GI (exam 4) Flashcards
What parts of the body are a part of the GI tract?
Mouth Esophagus Stomach Small Intestine Large Intestine Rectum Anus
Where does the majority of absorption occur?
Small intestine (90%)
When food passes through the GI tract is it considered to be internal or external?
External
What are the accessory organs of the GI system?
What do they do?
Liver
Gallbladder
Pancreas
Secrete substances into the GI to digest food
What are the functions of the GI tract?
Ingestion of food
Propulsion of food and wastes from mouth to anus (motility: segmentation and peristalsis)
Secretion of mucus, water, and enzymes
Mechanical digestion of food particles (masstication by mouth)
Chemical digestion of food particles
Absorption of digested food
Elimination of waste products by defacation
What are the 4 main organic substances we ingest?
What enzyme breaks each down?
Where does breakdown occur?
Carbs: amylase enzyme, in mouth and pancreas
Protein: proteases (pepsin, trypsin, chymokipsin), stomach secretes pepsin, pancreas secretes other two
Lipids: lipase after emulsification by bile, the liver produces bile, pancreas releases lipase
Nucleic acids: nuclease, DNA and RNA
What are the layers of the GI tract (inner to outer)?
Functions?
Mucosa: absorption
Submucosa: blood supply, glandular secretion
Muscularis: smooth muscle (2 layers: circular muscle layer- pinch and constrict, longitudinal muscle layer- propel food forward)
Serosa: visceral layer of peritoneum, serous membrane
What is the mesentery?
Function?
Part of the peritoneum
Holds everything in place
What is the job of the mouth?
What enzyme is released in the saliva?
Cranial nerves involved in mouth?
Teeth?
Chewing and mixing of food and saliva (start chemical digestion)
Amylase in saliva (carbs)
Taste buds: CN 7, 9: salty, sour, bitter, sweet, umami
Olfactory nerve: CN 1
32 permanent teeth
What are the salivary glands?
Submandibular (paired)
Sublingual (paired)
Parotid (paired)
What is in saliva?
What does it do?
Water with mucus, sodium, bicarb, chloride, potassium and amylase (carb digestion)
Start chemical digestion
Make a bolus of food to swallow
What is involved in swallowing (deglutition)?
Location/ Function?
Esophagus: peristalsis moves food
Upper esophageal sphincter: opening of esophagus, entrance
Lower esophageal sphincter (cardiac sphincter): enters into the stomach
What happens with an insufficient sphincter?
Can’t open or close, it is leaky
If lower sphincter get heartburn
What is a stenotic sphincter?
Risks?
To narrow of a sphincter
Upper: risk of choking
Lower: risk of vomitting
What is the stomach?
Muscles?
Parts of stomach?
Hollow, muscular organ that stores food, secretes digestive juices, mixes food with juices, propels partially digested food (chyme)
Muscle layers: longitudinal, circular, oblique (maximizes churning
Parts: cardiac sphincter- opening to stomach, pyloric sphincter- opening to duodenum, plylorus- called antrum and is lower region, fundus- upper rounded region, body
What is chyme
Bolus of food mixed with digestive juices
Gradually squirted into the duodenum
What is the order of food traveling in GI tract?
Mouth Upper esophageal sphincter Esophagus Lower esophageal sphincter Stomach (Fundus, body, antrum) Pyloric sphincter Small Intestine (Duodenum, Jejunum, Ileum) Ileocecal valve Large Intestine (cecum, ascending colon, transverse colon, descending colon, sigmoid colo, rectum, anus)
What gastric juices are secreted in the stomach?
Functions?
Mucus: help protect the stomach lining
HCl acid: converts pepsinogen to pepsin to denature proteins
Enzymes: pepsin is the major one, to digest proteins
Hormones: gastrin (regulates digestive juices) and ghrlein (tummy grumbles)
Intrinsic factor: binds to B12 and allows for absorption (not enough results in pernicious anemia)
What are the glands/ pits of the stomach?
Parietal cells: HCl acid (antimicrobial properties and denatures proteins) and intrinsic factor
Chief cells: do chief job (break down proteins) through pepsinogen
G cells: gastrin, ghrlein
What nerves innervate the stomach?
Vagus nerve (X)--> gastrin--> histamine (increase inflammation)--> parietal cells--> HCl Autonomic Nervous System Parasympathetic Nervous System Involuntary Release gastric juices
What are the phases of gastric secretion in the stomach?
Cephalic phase: brain part, thinking about food and salivate, cognitive phase
Gastric phase: stomach part, chemical signal, chemoreceptors (smell and taste) due to food exposure, secrete saliva and gastric
Intestinal phase: food leaves the stomach and enters the intestine, decrease secretions, inhibition phase
How long is the small intestine?
What is the main job?
What are the segments?
5-6 meters long
Absorption
3 segments: duodenum (10-12 inches, secretions from pancrease, liver and gallbladder enter here, bicarb to stop acidic digestive juices), jejunum, ileum
What makes up the edges of the small intestine?
Functions?
Villi: increase surface area for absorption, have epithelial cells with microvilli on it
Microvilli: increase surface area for absorption, form brush border
Lacteal: drains fat away
What are the pancreatic enzymes?
Functions?
Amylase: carb digestion
Trypsinogen and Chymotrypsinogen: protein digestion
Lipase: fats/ lipids digestion
Nuclease: RNA/ DNA
Where are bile salts made?
Stored?
Made in the liver
Stored in the gallbladder
What is absorbed in the intestines?
Carbohydrates Proteins Fats Water Electrolytes
What are the parts of the large intestine?
Cecum
Appendix: hang off the cecum, immune function- microbial flora storage
Colon (ascending, transverse, descending, sigmoid)
Rectum
Anus
What is the leading are for GI obstruction? Constipation? Colorectal cancer?
Sigmoid colon and rectum
Obstruction leads to constipation
Incidence of GI cancers highest in sigmoid and rectum and most fatal
Where are there high levels of intestinal bacteria?
Low levels?
Stomach: relatively sterile due to HCl acid
Duodenum: low due to bile acid secretion, motility and antibody production
Jejunum: low concentration of anerobes
Distal to ileocecal valve: highest # in colon
What is the hepatic portal system?
Venous drainage system
Highly nutrient rich deoxygenated blood into the liver and bad things
Liver filters and detoxifies it before it enters the vena cava
What are the types of cells in the liver?
Functions?
Hepatocytes: filter cells
Sinusoids: specialized capillaries
Kupffer cells: macrophages
What is the common bile duct?
Drains the bile away from the liver
What is bile?
Where is it produced?
What is it formed by?
Bile is an alkaline, bitter-tasting yellowish green fluid containing bile salts (emulsify fats), cholesterol, bilirubin, electrolytes and water
Bile is produced in liver (stored in gallbladder)
Formed by hepatocytes and secreted into the bile cancaliculi
What are the functions of the liver?
Blood storage
Bacterial and foreign particle removal
Synthesizes plasma proteins/ clotting factors
Produces bile
Metabolizes fats, proteins, and carbs
Detoxification of metabolic products/ wastes
Storage of minerals and vitamins
What is the function of the gallbladder?
Store and concentrate bile between meals
What are the regions of the pancreas?
Function?
Exocrin region: hormones (digestive)
Endocrin region: insulin and regulate blood sugar
Secrete enzymes
What are the secretions of the pancreas?
Bicarb Zymogens (trypsinogen, chymotrypsinogen, procarboxypeptidase) Pancreatic amylase Pancreatic lipase Nucleases
What happens if zymogens are activated to early?
Once activated zymogens digest proteins
If activated to early they autodigest pancreas cells
What are symptoms of GI dysfunction?
Anorexia: lack of appetite
Vomiting
Nausea: most common symptom, subjective experience
Retching: dry heaving, non productive vomiting
Abdominal pain: non specific, referred pain, dull, achy pain
Constipation: most often in sigmoid or rectum
Diarrhea: increased frequency or increased volume, fluidity, weight of the feces
GI bleeding
What are the types of diarrhea?
When do they occur?
Osmotic diarrhea: electrolyte change that draws fluid into diarrhea
Secretory diarrhea: bacterial toxins in our intestinal lumen (food poisoning)
Motility diarrhea: increased movement of food through GI tract decreasing absorption, increasing diarrhea, nerve or smooth muscle issue (caffeine)
What are the types of GI bleeds? Where are they located?
Upper gastrointestinal bleeding: esophagus, stomach, duodenum
Lower gastrointestinal bleeding: jejunum, ileum, colon, rectum
What is hematemesis?
When does it occur?
Vomiting blood
Upper GI bleed
What is hematochezia?
Where does it occur?
Red bloody stools
Bleed in sigmoid or rectum
What is melena?
Where does it occur?
Black, tarry stools
Bleed in jejunum, ileum or first half of colon
What is dysphagia?
How do we get it?
Motility disorder, difficulty swallowing
Get it through achalasia, which is the loss of nervous control or function
What is gastroesophageal reflux?
GERD
Reflux of chyme from stomach to esophagus
If it causes esophagus inflammation= Reflux Exophagitis
Cardiac sphincter insufficiency
What is a hiatal hernia?
Types?
Motility disorder
Protrusion of upper portion of stomach through diaphragmatic hiatus into thorax
Sliding
Paraesophageal
What is a pyloric obstruction?
Motility disorder
Blocking or narrowing of opening between stomach and duodenum
Leads to violent vomiting soon after eating
What is dumping syndrome?
Motility disorder
Rapid emptying of chyme from a surgically created residual stomach into the small intestine
Pyloric insufficiency
Clinical complication of partial gastrectomy or pyloroplasty surgery
Inducing violent diarrhea
What is an intestinal obstruction?
Motility disorder
Anything that prevents flow of chyme through the intestinal lumen or failure of normal intestinal motility
Mechanical blockage= true intestinal obstruction
What is an ileus?
Motility disorder
Obstruction of the intestines from folding, pinching, or lack of peristalsis
An intestinal obstruction (not a mechanical blockage)
ileus= bad blood flow= ischemia= necrosis
What is a peptic ulcer?
Peptic ulcer is an umbrella for all upper GI ulcers
A break or ulceration in the protective mucosal lining of the lower esophagus, stomach (gastric ulcers) or duodenum
When it erodes through mucosa and submucosa and hit muscle layer= true ulcer
What are the types of peptic ulcers?
Duodenal ulcers (most common)
Gastric ulcers
Stress ulcers
What are duodenal ulcers?
Most common peptic ulcer
Small intestine
Cause: Helicobacter pylori infection (#1) , hypersecretion of stomach acid and pepsin, use of NSAIDS (#2), acid production by cigarette smoking
What are gastric ulcers?
Stomach ulcers
Cause: overuse of NSAIDS (#1), helicobacter pylori infection (#2)
What are stress ulcers?
Peptic ulcer related to severe illness, neural injury or systemic stress/ trauma
What is maldigestion?
What does it lead to?
Failure of the chemical processes of digestion
Leads to malabsorption
What is malabsorption?
Failure of the intestinal mucosa to absorb digested nutrients
What is pancreatic insufficiency?
Insufficient pancreatic enzyme production
Causes: pancreatitis, pancreatic carcinoma, pancreatic resection, cystic fibrosis
What is lactase deficiency?
Lactose intolerant Inability to break down lactose Causes gas (cramping, pain, flatulence, etc), osmotic diarrhea
What is bile salt deficiency?
Can’t emulsify fats or absorb fat soluble vitamins
Can result from liver disease and bile obstructions
Fatty stools, diarrhea, loss of fat- soluble vitamins (A, D, E, K)
What are the fat soluble vitamin deficiencies?
Vitamin A: night blindness, retinal cells
Vitamin D: decreased calcium absorption, bone pain, osteoporosis, fractures
Vitamin K: needed for clotting, prolonged prothrombin time, purpura, petechiae
Vitamin E: regulates cell processes
What is gastritis?
Inflammation of stomach lining (gastric mucosa)
Acute gastritis: consumption of NSAIDs or alcohol
Chronic gastritis: infection (H. pylori)
What is ulcerative colitis?
Chronic inflammatory disease that causes ulceration of the colonic mucosa
Large intestine
May increase colon cancer risk
What is Crohn’s disease?
Idiopathic inflammatory disorder
Affects any part of digestive tract
Causes skip lesions (regions of bad, skip regions of good), and cobblestone effect (because of deep ulcerations, look like cobblestone)
What is diverticular disease of the colon?
Diverticula: out pouching of colon wall, weakening of wall, herniations of mucosa through muscle layers of colon wall (sigmoid)
Diverticulosis: having 1 or more diverticula, weakened wall
Diverticulitis: inflammatory stage of diverticulosis, food particles enter and get stuck causing inflammation and infection
What is appendicitis?
Inflammation of the veriform appendix
Right lower quadrant with rebound tenderness (pain when release not press in)
What is irritable bowel syndrome?
Idiopathis No specific structural or biochemical alterations More common in women 20-40 year olds Increase diarrhea
What is obesity?
Increase in body fat mass
BMI greater than 30
Apple: above waist
Pear: below waist
What are eating disorders characterized by?
Abnormal eating behavior
Weight regulation
Disturbed attitudes about body weight, shape and size
What country has the highest eating disorder rate?
Lowest?
USA highest
Sweden lowest
What is anorexia nervosa?
Refuses to eat
Can lose 25-30% of ideal body weight as a result of fat/ muscle depletion
What is bulimia nervosa?
Body weight remains near normal
Want weight loss
Binge eating (2 episodes per week for 3 months)
Self-induced vomiting
Pitted teeth, pharyngeal and esophageal inflammation, tracheoesophageal fistulas, rectal bleeding
What is starvation?
What is cachexia?
Effects of it?
Decreased caloric intake
Wasting away
Short term: glycogenolysis, gluconeogenesis
Long-term: marasmus (skin and bones), kwashiorkor (distended belly)
What is portal hypertension?
High BP in portal venous system caused by resistance to portal blood flow
Intrahepatic
Posthepatic
What are consequences of portal HTN?
Varices: back up venous blood, can lead to vein rupture and GI bleed
Splenomegaly
Ascites
Hepatic encephalopathy
What is hepatic encephalopathy?
Neurologic syndrome of impaired cognitive function
Rapid development during fulminant hepatitis
Slow development during chronic liver disease
What is jaundice?
Types
Lack of bilirubin metabolism in liver
Obstructive jaundice: posthepatic obstruction, intrahepatic obstruction
Hemolytic jaundice: prehepatic jaundice, excessive hemolysis of RBCs or absorption of hematoma
What is viral hepatitis?
Types?
Systemic viral disease of acute or chronic inflammation that primarily affects liver
A
B
C, D, E and G
How is Hepatitis A transmitted?
Risk factors?
fecal-oral transmission route
Crowded, unsanitary conditions
Food and water contamination
How is Hepatitis B transmitted?
What can it cause?
Treatment?
Transmitted through contact with infected blood, body fluids, contaminated needles
Maternal transmission if infected during 3rd trimester
Can cause chronic hepatitis
Vaccine available
Hepatitis C?
Responsible for most cases of post transfusion hepatitis
50-80% of cases result in chronic hepatitis
infections related to IV drug use
Hepatitis D?
Depends on hepatitis B for replication
Hepatitis E?
Fecal-oral transmission
Developing countries
Hepatitis G?
Recently discovered
Parentally and sexually transmitted
What is Cirrhosis?
Steps of it?
Irreversible inflammatory disease that disrupts liver function and even structure
Biliary channels become obstructed and cause portal HTN
1. Alcoholism
2. Liver cirrhosis
3. Hepatic portal HTN
4. Esophageal varices–> hematoemisis (puking blood)
5. Acitis
What is cholecystitis?
Obstruction or inflammation of gallbladder
Most common cause of gallbladder problems
What is cholelithiasis?
Gallstone formation
Cholesterol: most common
Pigmented: cirrhosis
What is pancreatitis?
Inflammation of pancreas
Caused by injury or damage to pancreatic cells and ducts
Chronic pancreatitis is related to chronic alcohol abuse
