Chapter 1 Digestive System Flashcards
What concepts connect to the digestive system?
- Nutrition
- Elimination
- Inflammation
Finish the process:
Food is consumed, (a) __________ , (b) __________ , Elimination
(a) food enters GI tract
(b) food moves along until broken down and enters blood stream to be used as energy
What forms of elimination relating to the digestive system does the body excrete?
(a) Urine
(b) feces
What is the digestive tract?
The digestive tract consists of a long hollow tube that runs from the mouth to the anus. At various points is connected to gland and organs which all work together to aid in the process of digestion
What are the major functions of the GI tract?(7)
- Ingestion of food (chewing and swallowing)
- Absorption of digested food
- Elimination of waste products by defecation
- Propulsion of food and waste from mouth to anus
- Secretions of mucous, water, and enzymes
- Immune and microbial protection against infection
- Mechanical digestion of food particles
Which of the two are involuntary and voluntary?
(a) Swallowing
(b) Peristalsis
(a) Voluntary
(b) Involuntary
The digestive tract consists of 4 layers. From the outside in, what are the layers called?
- Mucosa
- Submucosa
- Muscularis
- Serosa
In the digestive tract what is and does the mucosa layers do?
It is a epithelial layer that produces mucus, digestive enzymes, and absorbs nutrients
In the digestive tract what is and does the submucosa layer do?
It is a connective tissue layer containing nerves, blood and lymph vessels
In the digestive system what is and does the muscularis layer do?
It is a smooth muscle layer that allows proportion of food through GI tract (peristalsis)
In the digestive system what is and does the serosa layer do?
- It is an outer connective tissue layer forms the visceral peritoneum.
What other names does the serosa layer of the digestive system have?
Serous membrane also known as peritoneum has additional labelling depending on which part you are referring to.
What is the serosa layer called if it wraps around the bowel?
Visceral peritoneum
What is the serosa layer called if it wraps around the abdominal wall?
Parietal peritoneum (has a large surface area)
What does it mean when the GI tract surface changes related to function? Think of the 4 layers.
- The mucosa neck cells of the stomach protects gastric mucosa from digestive actions of acid and pepsin by creating a mucosal barrier
- Chief cells secrete pepsinogen a proteolytic enzyme that breaks down protein
- Parietal cells secrete hydrochloric acid and intrinsic factor
- Endocrine cells produce histamine and hematostatin
How is the surface layer of the S. intestine different than the L. intestine?
The S. intestine has a larger surface (villi) area for allowing more absorption of water and electrolytes.
L. intestine has deep crypts, have no villi, is smooth, and secretes mucous to lubricate the intestinal contents to transport through the bowel
What is intrinsic factor?
Vitamin B12 binds to it to form a complex
What is entering the GI tract and what is leaving the GI tract?
7L of fluid a day (saliva, bile, and stomach, intestinal, and pancreatic secretions)
+
2L of fluid/day consumed by average adult
= 9 Litres/day
How much fluid is reabsorbed in the GI tract and why does our body do that?
8.8L is reabsorbed and the purpose is that we cannot manage to replace a full 9L of water per day.
What are the common problems of the GI tract?
- Acid issues (occurs in upper GI tract)
- Inflammation/Erosion (affect GI functioning)
- Motility Issues (structural and neural) –> Increase/decrease or stop of movement
*Each can interrupt normal processes of nutrition and elimination
How does the 4 layers change in different parts of the GI tract?
You didn’t answer this in your notes
What do the gastric glands produce and what are their roles in the stomach
Gastric juice and protective mucous
How do secretions play a important role in our overall fluid balance?
Not sure where this is in your notes
What consists of the upper GI tract?
Mouth. esophagus, stomach
What are some mouth issues?
Easy to inspect for problems
Think about what you need.to properly chew food
What are some throat issues?
Swallowing is a voluntary act controlled by skeletal motor neurons.
Dysphagia can occur from mechanical obstruction or functional impairment (nerve or muscle problem)
What are the 3 common symptoms associated with GI disorders?
- Anorexia
- Nausea
- Vomiting
What is the definition, symptom, what condition it is associated with anorexia
Definition: Lack of desire to eat, loss of appetite
Symptom: Non specific
Often associated with: Nausea, abdominal pain, diarrhea, and psychological stress
What diseases does anorexia accompany?
Cancer, heart disease, and kidney disease
Anorexia can be a side effect of medication. TRUE or FALSE?
True
Define Nausea
Subjective feeling of discomfort in epigastrium with conscious desire to vomit
Define vomitting
Forceful ejection of partially digested food and secretions (emesis) from the upper GI tract
Which types of patients would we seethe symptoms of nausea and vomiting in?
Patients with GI diseases, pregnancy, infectious diseases, CNS disease, cardiovascular problem, metabolic disorders, allergies, fear/stress
What causes the sensation of nausea and vomiting and what part of the brain controls/allows for that?
- Chemoreceptor trigger zone (lies outside of BBB) uses receptors for dopamine, serotonin, opiate, acetylcholine
- Vestibular system sends info. to brain via cranial nerve VIII (plays role in motion sickness) and is rich in muscarinic receptors
- Enteric and Vagus nervous system in puts info. about state of GI. Once irritated it activates serotonin receptors
- CNS mediates vomiting that arises from psychiatric disorders and stress from higher brain centers
Part of brain: Emetic centre in the medulla
GI irritation can be caused by?
- Chemotherapy
- Radiation
- Distention (enlarged from pressure)
- acute infectious gastroenteritis
What are the 3 main causes of nausea and vomiting?
- Inflammation in any part of the GI tract
- Irritation/injury to the CNS
- Reaction to drug
Examples of inflammation in the GI tract causing nausea and vomiting include:
- Gastritis
- Gastroenteritis of food poisoning
- Gastroesophageal reflux disease
- Pyloric stenosis, bowel obstruction, peritonitis, ileus
- Overeating
- Food allergies
- Cholesytitis, pancreatitus, appendicitis, depatitis
Examples of irritation/injury to the CNS that causes nausea and vomiting include:
- Motion sickness
- Concussion
- Cerebral haemorrhage
- Migraine
- Brain tumors and ICP (increased intracranial pressure)
Examples of reaction to drugs causing nausea and vomiting include:
- Alcohol
- Opioids
- Selective serotonin re-uptake inhibitors (SSRIs for depression)
- Many chemotherapy drugs
What pathway does the neurotransmitter serotonin use?
Afferent pathway
Why are nurses concerned about nausea and vomiting?
- Aspiration: Passage of gastric contents into the lungs (infection)
- Mallory-Weiss tear: Tear in esophageal lining (bleeding)
- Fluid and electrolyte imbalance: Occurs with prolonged vomiting due to loss of HCL, K+, and increase of HCO 3- (metabolic acidosis)
If a patient has nausea and vomiting that results in vomiting why does an infection occur and why is it a concern?
Patient has aspiration.
- Stomach acid is highly acidic and contains bacteria which can irritate the lungs.
- The patient is most at risk are unconscious and have an absent gag reflex.
- Patients that just had sedation or had a stroke
If a patient has nausea and vomiting that results in a Mallory-Weiss tear why should a nurse be concerned about the bleeding?
Depending on the location, it can be difficult to stop the bleeding
What happens when vomiting is prolonged?
- The risk for dehydration increases
2. A patient can develop metabolic acidosis
What are the 3 mechanisms that explain vomiting complication
a) Physical loss of HCO 3- as duodenal secretions (which are alkaline) are lost in the vomit
b) Consumption of HCO 3- through lactic acid production (caused by hypovolemia and increased muscle activity)
c) Depletion of liver stores of glucose causes ketoacidosis
What are the roles of the emetic centre in nausea and vomiting?
- Once stimulated it will cause nausea and if stimulated, a lot can cause vomiting
- Transmits info about state of GI tract
Which pathway would control the nausea/vomiting response in a patient who has motion sickness?
Vestibular system to the brain via cranial nerve VIII
Which pathway would control nausea/vomiting response in a person who had food poisoning?
Enteric and Vagus nerve system
Why does a person with prolonged vomiting develop hypokalemia?
Fluid and electrolyte imbalances
How does prolonged vomiting affect acid/base balance?
Person can get metabolic alkalosis to metabolic acidosis if prolonged
What can go wrong in the upper GI tract? List 6 examples.
- Gastroesophageal reflux disease (GERD)
- Hiatal Hernia
- Peptic Ulcer Disease (PUD)
- Gastritis
- GI Bleeding
6 Esophageal cancer
Define GERD (Gastroesophageal Reflux Disease)
A condition where gastric contents move into the esophagus creating the sensation of heartburn and/or esophagitis
Why do people get GERD?
GERD can be caused by:
- Weak or incompetent LES (lower esophageal sphincter)
- Hiatal Hernia
- Impaired esophageal motility
- Decreased saliva function
- Delayed gastric emptying
What are 3 examples that can cause a weak or incompetent LES?
- Caffeine
- Eating larger frequent meals
- Anti-cholingerics, BB, CCB, and morphine
How does a patient who has impaired esophageal motility relate to GERD?
Esophagus does not push down properly. Can be due to viral infection.
How does a patient who has decreased saliva function relate to GERD?
Can be caused by medication(s)
How does a patient who has delayed gastric emptying relate to GERD?
Pressure in the stomach is too great that it overwhelms LES causing stomach contents to reflux back to the esophagus.
High pressure cause by increase in acid production or delayed gastric emptying (due to tumour or ulcer)
What are the common symptoms of GERD?
- Heartburn (Pyrosis)
- Respiratory Symptoms
- Regurgitation
Explain common symptoms of GERD for heartburn
Burning/tight sensation felt intermittently beneath lower sternum and spread to throat/jaw.
Occurs 30-60 mins after meal and worse when bending at the waist.
Explain common symptoms of GERD for respiratory symptoms
Aspirations of stomach content can cause wheezing, coughing. and dyspnea.
Stomach acid irritates respiratory tract.
Explain common symptoms of GERD for regurgitation
Effortless return of food or gastric contents into mouth. Often described as hot, bitter, sour liquid coming into mouth.
Due to regurgitation (food contents come back to the mouth).
What are the 3 chronic GERD complications with ongoing esophagitis?
- Esophageal Stricture
- Barrett’s Esophagus
- Ulceration and bleeding
Define esophageal stricture
Narrowing of esophagus caused by scar tissue formation (leads to dysphagia).
Summary: Scar tissue formed
Define Barrett’s Esophagus
Replacement of esophageal stratified squamous epithelium with simple columnar epithelial (like stomach/intestine).
10% of patients with Barrett’s will develop esophageal cancer.
Summary: Cellular changes
Define ulceration and bleeding
There’s too much acid or not enough mucus, the acid erodes the surface of the stomach or small intestine resulting in a open sore that can bleed.
Define Hiatal Hernia
Herniation of a portion of the stomach into the esophagus through an opening in the diaphragm
What are the contributing factors to hiatal hernia?
Weakening of muscles in the diaphragm around the esophogastric opening, increase in intra-abdominal pressure (obesity - extra fat , pregnancy, ascites, tumours, and heavy lifting - external)
What are the symptoms of hiatal hernia?
Similar to GERD and often occur when supine, after a large meal, with smoking/alcohol
What are two examples of hiatal hernia?
- Sliding hiatal hernia
2. Para-esophageal (rolling) hiatal hernia
What are 5 symptoms would a patient experience if they have esophageal cancer?
- Asymptomatic (early)
- Dysphagia - Meat (difficult ((first)) –> soft food –> liquids
- Neck pain
- Weight loss
- Bleeding (complication)
What does (a) LES stand for and what (b) is its main function?
(a) Lower esophageal sphincter
(b) Prevents stomach contents from moving up
Why can GERD cause respiratory symptoms?
Acid/stomach contents can cause aspiration
What is Barrett’s esophagus and why is it a significant?
Changes in cell structures. Can further into esophageal cancer.
What types of patients might be at increased risk for a hiatal hernia?
Obese, pregnant, weight lift, and ascites
Why does esophageal cancer cause dysphagia?
The tumour can cause blockage to the esophagus
How does peptic ulcer disease occur?
Occurs when ulcerative lesions are caused by exposure of the stomach or duodenal mucosa to HCL acid-pepsin secretions
What are 5 aggressive factors that cause PUD?
- H. Pylori
- NSAIDS
- Acid
- Pepsin
- Smoking
What are the 5 Defensive factors for PUD?
- Mucus
- Bicarbonate
- Blood flow
- Prostaglandins