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a & p II unit 6 > chapter 24: digestive system > Flashcards

chapter 24: digestive system Flashcards

1
Q

what is the collection of neurons in the peripheral nervous system that can control GI activity independent of the
CNS?

A

enteric nervous system

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2
Q

abdominal organs that are supported by mesenteries are called what organs whereas those that are anchored to the body wall are called which organs?

A

peritoneal & retropertioneal

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3
Q

what is the mesentery fold that supports the
intestine?

A

greater omentum

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4
Q

all venous return from the intestine enters the what for
circulation to be delivered to the liver?

A

hepatic portal

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5
Q

the GI epithelium is attached to an areolar connective tissue layer called the what?

A

lamina propria

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6
Q

what layer is located between the submucosa and the serosa (adventitia) & is used for peristalsis?

A

muscularis externa

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7
Q

the majority of saliva is produced by what salivary gland?

A

submandibular

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8
Q

what innveration of the salivary glands will result in less secretion?

A

sympathetic

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9
Q

the cells that produce and maintain dentin are what cells?

A

odontoblasts

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10
Q

the chisel shaped teeth at the front of the mouth are what?

A

incisors

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11
Q

the space at the back of the mouth is called the what?

A

pharynx (oropharynx)

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12
Q

what is the circular muscle thickening that constricts the esophagus at the stomach to prevent stomach contents from entering esophagus?

A

gastroesophageal sphincter/cardiac sphincter

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13
Q

what is another word for deglutition?

A

swallowing

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14
Q

the most superior part of the stomach that contacts the diaphragm is what?

A

fundus

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15
Q

the pyloric sphincter controls movement of material from the stomach to what?

A

duodenum

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16
Q

the accordion like folds of mucosa & submucosa in the stomach are what?

A

rugae

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17
Q

what cells produce intrinsic factor and HCl?

A

parietal cells

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18
Q

name the substance produced in the stomach of infants to curdle milk?

A

rennin

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19
Q

D cells of the stomach produce what functions to what stomach activity?

A

somatostatin & inhibit

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20
Q

an infection by Helicobacter pylori is the most common cause of what?

A

peptic ulcer

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21
Q

during the intestinal phase, what effect will lipids, carbohydrates, and peptides
have on stomach activity?

A

decrease & inhibit

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22
Q

what hormone is produced by either G cells of the stomach or the enteroendocrine cells of the small intestine functions to stimulate all stomach
activity?

A

gastrin

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23
Q

most of the digestion and absorption of food occurs in the what portion
of the small intestine?

A

jejunum

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24
Q

the finger-like extensions of the mucosa layer of the small intestine are the what?

A

villi

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25
Q

collectively the velvet-like collection of microvilli on the surface of the epithelium
of the small intestine is called the what?

A

brush border

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26
Q

what cells are the mucin-secreting cells among the columnar epithelial cells of the intestine?

A

goblet

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27
Q

the Peyer’s patches of the ileum are what?

A

lymphoid follicles/nodules

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28
Q

what reflex stimulates motility and secretion along the length of the small intestine?

A

gastroenteric

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29
Q

why does the soft palate rise during the emesis reflex?

A

to prevent vomit from shooting out your nose

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30
Q

what cells of the pancreas produce the enzymes & buffers?

A

acinar

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31
Q

pancreatic islets produce insulin and what to control blood sugar?

A

glucagon

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32
Q

trypsinogen is activated/converted into trypsin by the brush border enzyme what?

A

enterokinase

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33
Q

the liver has four lobes: right, left, caudate and which other?

A

quadrate

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34
Q

a portal triad consists of a hepatic artery, a hepatic portal vein, and a what duct?

A

bile duct

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35
Q

entry of materials into the duodenum from the common bile duct is controlled by what sphincter?

A

hepatopancreatic

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36
Q

the function of bile is to buffer chyme & what lipids?

A

emulsify

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37
Q

what’s the disease condition of chronic inflammation of the liver that results in the replacement of hepatocytes with collagen & adipose?

A

cirrhosis

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38
Q

cholecystitis is inflammation of what organ?

A

gallbladder

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39
Q

what’s released from the duodenum when chyme is acidic, stimulates the release of bile and buffers and reduces stomach activity?

A

secretin

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40
Q

the proximal end of the large intestine where the appendix is located is called
the what?

A

cecum

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41
Q

the color, odor & gas associated with feces all come from the activity of what?

A

bacteria

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42
Q

what contractions are the segmenting contractions of the colon that facilitate water absorption?

A

haustral

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43
Q

someone who is lactose intolerant does not produce what enzyme?

A

lactase

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44
Q

what functions to hydrolyze polysaccharides into di- & tri- saccharides?

A

amylase

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45
Q

water is absorbed from the intestine into the blood by what?

A

osmosis

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46
Q

digestive system

A

-responsible for providing raw materials to support life
-food molecules catabolized for energy & building blocks to supply anabolic reactions

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47
Q

ingestion (function of digestive system)

A

take in food

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48
Q

propulsion (function of digestive system)

A

move food through GI swallowing & peristalsis

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49
Q

mechanical processing (function of digestive system)

A

chewing, churning, mixing & compacting

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50
Q

chemical digestion (function of digestive system)

A

enzymatic breakdown of large molecules into building blocks

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51
Q

secretion (function of digestive system)

A

enzymes, acids, mucus, water & cell wastes

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52
Q

absorption (function of digestive system)

A

move organic molecules, electrolytes, vitamins, water from gut to interstitial fluid, lymph & blood

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53
Q

excretion (function of digestive system)

A

cell waste, secretions, indigestible foodstuffs ejected from body
-defecation of feces

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54
Q

digestive activity controlled by chemical or mechincal stimuli:

A

-stretching
-osmolarity
-pH
-substrate concentration
-end product cencentration

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55
Q

enteric nervous system (neural control)

A

nerve plexus of the gut

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56
Q

neural control of gut

A

-ENS
-short reflexes: ENS only “gut brain”
-long reflexes: involve imput from ANS (CNS)

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57
Q

hormonal control of gut

A

18 hormones produced by enteroendocrine cells in GI: target may be same organ or different organ (specific hormones for specific foods)

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58
Q

local mechanisms of gut

A

prostaglandins & histamine can trigger localized secretion based on contents of GI tract

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59
Q

location of the gut:

A

-most in peritoneal cavity in abdomen
-cavity: lined with parietal peritoneum
-organs: covered with visceral peritoneum
-both layers secrete peritoneal fluid to reduce friction during movement

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60
Q

ascites

A

excess peritoneal fluid -> swelling of abdomen, distortion of organs: can cause heart, indigestion, back pain

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61
Q

peritonitis

A

inflammation of peritoneum from damage or infection: can cause pain & organ failure

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62
Q

mesenteries

A

sheets of peritoneum that support the bulk of the digestive system
-mesenteries also hold blood vessels, lymphatic vessels, nerves & adipose (protection, insulation, energy reserve)

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63
Q

peritoneal organs

A

supported by mesenteries (sheets of peritoneum)

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64
Q

retroperitoneal organs

A

anchored to body wall

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65
Q

lesser omentum (special mesentery folds)

A

holds stomach

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66
Q

falciform ligament (special mesentery folds)

A

holds liver

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67
Q

greater omentum (special mesentery folds)

A

holds intestine

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68
Q

blood supply of the gut

A

-digestive organs receive 1/4 CO
-this can increase following a meal
-all venous return from GI enter hepatic portal circulation (liver)
-liver processes or absorbs nutrients from gut before blood returns to circulation

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69
Q

mucosa (mucous membrane)

A

-function to secrete mucus, digestive enzymes & hormones, to absorb and products of digestion and provide protection from pathogens
a. epithelium
b. lamina propria
c. muscularis mucosae

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70
Q

epithelium (mucosa membrane layer)

A

stratified squamous: oral cavity, pharynx, esophagus, anus
simple columnar: stomach, intestine: has goblet cells (mucus) & enteroendocrine cells (hormones)

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71
Q

lamina propria (mucous membrane)

A

loose areolar CT tissue with blood vessels, lymphatic vessels, nerves, mucous glands & lymphoid tissue (extending from submucosa): MALT or tonsils

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72
Q

muscularis mucosae (mucous membrane)

A

-band of smooth & elastic fibers: one layer circumferential one longitudinal
-functions to change shape of plicae & villi

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73
Q

villi (mucous membrane)

A

finger-like projections of mucosa layer & increases surface area

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74
Q

plicae (mucous membrane-small intestine)

A

folds of mucosa & submucosa & increase surface area

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75
Q

rugae (mucous membrane-stomach)

A

pleats of mucosa & submucosa & expand to accommodate volume

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76
Q

submucosa

A

-dense irregular CT, contains large vessels, glands to secrete digestive enzymes & mucus
-houses submucosal nerve plexus

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77
Q

submucosal nerve plexus (submucosa)

A

autonomic nervous system control of glands & smooth muscle of mucosa

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78
Q

muscularis externa

A

-consists of inner circular layer & outer longitudinal layer of smooth muscle for mixing & moving lumenal contents
-circular layer(thick) creates sphincters at junctions to prevent backflow
-contains myenteric nerve plexus

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79
Q

myenteric nerve plexus (muscularis externa)

A

controls GI mobility via local reflexes arcs & ANS stimulation

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80
Q

serosa

A

visceral peritoneum: areolar CT plus mesothelium, covers all abdominal/peritoneal GI tract organs

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81
Q

adventitia

A

dense irregular CT, anchors organs to surrounding tissues, covers oral cavity, pharynx, esophagus & rectum

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82
Q

movements in the gut:

A

-coordinated by short local reflex arcs of ENS
-most ANS to gut is parasympathetic

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83
Q

ENS innervated by ANS allowing extrinsic control of digestive activity:

A

-parasympathetic = increased muscle activity & secretion -sympathetic = decreased muscle activity & secretion

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84
Q

peristalsis (movement in gut)

A

waves of contraction, move food bolus along length of gut

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85
Q

segmentation (movement in gut)

A

single point contraction, chop up bolus, allow enzymes to access inner regions

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86
Q

oral cavity/mouth/buccal cavity

A

-connects environment to pharynx
-lined with stratified squamous epithelium
-walls = muscular cheeks
-floor contains tongue
-hard & soft palate

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87
Q

hard & soft palates (roof of mouth)

A

-hard palate: anterior
-soft palate: posterior -> close off nasopharynx during swallowing

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88
Q

function of the oral cavity/mouth/buccal cavity

A
  1. analyze food (taste buds)
  2. mechanically process food (chew)
  3. lubricate food (saliva)
  4. digest starches (amylase)
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89
Q

tongue (accessory organ of mouth )

A

-muscular
-surface covered by papillae: provide friction & house taste buds

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90
Q

functions of the tongue

A
  1. speech
  2. manipulate food into teeth for mastication
  3. compress food into bolus for swallowing
  4. analyze food for texture, taste, temp
  5. produce secretions
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91
Q

what are the 2 secretion made by the tongue?

A

a. mucin = lubrication
b. lingual lipase = start lipid digestion

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92
Q

salivary glands (accessory organs of mouth)

A

-produce 1-2L saliva/day
-low levels of saliva produced by parasympathetic stim. -> increased secretion (food cue) & sympathetic stim. -> decreased secretion (dry mouth)

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93
Q

saliva (salivary glands -> accessory organs of mouth)

A

99% water + enzymes (amylase for starch), electrolyte buffers, mucin (lubrication), antibodies & antimicrobials (lysozyme & defensins)

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94
Q

functions of saliva:

A
  1. cleanse mouth, control oral bacteria
  2. dissolve food chemicals for taste
  3. moisten food for bolus formation
  4. begin chemical digestion of carbohydrates
  5. buffer oral pH
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95
Q

parotid salivary glands

A

inferior to zygomatic arch, thick secretion, high salivary amylase (25% of saliva)

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96
Q

sublingual salivary glands

A

inferior to tongue, watery secretion, high in buffers (5% of saliva)

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97
Q

submandibular salivary glands

A

posterior floor of mouth, buffers, mucin, amylase (70% of saliva)

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98
Q

functions of teeth (accessory organ of mouth)

A

mastication, mechanical digestion

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99
Q

pulp cavity (structure of teeth)

A

soft center, blood vessels & nerved in CT called pulp

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100
Q

dentin (structure of teeth)

A

bone-like, surrounds pulp cavity, contains odontoblasts which secret & maintain dentin

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101
Q

crown (external surface of teeth)

A

exposed region, covered in enamel composed of hydroxyapatite (calcium salt crystals)(like bome but no collagen)
-cells that produce enamel degenerate after eruption (no repair)

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102
Q

root (external surface of teeth)

A

embedded region, covered in cementum, attached to periodontal ligaments: hold tooth in alveolus of jaw

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103
Q

incisors (type of tooth)

A

chisel-shaped, single root, 8 total, used for cutting

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104
Q

cuspids/canines/eyeteeth (type of tooth)

A

conical-shaped, single root, 4 total, used for tearing & piercing

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105
Q

bicuspids/premolars (type of tooth)

A

2 ridges/cusps, 1 or 2 roots, 8 total, used for crushing, mashing & grinding

106
Q

molars (type of tooth)

A

4-5 cusps, 3 or more roots, 12 total, used for crushing, grinding
3rd molars = wisdom teeth

107
Q

deciduous/milk teeth

A

under age 12 -> 20 teeth
-replaced by age 21 -> 32 permanent teeth

108
Q

impacted tooth

A

fails to erupt, remians in jaw causing pain
-surgical fix

109
Q

dental caries

A

demineralization of enamel & dentin by bacteria exposes nerve, pain

110
Q

periodontal disease

A

infection of gingival, immune response erodes bone around teeth, teeth fall out

111
Q

pharynx

A

-oropharynx (back of mouth)
-laryngopharynx (superior to voice box)
-connects oral cavity to esophagus
-shared space with respiratory system
-stratified squamous epithelium
-lamina propria has tonsils & mucus glands
-skeletal muscles surround for swallowing

112
Q

esophagus

A

-muscular tube connects pharynx to stomach
-25cm long
-passes through diaphragm to abdomen
-at rest, superior & inferior regions constricted to keep air out & stomach contents in

113
Q

gastroesophageal sphincter

A

inferior constriction point acts as a valve that keeps food & stomach acid in the stomach and prevents the stomach’s contents from regurgitating back into the esophagus.

114
Q

gastroesophageal reflux disease (GERD)

A

-“heart burn”
-gastric juice regurgitates into esophagus causing erosion

115
Q

features of esophagus:

A
  1. stratified squamous
  2. large folds in mucosa & submucosa to keep lumen closed during rest
  3. esophageal glands in submucosa secrete mucus to reduce friction
  4. upper 2/3 of muscularis externa contains skeletal muscle
  5. anchored by adventitia
116
Q

deglutition

A

-swallowing
-pharynx & esophagus function in food propulsion from mouth to stomach

117
Q

buccal phase - voluntary (deglutition)

A

-soft palate raised to protect nasopharynx
-bolus pushed against hard palate
-bolus pushed into oropharynx

118
Q

pharyngeal phase -Involuntary reflex (deglutition)

A

-epiglottis blocks entry to trachea
-contractions move bolus past glottis

119
Q

esophageal phase -involuntary reflex (deglutition)

A

-peristaltic waves push bolus toward stomach
-gastroesophageal sphincter opens
-bolus enters stomach

120
Q

stomach functions:

A
  1. store digested food (~1L)
  2. mechanical breakdown of food (churning)
  3. chemical breakdown of food (denatures & digests proteins)
  4. produce intrinsic factor for VitB12 uptake
  5. holds chyme
121
Q

chyme

A

acidic mixture of enzymes & food

122
Q

cardia (region of the stomach)

A

-where esophagus connects via gastroesophageal sphincter
-gastric glands produce mucus to protect esophagus

123
Q

fundus (region stomach)

A

superior region, contact diaphragm

124
Q

body (region of stomach)

A

-majority of stomach
-hold chyme
-gastric glands secrete enzymes & acids for digestion

125
Q

pylorus (region of stomach)

A

-inferior region
-connects to duodenum via pyloric sphincter: regulates chyme entry into duodenum
-gastric glands secrete hormones to stimulate gastric activity

126
Q

features of the stomach

A

-muscualris externa has 3 layers (oblique) to assist mixing chyme
-when empty mucosa & submucosa folded into rugae
-simple columnar epithelium with goblet cells(mucus)
-mucosa perforated by gastric pits, which connect gastric glands to laminate propria
-stem cells replaced every 3-6 days

127
Q

gastric glands

A

-produce 1-3L gastric juice/day: secretion vary per regiom
1. cardia
2. fundus & body
3.pyloric

128
Q

cardia gastric glands

A

mucus

129
Q

fundus & body gastric glands

A

digestive enzymes & acid
- 2 types: parietal & chief

130
Q

parietal cell (fundus & body gastric cell)

A

-secrete
1. intrinsic factor (VitB12)
2. H+ & Cl- ions combine to make HCl in stomach

131
Q

pepsinogen (chief cell -> fundus & body gastric cell)

A

converted to pepsin by acid in stomach: hydrolyzes proteins

132
Q

rennin (chief cell -> fundus & body gastric cell)

A

infants only, curdles milk protein to aid digestion

133
Q

acid production important to gastric function:

A
  1. kill microbes
  2. denature proteins
  3. breakdown plant cell walls & animal CT
  4. activate pepsin
134
Q

pyloric gastric glands

A

mucus & hormones
-2 important hormone-producing cells: G cells & D cells

135
Q

G cells (pyloric gastric gland)

A

-produce gastrin
-stimulates secretion by parietal & chief cells
-promotes contraction of gastric wall
secreted in response to food or parasympathetic stimulation

136
Q

D cells (pyloric gastric gland)

A

-produce somatostatin
-inhibits release of gastrin (thus inhibits gastric activity)
-secreted in response to sympathetic stimulation

137
Q

gastritis

A

inflammation of gastric mucosa caused by drugs, stress, infection: chronic can lead to ulcer

138
Q

peptic ulcer

A

erosion of stomach lining, caused by too much acid, not enough mucus, or, most commonly, helicobacter pylori (bacteria)

139
Q

regulation of gastric activity

A

-secretion & mobility controlled by 3 factors:
1. innervation from CNS (ANS)
2. reflexes of ENS
3. hormones
-mechanism relies on stimuli from three

140
Q

cephalic phase (regulation of gastric activity)

A

-CNS
-prepares stomach for food
-triggered by seeing, smelling, or thinking of food
-lasts a few minutes

141
Q

neural response of cephalic phase (regulation of gastric activity)

A

parasympathetic ANS triggers increase in all gastric secretions (mucus, enzymes, acid) & triggers G cells to release gastrin

142
Q

gastric phase (regulation of gastric activity)

A

-initiates stomach digestive activities
-triggered by food entering stomach (stimuli = dissension, peptides low, low acidity)
-lasts 3-4 hours

143
Q

neural response of gastric phase (regulation of gastric activity)

A

stretch receptors activate ENS reflexes & parasympathetic ANS innervation; both stimulate secretions from parietal cells (acid), chief cells (pepsin) & G cells (gastrin)

144
Q

hormonal response of gastric phase (regulation of gastric activity)

A

triggered by neural response, peptides & increased pH, G cells release gastrin, which triggers secretion by parietal & chief cells and gastric mobility

145
Q

local response of gastric phase (regulation of gastric activity)

A

triggered by distortion, mast cells release histamine, which stimulates parietal cells

146
Q

what sympathetic stimulation show down down in gastric secretion?

A

shuts down gastric secretion via somatostatin from D cells

147
Q

greatest acid production via 3 -fold stimulation of parietal cells:

A
  1. Ach from ENS & parasympathetic ANS
  2. gastrin from G cells
  3. histamine from mast cells
148
Q

intestinal phase (regulation of gastric activity)

A

-controls chyme entry into duodenum
-triggered by chyme entering duodenum
-last many hours
-involves excitatory & inhibitory control of gastric activity depending on chyme composition

149
Q

neural response of intestinal phase (regulation of gastric activity)

A

stretch receptors trigger enterogastric reflex, which turns off ENS & parasympathetic stimulation of G cells and stimulates sympathetic stimulation of pyloric sphincter

150
Q

hormone response of intestinal phase for lipids, carbohydrates & peptides (regulation of gastric activity)

A

cholecystokinin & gastric inhibitory peptide
-inhibit gastric secretion & motility (stimulates pancreas + gallbladder secretion)

151
Q

hormone response of intestinal phase for proteins (regulation of gastric activity)

A

intestinal gastrin
-stimulates parietal & chief cells, stimulates gastric mobility

151
Q

hormone response of intestinal phase for low pH (regulation of gastric activity)

A

secretin
-inhibits gastric secretion (stimulates pancreas + liver secretions)

152
Q

what are 2 things that are absorbed in the stomach?

A

drugs & alcohol

153
Q

food doesn’t remain in stomach for more than 4hrs but total depends on chemical makeup of food:

A

-carbohydrate-rich = passes quickly
-fatty foods can cause chyme to remain in stomach 6+ hrs

154
Q

small intestine

A

-major division organ
-chemical digestion completed
-90% of nutrients absrobed
-20ft long, 3 major subdivisions

155
Q

duodenum (small intestine)

A

-first 10 inches
-retroperitoneal
-receives chyme from stomach through pyloric sphincter
-receives digestive secretions from pancreas & liver through duodenal ampula controlled by hepatopancreatic sphincter
-mixing pot

156
Q

jejunum (small intestine)

A

-8ft
-peritoneal
-majority of chemical digestion & nutrient absorption occur here
-has the most plicae & villi

157
Q

ileum (small intestine)

A

-12ft
-peritoneal
-mucosa rich in lymphoid tissue
-connect cecum at ileocecal valve

158
Q

plicae (small intestine)

A

mucosa & submucosa folded into circular plicae that cause chyme to serial slowly

159
Q

villi (small intestine)

A

plicae covered with finder-like projections of mucosa called intestinal villi, base of each has crypt/intestinal gland

160
Q

microvilli (small intestine)

A

simple columnar epithelial cells have microvilli on apical surfaces: membrane collectively called brush border of intestine

161
Q

histology of small intestine

A

-4 layers adapted for absorption
-plicae + villi + microvilli = 3.6 ft
-lamina propria of each villus contains capillaries that carry small nutrient molecules to liver via hepatic portal vein
-contain lacteals

162
Q

lacteal

A

the special lymphatic capillary collects larger molecules that can’t enter capillaries (lipid-protein complexes)

163
Q

contraction of muscularis mucosae:

A

-move villi to expose surface to new chyme
-squeeze lacteals to move lymph

164
Q

goblet cells

A

between columnar epithelium cells
-secrete mucus (mucin)

165
Q

intestinal glands of small intestine

A

variety of cells in crypt, located in lamina propria at base of each villus
-produce: intestinal juice, lysozyme, hormones, epithelium cells

166
Q

intestinal juice (intestinal gland product of small intestines)

A

1-2L/day, watery mucus, aids solubilization & absorption of nutrients

167
Q

lysozyme (intestinal gland product of small intestine)

A

from Paneth cells, lyse bacteria

168
Q

epithelial cells (intestinal gland product of small intestine)

A

-stem cells in glands
-new cells created, migrate up villus, shed at tip, complete turnover 3-6 days
-shed cells carry digestive enzymes in plasma membrane that function in lumen

169
Q

brush border enzyme

A

complete digestion of carbohydrates & proteins
-epithelial cell

170
Q

Peyer’s Patches

A

aggregated lymphoid nodules in ileum for immune defense

171
Q

when does secretion from intestinal glands begin in the small intestine?

A

-before chyme enters due to parasympathetic stimulation
-when chyme present, stretch receptors & enterocrinin stimulate secretions of mucus, hormones & juice

172
Q

myenteric reflexes (ENS) (small intestine movements)

A

peristalsis to move chyme slowly through small intestine

173
Q

gastroenteric reflex (parasympathetic reflexes -> small intestine movement)

A

stimulates motility & secretion along whole small intestine

174
Q

gastroileal reflex (parasympathetic reflexes -> small intestine movement)

A

relaxes ileocecal valve, materials pass fro ileum to cecum (large intestine)

175
Q

emesis/vomiting reflex

A

-controlled by emetic center of medulla oblongata

176
Q

emesis/vomiting reflex process

A

1, pyloric sphincter relaxes, contents of duodenum & upper jejunum discharged in stomach
2. salivary secretion enhanced (buffer stomach acid)
3. soft palate rises to close off nasopharynx
4. diaphragm & abdominal wall muscle contract, stomach contents regurgitated

177
Q

pancreas

A

-retroperitoneal
-inferior to stomach
-exocrine & endocrine
-pancreatic juice released into pancreatic duct & joins with common bile duct
-enter duodenum at duodenal ampula & controlled by hepatopancreatic sphincter

178
Q

pancreatic islets

A

-endocrine, 1%
-cells secrete insulin & glucagon to control blood sugar

179
Q

pancreatic acini

A

-exocrine, majority
-acinar cells (simple cuboidal) produce digestive enzymes & buffers: pancreatic juices

180
Q

pancreatic juice

A

~1.5L/day in response to parasympathetic & hormonal control
-water + proenzymes + electrolytes (buffer)

181
Q

pancreatic enzymes

A

~70% secreted as proenzymes, activated in gut
-all proteolytic enzymes are secreted inactive must be activated in gut (prevent autolysis)

182
Q

enterokinase

A

-brush border enzyme
-activates pancreatic trypsinogen -> trypsin
-trypsin activates all pancreatic proteolytic pro-enzymes via cleavage

183
Q

pancreatic alpha-amylase (pancreatic enzyme)

A

hydrolyzes starch

184
Q

pancreatic lipase (pancreatic enzyme)

A

hydrolyzes lipids & fatty acids

185
Q

nucleases (pancreatic enzyme)

A

hydrolyze nucleic acids (RNA, DNA)

186
Q

proteolytic enzymes (pancreatic enzyme)

A

-majority
-each digest-specific peptide bond
- 2 main classes: proteases & peptidases

187
Q

proteases (proteolytic enzymes ->pancreatic enzyme)

A

hydrolyzes large proteins into peptides

188
Q

peptidases (proteolytic enzymes ->pancreatic enzyme)

A

hydrolyze peptide chains into amino acids

189
Q

pancreatitis

A

inflammation of the pancreas, ducts blocked -> injury to acinar cells
-necrotic cells release lysosome enzymes -> activate pro-enzymes -> autolysis

190
Q

diabetes mellitus

A

destruction of Islet cells due to pancreatitis or autoimmune attack results in loss of regulation of blood sugar levels

191
Q

liver

A

-right side, inferior to diaphragm
-largest visceral organ
-four lobes -> anterior separated by falciform ligament (fetal umbilical vein) & posterior: tiny caudate & quadrate lobe

192
Q

lobule

A

hexagonal functional unit of liver
-separated by interlobular septa
-central vein in middle
-six portal triads on hexagonal corners

193
Q

hepatic artery of liver

A

O2 rich blood

194
Q

hepatic portal vein of liver

A

nutrient-rich blood from small intestine

195
Q

bile duct of liver

A

collect bile produced by hepatocytes

196
Q

hepatocytes

A

function in nutrient regulation & bile production, arranged in rows around central vein, sinusoids between rows

197
Q

blood flow in lobule:

A

-blood from arteries & veins of triads flow through sinusoids
-allows molecule exchange with hepatocytes
-blood flows out through central vein

198
Q

Kupffer cells

A

-fixed macrophages in sinusoids
1. remove pathogen, cell debris, damages eyrhocytes
2. remove & store iron
3. remove & store lipids
4. remove & store heavy metals

199
Q

bile flow

A

-bile secreted by hepatocytes
-flows through bile canaliculi between cells
-canaliculi -> bile duct of triads -> merge into common hepatic duct
-hepatic duct exits liver, joins cystic duct from gallbladder creating common bile duct
-common bile duct connects to duodenum at duodenal ampula

200
Q

metabolic regulation (liver/hepatocyte function)

A

-hepatocytes regulate blood nutrient levels
-nutrient-rich blood from GI goes to liver so excess can be removed & deficits can be corrected

201
Q

carbohydrate metabolism by hepatocytes

A

-too much glucose -> hepatocytes store glucose as glycogen
-too little -> hepatocytes break down glycogen or perform glucogenesis

202
Q

what do hepatocytes carry out besides carbohydrate metabolism?

A

lipid & amino acid metabolism, waste removal, vitamin storage, mineral storage and drug & toxin inactivation

203
Q

hematological regulation (liver/hepatocyte function)

A

a. liver serves as blood reservoir
b. Kupffer cells recycle RBCs
c. Kupffer cells perform antigen presentation to lymphocytes
d. hepatocytes remove/recycle hormones & antibodies
e. hepatocytes & Kupffer cells remove, inactivate, or store toxins, drugs & heavy metals
f. hepatocytes produce plasma proteins

204
Q

bile components:

A

water, bilirubin, phospholipids, electrolytes, cholesterol & bile salts

205
Q

bile functions

A

a. buffer chyme (electrolytes)
b. emulsify fats: break large lipids globs into small droplets (phospholipids & bile salts

206
Q

function of emulsification

A

-allows enzymes to access lipids
-promote solubilization & absorption of lipids in blood & lymph

207
Q

digestion: bile synthesis & secretion (liver/hepatocyte function)

A

-bile creation
-emulsification
-circulation of bile
-secretin from duodenum promotes secretion of bile from liver

208
Q

enterohepatic circulation of bille

A

bile salts absorbed in lipid droplets & recycled back to liver, not metabolized

209
Q

hepatitis

A

inflammation of liver, due to viral infection, restricts blood flow to lover, six known viruses with different severity

210
Q

cirrhosis

A

chronic inflammation due to severe hepatitis or alcoholism: damaged hepatocytes replaced by fibrous tissue & adipose, can cause portal hypertension -> veins swell & rupture

211
Q

gallbladder

A

-anterior & inferior to liver
-functions to concentrate & store bile produced by liver
-cholecystokinin from duodenum causes release of bile by stimulating contraction of gallbladder & relaxation of hepatopancreatic sphincter

212
Q

gall stones

A

crystalization of over-concentrated bile

213
Q

cholecystitis

A

inflammation caused by large gall stones that block or damage the gallbladder

214
Q

ANS (neural mechanism in coordination of secretion & absorption in small intestine)

A

-parasympathetic = increased digestive activity
-sympathetic = decreased digestive activity

215
Q

ENS reflexes (neural mechanism in coordination of secretion & absorption in small intestine)

A

coordinate movement od material from one region to the next

216
Q

hormonal mechanisms (coordination of secretion & absorption in small intestine)

A

hormones from intestinal glands of duodenum control small intestine, stomach & accessory organs to coordinate digestive activities

217
Q

enterocrinin (hormonal mechanism in coordination of secretion & absorption in small intestine)

A

released when chyme enter duodenum, stimulates mucus production in duodenum

218
Q

intestinal gastrin (hormonal mechanism in coordination of secretion & absorption in small intestine)

A

released when chyme contains protein, stimulates gastric activity
-“activity” = secretion & motility

219
Q

gastric inhibitory peptide (hormonal mechanism in coordination of secretion & absorption in small intestine)

A

released when chyme contain lipids & carbohydrates, inhibits gastric activity

220
Q

secretin (hormonal mechanism in coordination of secretion & absorption in small intestine)

A

released when chyme is acidic, stimulates the release of bile from liver & buffers from pancreas and reduces gastric activity

221
Q

cholecystokinin (hormonal mechanism in coordination of secretion & absorption in small intestine)

A

released when chyme contains lipids & peptides, stimulates:
-secretion of enzymes from pancreas
-contraction of gallbladder for bile release
-relaxes hepatopancreatic sphincter to allow entry of bile & enzymes into duodenum
-inhibits gastric activity
-reduces hunger sensation (20 min post food consumption)

222
Q

vasoactive intestinal peptide (hormonal mechanism in coordination of secretion & absorption in small intestine)

A

released when chyme enters duodenum, inhibits gastric secretion, stimulates intestinal secretion, dilates local capillaries for absorption

223
Q

somatostatin (hormonal mechanism in coordination of secretion & absorption in small intestine)

A

released in response to sympathetic stimulation
-inhibits gastric activity
-inhibits secretion from pancreas & gallbladder
-inhibit blood flow to intestine, inhibiting absorption

224
Q

large intestine

A

~5ft long
-no digestion except microbes
-water absorption important to feces: too much = diarrhea -> too little = constipation

225
Q

functions of the large intestine

A
  1. reabsorb any remaining water & compact feces
  2. absorb vitamins & electrolytes
  3. storage of feces & defecation
226
Q

bacteria of large intestine produces vitamins:

A

-VitK: clotting factor
-biotin: glucose metabolism
-VitB5: steroid hormone & neurotransmitter synthesis

227
Q

bacterial metabolism produces characteristics of feces:

A

-bilirubin -> urobilins & stercobilins = brown
-fermentation of organics -> ammonia, indole, H2S = odor
-fermentation of carbs -> methane, CO2 = flatus

228
Q

histology specialization of large intestine

A

-mucosa has deep crypts with intestinal glands that produce mucus
-no plicae or vili
-lamina propria has large nodules
-epithelium is simple columnar with goblet cells

229
Q

taeniae coli (large intestine)

A

muscularis externa made up of 3 longitudinal bands of muscle

230
Q

haustra (large intestine)

A

pouches created by the contraction of taeniae coli

231
Q

cecum (subdivision of large intestine)

A

-attached to ileum via ileocecal valve
-functions to begin compaction of feces
-appendix hangs off side

232
Q

appendix (side of cecum -> large intestine)

A

has lymphoid nodules that are part of the MALT

233
Q

appendicitis

A

blockage of appendix results in bacterial growth, causing inflammation & swelling, rupture will release bacteria into abdomen -> peritonitis -> sepsis -> death

234
Q

colon (subdivision of large intestine)

A

-absorbs water, vitamins, electrolytes
-four major regions:
1. ascending colon
2. transverse colon
3. descending colon
4. sigmoid colon

235
Q

diverticulitis

A

pockets form in colon wall & are site of recurrent inflammation & infection due to a lack of fiber

236
Q

rectum (subdivision of large intestine)

A

-stores feces
-has 3 valves to separate feces & flatus
-exits at anal canal
-lined with stratified squamous
-defecation controlled by 2 sphincters: internal & external anal sphincters

237
Q

internal anal sphincter

A

smooth muscle from muscualris externa, involuntary

238
Q

external anal sphincter

A

skeletal muscle under voluntary control

239
Q

haustral contractions (large intestinal movement)

A

local, slow, segmenting contraction, shift feces for water absorption

240
Q

mass movements (large intestinal movement)

A

powerful peristaltic contractions, force feces toward rectum, occur few times per day, can trigger defecation reflex via stretch receptor in rectum

241
Q

defecation reflex (large intestinal movement)

A

stretch receptors -> parasympathetic stimulation -> contraction of sigmoid colon & rectum and relaxation of internal anal sphincter, voluntary control of external anal sphincter controls timing of defecation

242
Q

diarrhea

A

movement through large intestine too fast = too much water in feces

243
Q

constipation

A

movement too slow through large intestine = too little water in feces

244
Q

chemical digestion

A

-large molecules catabolized into monomers
-monomers absorbed by mucosa
-enzymatic breakdown = hydrolysis

245
Q

carbohydrate digestion method

A

-amylases (saliva, pancreas) = polysaccharides-> di- & trisaccharides
-brush border enzymes (small intestine) = di- & trisaccharides -> monosaccharides

246
Q

carbohydrate absorption method

A

-facilitated diffusion (w/ protein, no ATP) & cotransport of monosaccharides (2 substances at once, ATP used)
-cellulose (fiber) not digested aids in intestinal mobility

247
Q

lactose intolerant

A

fail to produce lactase (brush border enzyme); undigested lactose creates osmotic gradient that causes feces to remain hydrated (diarrhea), bacteria ferment lactose, producing flatus

248
Q

lipid digestion method

A

-bile salts (liver) = emulsification
-lipases (tongue, pancreas) = triglycerides -> monoglycerides & fatty acids

249
Q

lipid absorption method

A

-micelles form: monoglycerides, fatty acids & bile salts
-chylomicrons exocyst into lumen
chylomicrons absorbed by lacteal

250
Q

chylomicrons

A

micelles absorbed by intestinal epithelium, proteins added

251
Q

protein digestion method

A

-mastication (chewing) & churning (stomach) = disrupt protein structure
-pepsin + acid (stomach) = protein -> polypeptide
-proteases + peptidases (pancreas, brush border) = polypeptide -> amino acid

252
Q

protein absorption method

A

-facilitated diffusion (w/ protein, no ATP) & cotransport of amino acids (2 substances at once, ATP used)

253
Q

nucleic acid digestion method

A

-nucleases (pancreas) = nucleic acid -> nucleotides
-brush border (small intestine) = nucleotides -> nitrogenous bases + sugar + phosphate ions

254
Q

nucleic acid absorption method

A

activate transport (burn ATP to pump into blood) of nitrogenous bases + sugar + phosphate ions

255
Q

water digestion method

A

-no digestion required -> absorption
-2L from food, 7L from secretions

256
Q

water absorption method

A

-osmosis (95% in small intestine
~150ml lost in feces

257
Q

ion digestion method

A

-no digestion required -> absorption
-from food or secretion
-must be regulated for homeostasis
-control osmosis & pH, needed for enzyme function

258
Q

ion absorption method

A

diffusion (no ATP), cotransport & active transport (ATP required & pumped into blood)
*depends on the ion

259
Q

vitamin digestion method

A

-no digestion required
-fat-soluble = A, D, E, K
-water-soluble = most B & C
-VitB12

260
Q

vitamin absorption method

A
  • fat-soluble = mixed with fats (travel w/lipids) in micelle -> chylomicrons
    -water-soluble = diffusion
    -VitB12 = bound to intrinsic factor(intestine), binds receptors, endocytose to blood (B12)
261
Q

age-related changes

A
  1. epithelium division rates decline -> ulcers more likely
  2. smooth muscle tone decreases
    -constipation(slow movement)
    -diverticulitis & hemorrhoids from weak walls
    -GERD from open sphincters
  3. cumulative damage to teeth (wear, carries) & liver (toxin, lipid build-up)
  4. increased cancer rate

a & p II unit 6 (2 decks)

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