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Test 4: Part 1

Brianne Schmiegelow Animal Physiology Undergraduate Englisch 200 Karten

Test 4: Part 1

Karten in diesem Stapel (200)

  1. 1What are the 3 themes seen in the evolution of gas exchange?1. Expansion of surface area for gas exchange
    2. Development of efficient ventilatory or pumping mechanisms
    3. Evolution of respiratory pigments
  2. 2What would happen if gas exchange systems did not evolve?There would be severe constraints on size and metabolism so they could not be >0.5-1 mm
  3. 3How many alveoli are there in each lung?300 million
  4. 4How wide are alveoli?0.2 mm in diameter
  5. 5What is the respiratory surface area?50-100 m^2
    (vs. <2 m^2 in the rest of the body)
  6. 6What separates air from the blood?2 thin cells
    1 alveolar, 1 endothelial
  7. 7How much blood is in the pulmonary capillaries?60-140 mL spread over the surface area of 50-100 m^2
  8. 8What causes the alveoli and the lungs to tend to collapse?Elasticity and surface tension
  9. 9What is the distribution of recoil force?Elasticity = 1/3
    Surface tension = 2/3
  10. 10How are the lungs kept inflated?The pressure in the intrapleural spaces is ~5 mmHg less than that in the lungs
  11. 11What generates the lower amount of pressure in the intrapleural spaces?Generated partly by lymphatic drainage of pleural fluid and partly by structure of the chest
  12. 12How much of a pressure change is required to move air in and out of lungs?~1 mmHg
  13. 13What is the max expiratory effort?~100 mmHg
  14. 14What is the max inspiratory effort?~ -80 mmHg
  15. 15How does quiet breathing work?Occurs via movements of the diaphragm
    - Inhalation: diaphragm moves down
    - Exhalation: resting occurs via passive recoil
  16. 16What happens during heavy breathing?Intercostal muscles raise and lower the rib cage
    During forced exhalation, there is an additional contraction of the abdominal muscles
  17. 17What are phospholipid surfactants?They are found in the fluid lining the alveoli
    Reduce surface tension and aid in breathing
    Secreted by Type 2 alveolar cells
    Lowers surface tension by >10x
  18. 18How much pressure does it take to inflate lungs without surfactant?~ - 25 mmHg
  19. 19What is Respiratory Distress Syndrome? (RDS)Often found in premies as a result of undeveloped surfactant secretion which normally begins at ~32 weeks
    First breaths are strong: ~ -60 mmHg
    Treatment includes surfactants and cortisol to speed maturation
  20. 20What is Boyle's Law?Pressure of a given quantity of gas is inversely proportional to its volume
  21. 21What determines respiration rates under normal circumstances?CO2 or H+ concentrations
  22. 22Where are gas concentration receptors located?Arterial system and medulla of the brain
  23. 23Respiration is adjusted to maintain PCO2 levels at what pressure?40 mmHg
  24. 24What is hypocapnia?State of reduced carbon dioxide in the blood
    Caused by hyperventilation
    Leads to cerebral vasoconstriction, reduced perfusion, dizziness, ischemia (inadequate blood supply to a part of the body), and acidotic condition in the brain
    Reduced by breathing into a paper bag
  25. 25What is tidal volume?The amount of air breathed in and out during normal respiration
  26. 26Inspiratory reserve volumeAmount of air that can be forcefully taken in above normal inspiration
  27. 27Expiratory reserve volumeAmount of air that can be forcefully expelled from the lungs following a normal expiration
  28. 28Residual volumeAir that remains in the lungs that can't be forced out
  29. 29Total lung capacitySum of tidal volume, inspiratory reserve volume, expiratory reserve volume, and residual volume
  30. 30Vital capacityAmount of air that can be expelled following a maximal inspiration
  31. 31Functional residual capacityAmount of air remaining in lungs after normal expiration
  32. 32Inspiratory capacityAmount of air that can be inspired following normal expiration
  33. 33How much O2 do we use and CO2 do we produce per minute?~200 mL
  34. 34Where do local decreases in O2 or pH cause local vasoconstriction? Wha? What is the significance of this?In the alveoli ONLY
    This means that blood only passes through well-ventilated alveoli
  35. 35How much more soluble is CO2 that O2 in water?20x
  36. 36How is O2 transported?It diffuses from the alveoli into the capillaries, then dissolves in plasma and then into RBCs where it combines with hemoglobin.
  37. 37What is our respiratory pigment?Hemoglobin
  38. 38How much does hemoglobin increase the O2 carrying capacity of our blood?60-70x
  39. 39Which is a brighter red: oxy- or deoxy-hemoglobin?Oxyhemoglobin
  40. 40What effect does packaging hemoglobin inside RBCs have on osmotic pressure?It keeps the OP low
  41. 41How is the Antarctic Icefish able to survive without respiratory pigment?O2 is more soluble in cold, so they live in cold water and have a low metabolic rate
  42. 42Describe vertebrate hemoglobinHas 4 polypeptide globin subunits (beta 1&2 and alpha 1&2), each with a heme group
    Each heme group has Fe++ which binds 1 O2 loosely. Four molecules of O2 can be transported for every 1 heme group.
  43. 43Difference between HbA, HbF, and HbSHbA (adult hemoglobin) has mostly 2 alpha and 2 beta subunits
    HbF (fetal) has mostly 2 alpha and 2 gamma subunits. The gammas switch to betas at birth
    HbS (sickle cell anemia) has 2 alpha and 2 sickles
  44. 44What is sickle cell anemia?A disease that causes individuals to have 2 sickle hemoglobin chains instead of 2 betas (the sickle chain has 1 AA different than beta)
    Causes hemoglobin to polymerize and crystallize, which causes RBC rigidity and capillary obstruction
    ESPECIALLY in low O2 environments
  45. 45How much higher is hemoglobin's affinity for CO than for O2?200x
  46. 46What are the three means of CO2 transport in the blood?7% in solution as: CO2 + H20<->H2C03 <->H+ + HCO3-
    70% is transported inside RBCs as: CO2 + H20 <->H2C03 <-> H+ + HCO3- <-> H+:Hb
    15-25% as: CO2 + Hb -> Carbaminohemoglobin
  47. 47What is carbonic anhydrase?Speeds up the CO2 transportation reaction inside RBCs by 5000x
  48. 48Where does CO2 attach to hemoglobin?An amino acid
    NOT the site where O2 binds
  49. 49What is the O2 pressure at sea level?160 mmHg
  50. 50What is the pressure of O2 in the alveoli? Why?105 mmHg
    Because air in the alveoli is subjected to removal of O2 as soon as it enters
  51. 51Is the O2 partial pressure higher in tissures during rest or during exercise?Rest (40 vs. <20)
  52. 52What is the Bohr effect?In acidic conditions, hemoglobin has a lower affinity for O2
    This lets Hb load more O2 in the lungs where pH is higher and unload more in the tissues where pH is lower
  53. 53What is normal arterial pH?7.40
  54. 54What is the pH of blood during rest after it passes through the capillaries?7.36
  55. 55What is the pH in muscle with exercise?Down to 6.9
    Increases O2 unloading
  56. 56How much does the temperature of active muscles change?Can increase by 3-4 degrees
    Causes unloading of O2
  57. 57What is subunit cooperativity?As each hemoglobin subunit binds O2, it increases the affinity of other subunits for O2
  58. 58What is the T (taut) state?It is the state in which a hemoglobin subunit is not bound to O2
    In "low-affinity" state
  59. 59What is the R (relaxed) state?It is the state after the 1st subunit of hemoglobin binds O2 in which the other three subunits have a higher affinity for O2
    SUBUNIT COOPERATIVITY
  60. 60How does O2 binding/unloading in hemoglobin affect CO2 affinity?As Hb binds O2, its affinity for CO2 decreases and as it unloads O2 its affinity increases
  61. 61What is the Haldane Effect?Causes hemoglobin to load 2X more CO2 than oxygen in the tissues and unload the same amount more in the lungs
  62. 62What is 2, 3 BPG?Biphosphoglycerate
    Byproduct of glycolysis that has a high affinity for the T form of hemoglobin and decreases its affinity for O2
    It is higher in tissues where it enhances O2 unloading
  63. 63What can cause a lowered affinity for O2 in hemoglobin?2, 3 BPG binds to T form and decreases its affinity for O2
    Binding of H+ and CO2 to hemoglobin in tissues shifts hemoglobin to T form, lowering its affinity for O2
  64. 64Why do smokers not load as much O2?They have more 2,3 BPG in their blood
  65. 65What happens to 2,3 BPG levels during pregnancy? What does this cause?30% increase
    Lowers the mom's affinity for O2 so more can be offloaded to the fetus. HbF (fetal) doesn't bind much BPG, so it has a higher affinity for O2 to extract it from the mom.
  66. 66What happens to the hemoglobin/O2 saturation graph in sickle-cell anemia?The curve is shifted right
  67. 67What is the inspiratory region?Region in the brainstem that generates basic rhythm for breathing by sending signals to the diaphragm
  68. 68What is the expiratory region?Region of the brainstem that stimulates expiratory muscles during heavy breathing
    Not activated during quiet breathing
  69. 69What is the pneumotaxic center?A region of the brainstem whose activity increases ventilation rate
  70. 70What is the apneustic center?Region of the brainstem that creates long breaths when activated
  71. 71What is the Hering-Breuer Reflex?When inhalation >1.5 L, stretch receptors begin firing to protect against overinflation
  72. 72What is the goal of respiration?Maintain proper concentrations of O2, CO2, and H+
  73. 73How does the body maintain proper concentrations of O2, CO2, and H+?Blood is monitored by central and peripheral chemoreceptors to detect changes in gases. The receptors automatically adjust ventilation to keep blood gases within set limits.
  74. 74Which chemoreceptors respond most to CO2 and H+?Central chemoreceptors in the brainstem
    Increased levels lead to increased ventilation by action of CCs in other respiratory regions
    Decrease O2 levels have no effect in the brain on respiration
  75. 75What chemoreceptors respond the most to low levels of O2?Peripheral chemoreceptors in the carotid and aorta
    Only way low O2 affects respiration
    The act by causing the respiratory centers to increase breathing rate
  76. 76What is the normal ventilation rate?12-14 breaths/min
  77. 77When PO2 decreases by 1/2, how much does ventilation increase?1.5x
  78. 78How does the ventilation rate change with a drop in pH from 7.4 to 7.0?Leads to a 4x increase in ventilation
  79. 79What is the effect on ventilation of increasing the pressure of CO2 by 50%It leads to a 10x increase in ventilation
  80. 80What is the "Braking Effect"?The reason low O2 pressure has small effects
    Occurs because increased ventilation "blows off" too much CO2, causing decreased H+
    Low CO2 and H+ causes dramatic inhibition of ventilation via effects on control centers, therefore the O2 pressure usually has little control over ventilation
  81. 81Why does low CO2 and H+ cause dramatic inhibition of ventilation?Because their regulation is important for acid-base balance
  82. 82At most O2 pressures, is hemoglobin saturated or unsaturated with O2Saturated
  83. 83What provides the strongest stimulus to breathe?CO2 levels
  84. 84What is the functional unit of the kidney?Nephron
  85. 85How many nephrons are there per kidney?1 million
  86. 86What are the two types of nephrons?Cortical: not so important for water reabsorption (5x more)
    Juxtamedullary: important for water reabsorption
  87. 87How thick are the walls of the nephron?1 cell thick
  88. 88What is the glomerulus?Capillary bed inside of Bowman's Capsule
    Supplied by the afferent arteriole and drained by the efferent arteriole which allows control of blood pressure on either side of the glomerulus (because of arteriole sphincters)
  89. 89What is the vasa recta?Comes from the efferent arteriole
    Capillary system that surrounds each juxtamedullary nephron
    Important for reabsorption and secretion
  90. 90What is the osmotic gradient from the cortex to the medulla?300 mOsm (cortex) to 1200 mOsm (medulla)
  91. 91What determines how concentrated urine can be?Length of the Loop of Henle and the size of the osmotic gradient
  92. 92What can urine osmolarity be in some desert animals?3000+ mOsm
  93. 93What are the three steps of urine formation?Filtration, reabsorption, and secretion
  94. 94What detects dehydration?Hypothalamus
    Secretes ADH which causes the kidney to conserve
  95. 95What drives glomerular filtration?10 mmHg net pressure in the glomerulus
  96. 96What gets filtered into Bowman's Capsule?Anything less than 5,000 MW is freely filtered into the BC
    Based ONLY on molecule size
  97. 97What are the pressures like around Bowman's Capsule? (picture)What are the pressures like around Bowman's Capsule? (picture)
  98. 98What does fenestrated mean?To have holes
    Glomerular capillaries are fenestrated
    Causes glomerular capillaries to be 100x more permeable than most other capillaries
  99. 99What are podocytes?"foot cells"
    What make up the inner layer of Bowman's Capsule and cover the glomeruli
  100. 100What are filtration slits?Slit between pedicels of the podocytes which dictate what size molecules can be filtered (prevent anything too big from getting through)
  101. 101What percentage of water and solutes passing through the glomerulus is filtered?15-25%
  102. 102How many milliliters of water/solutes pass through the glomerulus per minute?125 mL/min
    (=45 gals/day of water)
  103. 103What things are too large to be filtered through the glomerulus?RBCs and most proteins
  104. 104How much of water/salts is reabsorbed before the kidney produces final urine?99%
    Reabsorption is selective so that some wastes (like urea) become concentrated
  105. 105How does reabsorption occur?By transport and diffusion
    Ions are transported and water follows
  106. 106What compounds are 100% reabsorbed in the kidney?Glucose, vitamins, and amino acids
  107. 107How are 2/3 of filtered Na+ reabsorbed?Through active transport
  108. 108What is the driving force for most that happens in the proximal convoluted tubule?R
  109. 109How are filtered proteins reabsorbed?By endocytosis
  110. 110How much of total filtrate is reabsorbed on the PCT?2/3s
    If he says "most reabsorbed".....assume PCT!
  111. 111Drugs, toxins, and H+ can be secreted in the PCT. How?The liver tags drugs/toxins with glucuronate or sulfate groups. The kidney recognizes and secretes these.
  112. 112What are the functions of the Descending Loop of Henle?Passive H2O reabsorption
    NO active transport of salts
  113. 113What are the permeabilities in the Descending Loop of Henle?Salt is moderately permeable
    Urea has low permeability
    High H2O permeability (H2O is pulled out by high osmolarity in the medulla via Aq1 aquaporins)
  114. 114What controls Aq2?ADH
  115. 115What are the functions of the Ascending Loop of Henle?Passive salt reabsorption in the thin part and active reabsorption in the thick
  116. 116What are the permeabilities in the Ascending Loop of Henle?High salt permeability (pulled out by decreasing osmolarity of the ECF as pre-urine moves toward the cortex)
    Low urea
    Low water
  117. 117What is the Diluting Segment?The thick part of the Ascending Loop of Henle
    Called that because the filtrate become hyposomotic as salt is actively transported out
  118. 118What is the osmolarity of pre-urine at the end of the Diluting Segment?100 mOsm (1/3 of blood)
  119. 119What do the actions of the Distal Convoluted Tubule and the Cortical Collecting Duct depend on?Hormones and acid-base balance
  120. 120Where does aldosterone stimulate Na+ reabsorption and K+ secretion?Distal Convoluted Tubule and the Cortical Collecting Duct
    Way that the potassium concentration in the urine is controlled
  121. 121When are the DCT and CCT permeable?Only when ADH is present
  122. 122What can be secreted into urine and reabsorbed from pre-urine?Secreted into: K+, H+, and NH3
    Reabsorbed from: Na+, Cl-, and HCO3-
  123. 123What happens if pre-urine is too acidic?Too basic?Acidic: H+ can be secreted (against up to a 1000x gradient)
    Basic: HCO3- can be secreted
  124. 124What is the function of the medullary CD?Mainly in variable H2O reabsorption (depends on state of hydration and concentration of ADH)
  125. 125What happens when ADH is present?The Medullary CD becomes permeable to H2O and the pre-urine equilibrates with the high osmolarity of medulla
    ADH stimulates the insertion of aquaporins (Aq2) into the membrane
    Also stimulates facilitated transport of urea out of pre-urine into the medullary ECF
  126. 126How does ETOH dehydrate?Reduces the release of ADH
  127. 127When does the gradient reach 1200 mOsm?Only when ADH is high
    Urine will be between 100 and 1200 mOsm depending on the concentration of ADH
  128. 128What are the two mechanisms that produce the up to 900 mOsm gradient/Active transport of salts in the diluting segment creates 600 mOsm of gradient
    Facilitated transport of urea out of the medullary CD creates 300 mOsm
  129. 129How does facilitated transport of urea out of the medullary CD create part of the gradient?Urea becomes concentrated by ~65x as pre-urine flows through the nephron
    In the Medullary CD it is transported down its concentration gradient into extracellular fluid when ADH is high
  130. 130How is the glomerular filtration rate controlled?Through both ANS and local control
    ANS: strong sympathetic activity via fight/flight, exercise, or bleeding causes vasoconstriction of the afferent arteriole. This shunts blood away from the kidney, leading to decreased filtration to maintain blood volume
    Local: also called autoregulation; maintains filtration fairly constant over BPs from 75 mmHg to 160 mmHg because if filtrate flows through nephron fast then too little is reabsorbed (and vice versa)
  131. 131What is myogenic autoregulation?When high blood pressure stretches the afferent arteriole, causing a reflex smooth muscle contraction that leads to a decreased glomerular filtration rate
    Decreased blood pressure causes dilation of the afferent arteriole and constriction of the efferent, increasing GFR
  132. 132What is the Juxtaglomerular Apparatus?When activated the JGA causes increased glomerular filtration rate
    Area located in the angle between the afferent and efferent arterioles in the region of the DCT just after the diluting segment
    Formed from aff/eff arterioles + the adjoining DCT
  133. 133What is the macula densa?DCT cells that touch arterioles and sense [Na+]
    When [Na+] is low, it causes the macula densa to release NO which dilates the afferent arteriole and PGs which cause granular cells to secrete renin.
  134. 134Why does low [Na+] cause the macula densa to release NO to dilate the afferent arteriole?low Na+ can be caused by over-absorption in the diluting segment due to low flow, so dilating the aff. arteriole increases that flow
  135. 135What are the granular cells?Cells between the macula densa and the afferent arteriole which secrete renin both in response to PGs from the macula densa and in response to BP or sympathetic NS stimulation
  136. 136What is RAAS?renin angiotensin aldosterone system
  137. 137What is renin?It is an enzyme produced by granular cells that converts angiotensinogen from the liver to angiotensin I
  138. 138How do you make Angiotensin II?A converting enzyme in the lungs converts Angio I to Angio II
  139. 139What does angiotensin II do?Causes systemic vasoconstriction (greater effect on efferent arteriole than aff. to maintain SOME kidney filtration)
    Stimulates sympathetic NS activity
    Stimulates ADH secretion
    Stimulates thirst
    Causes the adrenal cortex to release aldosterone, which increases Na+, H2O, and Cl- reabsorption and K+ secretion.
  140. 140How do ACE inhibitors work?The block the angiotensin converting enzyme in the lungs
  141. 141What are the three natriuretic peptides? Where are they produced?Atrial natriuretic peptide (ANP): hormone produced by the atria
    B-type natriuretic peptide (BNP): hormone produced by the ventricles
    C-type natriuretic peptide (CNP): paracrine compound produced in the endothelium and the heart
  142. 142What do natriuretic peptides do? When are they released?Released when high blood volume stretches the tissues that produce them
    Act opposite to RAAS: inhibit sympathetic system and secretion of renin, aldosterone, and ADH
    Cause vasodilation and loss of Na+ and water
    Causes lipolysis which reduces the fat load on the heart
  143. 143Why are BNP levels used to assess heart failure?The heart output during heart failure can't match the venous return, so the ventricles get stretched. When they are stretched, they release BNP.
  144. 144What are diuretics?Most inhibit reabsorption of Na+ and Cl- so you lose both NaCl and H2O
    Used to treat heart failure, high blood pressure, and kidney disease
  145. 145What are the #1 and #2 causers of nephropathy? (kidney disease)1. Diabetes
    2. High blood pressure
  146. 146What does nephropathy cause?Albuminuria (loss of albumin) and hyperfiltration
  147. 147What causes nephropathy?High glucose and high blood pressure lead to the loss of podocytes
  148. 148How long is the tube of the digestive tract?17-20 feet
  149. 149What is the primary method of chemical digestion?Hydrolysis
    Molecules are split by adding water
  150. 150What does saliva contain?Amylase: breaks down starch
    Lipase: breaks down fat
    Lysozyme: enzyme that lyses gram+ bacteria
  151. 151How does the autonomic nervous system affect saliva release?Parasympathetic stimulates
    Sympathetic inhibits
  152. 152What is chyme?Mix of food and gastric secretions from the stomach
  153. 153What produces gastric secretions?Cells of the gastric pits in the stomach
  154. 154What does the stomach do?Produces chyme
    Denatures proteins
    Disinfects
    Produces gastric secretions (including acid and mucus)
  155. 155What are mucous neck cells?Cells in the gastric glands of the stomach that produce a thick mucus/bicarbonate (basic) layer for protection
  156. 156What are chief cells?Cells in the gastric glands of the stomach that produce pepsinogen
    Pepsinogen is converted by HCl from the stomach to pepsin, which cuts proteins into small peptides
  157. 157What does pepsinogen do?Pepsinogen is converted by HCl from the stomach to pepsin, which cuts proteins into small peptides
  158. 158What are parietal cells?Cells in the gastric glands in the stomach that secrete [HCl] at a pH of about 1
    Inhibited by Prilosec, Prevacid, and others
  159. 159How strong is the proton pump of parietal cells?Can pump against a million times gradient
  160. 160What is the function of [HCl] in the stomach?Disinfects, is a good solvent, and denatures 3rd degree structures of proteins
  161. 161What are G cells?Cells of the gastric glands of the stomach which secrete gastrin
  162. 162What is gastrin?Peptide hormone released by the G cells in the gastric glands which indirectly stimulate parietal cells to release HCl
    Excessive amounts are related to ulcers
  163. 163How does gastrin stimulate the release of HCl?Stimulates the secretion of histamine by the ECLs (enterochromaffin-like cells) of the gastric pits
    The histamine acts as a paracrine to stimulate the parietals which then release HCl
  164. 164How do Zantac and Pepcid work?They block histamine receptors to prevent the stimulation of parietal cells which secrete acid in the stomach
  165. 165What effect does the parasympathetic have on parietal cells and ECLs?Stimulates both!
    "Rest/DIGEST"
  166. 166What can the stomach absorb?Some small molecules
    ETOH, H2O, glucose, especially non-polars
  167. 167How often is the lining of the stomach replaced?Every 3 days
  168. 168What is the intrinsic factor?A polypeptide that is produced by parietals that is necessary for absorption of vitamin B12 in the small intestine
  169. 169What is pernicious anemia?Anemia that results from a lack of vitamin B12
    B12 is necessary for RBC production, so too little results in low hematocrit (anemia)
    Occurs mostly from autoimmune attack against parietals or intrinsic factor
  170. 170Where does most digestion occur?Small intestine
  171. 171How long is the small intestine? How big is the absorptive area?10 feet long
    Size of a tennis court
  172. 172Describe the surface of the inside of the small intestineHighly folded, covered with finger-like villi (looks like carpet), has tight junctions so nutrients have to move across membranes
  173. 173What are microvilli?Cover the villi of the small intestine
    Secrete enzymes for complete breakdown of food molecules to monosaccharides and amino acids prior to absorption
  174. 174What part of the small intestine functions in reabsorption of nutrients? Fats?Capillaries in the villi (nutrients)
    Lacteals, which are blind-ending lymph capillaries (fats)
  175. 175How long does it take for chyme to move through the small intestine?Several hours
  176. 176Where is the pancreas?Below the stomach and connected to the small intestine via the pancreatic duct
  177. 177What enzymes are secreted by the pancreas?Amylases: convert starches to smaller saccharides
    Lipase: converts triglycerides into free fatty acids and monoglycerides
    Proteases: convert proteins into dipeptides
    Bicarbonate: neutralizes stomach acid
    ALL PRODUCED AND SECRETED IN INACTIVE FORM
  178. 178Why are pancreatic enzymes produced and secreted in the inactive form?Because they are so powerful that they can digest the pancreas itself if in active form
    Normally activated in the small intestine
  179. 179What is acute pancreatitis?Pancreatic enzymes become active in the pancreas instead of in the small intestine
    Can cause death in a few days if not stopped
  180. 180What is the pH in the small intestine?6.5-7.5
  181. 181Digested carbohydrates and proteins are absorbed by capillaries in the small intestine villi. Where do they go next?Directly to the liver via the hepatic portal vein
  182. 182What does the liver do?Detoxifies blood
    Processes nutrients
  183. 183What is the first pass effect? How do you avoid it?Many drugs absorbed by the GI tract are broken down in the liver
    To avoid this, they have to be injected, absorbed transdermally, or in suppository
  184. 184What are prodrugs?Drugs that are designed to be absorbed in the GI tract and activated in the liver
    Example: dextromethorphan (cough suppressant) is activated in the liver to dextrorphan
  185. 185What are bile acids?Emulsifying, detergent-like molecules produced by the liver that are the first step in fat digestion
    Secreted by the liver constantly and stored in the gall bladder
  186. 186What happens to the gall bladder after meals?It contracts, sending bile to the small intestine
  187. 187What does emulsification do?Increases surface area for lipase to covert fat to fatty acids and monoglycerides
    Forms micelles
  188. 188What are micelles?Aggregates of fatty acids and monoglycerides that are coated with bile acids
  189. 189What happens to the fatty acids and monoglycerides produced by lipase?Absorbed by the small intestine villi and most then used to resynthesize triglycerides in smooth ER of the villi
    Some of the small fatty acids are absorbed by capillaries in the villi and go to the liver
  190. 190What are chylomicrons?Made in the small intestine villi
    Triglycerides and cholesterol are packaged with a phospholipid and lipoprotein coat
    Chylomicrons are then secreted into the lacteals (lymphatic system)
  191. 191Why is plasma taken after meals often cloudy?Because of the chylomicrons being released into the lymphatic system
  192. 192How long is the large intestine (colon)?4 feet
  193. 193How much water does the large intestine absorb?0.5-2L per day
  194. 194What does the large intestine absorb?Water, vitamins, drugs, suppositories
  195. 195Why is the large intestine slow-moving?Lets bacteria digest unabsorbed material (mostly cellulose)
  196. 196How many species of bacteria are there in the large intestine?400+
  197. 197How much of the mass of feces is of bacterial origin?1/3
  198. 198What is flatus?Gas produced by bacteria in the large intestine
  199. 199Why do beans give you gas?They contain undigestable carbohydrates which bacteria convert to gas
  200. 200What do bacteria in the large intestine produce from fiber?Vitamin K, vitamin B, and fatty acids

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Test 4
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Brianne Schmiegelow · Apr 2016
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13 Aug 2016
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