GI Flashcards
Basic Functions of the GI system
Skeletal muscle turns into smooth in the esophagus
Stomach aids in breaking foodstuffs down for absorption (very little absorption occurs here, alcohol and aspirin for example)
Small intestines absorb nutrients and send them to the liver (including bile salts)
The large intestine is important to reabsorb water, make some vitamins
The liver processes nutrients and destroys toxins
Pancreas helps with digestion of carbs, lipids, proteins
Tunica Mucosa
Inner most layer
Provides a protective layer of epithelium that will selectively absorb substances
Microvilli will increase service area on the cells in the mucosal layer
Creates some digestive enzymes (along with organs) to break down macronutrients
Tunica Submucosa
Has glands to aid with digestion
Also aids with the GALT (gut associated lymphatic tissue) which is a layer of white bloods cells that are in the mucosa and submucosa in the GI tract. These provide prtoection from ingested substances.
Tunica Muscularis
Two layers of muscle in the GI tract (3 in stomach) which push food foward and also churn it
Tunica Serosa
The outer layer that helps to anchor the GI organs and to protect them
Enteric (Gut) nervous system
- Autonomic (automagic)-Sympathetic stops digestion parasympathetic increases
- Submucosal nerve plexuses- Submucosa, glands and muscle control in the mucosa
- Myenteric nerve plexuses- between circular and longitudinal layers of tunica muscularis
Chemical Digestion
Carbohydrates
-Primarily Amylase in the mouth and from the pancrease
-Lactose intolerant
Proteins
-Broken into amino acids by pepsin from the stomach’s chief cells (pepsinogen)
Lipids
-Emulsified with bile salts into fatty acids & broken down by lipases from the pancreas
Nucleic Acids
Nucleotides broken down by pancreatic nucleases
Absorption
Mostly small intestine Ileum reclaims bile salts Carbohydrates Proteins Nucleic acids Lipids -chylomicrons
Expulsion from the GI Tract
Vomiting
-From the stomach and/or small intestines
-The medulla oblongata has a vomiting center that is exposed to our blood. It is one of the few breaks in the blood-brain barrier, so we have quick access to the blood to examine it for infectious agents (it may respond to some medications as well) This area is known as Chemoreceptor trigger zone, also receives input from the inner ear (where balance) is sensed so people who are prone to being motion sick are stimulating the CTZ.
Mallory Weiss Syndrome
-Mucosal tears that allow blood into the lumen and then vomit, correlated with an esophagus that is not relaxed
-Due to severe retching periods of vomiting due to severe alcoholics or post general anesthesia
Diarrhea
- Normal defecation occurs when there is feces moved into the rectum after large peristaltic movements along the colon
- Increase in frequency and fluid contributes to diarrhea
- Secretion of fluid into the lumen can occur with infections in an attempt to dilute and evacuate them
- Osmosis occurs when there are more particles in the tract from undigested foods or foods that cannot be digested (fiber for example). This draws fluid into the colon.
- Impaired water absorption
- May lead to dehydration and acidosis (since the patient loses bicarbonate ions in diarrhea)
IBS
AKA spastic colon
Abdominal discomfort, cramping, fatigue and alternating constipation and diarrhea with increase mucus in the stools
Cramping may be due to abnormal peristaltic movements which may indicate that there is some sort of nervous system involvement
Esophagitis
Reflux esophagitis causing heartburn and can lead to Barrett’s esophagus
Seen in pregnant women or obese. Or some patients just have it.
Also may be due to a sliding hiatal hernia through the esophageal hiatus
-Paraesophageal hiatal hernia is when there is a bulge to the side rather than the esophagus coming above the diaphragm
Inflammations of the stomach
Inflammation that is named according to the locations: gastritis, enteritis, gastroenteritis, enterocolitis, or colitis
Helicobacter pylori can cause it
Acute erosive gastritis may be due to increase alcohol, aspirin and NSAID use
Appendicitis
Vermiform appendix (worm like) is attached to the cecum
Obstruction of the lumen with feces (fecalith) cause the appendix to swell and also allows bacteria to thrive
Pain pattern can begin with obscure periumbilical pain with it progressing to lower right quadrant. As it presses on the perietal peritoneum, the pain is easier to localize due to more nerves in the parietal portion of the peritoneum
Can progress to peritonitis if the appendix is removed
Peritonitis
Visecral vs parietal peritoneum
Bacteria may be introduced from the external environment as well such as STDs or wounds
Acute abdomen- the sudden syndrome that presents as acute pain, fever, vomiting
May begin as diffuse pain and then localize as the pressure pushes on the more sensitive parietal peritoneum
Likes to form a fibrinous exudate which will lead to scar tissue
Fistula may form between adjacent organs
Diverticulitis
Diverticula are the puches (diverticulum are pleural) diverticulosis is the condition of diverticula
Usually in the sigmoid colon and possibly in the left descending colon
The inner mucosa pushes through the inner circular layer where BLOOD VESSELS pass through, then it can sneak its way through the longitudinal layer because there are only 3 strips of the muscle
Fiber is huge in prevention, BUT cannot be used in flare ups (aids in moving bowels and preventing the patient from bearing down too hard)
If feces gets trapped, fecaliths may form and lead to infection.
Fibrosis of the colon due to repeated inflammations can lead to stenosis of the colon.
