- emulsifies fats - allows for excretion of hydrophobic molecules - helps neutralize gastric acid (it's alkaline)

Gastro Physiology Flashcards by Andrea Mueller

During the intestinal phase of digestion, the typical fluid load to the jejunum is ______ L per day. Consisting of dietary water, saliva, gastric juice, pancreatic juice, intestinal secretion, and about 0.5 L of _____

7-10

Bile

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Specializations of the GI tract to accomplish it’s functions

Stomach acid and other digestive fluids
The villi and microvilli of the small intestine
The enteric nervous system
The splanchnic circulation
The colonic microbiome

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What cells are responsible for ingesting foreign bodies entering the blood via the gastrointestinal tract?

Kupffer cells

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In this type of swallowing the nasopharynx is closed by the soft palate, deflection of the food bolus by the epiglottis (away from the larynx), and relaxation of the upper esophageal sphincter

Involuntary

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Endocrine functions of the pancreas

secrete the hormones insulin and glucagon

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What 3 things work together to stimulate gastric acid formation

Gastrin, histamine, and acetylcholine

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What type of highly phagocytic cells, located in the liver, are exposed to the portal blood flow and serve as a sentinel for antigens/bacteria arising from the intestine?

Kupffer cells

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What is secreted in the pyloric gland area of the stomach?

Endocrine secretions:

Gastrin, Somatostatin, Histamine

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The colon contains a longitudinal layer of smooth muscle called

Teniae coli

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What keeps the stomach from digesting itself?

A mucus-bicarbonate barrier at the mucosal surface

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In what condition do patients lack a functional Cl- channel in the luminal membrane of the pancreatic duct cells ultimately causing malabsorption?

Cystic Fibrosis

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What must relax to allow the food bolus into the stomach?

Lower esophageal sphincter, controlled by autonomic nerves

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GI circulation is also known as ______ circulation, and is most effected by the SNS

Splanchnic

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Extraintestinal diseases that have been shown to be affected by the gut microbiome include:

weight control (obesity)
inflammatory bowel disease
the general immune response (autoimmune diseases)
resistance to infectious disease

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What is the functional unit of the intestines?

Villus

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Functions of the colon during the intestinal phase of digestion

Absorption of fluid
Transport of electrolytes
Storage and elimination of fecal waste

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Most common cause of pancreatitis in women?

gallstones

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Functions of bile

emulsifies fats
allows for excretion of hydrophobic molecules
helps neutralize gastric acid (it’s alkaline)

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What are the Motor functions of the stomach?

Reservoir for ingested food, mixing of ingested food, regulates the delivery of food to the small intestines at appropriate rate and consistency

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About ____ liters of fluid is delivered to the colon per day, and approximately _____ liters are absorbed.

The maximum reabsorption capacity of the colon is ____ liters. If the total fluid load exceeds this, _______ occurs.

1.9

Diarrhea

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Parts of the GI tract

mouth, esophagus, stomach, duodenum, jejunum, ileum, cecum, colon, rectum, anus

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How do proton pump inhibitors work?

They bind and inhibit the H+/K+ -ATPase pump on the luminal surface of parietal cells

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Major functions of the organs in the GI tract

Nutrient intake and processing for absorption
Water balance
Protection from invasive organisms and toxins
Endocrine functions mostly involving the regulation of nutrients (eg glucose and lipid metabolism, protein synthesis)

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How is the food bolus moved through the esophagus?

smooth muscle peristalsis, coordinated by the enteric nervous system

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In what ways do non-pathogenic bacteria benefit the GI system?

- provide beneficial metabolic functions | - provides increased resistance to pathogens/allergens

What stimulates the feedback loop to shut off secretion of gastric acid

Somatostatin

If bacterial antigens survive the acid in the stomach and bind to the luminal surface of the distal small bowel, they stimulate this type of lymphocytic cell to circulate and populate all of the musical tissues of the body?

IgA-secreting plasma cells

Sympathetic noradrenergic activity in the enteric nervous system has what effect in the GI tract

decreases intestinal smooth muscle activity and causes sphincters to contract

In Splanchnic circulation, all the blood from the GI tract drains to the liver via

hepatic portal vein

What stimulates and releases Gastrin in the stomach?

Stimulated by stomach stretch, released by Gastrin-releasing peptides (GRP) by enteric nervous system

Contraction of the gallbladder occurs during what phase of digestion?

intestinal in response to a meal

What phase of gastrointestinal response involves gastrin, histamine, and acetylcholine that bind to parietal cells to stimulate gastric acid production?

Gastric phase

What is involved in cobalamin absorption?

Intrinsic factor

The major network of nerve fibers involved with secretions in the gastrointestinal tract

Submucous plexus (Meissner)

What must relax to allow food into the esophagus?

Upper esophageal sphincter, controlled but the extrinsic nerves

What is involved in the Exocrine functions of the stomach?

Water- dissolve & dilute ingested food Acid (HCl)- denature dietary proteins and sterilize the meal Enzymes (pepsin & gastric lipase)- protein & fat digestion Intrinsic factor- a glycoprotein that is necessary for B12 absorption Mucus-bicarbonate barrier- protects against corrosive properties of the gastric juices

Components that STIMULATE gastric acid production

Gastrin Histamine Acetylcholine

Bile is composed of what 4 things?

Bile acids Bile salts Micelles of bile salts Bile pigments (bilirubin)

This phase is characterized by the anticipation and sight, smell and taste of food. There is vagal outflow from the brain that stimulates release of GRP and acetylcholine, and encourages secretory function in the salivary glands and stomach

Cephalic phase

Contractions in the colon form bulges known as

Haustra

What part of the stomach contains the antrum and the pylorus (20%)

Pyloric gland area

This is composed of enterocytes, mucous-secreting goblet cells, and endocrine cells

Villus epithelium

Endocrine cells in the duodenal wall produce...

cholecystokinin (CCK) and secretin

Endocrine secretions in the pylorus

Gastrin, Somatostatin, Histamine

This feature of the anus is skeletal muscle around the anal canal controlled by the extrinsic nerves

External anal sphincter

How is the surface area in the small intestine amplified for greater absorption?

Transverse folds in mucosa (place circulares), arrangement of mucosa into villi, microvilli on the enterocytes that line the small intestine

This phase of the gastrointestinal response involves the movement of chyme into the intestines, a feedback inhibition of gastric acid production via the release of enterogastrones (Secretin) from the small intestines, with further digestion, absorption of nutrients and water, motility, and eventually elimination

Intestinal phase

Other functions of the liver

- carb, lipid, & cholesterol metabolism - amino acid & protein synthesis - storage of vitamins A, D, E, K, B12, iron and copper - detox & biotransfomation

Functions of saliva

- lubricates food - solvent for food molecules that stimulate taste buds - adds digestive enzymes to help break down food - antibacterial activity in the oral cavity

Functions of the rectum

- electrolytes and water continue to be absorbed - indigestible luminal contents are further broken down by anaerobic bacteria - stool is thickened and mixed with mucous

What does the normal flora of the intestinal tract do?

- Help with digestion and nutrient acquisition - Create a protective host defense mechanism in numbers - Play a role in extraintestinal disease in the body

What are involved in the Endocrine functions of the stomach?

Ghrelin- regulation of hunger and satiety Gastrin- stimulates parietal cells Somatostatin- deactivates G cell secretion of gastrin

Salivation is stimulated by...

thought, smell or taste of food by conditioned reflexes, and by nausea.

Test to assess swallowing and esophageal function

Esophageal manometry

What components INHIBIT gastric acid production?

Somatostatin Prostaglandin E2 G cells- directly inhibited when pH in stomach is at or below 3

What part of the stomach contains the cardia, fungus, and body (80% of stomach)

Parietal Gland area

Another name for digested food bolus

Chyme

3 classes of functions of the stomach

Motor, endocrine, exocrine

The major network of nerve fibers involved with motility in the gastrointestinal tract

Myenteric plexus (Auerbach)

Rectal distension initiates the

rectosphincteric reflex - Internal sphincter relaxes and initiates the urge to defecate. - Voluntary contraction of the external sphincter can override this reflex.

What inhibits breathing during swallowing?

Reticular formation in the brainstem. A stroke in this area may cause pt to have difficulty with swallowing

The process of bile acid secreted by hepatocytes, delivered to GI tract via biliary tract, absorbed by the small intestine, and then returned to the liver via the portal venous system is called?

enterohepatic circulation of bile acids Important process because the bile acid pool is not large enough to assimilate the lipid contents of a typical meal. @95% of bile salts are reabsorbed

The acinar cells of the pancreas create these enzymes...

Acetylcholine (vagus) Cholecystokinin (small intestine) They are stimulated by secretagogues

Digestive enzyme that breaks down fats

Lipase

In this type of swallowing the food bolus is pushed to the back of the tongue and pushed in to the pharynx

Voluntary

Hepatocytes secrete...

canalicular bile w/ bile salts, cholesterol, phospholipids, and bile pigments

It takes about ____ seconds for food to reach the stomach from the mouth

This feature of the anus is smooth muscle controlled by the autonomic nerves.

Internal anal sphincter

Absorption of iron and calcium occurs in the...

duodenum

3 salivary glands

Sublingual, submandibular, parotid

What hormone stimulates gallbladder contraction and mediates the relaxation of the sphincter of Oddi, allowing billiard and pancreatic secretions to enter the duodenum?

CCK

What are the 3 phase of gastrointestinal response?

1- cephalic phase 2- gastric phase 3- intestinal phase

During the intestinal phase in the Jejunum and Ileum, what is absorbed?

Carbs, protein, fat, salts, and water. bile acids and B12 are absorbed in the distal ileum.

Main digestive function of the pancreas

secrete enzymes that break down the macromolecules in food to produce smaller nutrient molecules for intestinal absorption

What is secreted in the parietal gland area of the stomach?

Parietal cells secrete hydrochloric acid (HCl) & intrinsic factor. +Peptic (Chief) cells secrete pepsinogen

What are the 2 major networks of nerve fibers intrinsic to the gastrointestinal tract?

Myenteric plexus (Auerbach plexus)- between outer longitudinal and middle circular muscle layers Submucous plexus (Meissner plexus), between the middle circular layer and the mucosa.

Fancy name for swallowing

deglutition

30% of cardiac output is pumped to the GI system via these 3 arteries

celiac a. superior mesenteric a. interior mesenteric a.

Salivation is inhibited by...

sleep, dehydration, fatigue, fear

What is involved in the prevention of pancreatic autodigestion?

Acinar cells produce zymogens in vesicles. Trypsin is activated in small intestines and required to activate other zymogens. Pancreas produces a trypsin inhibitor

parasympathetic cholinergic activity in the enteric nervous system has what effect in the GI tract

increases the activity of intestinal smooth muscle

What is the major location of commensal bacterial in the body? And what percentage of the feces consist of mostly anaerobic bacteria?

Colon 20%

Giant colonic peristaltic contractions triggered by the entry of food into the stomach and duodenum.

Gastrocolic reflex

Digestive enzyme that breaks down carbs

Amylase

_____ L of saliva is secreted daily

1.5 liters

Major accessory glands of the GI tract

Salivary glands, gastric mucosal glandular structures, intestinal mucosal glandular structures, pancreas, liver, gallbladder

The Sphincter of Oddi and the Brunner's glands (that secrete mucous) are in what part?

duodenum

Bile is produced in the _____ and secreted via the _____

liver biliary tract

Most common cause of gallstones in men?

alcohol use

This phase of digestion includes mixing chyme with digestive secretions and enzymes, propulsion of luminal contents away from the mouth via segmentation and peristalsis

Intestinal phase in Jejunum and Ileum

What are the two types of gallstones?

Cholesterol and Pigment (calcium bilirubinate)