Gastrointestinal Function Flashcards
What are 7 general functions of the GI tract?
- Ingestion of food
- Propulsion of food
- Secretion of mucus, water and enzymes
- Mechanical digestion of food
- Chemical digestion of food
- Absorption of digested food
- Elimination of waste products
The ____ is the innermost layer of the gastrointestinal wall and is exposed to dietary nutrients
Mucosa
In the villus, there is absorption of ___ and ___
Water and nutrients
The ____ is the next innermost layer of the GI wall; this carries the nerve plexus that innervates the mucosa and the muscle layers of the intestine
Submucosa
The ____ is the next layer of the GI wall; it contains the circular smooth muscle layer and the longitudinal muscle layer; this layer contacts to drive peristalsis to keep food moving through
Muscularis
The ____ is the outmost layer of the GI wall; it is the secretory adventitial layer; it keeps everything in place and is continuous from the mouth to the anus; it also secretes lubrication
Serosa
The autonomic nervous system controls what in the GI system?
-Direct neural stimulation
-Hormonal
-Peristalsis
-Defecation
Defecation is controlled by internal and external ____ ____
Anal sphincters
The ___ ___ ___ is a set of nerves connected to the autonomic nervous system and it is also connected to the gut; it is the third arm of the ANS (along with sympathetic and parasympathetic)
Enteric nervous system
The enteric nervous system can function ____ of the ANS and interacts with all arms of the ANS
Independently
What influence does the enteric nervous system have on GI function?
Regulates peristaltic reflex, hormones, and secretions
Stress or high fat/sugar intake triggers a response from ____ ___ that leads to increased food intake, increase fat uptake, decreased energy utilization, and decreased anxiety
Neuropeptide Y
Neuropeptide Y also blocks ____ to the CNS which releases pain
Nociceptors
Neuropeptide Y is an ____ chemical
Endogenous
What are some other examples of endocrine hormones that have an impact on the GI system?
-Gastrin
-Ghrelin
-Secretin
-Somatostatin
What are functions of the mouth?
-Mastication (physical breakdown of food in the mouth)
-In the mouth, saliva mixes with the food, and salivary amylase begins to break down carbohydrates and lingual lipases begin to break down fats
-Saliva also lubricates food to travel to the esophagus
The ____ is a passageway to the stomach; food is not being processed or absorbed here
Esophagus
____ is a neural dysfunction resulting in decreased smooth muscle movement in the middle and lower portion of the esophagus
Achalasia
What are the three sections of the stomach?
-Fundus
-Body
-Antrum
The antrum leads to the ____
Pylorus
A lot of food ____ happens in the stomach
Breakdown
The stomach rolls food around to produce ____
Chyme
In the stomach, cells secrete substances to breakdown food and protect against ____
Bacteria
What type of cells secrete gastrin?
G cells
G cells release gastrin when there is presence of ____ in the stomach
Proteins
What are the functions of gastrin?
-Increase motility
-Stimulates parietal cells to secrete HCL and chief cells to secrete pepsinogen
What type of cells secrete HCL?
Parietal cells
Parietal cells release HCL in response to…
-H2 receptors
-Parasympathetic stimulus
Functions of HCL:
-Denatures proteins
-Creates an acidic environment
What type of cells secrete ghrelin?
P/D1 cells
P/D1 cells secrete ghrelin in response to…
Low glucose levels
Functions of ghrelin:
-Hunger hormone
-Regulates appetite and motility
-Increases before meals
-Decreases after meals
What type of cells secrete somatostatin?
D cells
D cells secrete somatostatin in response to…
Low gastric pH
Roles of somatostatin:
-Decreases rates of gastric emptying and smooth muscle contraction
-Inhibits growth hormone production
-Suppresses release of gastrin, cholecystokinin, VIP, and others
What type of cells secrete Pepsinogen?
Chief cells
Chief cells secrete pepsinogen in response to…
-HCL
-Gastrin
-Vagus nerve stimulation
Roles of pepsinogen:
-Converted to pepsin if pH<5
-Protein breakdown
The mucous barrier of the stomach protects the stomach from ___
Acid
The ____ of the stomach controls gastric emptying
Pylorus
What may cause decreased gastric emptying?
-High-fat meals
-Diabetic neuropathy
-Eating in the evening
-Drugs like anesthesia
-Traum
____ is the forceful expulsion of gastric or intestinal contents
Vomiting
The vomiting center of the brain is called the ____ ____
Area postremia
The area postremia has no ___-___ barrier
Blood-brain
The area postremia can be stimulated by…
-Chemicals: opioids, high levels of toxins in the blood
-Mechanical: high pressure in the brain, myocardial infarction, gag reflect, infection
-Vestibular: rollercoasters
Consequences of vomiting:
-Acid-base imbalances
-Aspiration pneumonia
-Ruptured esophagus or the vessels that line the esophagus
-Tearing of the stomach lining
Most digestion and absorption of nutrients occurs in the ___ ___
Small intestine
What are the three regions of the small intestine?
-Duodenum
-Jejunum
-Ileum
Chyme moves from the pylorus to the ____ ___
Ileocecal valve
The small intestine contains villi with microvilli (brush borders) which break down ____
Polysaccharides
The ileocecal valve controls flow to the ____ ____
Large intestine
The duodenum secretes ____ in the presence of chyme in the duodenum
Secretin
In the intestines, secretin has what functions?
-Increases water and bicarb release
-Increases pancreatic and gallbladder contractions
I cells in the small intestine secrete _____ in the presence of chyme in the duodenum
Cholecystokinin
Roles of cholecystokinin in the intestine:
-Stimulates pancreatic enzymes
-Stimulates gallbladder contraction
-Increases gastric motility
-Suppresses hunger
-Induces anxiety
The duodenum and jejunum release ____ ____ ____ in response to hyperosmolarity of glucose in the duodenum
Gastric inhibitory peptide
Role of gastric inhibitory peptide in the intestine:
Induces insulin secretion
The small intestine and the Delta cells of the pancreas release ____ in response to low gastric pH
Somatostatin
Roles of somatostatin in the intestines:
-Decreases gastric emptying and smooth muscle contractions
-Suppresses other gastric secretions and pancreatic hormones
-Inhibits glucagon and insulin release from the pancreas
The intestine and hypothalamus release ____ ____ ____
Vasoactive Intestinal Polypeptide (VIP)
Roles of vasoactive intestinal polypeptide in the intestine:
-Increase GI motility and vasodilation
-Promotes H2O/lyte secretion
-Inhibits gastric acid and pepsinogen
-Variety of non-GI effects
VIP is released when the stomach is ____ and ____, but can also be secreted from the hypothalamus, can regulate sleep, increase vaginal lubrication, etc.
Distended and full
Gastric inhibitory peptide (GIP) can neutralize ____
HCl
The large intestine is also known as the ____
Colon
The large intestine lacks ____
Villi
The large intestine does not do much ____ (but has many glands)
Absorption
In the large intestine, we have a _____ that provides beneficial things for our body and helps to ferment food
Microbiome
The large intestine absorbs ____, ____, and some ____
Water, vitamins, electrolytes
When you have _____, things are moving through the large intestine too fast which leads to increased frequency and fluidity of bowel movements
Diarrhea
When you have _____, you have decreased amount of bowel movements and decreased fluidity
Constipation
The ____ is controlled by internal (autonomic NS) and external (consciously controlled) sphincters
Rectum
In the GI system, more fluids are ___/___ than lost (7000 mL)
Absorbed/reabsorbed
50-200 mL of fluid is lost through the ____ each day
Stool
Where are carbohydrates broken down (3)?
-Mouth: some carbs broken down by salivary amylase
-Stomach: some carbs broken down with HCl in stomach
-Small intestine: most carbs are broken down at the brush border of the small intestine
Where are proteins broken down (2)?
-Stomach: HCl and pepsin
-Small intestine: most enzymes here from the pancreas work to breakdown/reabsorb protein
Where are fats broken down (1)?
-Small intestine: pancreatic enzymes and gallbladder enzymes break down fats and most pass through the large intestine
GI ____ affects 50-150 of 100,000 people
Bleeding
____ ____ bleeding (above the jejunum) accounts for 85% of all GI bleeds
Upper GI
What are some possible etiologies of upper GI bleeds?
-Esophageal varices: bleeding that can come from excess vomiting, older age from fragile vessels, or liver problems
-Esophagitis: inflammation of the esophagus that can result from ingesting dyes or toxins, alcohol abuse, or infections
-Mallory-Weiss tears: tear in the lining that leads to bleeding caused by excess vomiting
-Gastric (peptic) ulcer: coexist in people with H. pylori in the stomach, causes inflammation of the stomach and can result from chronic NSAID use or smoking
-Duodenal ulcer: caused by NSAIDs, smoking
-Duodenitis: inflammation of the duodenum caused by infection or NSAID use
Manifestations of upper GI bleeding?
-Hematemesis: bloody vomiting (if vomit has been in the stomach, it will look like coffee grounds)
-Melana (black, tarry stool): iron in the stool gets oxygenated and turns black
-Hemorrhagic shock: people who lose 25% of blood volume, not enough blood in cardiovascular system
-Increased BUN
-Possible mental status change
A lower GI bleed is from the ____ and below
Jejunum
Possible etiology of lower GI bleeds:
-Carcinoma of the colon
-Diverticular disease
-Inflammatory bowel disease
-Polyps
What are some manifestations of a lower GI bleed?
-Hematochezia (blood in the stool)
-Melana (less often-> black, tarry stool)
-Hemorrhagic shock
____ ___ is malformation of the esophagus
Tracheoesophageal fistula
Tracheoesophageal fistulas occur in 1 out of every ___-___ liver births
3,000-4,000
Mechanism of tracheoesophageal fistulas:
-During the first 4-6 weeks of development, the esophagus and trachea and forming
-There is a failure of these to separate which causes a connection between the esophagus and trachea
A Tracheoesophageal fistula can also be seen in kids or adults with a ____ or ____ tube
Trach or NG
What are some manifestations of Tracheoesophageal fistulas?
-Aspiration: food goes from the esophagus to the trachea through a “bridge”
-Pulmonary complications: pneumonia, atelectasis
-In infants: FTT, no weight gain, vomiting with every feeding, coughing, etc.
____ ____ ____ results from chyme from the stomach moving back into the esophagus
Gastroesophageal Reflux Disease (GERD)
Is GERD more common in children or adults?
Adults
Mechanism of GERD:
Stomach contents move into the lower part of the esophagus and the lower esophageal sphincter relaxes which allows stomach acid to come up into the esophagus
Manifestations of GERD:
-Heart burn after eating (especially when laying down)
-Dysphagia
-Ulcerations of the esophagus (inflammation and scar tissue)
A ____ ____ is the movement of the stomach through the opening for the esophagus into the diaphragm
Hiatal hernia
Hiatal hernias affect as many as ___% of adults
50
Possible etiologies of hiatal hernia:
-Ascites
-Chronic coughing
Manifestations of hiatal hernias:
-Heartburn
-Dysphagia
-Epigastric pain
-Reflux
____ ____ is caused by metaplasia of inner esophageal cells
Barrett’s Esophagus
Barrett’s esophagus is most common in what demographic?
White males
Etiology of Barrett’s Esophagus:
-Anything that causes chronic inflammation of the esophagus (GERD, alcoholism)
Mechanism of Barrett’s Esophagus:
-Metaplasia where epithelial cells turn to squamous cells
Manifestations of Barrett’s esophagus:
-Heart burn
-Hematemesis
(largely asymptomatic)
Many times, Barrett’s Esophagus is a precursor to ____
Cancer
____ is inflammation of the gastric mucosa (top layer of the stomach)
Gastritis
Mechanism of gastritis:
-Inflammation leads to hypersecretion of gastric acid which leads to leaky blood vessels
Manifestations of gastritis:
-Mild: gastric distress (upset stomach)
-Severe: vomiting, bleeding in the stomach
___ ____ ____ causes ulcers to develop in the upper GI tract
Peptic Ulcer Disease
About ___% of people will develop a peptic ulcer at some point
10%
Possible etiologies of peptic ulcer disease:
-Bacterial endotoxin
-Caffeine
-Alcohol
-H. pylori
-Aspirin
-NSAIDs
Mechanism of peptic ulcer disease:
Increased acid which breaks down mucous
Manifestations of peptic ulcer disease:
-Stomach ache between meals
-Weight loss
-Hematemesis
-Hemorrhagic shock
-Severe bleeding (not good)
____ ____ ____ causes chronic and recurrent intestinal symptoms
Irritable bowel syndrome
IBS can affect either the ___ or ___ ____
Large or small intestine
IBS affects about ___% of the population (many don’t get treatment)
15
Etiology of IBS:
-Perhaps a brain-gut disconnect that leads to hyperactivity of the bowel
-Possible imbalance of microbiota or increased growth of microbiota
Manifestations of IBS:
-Abdominal pain
-Complains of gas pain
-Bloatedness
-Nausea
-Anorexia
-Anxiety
-Depression
-Changes in stool frequency and consistency
What are two examples of Inflammatory Bowel Diseases?
-Chron’s Disease
-Ulcerative colitis
___ ___ is recurrent inflammatory response which affects all layers and any portion of the GI tract
Crohn’s Diseases
Crohn’s disease most commonly affects the ___ or ___
Ileum or colon
Crohn’s disease affects ____ Americans, usually 15-35 years old
1/2 million
Crohn’s disease is most common in ___
Smokers
The etiology of Crohn’s disease is largely unknown, but may include…
-Hereditary component
-Possible autoimmune issue
People with Crohn’s are at an increased risk for the development of ____
Arthritis
Manifestations of Crohn’s disease:
-Diarrhea
-Fecal urgency
-Weight loss (malabsorption)
Complications of Crohn’s include…
-Fistulas
-Abscesses
____ ____ is an inflammatory condition of the colon
Ulcerative colitis
Incidence of ulcerative colitis is about ___% of the US population (usually starts in teens to late 20s)
1
Mechanism of ulcerative colitis:
-Lesions form in the mucosal layer of the intestinal wall (differs from Crohn’s that affects all layers)
Manifestations of ulcerative colitis:
-Anorexia
-Fatigue
-Frequent stools (possibly mucousy or bloody)
-Cramping
Possible complications of ulcerative colitis:
-Arthritis (25% of patients)
-Colon cancer (12% of patients)
____ ____ causes out pouchings in the colon
Diverticular disease
_____ is characterized by the presence of diverticula
Diverticulosis
Diverticulosis common affects the ____ ___
Sigmoid colon
Most people with diverticulosis have no ____, but some might have pain in the lower left quadrant
Symptoms
_____ is when diverticula become inflammed, usually causing left lower quadrant pain
Diverticulitis
____ usually helps prevent diverticulitis
Fiber
Manifestations of diverticulitis:
-Pain
-N/V
-Fever
Complications of diverticulitis:
-Increased white cell count
-Peritonitis
-Bowel obstructions
-Fistula
___ ___ causes inflammation of the small intestine in response to ingestion of gluten
Celiac disease
Etiology/risk factors of celiac disease:
-Possible genetic mutation of the HLA gene
-Possible viral infections early in life
-Possible ingestion of gluten before 4-6 months of life
-Breastfeeding is found to be protective
Mechanism of celiac disease:
-Ingestion of gluten leads to inflammation of the small intestine
-When gluten is in the small intestine, gliadin is recognized as abnormal and broke to T-glutaminase which the immune system attacks and causes an inflammatory response
-Causes loss of microvilli and malfunction of the small intestine
-Causes decreased absorption of nutrients
Manifestations of celiac disease:
-Weight loss
-Cramping
-Bloating
-Diarrhea
-Malnutrition
-Anemia
-Dermatitis
-Possibly asymptomatic
What are 7 functions of the liver?
- Production of bile salts
- Metabolism of drugs
- Carbohydrate metabolic
- Protein metabolism
- Synthesis of plasma proteins
- Synthesis of clotting factors
- Filtration of blood and bacteria
_____ produce bile salts which helps with digestion of fat
Hepatocytes
The ____ ____ in the liver breaks down urea to ammonia, breaks down alcohol, as well as many other drugs
CP450 pathway
What is formed in the liver?
-Fatty acids
-Triglycerides
-Cholesterol
Functions of the gallbladder:
-Stores bile
-Stores enzymes that the liver makes to break down fats
The pancreas has ____ and ____ function
Endocrine and exocrine
The endocrine function of the pancreas is to produce ____ (insulin, glucagon, somatostatin, pancreatic peptide, ghrelin)
Hormones
The exocrine function of the pancreas is to produce ____ like bicarbonate and digestive enzymes
Enzymes
Pancreatic hormones are always released inactive and are activated once in the ____ to break down proteins
Duodenum
___ ___ is caused by anything that blocks flow through any of the vessels of the liver/increases pressure
Portal hypertension
What are examples of things that may cause portal hypertension?
-Esophageal varices
-Hepatomegaly and splenomegaly (they become engorged with blood)
-Ascites
-Hepatic encephalopathy (liver isn’t clearing toxins well-> confusion, swelling of the brain, comatose)
-Hepatorenal syndrome (pre-renal failure)
____ is a yellow pigmentation of the skin and eyes
Jaundice
Jaundice can be ___, ____, or ____
Obstructive, hepatocellular, or hemolytic
Obstructive jaundice results from ___ ___ that would cause bilirubin to build up
Liver failure
_____ ____ causes an alteration of blood flow to the kidney
Hepatorenal syndrome
Hepatorenal syndrome is more common when there is ____ deterioration of blood flow
Rapid
Hepatitis A is an ____ virus
RNA
The incubation period of Hepatitis A is ___-___ days
15-45
Hepatitis A is transmitted by…
-Fecal oral route
-Can be transmitted by food that was exposed to the infectious route
-Sexual contact
Symptoms of hepatitis A:
-Fever
-Malaise
-Anorexia
-Jaundice (develops 28 days-1 month from initial exposure)
-Most people make a full recovery
Hepatitis B is a ___ ___ virus that replicates by reverse transcriptase
Double stranded
There are ___-___ new cases of hepatitis B per year
2,000-3,000
What groups are at highest risk of hepatitis B?
-Infants born to mothers with hepatitis B
-People who inject drugs or share needles, syringes, and other types of drug equipment
-Sex partners of people with hepatitis B
-Men who have sex with men
-People who live with someone who has hepatitis B
-Healthcare and public safety workers exposed to blood on the job
-People on dialysis
How can hepatitis B be transmitted?
Blood or body fluids
What antibodies can you detect with hepatitis B?
-Core antibody: appears at the onset of symptoms in acute hep B and persists for life
-Surface antigen: can be detected in high levels in serum during acute or chronic hepatitis; indicates that someone is infectious
-e Antigen: exists in the serum during early phases of hepatitis B infection
With ___/___ ___ hepatitis B, antibodies form around 2 months after exposure; then someone will have symptoms like jaundice and inflammation and antibodies and antigens increases and then get better; 6 months later, they still have antibodies
Acute/self-limiting
With ____ hepatitis B, someone will develop an immune system response from antibodies, become symptomatic, and will then always have antibodies and symptoms after that (it does not go away)
Chronic
People can also be an ____ ____ of hepatitis B in which antibodies and antigens form and symptoms and mild and don’t last long; for the rest of their lives, they still have antigens and antibodies but they are still infected forever and wouldn’t know
Asymptomatic carriers
Hepatitis C is an ____ virus
RNA
Hepatitis C affects ____ people worldwide
1/4 million
Hepatitis C is transmitted by…
-Blood
-Bodily fluids
-Contaminated needles
-Unprotected sex
Many people clear hepatitic C without knowing they were infected, but half wind up with chronic hepatitis C which can lead to ____ ___
Liver failure
Symptoms of hepatitis C do not appear for ___-___ months and many infections are not apparent
2-3
_____ is the conversion of normal liver architecture into structurally abnormal nodules
Cirrhosis
One example of cirrhosis is ____ ___
Alcoholic cirrhosis
Stages of development of alcoholic cirrhosis:
-Someone who is drinking a lot will have inflammation and scar tissue formation
-Fatty liver will develop
-Leads to fibers forming
Signs and symptoms of alcoholic cirrhosis:
-Anorexia
-Weight loss
-Bleeding disorders
-Hepatomegaly
-Portal hypertension
-Kidney failure
_____ is another name for gallstones
Cholelithiasis
_____ is inflammation of the gallbladder
Cholecystitis
As much as ___% of people experience cholecystitis, but it is normally asymptomatic
80
Etiology of cholecystitis:
-Stone travels out of the gallbladder and gets stuck, causing bile to back up and damage the gallbladder
-This can lead to massive inflammation and possible rupture
-Inflammation will continue to spread
-Lower level of inflammation will cause a more chronic form of cholecystitis
Manifestations of cholecystitis:
-Pain in the left upper quadrant precipitated by a fatty meal
-Vomiting
-Jaundice
-Fever
-Elevation of some liver function tests
-Problems with liver function
______ is gallstones in the common bile duct
Choledocholithiasis
What are two examples of disorders of the pancreas?
-Diabetes Mellitus
-Cystic fibrosis
Cystic fibrosis causes endocrine pancreatic dysfunction that causes ____
Scarring
Cystic fibrosis causes features of both ___ and ___ ___
Type 1 and type 2 diabetes
Cystic fibrosis may also impact exocrine function by a ____
Blockage
____ ____ ____ is caused by a loss or lack of digestive enzymes
Exocrine Pancreatic Insufficiency
Signs and symptoms of exocrine pancreatic insufficiency:
-Weight loss
-High fat levels in stool
-Fatigue due to poor absorption
-Flatulence due to malabsorption
-Distended abdomen
-Edema
-Bleeding disorders
_____ is an autodigestive disease
Pancreatitis
Pancreatitis affects ____ people per year
80,000
Etiology of pancreatitis:
-Inflammation of the pancreas
-Common in people with biliary tract diseases
-People who abuse alcohol make up 80%
-Common in people with gallstones or after polytrauma
-Autoimmune form is common in people with autoimmune disorders
-Common in people after Mupms
Manifestations of pancreatitis:
-Severe upper abdominal pain that radiates to the back
-Elevated blood pressure
-N/V due to pain
