Gastrointestinal Tract and Kidney Flashcards
1
Q
Mouth and Esophagus
A
- Food is ground by teeth; amylases break down glucose polymers
- Peristalsis moves food down throat to stomach
- The gastroesophageal sphincter prevents regurgitation of food into esophagus
- Faulty sphincter –> heartburn
2
Q
Stomach Function
Gastrin
HCl
Pepsin(ogen)
Intrinsic Factor
A
- The stomach:
- Breaks down food into smaller particles
- Detoxifies food particles (acid)
- Surface__ cells secrete mucus
- Gastrin is secreted by endocrine cells at the stomach basement in response to proteins
- Gastrin stimulates the secretion of:
- HCl by parietal cells__
-
P__epsinogen by chief cells
- __Pepsinogen is a zymogen that becomes pepsin in low pH
- Intrinsic factor is a glycoprotein secreted by parietal cells that is required for sequestering B12
3
Q
HCl and Histamines
A
- Histamines bind to parietal cells and stimulate the release of HCl
- Histamine antagonists can help decrease HCl secretions, a useful way to help treat ulcer patients
4
Q
Small Intestine
Cholecystokinin
Secretin
A
- The chyme (dissolved food) travels into the small intestine
- 90% of the digestion and absorption that takes place in the gastrointestinal tract takes place in the small intestine
- Neutralizes acid from stomach
-
Cholecystokinin (CCK) is released from the intestinal mucosa as a result of small intestine enlargement
- Goes to pancreas
-
Secretin is a hormone that is released when chyme enters
- Secretin is absorbed in blood and goes to pancreas
5
Q
Pancreas, CCK, and Secretin
A
- The pancreas has endocrine cells that release insulin and glucagon
- The pancreas reacts to CCK by secreting digestive enzymes to the small intestine
- Pancreas will react to secretin and release acini, which has a lot of bicarbonate
- This helps neutralize the chyme
6
Q
Liver and Gall Bladder
A
- The liver creates bile; bile is stored in the gallbladder
- Bile contains bilirubin (major pigment from metabolized Hb)
- Bile also contains bile salts that help emulsify fats
- Bile enters the small intestine through the sphincter of Oddi
- Fats in the small intestine stimulate the release of CCK, which stimulates the release of bile
7
Q
Small Intestine Absorption
A
- Majority of fluid and nutrient absorbtion occurs in the small intestine
- Epithelial cells have transport proteins to help absorb ions, sugars, amino acids, vitamins, ect
- Fats are degraded into fatty acids and glycerol via lipases and enter epithelial cells
- Triglycerides are resynthesized in the cells and are transported in the lymph as chylomicrons
8
Q
Large Intestine
A
- Absorbs mosf of the water and ions that are left in the chyme
- Sodium and chloride ions are absorbed to establish an osmotic gradient, which facilitates the reabsorbtion of water
9
Q
Osmoconformers and Osmoregulators
A
- An osmoconformer is an organism that can change the internal ionic concentration of its body fluids to meet that of the surrounding environment
- Osmoregulators are organisms that cannot change their internal ion concentrations
- Recall, osmolarity of a given solution details the amount of solute in solution; osmolarity is inversely proportional to water concentration
10
Q
Generalized Kidney Function
A
- Three main functions:
- Filtration of blood through the nephron
- Reabsorption of organic and inorganic compounds
- Excretion of waste, salts, and excess water
11
Q
General Kidney Physiology
A
- Blood enters the kidneys from the renal artery, and leaves the kidneys by the renal vein
- Ureters leave each kidney and transport urine to the bladder; urine exits the bladder by the urethra
- Kidneys have more than a million nephrons, the functional unit of the kidney
12
Q
The Nephron and Its Basic Physiology
A
- Functional unit of the kidney is the nephron
- The afferent arteriole enters into the Bowman’s capsule, forming the capillary bed known as the glomerulus
- The efferent arteriole leaves the glomerulus and forms a capillary network around renal tubules
- The Bowman’s capusle extends into long tubular structure, divided into the proximal convoluted tubule (PCT), loop of Henle, distal convoluted tubule (DCT), and the collecting duct
- __Capillary network from the effernt arteriole surrounds these tubular structures
13
Q
Glomerulus and Bowman’s Capsule
A
- The glomerulus is a collection of capillaries that recieves blood from an afferent arteriole
- Blood is pumped into the glomerulus by the hydrostatic pressure of the heart
- The Bowman’s capsule receives the blood forced through the capillary walls of the glomerulus
- The ultrafiltrate found in the Bowman’s capsule is essentially plasma minus the large proteins and blood cells
- Contains ions, sugars, amino acids
14
Q
Osmolarity of Filtrate
A
- Osmolarity of the filtrate in the Bowman’s Capsule is 300 milliosmols (about the same as plasma)
- If the filtrate has an osmolartiy that is less than 300 milliosmols, urine will be dilute
- If the filtrate has an osmolarity that is greater than 300 milliosmols, urine will be concentrated
15
Q
Proximal Convoluted Tubule
A
- Part of the cortex
- The proximal convoluted tubule (PCT) is the obligatory section of the nephron; roughly 65% of all reabsorption and secretion occurs here
- Tons of active transport in theese epithelial cells
- 100% of all glucose, small proteins, amino acids, and vitamins are reabsorbed
- 80% of sodium, chloride, and water are reabsorbed
- Little regulation in the PCT
