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KNES 260 FINAL > digestive system > Flashcards

digestive system Flashcards

1
Q

what are the parts of the alimentary canal?

A

GI tract: mouth–> pharynx–> esophagus–> stomach–> small intestine –> large intestine

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2
Q

what are the 6 accessory glands?

A

-teeth
-tongue
-gallbladder
-liver
-pancreas

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3
Q

what are the 6 essential activities in digestion?

A

ingestion–> propulsion–> mechanical digestion–> chemical digestion (secretion) –> absorption –> defacation

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4
Q

what are the 4 major tissue layers of the digestive tract?

A
  1. mucosa (INNERMOST, secretions, absorption)
  2. SUBmucosa (blood/nerve supply)
  3. muscularis external (motility)
  4. serosa (outer CT layer)
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5
Q

what are the GI tract sensory receptors?

A

-mechanoreceptors (stretch from food passing)
-chemoreceptors (osmolarity and pH changes, digestive substrate/end products)

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6
Q

extrinsic vs intrinsic controls and what do they effect?

A

-extrinsic= from outside of digestive tract
-intrinsic = from inside of digestive tract
-both affect motility and secretion of enzyme/homrones

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7
Q

what are the 3 GI tract regulatory mechanisms?

A

-short reflexes: nerve plexuses (gut-brain) respond to GI tract stimuli
-hormones: stomach to small intestine and stimulate target cells in organs
-long reflexes: response to stimuli in/out of the GI tract, autonomic control/CNS system

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8
Q

What are the 4 digestive processes?

A

motility
secretion
absorption
digestion

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9
Q

what is motility and the 2 types?

A

motility is muscular contractions that mix/move contents of digestive tract forward
1) peristalsis (propulsive)
2) segmentation (mixing for digestion and absorption)

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10
Q

where do digestive enzymes and mucus come from?

A

-mouth
-stomach
-small intestine

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11
Q

what structures help in absorption?

A

villi and microvilli increase surface area for absorption

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12
Q

what are the 2 parts of digestion?

A

-mechanical digestion by chewing
-chemical breakdown by enzymes

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13
Q

how are carbohydrates digested?

A

starch –> maltose–> glucose
-amylase from salivary glands and pancreas act in the mouth and SI
-lactase and maltase from the SI wall act in the SI
-glucose is directly absorbed into the blood

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14
Q

what are examples of di- and monosaccarides?

A

-disaccarides=ducrose, lactose
-monosaccarides=glucose

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15
Q

how are complex carbohydrates digested? examples?

A

complex carbs. such as fiber, is digested in the large intestine
humans lack the enzyme glactosidase to digest them so it moves to the large intestine where it is digested by E.coli
-fermentation; gas production

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16
Q

how are proteins digested?

A

protein –> polypeptide–> dipeptide–> amino acids
-pepsin from the stomach
-trypsin/chymotrypsin, carboxypeptidase, and aminopeptidase are from the pancreas but act in the SI
-dipeptidases are from the SI
-many different enzymes are needed to break the bonds between different amino acids
-amino acids are directly absorbed into the blood

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17
Q

how are fats digested? what is needed>?

A

fat–> smaller fat globules–> glycerol (lymph to blood) and fatty acids (directly into blood)
-non-polar
-emulsifier is needed in the form of bile
-the enzyme lipase is from the pancreas and acts in the small intestine

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18
Q

how does lipase act?

A

-acts on emulsified droplets
-gets monoglycerides and fatty acids that can enter absorbative cells or form micells
-within cell, they form chylomicrons whch are absorbed into lymph

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19
Q

how are nucleic acids and vitamins digested?

A

-digested by nucleases that are from the pancreas and act in the SI
-SI enzymes
-vitamins are absorbed as whole from the carriers

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20
Q

what does the mouth add to digestion?

A

-chewing increases surface area and decreases choking
-secretion of mucus for lubrication and salivary amylase for starch digestion

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21
Q

what is the swallowing reflex?

A

it is triggered by food in the pharynx and coordinated contractions from the medulla

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22
Q

how is the esophagus separated from the stomach?

A

-gastroesophageal (cardiac) sphincter and valve

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23
Q

what are the 3 sections of the stomach? sphincters? rugae?

A

sections: fundus, body, antrum
sphincters: gastroesophageal, pylorus
rugae: deep folds that allow for expansion

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24
Q

what are the 4 functions of the stomach?

A

storage, mixing, absorption, secretion

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25
Q

what is secreted by the stomach?

A

-acid (activates pepsin from parietal cells)
-mucus (acid protection
-pepsin (protein digestion, chief cells)
-intrinsic factors (absorption of B12 in SI)

26
Q

what do chief and parietal cells do?

A

-chief cells/pepsinogen are the inactive form
-parietal cells convert pepsin to HCl

27
Q

what are the functions of hydrochloric acid in the stomach?

A

-activates pepsin
-breaks down connective tissue and muscle
-kills pathogens
-stomach protects itself with mucus, tight junctions, and cell replacements

28
Q

what causes gastric emptying and mixing?

A

antral peristaltic contractions

29
Q

what is gastrin?

A

a hormone that increases HCl secretion, pepsinogen,and motility
-it is stimulated by proteins, distension and smell

30
Q

what is heart burn?

A

leaky valve between the esophagus and the stomach leading to acid reflux

31
Q

what is a gastric/peptic ulcer?

A

it is a hole caused by inflammation and necrosis in the stomach
-caused in part by pepsin and helicobacter pylori
-affects the stomach and duodenum

32
Q

what are symptoms and treatment of an ulcer?

A

pain and bleeding
-treated by reduction of contributory factors, antacids, and surgery in severe cases

33
Q

what occurs in the small intestine?

A

it is the site of digestion, secretion, and absorption
-alternates between segmentation and peristalsis

34
Q

what does the gallbladder secrete?

A

bile

35
Q

what does the pancreas secrete and into where?

A

amylase
trypsin/chymotrypsin
pepsidases
lipase
nucleases
bicarbonate/neutralizer
-these secretions are dumped into and act onto the duodenum

36
Q

what is CCK?

A

cholecystokinin
it is triggered by a small bolus of food entering the SI
-acts on the pancreas and gallbladder to increase release of enzymes and bile

37
Q

when would CCK be released?

A

-released if the duodenum is distended or if fat content in SI increases

38
Q

what is gastric inhibition?

A

the distention of duodenum inhibits gastric emptying
-this allows time for digestion and absorption in the SI

39
Q

what is secretin and when is it released?

A

it is a hormone that causes the pancreas to release bicarbonate (neutralize acids). it increases bile formation in liver and inhibits gastric motility
-it will be released if the SI is too acidic

40
Q

what is motilin?

A

hormone that promotes motility in the SI

41
Q

how are amino acids and sugar absorbed in the SI?

A

into villi capillaries

42
Q

how are fatty acids absorbed in the SI?

A

into the lacteals of lymph vessles then into blood
via carriers

43
Q

how are carbohydrates absorbed in the SI?

A

they are quickly absorbed in the first half of the jejunum
takes 2-3 hours to empty stomach

44
Q

how long does it take for fats and proteins to be absorbed in the SI?

A

slower to digest
takes 8-10 hours

45
Q

how are vitamins absorbed in the SI?

A

fat soluble=with micelles
water soluble=by carriers
water reabsorption is by osmosis and follows solutes

46
Q

how is calcium absorption regulated?

A

regulated by vitamin D and PTH

47
Q

what are the features of the large intestne?

A

haustral contraction (slow)
-Na+ and water reabsorption
-E.coli digestion of fiber (incomplete)

48
Q

what is the defecation reflex?

A

-the distension of rectum
-PARAsympathetic response; relaxes the sphincter and contracts rectal walls
-it can override the higher brain centers

49
Q

what is a hemorrhoid?

A

varicose veins in the rectum that can be internal or external
-can be caused by pressure in the anal area, and constipation. prolonged, standing, or childbirth/pregnancy

50
Q

what are the 3 types of cells in the pancreas and their secretions?

A

exocrine/endocrine functions
-duct cells - secrete bicarbonate
-acinar cells - secrete bile
-endocrine cells - secrete insulin and glucagon

51
Q

how does the liver receive blood?

A

-hepatic artery
-hepatic portal vein (gut)

52
Q

what are hepatocytes?

A

the cells of the liver that are arranged in sinusoids

53
Q

what does the liver excrete and store?

A

stores: glycogen, fats, iron, copper, vitamins
excretes: cholesterol and bilirubin
-synthesizes plasma proteins

54
Q

how is bile formed?

A

cholesterol based and is stored in the gallbladder between meals
-bilirubin gives bile the yellow colour
-cholesterol, lecithin

55
Q

what are bile salts for?

A

important in fat digestion and derived from cholesterol
-they are recycled within the gut

56
Q

how does the gallbladder contract

A

with CCK

57
Q

what is liver cirrhosis?

A

-chronic, irreversible, degenerative damage from alcohol, toxins, or disease
-loss of normal liver cells
-no organization and scar tissue

58
Q

what are ascites?

A

a symptom of liver cirrhosis that causes high abdominal venous pressure
-organs swell and bleed

59
Q

what are gallstones?

A

consists of cholesterol, bilirubin, calcium
-it can block ducts (if small, gravel)

60
Q

what are the 5 risk factors for gallstones?

A

female
fair complexion
fat
fertile
forty or older

61
Q

what is Crohn’s disease?

A

InflammatoryBowelDisease
-often in the SI

KNES 260 FINAL (9 decks)

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