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Botany > digestive - phyanalec > Flashcards

digestive - phyanalec Flashcards

1
Q
  • helps keep the oral cavity moist
  • contains enzymes that begin the process of digestion
  • secreted at rate of 1L per day
  • prevents bacterial infection in the mouth by washing the oral cavity
  • contains lysozyme
A

saliva

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2
Q

part of saliva that dissolves molecules, which must be in solution to stimulate taste receptors

A

serous

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3
Q

– enzyme that has a weak antibacterial action

found in saliva

A

lysozyme

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4
Q

acts as buffer to neutralize the acids produced by oral bacteria
-reduces the harmful effects of bacterial acids on tooth enamel

A

Bicarbonate ions in saliva

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5
Q

a digestive enzyme in the serous part of saliva
-breaks covalent bonds between glucose molecules in starch and other polysaccharides to produce disaccharides maltose and isomaltose

A

salivary amylase

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6
Q

have a sweet taste

-digestion of polysaccharides by salivary amylase enhances the sweet taste of food

A

Maltose & Isomaltose

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7
Q

Food spends how much time in the mouth

A

very little

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8
Q

– a proteoglycan that gives a lubricating quality to the secretions of the salivary glands
-contained in the secretions of submandibular and sublingual glands

A

mucin

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9
Q

salivary gland secretion is regulated by primarily

A

parasympathetic NS

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10
Q

-increase in response to tactile stimulation and sour tastes, thought of food, odors, sensation of hunger

A

SALIVARY GLAND SECRETION

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11
Q

-sympathetic stimulation increases

A

mucous content of saliva (dry mouth with thick mucus)

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12
Q

-breaks large food particles into many small ones, which have a larger total surface area

A

MASTICATION

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13
Q

-increases efficiency of digestion because digestive enzymes act on molecules only at the surface of food particles

A

MASTICATION

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14
Q

phase of swallowing
bolus is formed in the mouth
-bolus pushed by the tongue against hard palate
-bolus goes into the oropharynx

A

voluntary

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15
Q

phase of swallowing
– moving food from pharynx to stomach
-muscular contractions of esophagus occur in peristaltic waves

A

esophageal

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16
Q

phase of swallowing
reflex initiated when a bolus of food stimulates receptors in oropharynx
-begins with elevation of the soft palate (closes the passage between oropharynx and nasopharynx)
-pharynx elevates to receive bolus of food from mouth
-pharyngeal constrictor muscles contract in succession, forcing food through pharynx
-upper esophageal sphincter relaxes, food goes to esophagus

A

pharyngeal

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17
Q
  • sufficiently forceful to allow a person to swallow even while doing a headstand or floating in the zero-gravity environment
  • causes relaxation of the lower esophageal sphincter in esophagus as peristaltic waves approach stomach
A

peristaltic waves

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18
Q

• Wave of of esophageal muscles precedes the bolus of food down the esophagus

A

relaxation

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19
Q

Wave ofof circular muscles propels bolus through esophagus

A

strong contraction

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20
Q

assists movement of the material, especially liquids, through the esophagus

A

Gravity

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21
Q
  • function primarily as storage and mixing chamber for ingested food
  • some digestion occurs, but it’s not its principal function
A

stomach

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22
Q

– semifluid mixture of food and stomach secretions; acidic

A

chyme

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23
Q

stomach secretion
– produces a ph of 2.0 in the stomach
-kills microorganisms and activates pepsin (active) from pepsinogen (inactive)

A

HCl

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24
Q

stomach secretion
breaks covalent bonds of proteins to form smaller peptide chains
-exhibits optimum activity at a ph of about 2.0

A

pepsin

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25
Q

stomach secretion
– lubricates and protects the epithelial cells of stomach wall from damaging effect of acidic chime and pepsin
-irritation of stomach mucosa stimulates secretion of greater volume of mucus

A

mucus

26
Q

stomach secretion
binds with Vit B12 and makes it more readily absorbed in small intestine
-important in DNA synthesis and RBC production

A

intrinisc factor

27
Q

neural mechanisms in digestive tract

A
  • CNS in medulla oblongata

* Enteric plexus in digestive wall

28
Q

PHASES OF THE STOMACH REGULATIONS
– different sensations stimulate centers in medulla oblongata
-AP are sent along parasympathetic axons within vagus nerve
-in stomach wall, preganglionic stimulate postganglionic in enteric plexus
-postganglionic stimulate secretory activity in cells of stomach mucosa, causing release of different secretions (HCl, pepsin, etc)
-neurons stimulate release of gastrin and histamine from endocrine cells

A

cephalic

29
Q

PHASES OF THE STOMACH REGULATIONS
– period of greatest gastric volume secretion
-activated by presence of food in stomach
-food in stomach is mixed with gastric secretions (chyme formation)
-stomach distention stimulates stretch receptors
-stretch receptors generate AP to activate CNS and local reflexes
-result is increased secretion
-peptides ~ gastrin ~ additional HCl

A

gastric

30
Q

PHASES OF THE STOMACH REGULATIONS
– inhibits gastric secretion
-controlled by the entrance of acidic chime into duodenum, which initiates both neural and hormonal mechanism
-when chime ph in duodenum is 2.0 or below, the inhibitory influence of IP is greatest
-secretin is released in response to low ph
-cholecystokinin is released in response to fatty acids and peptides, inhibits gastric secretions
-acidic chime inhibits CNS stimulation, initiates local reflexes that inhibit gastric secretion

A

intestinal

31
Q

TYPES OF STOMACH MOVEMENT
– cause relatively weak contractions
-thoroughly mix ingested food with stomach secretions to form chime
-more fluid part of chyme is pushed toward pyloric sphincter
-more solid part of chime is pushed toward body of stomach

A

mixng waves

32
Q

TYPES OF STOMACH MOVEMENT
cause stronger contractions
-force chyme toward and through pyloric sphincter
-pyloric sphincter usually remains closed because of mild tonic contraction
-each peristaltic contraction is sufficiently strong to cause partial relaxation of pyloric sphincter
-↑motility, ↑emptying

A

peristaltic waves

33
Q

– major inhibitor of motility and emptying

-stomach emptying is slower after a fatty meal due to the release of

A

cholecystokinin

34
Q

major stimulus of gastric motility and emptying

A

Distension of stomach wall –

35
Q

uncomfortable sensation resulting from low blood glucose levels
-begin 12 – 24 hours after the previous meal

A

HUNGER PANG –

36
Q

ENZYMES OF SMALL INTESTINE:

break peptide bonds In proteins to form amino acids

A

Peptidases –

37
Q

ENZYMES OF SMALL INTESTINE:

– break down disaccharides (like maltose) into monosaccharides (glucose)

A

disaccharidases

38
Q

ENZYMES OF SMALL INTESTINE:
produced by duodenal glands and goblet cells
-dispersed throughout the epithelial lining of small intestine

A

mucus

39
Q

type of contraction

– proceed along the length of the intestine for variable distances and cause chyme to move along small intestine

A

peristaltic

40
Q

propagated for only short distances and mix intestinal contents

A

SEGMENTAL CONTRACTIONS –

41
Q

most absorption occurs in

A

duodenum and jejunum, some in ileum

42
Q

contains no digestive enzymes
-dilutes and neutralizes stomach acid

  • dramatically increases efficiency of fat digestion and absorption
  • contains excretory products (cholesterol, fats, bile pigments like bilirubin)
A

bile

43
Q

– major function of small intestine

A

ABSORPTION IN SMALL INTESTINE

44
Q

– bile pigment that results from hemoglobin breakdown

A

bilirubin

45
Q
  • emulsify fats, breaking the fat globules into smaller droplets (digestive enzymes cannot act efficiently on large fat globules)
  • most are reabsorbed in the ileum
A

BILE SALTS

46
Q

BILE SECRETION

-stimulated by (3)

A

parasympathetic stimulation through vagus nerve
by secretin
cholecystokinin

47
Q

stimulates gallbladder to contract and release bile into duodenum)

A

cholecystokinin

48
Q

EXOCRINE SECRETIONS of pancreas
neutralize acidic chyme that enters small intestine from stomach
-increased ph resulting from HCO3 secretion stops pepsin digestion but provides proper environment for the function of pancreatic enzymes

A

bicarbonate ions

49
Q

EXOCRINE SECRETIONS of pancreas
major proteolytic enzymes
-continue protein digestion that started in the stomach

A
  1. TRYPSIN, CHYMOTRYPSIN, CARBOXYPEPTIDAS
50
Q

EXOCRINE SECRETIONS of pancreas

continues polysaccharide digestion that began in oral cavity

A
  1. PANCREATIC AMYLASE –
51
Q

EXOCRINE SECRETIONS of pancreas

lipid-digesting enzyme

A

. LIPASE

52
Q

EXOCRINE SECRETIONS of pancreas

enzymes that degrade DNA and RNA to their component nucleotides

A
  1. NUCLEASES
53
Q

initiates release of watery pancreatic solution that contains large amount of HCO3
-stimulus of secretin release: presence of acidic chyme in duodenum

A

SECRETIN –

54
Q

– stimulates pancreas to release an enzyme-rich solution

-primary stimulus: presence of fatty acids and amino acids

A

CHOLECYSTOKININ –

55
Q

KIND OF STIMULATIONSTIMULATION – stimulates secretion of pancreatic juices

A

PARASYM

56
Q

inhibits secretion of pancreatic juices

A

SYM

57
Q

time required for material to pass through large intestine

A

18 – 24 hrs –

58
Q

time required for chyme to pass through small intestine

A

3 – 5 hrs –

59
Q

chyme in the colon (converted to feces in colon)

A

FECES

60
Q

– elimination of feces

A

Defecation

61
Q

stores feces until defecation

-inhabited by many bacteria

A

COLON

62
Q

– strong contractions undergone by large parts of colon every 8-12 hours

  • propel the colon contents toward anus
  • very common following some meals, especially breakfast
A

MASS MOVEMENTS

Botany (324 decks)

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