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GI pathophysiology II

Terms in this set (35)

When do you first start to feel symptoms of appendicitis?
When the tissue is in the hypoxic phase.
Describe the stages of appendicitis that lead to symptoms which requires surgical removal.
Appendix becomes inflamed for an unknown cause ---> Continues to secrete mucus ---> intraluminal pressure increases ---> venous blood flow becomes limited ---> Hypoxia sets in --->ulcers form ---> bacteria invades and causes infection ---> intraluminal pressure further increases ---> arterial circulation becomes thrombosed ---> gangrene sets in
What is diverticular disease?
Persistant, recurrent infections of diverticulitis. Note that it typically only occurs in the elderly
What is diverticulosis?
The development of many diverticulum in the colon.
What is diverticulitis?
Inflammation and infection of a diverticulum in the colon. They have the potential to rupture and become infected.
What is a diverticulum?
This is a herniation of the mucosal lining and blood vessels through the smooth muscle of the colon, most often the sigmoid colon.
Why does diverticulosis most commonly develop in the sigmoid colon?
Sigmoid colon is the most narrow portion of the colon and thus has the highest amount of wall tension.
What is malabsoprtive syndrome? What are the symptoms?
This is a collection of symptoms that might arise from multiple causes and is characterized by a reduction in the small intestine's ability to absorb. Things that might cause it include celiac's disease, chron's disease, or bowel resection.

Symptoms: Nutritional deficiencies that depend on what part of the digestive tract is affected. More common symptoms include diarrhea, steatorrhea, flatulence, bloating, abdominal pain, cramps, abdominal distention, muscle wasting, weight loss, easy bleeding, easy bruising, and bone pain.
What is celiac sprue?
Rare condition in which there is a characteristic mucosal lesion of the small intestine. It impairs nutritional absorption. Symptoms tend to improve when gluten is removed from the diet, and thus believed to be an immune response to gluten. Creates loss in absorptive vili. Really it is an allergy to gladian, which is a protein that can't be digested/broken down.
Lobes of the liver.
RIght left, quadrate, caudate.
Largest organ in the body?
Liver
Functional unit of the liver
Lobule
Describe the organization of the lobule
Portal triads on the periphery (bile duct, portal vein, hepatic artery)
Center is a central vein that dumps to the hepatic vein.
Sinusoids created by conjoining hepatic portal veins and hepatic arteries.
All hepatocytes are connected to these sinusoids.
What is the name of the important cells that are in-between the liver heaptocytes and the endothelial cells of the sinusoids.
Stellate cells. In healthy cells they are quiescent and store vitamin A. In pathological states they become activated into myofibroblasts and lay down fibrous tissue inbetween the sinusoids. This is the scarring that you see in the liver.
What are kupfer cells?
These are cells in the liver. They are one of the main cells in the reticular endothelial system (cells that recycle RBCs).
What are some of the functions of the liver
Carbohydrate metabolism (gluconeogenesis, glycogen storing)
Bile synthesis
Detoxificationo f blood
Beta oxidation of fats
Deamination of aa
Cholesterol synthesis
Storage of Vitamin B12 and iron
Synthesis of plasma proteins (albumin, clotting factors)
IGF (insulin like growth factor)
Degrades steroid hormones
What is cholestasis? What are some common symptoms associated with cholestasis.
Decrease in bile flow. Thus materials that normally are excreted through the bile begin to accumulate in the blood.

Sx: Jaundice (bilirubin), pruritis, skin xanthomas (cholesterol build up products in the skin), nutritional deficiencies
Describe how bilirubin is made in the body and the path that it takes through the body.
Made during RBC recycling. Comes from the heme unit. Heme is broken down to bilverdin in the blood. This is oxidized to make bilirubin. Bilirubin attaches to albumin and is dropped off in the liver. Here it is conjugated with lipopolysaccharides and secreted into bile ducts. Once in the small intestine it is converted to urobilinogen where it will either be secreted or reabsorbed into the blood. It can also be filtered by kidneys and released in urine.
The general causes of jaundice.
Excessive degradation of RBCs (prehepatic)
Impaired uptake of bilirubin in the liver (intrahepatic)
Decreased conjugation of bilirubin (intrahepatic)
Obstruction of bile flow (post hepatic)
What is dyserythropoesis?
malformation of RBCs
Symptoms that arise from portal HTN.
Splenomegaly
Ascites
Portosystemic shunts (caput medusa, esophageal varices)

Typically only comes from intrahepatic portal HTN issues.
What are the contributing factors to the development of ascites due to liver failure?
1.) Portal HTN (hydrostatic pressure increase)
2.) Decreased Albumin production (decrease in oncotic pressure)
3.) Decreased aldosterone metabolism (aldosterone levels are high, Na is retained, water is retained, portal HTN is exacerbated).
What are some of the manifestations of liver failure?
1.) Hematological disorders - anemia (lack of iron and B12 stores), thrombocytopenia (liver releases thrombopoetin), coagulation defects (clotting factors made in the liver).
2.) Endocrine disorder - inability to clear blood of steroid hormones. Disturbances in gonadal function is common, menstrual cycle irregularites, testicular atrophy, gyenocomastia. Decreased aldosterone clearance leading to increased Na and water retention (thus HTN).
3.) Skin disorders - skin xanthomas, vascular spiders (due to estrogen levels), palmar erythema (significant vasodilation to blood vessels of the hand).
4.) Hepatorenal syndrome - The issue is that there is underfilling to the kidney, not an intrinsic problem with the kidney.
5.) Hepatic encephalopathy - CNS mainfestations. Ranges from lack of mental alertness to coma. Memory loss and personality changes are common. Believed to be caused by the increase in ammonia levels (remember urea cycle happens in the liver).
Main causes of liver failure
1.) Hepatitis
2.) Cirrhosis
3.) Liver Cancer
List the different viruses that cause hepatitis, of these which can lead to chronic hepatitis?
A,B,C,D,E,G

A,E don't lead to chronic hepatitis
B,C,D,G lead to chronic hepatitis
What are the mechanisms for how the hepatitis viruses cause liver injury
1.) Direct cellular Injury
2.) Induction of the immune response against a viral antigen
Hepatitis A
RNA virus
Fecal oral transmission
4-6 week incubation phas
Hepatitis B
dsDNA
Transmitted from infected blood, needles, or body fluids.
Can be transmitted from mother to fetus
What is cirrhosis?
Irreversible inflammatory disease that disrupts liver function and structure. The decrease in liver function is a result of increased fibrosis and nodular regneration. Can cause bile obstruction and portal HTN due to fibrosis.
Describe the pathogenesis of alcoholic liver disease
Increases fat in hepatocytes and increases fibrosis.

Alcohol --> acetaldehyde --> impairs mitochondrial ETC system --> H+ are shuttled out of the mitochondria ---> ultimately increases lipid synthesis (fatty liver) ---> lipoproteins aren't released and mitochondrial beta oxidation decreases.

Acetaldehyde also increases collagen synthesis and fibrogenesis in the liver. This leads to a fibrotic liver
What is the major activator of the pancreatic enzymes?
Trypsin
Describe the pathogenesis of acute pancreatitis.
This is the escape of activated pancreatic enzymes into the pancreas and surrounding tissues. Two main causes are gall stones and alcohol. Both activate trypsin in the pancreatic acinar cells, which causes the activation of all the other pancreatic enzmyes (chymotrypsin, pancreatic amylase, lipase, ribonuclease, carboxypolypeptidase).
Sx include extreme pain, nausea, and vomiting.
What is chronic pancreatitis?
Typically is a condition that is caused by frequent bouts of acute pancreatitis. Number one cause is alcohol. Alcohol decreases trypsin inhibitor, it also increases basal pancreatic secretions. This might lead to protein plugs, pancreatic duct obstructions, and calcification leading to chronic pancreatitis. Note it can affect the function of the whole pancreas and might progress to diabetes.
What are the two types of gall stones
Cholesterol (white stones) or bilirubinate (pigmented stones).
What are the factors that lead to the formation of gall stones?
Bile stasis
Abnormalities in the composition of bile
Inflammation of the gall bladder
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