors are stimulated by distention following contractions leading to stuff getting into the rectum-->open sphincter 2)then the glottis closes (held breath), generating pressure-->defecation |
| How about for people with High blood pressure? |
they could be given laxatives that wouldn't allow them to stress themselves when defecating |
| Is defacation voluntarily controlled? |
It can be; via somatic nerves to the skeletal muscles |
| PATHOPHYSIOLOGY |
PATHOPHYSIOLOGY |
| Ulcers do what? |
Destroy mucos barrier, expose to acid and pepsin |
| So, what usually prevents this breakdown of the mucosal barrier? |
alkaline mucos, tight junctions that block acid, and rapid replacement of epi cells |
| GAllstones are the result of? |
Crystelizing fat-->block gall bladder, can't release bile to break down fat |
| If you're lactose intolerant and you drink milk, what happens? |
Gas and diarrhea when you drink it |
| What is constipation? |
Food breakdown problem b/c of the colon |
| What neural thing controls vomiting? |
medulla oblongata |
