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PHGY 210 > digestion - lecture 8 > Flashcards

digestion - lecture 8 Flashcards

1
Q

describe pancreatic lipases

A

Pancreatic procolipase – trypsin –> colipase

triglycerides – pancreatic lipase ph 8 –> fatty acids, di and monoglycerides
NEEDS colipase = cofactor, only happens when have it

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2
Q

describe liver

A

largest gland of body
right and left lobes
for storage, synthesis, detox, metabolism

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3
Q

what does liver secrete

A

bile from hepatic ducts
bile travels in common bile duct
bile released into si at same place as pancreatic juices

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4
Q

describe liver bile composition -comp stuff

A

0.5-1l/day
isotonic fluid - sodium, potassium, chloride, BICARB
ph 7.8-8.2 = helps neutralize acidic chyme

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5
Q

describe liver bile composition -solids stuff

A

~3% solids - NO digestive enzymes tho
bile acts - bile salts
bile pigments - hemoglobin breakdown products
cholesterol
phospholipids

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6
Q

describe bile secretion by liver

A

continuous
~0.5-1.0 l/day

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7
Q

describe entrance of bile into duo

A

intermittent = only when meal
volume of bile entering si is <500-700ml/day
moves into gallbladder

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8
Q

what is function of gallbladder

A

concentrates solids =
hepatic bile 3%
gall bladder bile 10-20% of bile
viscocity increases

reduces ph =
Hepatic bile 7.8-8.2
gall bladder bile 7.0-7.5 - less bicarb

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9
Q

what does gallbladder not do

A

DOES NOT synthesize bile salts = stores and concentrates THEMMM

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10
Q

What are the results of CHOLECYSTECTOMY

A

gall bladder removal
Usually bc gallstones
bile salts made from phospholipids precipitates and cholesterol = if not enough bile salts = gallstones and if block cystic duct = bad
but now if removed = still have liver bile only

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11
Q

what are bile salts

A

synthesized in liver from cholesterol

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12
Q

what do bile salts do

A

facilitates digestion, transport and absorption of FAT (including cholesterol) by forming water soluble complexes with fats = micelles
facilitates transport and absorption of fat soluble vitamins = a,d,e,k
reduces surface tension and stabilize emulsions = now can be acted upon by lipases

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13
Q

describe bile salts and micelle formation

A

ampthatic
micelle = inside non polar and outside polar
mixed micelle = a,d,e,k travel in micelle
Surrounded by bile acids
smaller if more bile salts
Circular smaller droplets = more lipases can act
help form stable emulsions = small emulsions = more sa for lipases to act

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14
Q

Describe bile salts - amounts in body

A

bile salt pool = 3.5g
daily synthesis= 0.5g
daily release into intestine = 15-20g
more bile salts reabs into portal blood and returned to liver via enterohepatic circ
entire bile salt pool recirculated several times a day between liver–>git–>liver

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15
Q

describe hepatic circulation

A

heart = via aorta to liver and via aorta to intestinal tract
liver secretions go to si
si to liver via hepatic portal vein
liver to heart = via hepatic vein to inferior vena cava

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16
Q

describe enterohepactic circulation

A

bile salts have diff roles in diff parts of body
absorb recycled and used
back to liver = portal venous return

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17
Q

name intraporal functions of bile salts - 2

A

regulate hepatic bile flow
regulate synthesis of new bile salts

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18
Q

Describe intraportal functions of bile salts - regulate hepatic flow

A

the more bile salt returned via portal blood = larger the vol of bile secreted
pos feedback

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19
Q

What will happen to bile secretion if we remove ileum

A

decrease since less reabs

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20
Q

Describe intraportal functions of bile salts - regulate synthesis of new bile salts

A

the more bile salt returned in portal blood = smaller the amount of new bile salt being synthesized = more comes back so make less
neg feedback

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21
Q

What will happen to bile salt synthesis if we remove ileum

A

liver produces more bile salts

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22
Q

name and describe intrahepatic functions of bile salts

A

keep cholesterol in solution = cholesterol is insoluble in water
if cholesterol precipitates = gives rise to gallstones
in bile solubility of cholesterol increases by 2x10^6

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23
Q

Describe intra intestinal functions of bile salts - 2

A

intestinal lumen contains v watery medium
act as detergents and help form stable emulsions
assist in transport of fat and fat soluble vitamins (a,d,e,k) from si lumen into intestinal cell

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24
Q

Describe intracolonic functions of bile salts - regulate hepatic flow

A

inhibit sodium transport and h20 absorp = do not want to absorb too much = constipation
excess bile salt in colon = diarrhea

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25
summarize bile salt function
intraportal = regulate volume of bile secreted by liver and synthesis of new bile salts intrahepatic = keep cholesterol in soln intraintestinal = si - emulsify and transport fats intracolonic = prevents too much water absorp
26
describe purpose of phases of secretion
cephalic = psychic and gustatory, increase secretion from lover and pancrease to prepare for meal gastric = not increase secretion at level of si Intestinal = also increase secretion at si
27
describe regulation of pancreas secretion
contains cells that release = larg vol of juice rich in bicarb small vole of juice rich in - if have lots of acid in duo, decrease acidity of chyme enzymes - fatty meal and need lots of lipases
28
describe regulation of bile flow
choleretics = agents which cause liver to secrete larger amount of bile cholagogues = agents which cause increase in gall bladder emptying
29
describe law of reciprocal activity
if gallbladder contarcted the spincter of oddi will be realxesd and vise versa if have cck in system
30
describe summary of Summary of Regulation of Bile and Pancreatic Juice - vagus
cephalic - thinking of food liver = + gb contracts and sphincter relaxes = +++ pancreas (low vol/high enzyme/low ph )= +++ pancreas (high vol/low enzyme/high ph) = --
31
describe summary of Summary of Regulation of Bile and Pancreatic Juice - gastrin
gastric - food in stomach liver = + gb contracts and sphincter relaxes = + pancreas (low vol/high enzyme/low ph) = + pancreas (high vol/low enzyme/high ph) = +
32
describe summary of Summary of Regulation of Bile and Pancreatic Juice - cck
released from duo, when fat and protein rich meal liver = -- gb contracts and sphincter relaxes = +++ pancreas (low vol/high enzyme/low ph) = +++ pancreas (high vol/low enzyme/high ph) = --
33
describe summary of Summary of Regulation of Bile and Pancreatic Juice - secretin
lots of acidic conetnts in si liver = + vol/hco3 gb contracts and sphincter relaxes = -- pancreas (low vol/high enzyme/low ph) = -- pancreas (high vol/low enzyme/high ph) = +++
34
describe summary of Summary of Regulation of Bile and Pancreatic Juice - bile salts
liver = +++ gb contracts and sphincter relaxes = -- pancreas (low vol/high enzyme/low ph) = -- pancreas (high vol/low enzyme/high ph) = --
35
what happens to polysaccharides as a result of salivary, gastric, pancreatic, and hepatic secretions
salivary and pancreatic amylase make polysacc to dissach must still go to monosacc tho
36
what happens to proteins as a result of salivary, gastric, pancreatic, and hepatic secretions
pepsin, trypsin and chymotrypsin = convert proteins to small peptides must still go to aas, di and tri peptides
37
what happens to fats as a result of salivary, gastric, pancreatic, and hepatic secretions
fats ---> mono, diglycerides and FAs by lipase, colipase and bile salts
38
describe final steps in digestion
Mediated by intestinal enzymes produced by mucosa at site where absorption happens
39
what does si secrete
intestinal juice = water mucus ions
40
what does si receive
pancreatic juice enzymes to aid digestions
41
what does si contain
brush border enzymes attached to microvilli of si epi cells
42
describe si mechanical digestion
involves segmentation at si = contact absorptive cells
43
describe si chemical digestion
occurs as chyme mixes with pancreatic juice, intestinal juice and bile
44
describe si absorption
of digested nutrients at level of si
45
describe Increased Surface Area in the Stomach for Secretion
tubular glands - secretion enterocytes = have microvilli, in villus region and also has crypt region = invaginations where fluid secretion happens, completes digestion and absorption - secretion, digestion and absorption
46
describe crypt cells
lack digestive enzymes Secrete a large vol - 3l/day of alkaline fluid known as succus entericus
47
describe secretions in si
crypts --> succus entericus vol = 3l.day isotonic = na, k, cl, hco3- ph ~7.5-9 VILLI do not secrete fluid
48
what are villi cells
dont secrete fluid but complete digestion and absorb nutrients and fluids enterocytes in villi make digestive enzymes which remain in brush border
49
describe small intestine enzymes - vili
enterokinase - lumen epi cells amylase, lipase, aminopeptidases, dipeptidases
50
describe disaccharases - vili
brush border sucrase, maltase, isomaltose, lactase
51
what do villi cells do
RAPId turnover cells mature as they migrate up to villus regions - divides and differentiates upwards cells at tip apoptose and slough into lumen - die by enzymes
52
describe absorption of digested nutrients in villus
fats absorbed via lacteals = chylomicrons - absorbed at lacteal carbs and sugars absorbed via capillaru and go to liver via hepatic portal vein
53
name added enzymes by si = for digestion
disaccharases = disacc to monosacc peptidases = small peptides to aas di and tripeptides
54
where is digestion and absorption of nutrients completed
in small INTESTINEEE
55
describe colonic secretions
small vol alkaline [bicarb] = 100-150meq/l and [potassium] = 100-150meq/l lots of mucin for lube no digestive enzymes or absorption Bacterial activity = health of body and git, keep bacteria at level of colon
56
describe regulation of intestinal secretions
Local enteric reflexes Vago-vagal reflexes Hormonal factors
57
describe input vs output - daily (feces)
in = 2000ml h2o, solids 500g out = 100ml h2o, solids 50g = (30% bacteria, 30% undigested fiber, 10-20% lipids, 10-20% inorganic matter)
58
describe daily ml of secretion
Salivary glands = 1500ml stomach = 2500ml bile = 500ml pancreas = 1500ml intestine = 1000ml 2l ingested + 7l secreted = ~9l must be reasb
59
what else is reabs into git - besides water
Very large quantities of ions are also reabsorbed from lumen of the GIT
60
describe Proteins Released into the GIT via Secretions
50g enzymes 30g as cells 80g protein - broken down into aas = aa pool need to return aas for homeostasis
61
WHAT is being absorbed?
Most of absorption is REABSORPTION
62
WHERE is it being absorbed?
sites of exchange characterized by = v large sa of si and intimate contact with bvs
63
describe structure of si
circular folds, villi, microvilli, relative sa = 600 area in excess of need only gi organ essential to life = colon cannot take over nutrient absorption
64
describe villus
postprandial flow to intestine = 1-2l/min efficient absorption = each villus has capillary loop and lacteal, large sa close to blood and lymph flow Lymph flow = 1-2l/min
65
name and describe major areas of absorption
duo = most of iron, calcium, cho and protein lipids sodium and water, least bile salts jejunum = less than duo but still cho and proteins lipids na and h2o, little bile salts Ileum = less than both above but still cho, proteins lipids na and h20, also only place to have vit b12 and most of bile salts
66
HOW does absorption take place?
Simple Diffusion Facilitated Diffusion Active Transport Pinocytosis osmosis - water always follows osmotic gradient generated by movement of ions and nutrients
67
What Limits Absorption?
requirements for absorption = Adequate Digestion – Enzymes (activated), optimal pH and ionic composition Adequate Sites for Absorption Adequate Transit Time for Absorption Adequate Co-factors, Transporters
68
describe absorption - by which parts
si = 7l and colon = 2l
69
describe absorption of water
can absorb more than we usually take in mac capacity of si = 15l/day max capacity of li = 4-5l/day
70
describe carb digestion and absorption
lactose - if no lactase = lactose intolerance -- broken down to galactose and glucose starch = need salivary amylase, and pancreatic amylase and many si enzymes in brush border - critical for them to move into cells -- broken down to glucose sucrose -- broken down to fructose and glucose
71
describe protein digestion and absorption
need pepsin, pancreatic proteases - broken down to aas either peptidases break in to small peptides or free aas go through carrier mediated transport to aas into cel
72
describe fat digestion and absorption
triglycerides converted. by lipase, colipase, bile salts to monoglycerides and free fatty acids monoglycerides either become free fatty acids or glycerol and go directly to capillary if free fatty acids = makes micelle, help of conjugated bile salts, liver and ileum micelle into enterocyte = triglycerides resynthesized and mixes with protein, cholesterol and phospholipids to make chylomicrons and go to lacteals
73
describe efficiency of git
carbs = 99% fats = 95% Proteins = 92%
74
why is git highly efficient
effective coordination of activities - neural, hormonal, motor, secretory, enzymatic - within an organ and between organs
75
in response to a meal...
wave of secretory activity preceding, accompanying and trailing behind meal wave of motor activity which receives, accommodates and conveys the meal
76
describe git transit times
related to functional activities of each organs = times tailored to what needs to be done in terms of processing mouth = <1sec eso = seconds stomach = mins-hours si = several hours li = hours -days
77
name all protective mechanisms
Mucin Inactive Proteases, Trypsin Inhibitor Gastric Mucosal Barrier Sphincters prevent reflux Negative Feedback Inhibition of Gastrin Neutralization of duodenal contents MyogenicMotorComplex= “HOUSEKEEPiING” * Etc.,Etc.
78
what does liver produce
bile salts

PHGY 210 (36 decks)

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