Chapter 24 [ EXAM #4 ] Flashcards

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1
Q

what is catabolism

A

Larger molecules broken down into smaller

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2
Q

what anabolism

A

Smaller molecules used to make larger essential molecules

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3
Q

what is peristalsis

A

involuntary, ADJACENT alternating STRONG waves of contraction and relaxation of smooth muscle to move food along

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4
Q

what is secretion

A

release of enzymes, acids, buffers, bile into GI tract

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5
Q

what is mastication

A

breaking up food into smaller pieces with teeth

incisors bite into

canines tear into

premolars chew and grind

molars chew and grind

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6
Q

what is absorption

A

passive movement of nutrients to blood or lymph

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7
Q

what is excretion/defection

A

waste, indigestible

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8
Q

what parts consist of the GI tract

A

Mouth

Pharynx

Esophagus

Stomach

Small intestines

Large intestines

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9
Q

what is the submucousal plexus

A

sensory and motor neurons, regulates activity of glands and smooth muscle in mucosa and submucosa

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10
Q

what is the myenteric nerve plexus

A

controls GI tract motility

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11
Q

what is the enteric nerve plexus

A

submucosal and myenteric nerve plexus

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12
Q

what are the accessory organs in the digestive system

A

Teeth and tongue, gallbladder

salivary glands, liver, pancreas

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13
Q

how does motility work in the muscularis externa

A

through peristalsis and segmentation

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14
Q

what is segmentation

A

NON-ADJACENT

mixes food back and forth with digestive juices / enzymes

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15
Q

what’s the diff between serosa and adventitia

A

serosa is serous membrane in peritoneal cavity

adventitia is fibrous attachment in oral cavity, pharynx, esophagus, and rectum

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16
Q

what are the two kinds of sensory receptors in digestive system

A

mechanoreceptors: stretch and pressure
chemoreceptors: chemical content, osmolarity, pH

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17
Q

what nervous system will enhance secretory activity and GI motility

A

parasympathetic NS

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18
Q

what’s the diff between mechanical digestion and chem digestion

A

mechanical = physical change through mastication and tongue movement

chemical = chemical bonds broken in mouth, stomach, and small intestines

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19
Q

where is MALT located and what does it do

A

lamina propria and protects

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20
Q

what is the submucousal plexus

vs.

what is the myenteric nerve plexus

A

submucousal plexus = regulates activity of glands and smooth muscle in mucosa and submucosa

myenteric nerve plexus = controls GI tract motility

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21
Q

what dat sphincter do

A

forward movement, prevents backflow

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22
Q

what do enteroendocrine cells do

A

produce 3 hormones

Gastrin: stomach

Secretin: small intestines

CCK: small intestines

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23
Q

what are the three main hormones of digestive system

where are they from and what do they do

A

gastrin from G cells

↑ gastric juice (pepsinogen, HCl ) and stomach motility

secretin and CCK from enteroendocrine cells

Inhibit gastrin release, ↓ gastric secretion and motility, ↑ bile pancreas

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24
Q

what is the function of salivary amylase

A

starts carb/strach breakdown

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25
Q

where is lingual lipase released and activated

what is its function

A

lingual lipase released in mouth but activated in stomach

lipid breakdown

26
Q

define bolus

A

a solid rounded mass of food

27
Q

define mucus

A

lubricating and protecting substance

28
Q

what NS controls salivation

explain the process of salivation

A

parasympathetic control

stimulation of salivary nuclei
• machano- and chemo- receptors ↑ PNS activity and gland secretion

29
Q

what would happen to salivation if a strong sympathetic activation occurred

A

dry mouth or viscous saliva

30
Q

what is the composition of saliva

A

99.4% water
0.6% dissolved solute=
• ions, buffers, Abs, mucins, enzymes

31
Q

function of saliva

A

lubricates mouth

moistens food

dissolves food chems to stim taste buds

start carb digestion

contain lingual lipase for lipid digestion (used in stomach)

32
Q

** describe the events that take place within the three phases of deglutition (swallowing) and how they are controlled

A
  1. Voluntary (buccal) phase
    • VOLUNTARY
    • controlled by cerebral cortex
    • bolus formed and moved toward oropharynx
  1. Pharyngeal phase
    • INVOLUNTARY
    • bolus arrives at oropharynx and stims swallowing reflex (tactile receptors)
    • bolus moves towards esophagus
  1. Esophageal phase
    • INVOLUNTARY
    • peristalsis pushes bolus down esophagus
    • gastroesophageal sphincter relaxes, food enters stomach
33
Q

what prevents food from entering into the respiratory passages during swallowing

A

during pharyngeal stage

swallowing reflex as bolus contacts oropharyngeal tactile receptors

uvula closes off nasopharynx

larynx elevates and epiglottis closes

breathing temporarily inhibited

34
Q

define rugae

A

storage of ingested food

2 - 4 hours, fats stay longer

35
Q

define chyme

A

partially digested food mixed with gland secretions (gastric mixing)

36
Q

role of pyloric sphincter

A

gastric emptying,

empties chyme from stomach to small intestines

37
Q

what are the 5 cells in the stomach wall, their function, and location

A

SURFACE MUCOUS CELLS =
• alkaline mucus layer
• protection from acid and gastric enzymes

• MUCOUS NECK CELLS: produce acidic mucus

PARIETAL CELLS (exocrine) =
• Secrete intrinsic factor and hydrochloric acid
 • Activation of pepsinogen into active pepsin (protein digestion)
CHIEF CELLS (exocrine) =
• Secrete inactive pepsinogen and gastric lipase 
G CELLS (endocrine)
• Secrete gastrin hormone into blood
38
Q

why is there little absorption in the stomach

A

Mucus coating

Lack of transport

Digestion not complete

Some drugs and alcohol absorbed

39
Q

what’s the diff between the gastric pit and gastric glands

A

gastric pit = indented epithelium

gastric glands = at base of gastric pit containing parietal, chief, and G cells

40
Q

what do parietal cells secrete and what’s their function

A

parietal cells secrete…

INTRINSIC FACTOR
• B12 absorption for maturing RBCs

HCl
• denatures proteins
• activation of pepsinogen into pepsin

41
Q

what do surface mucous cells secrete and what’s their function

A

alkaline mucous layer

protection from acid and gastric enzymes

42
Q

what do chief cells secrete and what’s their function

A

secrete pepsinogen to later be activated by HCl into pepsin (protein digesting enzyme)

43
Q

** what two things make pepsin and what cells secrete them

A

HCl activates pepsinogen into active pepsin

parietal cells secrete HCl

chief cells secrete pepsinogen

44
Q

what makes gastrin and what does gastrin do

A

g cells make gastrin

gastrin stimulates chief and parietal cells to make pepsinogen and HCl respectively

45
Q

what might cause stomach (peptic) ulcers

A

gastritis = due to high acid / low mucous

pylori bacteria = burrows through mucous

46
Q

what is gastric mixing

A

mix bolus with gastric juice to form chyme

47
Q

what is gastric emptying

A

empty chyme from stomach through the pyloric sphincter

48
Q

** three phases of gastric secretion

A

CEPHALIC

  • parasympathetic NS reflex via vagus nerve
  • ↑ saliva
  • ↑ in gastric juice production
  • ↑ contractile force (growl)

GASTRIC

  • when bolus reaches stomach
  • ~2/3 gastric juice secretion and ↑ mixing
  • forms chyme and empties into small intestines

INTESTINAL

  • Begins when chyme enters small intestines
  • enterogastric reflex: protect small intestines from overload
49
Q

describe enterogastric reflex

A

Duodenal stretch receptors and chemoreceptors
↓ PNS: ↓ gastric secretion and mixing
↑ symp. NS: contraction of pyloric sphincter
Protect sm. Intestines from overload

50
Q

** importance of circular folds, villi, microvilli in small intestines

A

Circular folds : slows chyme down, more SA:V

Villi: velvety surface
• Absorptive and goblet cells

Microvilli: fuzzy brush-border full of enzymes for final digestion

51
Q

role of CCK and secretin

A

account for most digestion in small intestines

52
Q

what are paneth cells

A

enzyme defense against bacteria in small intestines

53
Q

what are goblet cells

A

mucus cells

54
Q

what happens as you move along the small intestines

A

fewer intestinal crypts

more goblet cells

more Peyer’s patches

55
Q

what are intestinal crypts

A

pits between villi that contain stem cells for rapid replacement

56
Q

what are brush boarder enzymes

A

final breakdown in digestion of proteins lipids and carbs

57
Q

what is gastroileal reflex

A

stomach distention causes movement in sm. intestine

58
Q

function of pancreas

A

Secrete pancreatic juice: controlled by duodenal hormones CCK and secretin and PNS
Break down all foodstuffs!

59
Q

function of gallbladder

A

Stores and concentrates bile from liver released into cystic duct when stimulated by CCK

60
Q

function of liver

A

Produce and excretes bile

receives nutrient rich blood coming from sm. intestines

61
Q

pancreatic juice contents

A

Starch digestion:
Pancreatic amylase

Fat digestion:
Pancreatic lipase

Nucleic-acid digestion:
Nucleases