Digestion/Liver Flashcards
Name the digestive tract organs. (6)
Mouth, esophagus, stomach, small intestine, large intestine, rectum
What are some accessory glands to the digestive tract?
Salivary glands, liver, gall bladder, pancreas.
Where do exocrine cells secret to?
Exocrine cells secrete into ducts.
What three organelles are found in large amounts in the exocrine gland cells?
Endoplasmic reticulum, mitochondria, secretory vesicles.
What do secretory vesicles contain?
Enzymes
What are secretory cells in groups called?
acini
What is in saliva?
Water, electrolytes, amylase, mucus, lysozymes (protects from pathogens)
What is in gastric juice?
Water, mucus, pepsin, HCl, rennin (chymosin)
What is in pancreatic juice?
Water, bicarbonate, amylase, lipase, carboxypeptidase, trypsinogen
Is the mouth basic, neutral, or acidic?
Slightly basic (pH 7-8)
What receptors are present in the stomach? (2) What do they detect?
Chemoreceptors detect peptide and Stretch receptors detect distention.
What is digestive juice secretion controlled by? (2)
Nerves/hormones
What can the sight or smell of food cause your brain to do?
Send nerve impulses to gland cells of the stomach wall to secrete pepsinogen and acid.
What is secreted when the brain sends signals via the vagus nerve to the duodenum?
Gastrin
What does gastrin stimulate the secretion of? From where?
Acid and pepsinogen from the stomach wall.
What inhibits the secretion of gastrin if pH in stomach falls too low?
Secretin and somatostatin
Why is gastric juice acidic? (2)
Low pH is optimal for pepsin and helps control pathogens.
What was William Beaumont able to figure out about gastric digestion?
That gastric digestion was both physical and chemical (not just chemical)
Who got the gunshot that allowed doctors to study his stomach?
Alexis St. Martin
What type of infection can cause ulcers?
Helicobacter pylori
How can someone with H. Pylori bacteria be treated?
A combination of antibiotics and proton pump inhibitors
How can you detect H.pylori?
H.pylori produces the enzyme urease so a urea breath test can be used. The patient is given some radioactive urea orally and see if they breath out radioactive carbon dioxide.
How do proton pump inhibitors work?
They irreversibly bind to ATPase or a protonpump to stop the acidic environment that is created by this proton pump.
What did Marshall and Warren discover? Why was it hard for their results to be accepted?
They discovered that antbiotics can cure ulcers but it was difficult for others to accept that as ulcers where known to be a result of excess stomach acid not a bacteria.
What does lipase do? Is it water-soluble or fat-soluble?
Lipase is a water soluble enzyme that is designed to break down a hydrophobic substance. Can only access the surface of lipids.
What does bile do to lipids? Why? Where is lipase made?
emulsifies lipids to increase the surface area. lipase is made in the pancreas
Draw the ileum.
What are the three parts of the small intestine in order?
Duodenum, jejunum, ileum
What does the epithelial cell of the villus contain?
Pinocytotic vesicles, mitochondria
What is the pinocytic vesicles for in the epithelial cell of the villus?
Contains fluid and dissolved minerals from the lumen
What function in the villus ensures most materials will pass through cells before the blood?
Tight Junctions
Draw the villi cross section.
What happens to lipids in the epithelial cell? What is the end product called?
They reassemble into triglycerides and become coated in proteins and chloresterol. This is called a lipoprotein complex.
What lipid forms diffuse into the villi membrane of the small intestine?
Monoglycerides, bile salts, fatty acids
What do lipoproteins enter? How do they travel to the blood?
Lipoproteins enter the lacteal and travel through the lymphatic system to the circulatory system.
What is the main function of the small intestine? (2)
To complete digestion and to absorb the nutrients to distribute throughout the body.
What is facilitated diffusion? What substances pass into the epithelium by facilitated diffusion? Why does it use this method of transport?
Facilitated diffusion is the passive transport of molecules using integral proteins. Fructose passes into the epithelium by facilitated diffusion and it uses this method because it is hydrophilic.
What things are absorbed into the epithelium via active transport? (3)
Glucose, amino acids, some minerals
How does active transport work to absorb sodium?
Active transport sets up high concentrations of sodium in lumen so that it can make a passive re-entry of sodium accompanied by nutrients.
What is the benefit of actively transporting materials into the epithelial cells?
Can facilitate diffusion of those materials into the bloodstream.
Are carbs absorbed whole into the small intestine?
No, they are absorbed in there monomer form, ex glucose.
What is the difference between endocytosis and pinocytosis?
Pinocytosis is a form of endocytosis.
What materials are not absorbed by the small intestine?
Plant fibres (cellulose, lignin), bile pigments, bacteria, intestial cells
What is absorbed via pinocytosis at the epithelial cells? (2)
Small amounts of fluids and undigested fats.
What causes cholera?
The bacterium Vibrio cholera
How is the toxin, cholera, brought into the cells?
By endocytosis
What does the bacterium cholera trigger in the cell? What does this lead to?
A cascade response that leads to efflux of chloride ions and HCO3- irons from the epithelial cell into the intestine. Water follows and diaherra results.
What structure brings oxygen-rich blood from the heart to the liver?
Hepatic artery
What structure brings blood from the gut to liver?
Hepatic Portal Vein
What does the hepatic portal vein divide into in the liver? What is that structure?
Sinosiods which are a different type of capillaries that are wider and not continually lined with cells.
What do sinosoids allow for? (2)
Blood to come into contact with hepatocytes and allows proteins/albumin to enter and leave the blood.
What are hepatocytes?
Specialized liver cells that carry out functions such as detox.
What is the hepatic artery divided into?
Arterioles
How does the hepatic artery get oxygen?
Joins with sinusoids at various points.
What do sinosoids merge into?
Venules which lead to the hepatic vein and vena cava.
How does the liver regulate blood nutrients? (2)
Key role in glucose regulation and breaks down excess proteins and amino acids.
What type of waste does the liver process?
Nitrogenous waste
Which nutrients does the liver store? (4)
Carbs (stored in hepatocytes as glycogen), iron (breaks down dead erythrocytes and stores iron as ferritin), vitamin A (stores for use in vision, is fat soluble), vitamin D (stores for use in calcium uptake, is fat soluble)
What is vitamin A a vital component of?
Rhodopsin
What two things does the liver synthesize? What is their purpose?
Cholesterol(component in bile, animal cell membranes, component of steroid hormones) and Plasma proteins (albumin which regulates osmotic pressure and creates fibrinogen which is a precursor to fibrin)
What is HDL?
High density lipoprotein and is considered healthy as it helps remove LDL, “good cholesterol”
What is LDL?
Low density lipoprotein, “Bad” cholesterol
Why do we have lipoproteins?
Transport lipids from intestine to liver and throughout the blood
What role does the liver play in detoxification?
Liver cells(hepatocytes) absorb toxic substances from blood and convert them into less toxic substances.
What does the liver break down alcohol into?
Ethanol dehydrogenase
What is the lifespan of an erthrocyte?
120 days
What is the difference between phagocytosis and pinocytosis?
Phagocytosis engulfs solid material while pinocytosis engulfs fluids.
What happens as red blood cells age?
They swell and become engulfed (phagocytosis) by Kupffer cells.
Where are Kupffer cells located?
Line sinusoids of the liver.
What happens to the erthrocyte inside the Kupffer cell?
Hemoglobin is split into globin chains and heme group.
What happens to the amino acids in the globin chains of the hemoglobin once it is engulfed by the Kupffer cell?
It is recycled, digested by peptidases
What happens to the heme group as it is being broken down in the Kupffer cells?
It breaks into iron and bilirubin (bile pigment)
Where can iron from the liver be transported to make red blood cells?
Bone marrow
What is produced during alcohol detoxification that can accumulate in the liver?
Fatty acids
What can long-term alcohol consumption cause liver fat storing cells to produce? What does it form?
Collagen which forms scar tissue
Is bile acidic or basic?
It contains bicarbonate so it is basic.
What is cirrhosis? What is it a deposition of?
Scarred liver, it is the deposition of collagen
What is the pathway of bile from the liver to the gall bladder?
Heptocytes then bile canaliculi then gale bladder
What can accumulation of fats in the liver cause? What is it?
Hepatitis, it is the inflammation of the liver
What is jaundice a build up of?
Bilirubin (bile pigment)
Is jaundice a disease? What is it a result of?
No, it is a symptom. Can be a result of hepatitis, liver cancer, or obstruction of bile duct.
What is newborn jaundice a result of?
High turnover of red blood cells, which produces bilirubin. Liver can still be developing.
How can you treat jaundice?
Treat the disease or break down bilirubin in skin using a UV light.
