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Biology
Gastrointestinal Tract & Kidney
| Question | Answer | Answer pt.2 |
|---|---|---|
| Define digestion | It is the process by which food that is eaten is broken down into progressively smaller particles and ultimately absorbed by the intestinal tract | |
| The gastrointestinal system includes what organs? | The mouth and associated salivary glands, esophagus, stomach, small and large intestines, and certain aspects of liver and pancreas | |
| What enzymes are used to break down starch, glycogen, and cellulose? | -Starch and glycogen is broken down to glucose with the enzyme amylase -Cellulose is broken down to cellulose with the enzyme cellulase -Humans cannot digest cellulose b/c we don't have the enzyme cellulase in us | |
| What enzymes are used to hydrolyze proteins and fats? | -Proteins are broken down to amino acids by the enzyme protease -Fats are broken down into fatty acids glycerol by the enzyme lipase | |
| What is the first part of the gastrointestinal tract process? | -Food is eaten & chewed -Salivary amylase secreted to digest the starch & glycogen (controlled by the parasympathetic nerve) -Food is swallowed, a tissue called the epiglottis covers the larynx from getting into the lungs. | Instead food goes through the esophagus and to the stomach (reflex controlled by centers in the medulla) -Once in stomach, gastroesophageal sphincter contracts, preventing food from going back up the esophagus |
| What is the function of the stomach? | -To break the food into smaller particles -To detoxify it by acid secrections | |
| What are major secretions in the stomach? | -Mucus -Gastrin -Parietal cells: HCl -Chief cells: pepsinogen | |
| Define mucus | It is secreted by surface cells and acts to protect the lining of the stomach and lubricate the food | |
| Define gastrin | Located in endocrine cells in the lower portion of the stomach. It is secreted in response to protein entering into the stomach | |
| The hormone gastrin stimulates the secretion of what? | HCl and pepsinogen (inactive form of pepsin) | |
| What do parietal cells in the stomach secrete? | -HCl: breaks down the bolus -Intrinsic factor: it is a glycoprotein that helps w/ the absorption of vitamin B12, which will be transported into the bloodstream | -Vitamin B12 is important for erythrocyte (RBC) formation |
| What do chief cells in the stomach secrete? | -It releases pepsinogen so that is can be converted to pepsin (w/the help of HCl). Pepsin then hydrolyzes proteins -Once pepsin is formed it can automatically act on pepsinogen to form more pepsin | |
| What is one of the most powerful stimulants that causes HCl to be released into the lumen of the stomach? | Histamine | |
| What are ulcers and how can ulcers occur in the stomach? | -They are erosions of the walls of the stomach and small intestine, and if they are extensive enough, they can cause bleeding -They can occur due to too much acid being secreted into the stomach | |
| What is cimetidine (tagamet)? | -It is a compound that inhibits the binding of histamine to its receptors on the parietal cells -This reduces the amount of HCl secreted in the lumen of the stomach | |
| Where does ∼ 90% of all digestion and absorption take place? | In the small intestine | |
| What causes the hormone cholecystokinin (CCK) to be released? | The distension (enlargement) of small intestine causes its release from the intestinal mucosa | |
| What does CCK do in the small intestine? | It diffuses by the bloodstream to the pancreas where it causes the pancreas to release digestive hormones | |
| What does the hormone secretin do in the small intestine and what triggers its release? | -It is absorbed by the blood & it transported to the pancreas where it causes the release of bicarbonate ion & other fluids -The entering of chyme from the stomach triggers the release of secretin | |
| What is the structure of acini? | It is secreted by the pancreas. It has a high bicarbonate content. Combined w/ HCl it produces carbonic acid, which is then converted into carbon dioxide and water | |
| What does the liver do in terms of the small intestine? | -It synthesizes a compound called bile which is stored in the gallbladder -Bile contains something called bile salts which is important in the digestion and absorption of fats | |
| How does bile actually get to the small intestine? | It leaves the gallbladder & goes through a duct that connects to the pancreatic duct, through a constriction called the sphincter of oddi, and empties into the small intestine | |
| What does the large intestine do? | -It absorbs most of the water and ions that are left in the chyme as it passes from the small intestine -What is not absorbed is passed out of the body in the feces | |
| What is the relationship between osmolarity and water concentration? | ↑ osmolarity = ↓ [water] | |
| Define osmoconformers | It is organisms that can change the internal ionic concertation of its body fluids to meet that of the surrounding environment | |
| Define osmoregulators | It is organisms that do not change their internal ionic concentration of their body fluids to meet that of a surrounding environment | |
| What are the functions of the kidney? | 1) Filtration: the filtrate in bowman's capsule is essentially the plasma minus the proteins 2) Reabsorption: of organic & inorganic compounds from the filtrate in bowman's capsule 3) Excretion: waste, salts, & excess water | |
| What is the functional unit of the kidney? | The nephron, which consists of a glomerulus, bowman's capsule, and a tubular system | |
| How does blood enter and exit the kidney? | -Blood from the descending aorta enters into the renal artery & eventually into the glomeruli of the nephrons -Blood leaves the kidney by way of the renal vein which itself empties into the inferior vena cava | |
| What does the color of your urine say about the osmolarity of your body? | -If you have dilute urine then your osmolarity is ∼ 0.7 times that of the osmolarity of the plasma -If you have a concentrated urine then your osmolarity would by high; ∼ 4.2 times the osmolarity of the plasma | |
| What is absorbed in the proximal convoluted tubule (PCT)? | - ∼ 65% of all absorption & secretion occurs here -Glucose, small proteins, amino acids, & vitamins are 100% reabsorbed in the PCT - ∼ 80% of Na+, Cl- , & water are reabsorbed in the PCT | |
| Where in the loop of Henle is the filtrate the most dilute? | -In the ascending thick portion of the loop. It gets more & more dilute as it goes up into the distal convoluted tubule (DCT) -Meaning there are low osmolarity and higher concentration of water | |
| What areas on the nephron are sensitive to the hormone aldosterone? | The two areas are the epithelial cells of the segment of the DCT closet to the collecting duct and the portion of the collecting duct located in the cortical region of the kidney | |
| What does aldosterone do? | Aldosterone regulates sodium absorption. It is secreted by the cortex of the adrenal glands that sit on top of the kidneys | |
| What happens when there's an increase in concentration of aldosterone? | It causes sodium to be reabsorbed by the epithelial cells and into the interstitial space. Potassium ions are also simultaneously being transported into the lumen | |
| What does antidiuretic hormone (ADH) do and where is it produced? | -It regulates water absorption -It is produced by the hypothalamus and released by the posterior pituitary | |
| What inhibits ADH? | Alcohol | |
| What are the different ways that you can get rid of nitrogen from the body? | -Ammonia -Urea -Uric acid | |
| What is cholera? | -It is an acute intestinal infection transmitted by contaminated water or food -Results in rapid fluid loss through diarrhea, vomiting, dehydration, a potential circulatory collapse, and shock is not treated | |
| What is the proton pump inhibitor (PPI)? | It is a class of drugs that inhibit the enzyme known as the proton pump | |
| Define proton pump | It is responsible for pumping hydrogen ions (H+) into the stomach lining | |
| Salivary amylase aids in the digestion of what? | Polysaccharides |
Created by:
Gabbgabb04
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