Lyons Phs4904 Ch 18 Digestion

Front 1

digestion occurs by the means of ______ reactions

Back 1

hydrolysis

Front 2

2 protective mechanisms to prevent digestive enzymes from digesting ones own tissues:

Back 2

inactivation of digestive enzymes & fully active digestive enzymes are confined to GI lumen

Front 3

2 mechanisms by which ingested material is ensured to propel forward (one-way mvmt called peristalsis):

Back 3

control of waves of muscle & sphincters

Front 4

ingestion involves (2):

Back 4

mastication & deglutition

Front 5

Endocrine or Exocrine secretions?

water, HCI, bicarb, & digestive enzymes

Back 5

exocrine secretions into lumen of GI tract

Front 6

Endocrine or Exocrine secretions?

hormones that aid in regulation

Back 6

endocrine secretions from stomach & SI

Front 7

taking substances from the lumen to the blood/lymph is known as:

Back 7

absorption

Front 8

tight junctions, HCI, & peyers patches function as:

Back 8

immune function of DT

Front 9

teeth, tongue, salivary glands, liver, gallbladder, pancreas function as:

Back 9

accessory organs

Front 10

the oral cavity, pharnyx, esophagus, stomach, SI & LI function as:

Back 10

organs of the GI tract

Front 11

layer of GI tract involved in absorption & secretion:

Back 11

mucosa

Front 12

-capillary spaces lined by fenestrae,
-very permeable,
-fats & cholesterol pkg in apoproteins
-kupfer cells here (macrophages)

Back 12

sinusoids of liver

Front 13

contains:
-goblet cells (simple columnar),
-lamina propia (aerolar connective & lymph)
-muscularis mucosa:

Back 13

mucosa

Front 14

vascular connective tissue layer of GI tract involved in secretion:

Back 14

submucosa

Front 15

contains:
-glands & nerve plexuses
-Meissner's plexus (secretion)
-vascular connective tissue

Back 15

submucosa

Front 16

smooth muscle layer of GI tract involved in segmentation & peristalsis (motility):

Back 16

muscularis (externa)

Front 17

contains:
-inner circular & outer longitudinal layer
-myenteric plexus (major nerve supply to GI)
-SNS & PNS innervate

Back 17

muscularis (externa)

Front 18

churns chyme with mucus:

Back 18

segmentation

Front 19

function in digestion:
-forms bolus
-antimicrobial agents
-starch breakdown here (salivary amylase)

Back 19

mastication- mixes food with saliva

Front 20

function in digestion:
-voluntary & involuntary phases
-larnyx raises
-tongue elevates (keeps food in mouth)
-epigolttis covers respiratory trct

Back 20

deglutition (swallowing)

Front 21

phases of deglutition (3):

Back 21

oral, pharyngeal, & esophageal
(oral- voluntary, others-involuntary) coordinated by medulla

Front 22

stratified squamous protects against abrasion in this 10 inch muscular tube:

Back 22

esophagus (connects pharnyx to stomach)

Front 23

-moves bolus from superior esophagus to gastroesophageal junction
-waves of muscle contraction
-circular muscle contracts (behind)
-relaxes (front)
-then longitudinal muscle shortens (at junction)

Back 23

peristalsis in esophagus (bigger bolus=bigger contraction)

Front 24

defined by sphincter, but not a true sphincter...
really a thick circular muscle -functions to prevent backflow from stomach
-not fully functional in babies

Back 24

gastroesophageal sphincter

Front 25

heartburn is caused by:

Back 25

-backflow stomach acid which leaked thru gastroesophageal sphincter
(in babies: spit up)

Front 26

what can cause esophagitis (ulcers in esophagus)?

Back 26

gastroesophageal reflux

Front 27

functions:
-food storage
-protein digestion begins here
-bactericidal
-chyme production

Back 27

stomach

Front 28

food is delivered via peristatic waves from esophagus to this region of the stomach:

Back 28

cardiac region

Front 29

chyme exits stomach & enters duodenum by passage thru this sphincter:

Back 29

pyloric sphincter (most distal region of stomach)

Front 30

gastroesophageal reflux disease & treatments:

Back 30

-frequent heartburn/ complications
-treat: reduce stomach acid
proton pump inhibitors
H2 histamine receptor blockers

Front 31

cells in gastric glands of stomach & SI
-secrete histamine & serotonin

Back 31

ECL enterochromaffin cells aka enteroendocrine

Front 32

cells in gastric glands
-secrete HCI & intrinsic factor

Back 32

parietal cells

Front 33

cells in gastric glands
-secrete pepsinogen

Back 33

chief cells

Front 34

cells in gastric glands
-secrete gastrin (hormone) into blood

Back 34

G cells

Front 35

cells in gastric glands
-secrete somatostatin (hormone that inhibits digestion)

Back 35

D cells

Front 36

cells in gastric glands
-replace epithelium (because exposed to harsh environment-damage)

Back 36

stem cells

Front 37

goblet cell function? where are they found?

Back 37

cells in gastric glands
-secrete mucous

Front 38

the only stomach function that appears to be functional for life:

Back 38

parietal cell secretion of intrinsic factor (polypeptide needed for B12 absorption)

Front 39

function of B12:

Back 39

required for maturation of RBCs in bone marrow (without B12 pernicious anemia will develop)

Front 40

what is pernicious anemia?

Back 40

disease resulting from insufficient B12 (B12 is required for RBC maturation in bone marrow)

Front 41

deglutition results in relaxation of:

Back 41

stomach (medulla mediates- prepares to receive food)
>persistalsis begins shortly after

Front 42

what function do the pacemaker cells in muscularis externa of stomach govern?

Back 42

-peristalsis of stomach (contractions)
-churn produces chyme
-wave reaches pyloric sphincter & squeezes shut
-each wave: 3mL chyme>>SI

Front 43

what might happen if stomach moved chyme into>>duodenum all at once?

Back 43

duodenal ulceration

Front 44

antrum holds 30 mL of chyme. why does only 3mL chyme>>duodenum at a time?

Back 44

ensures:
-time to churn well in stomach
-duodenum time to neutralize acidity
-time for enzymes to work
- time for absorption

Front 45

negative feedback function if duodenum became overfilled?

Back 45

inhibits gastric motility (so stomach stops pushing chyme>>duodenum)

Front 46

gastric secretions in stomach mix with ______

Back 46

chyme (while churning-peristalsis)

Front 47

salivary & gastric enzymes begin process of digestion in the _____

Back 47

stomach (but most digestion is in the SI)

Front 48

the ____ is slightly acidic, wheras the _____ is slightly alkaline

Back 48

stomach- acidic
SI- alkaline

Front 49

-inner surface of stomach
-macroscopic
-long folds

Back 49

rugae

Front 50

-inner stomach
-microscopic
-folded

Back 50

gastric mucosa

Front 51

-openings of folds into stomach lumen
-between gastric mucosa

Back 51

gastric pits

Front 52

-cells that line the deeper portion of gastric pits in gastric mucosa folds

Back 52

gastric gland

Front 53

-exocrine secretions & water
-highly acidic
-2-4 L per day

Back 53

gastric juice

Front 54

parietal cells release ____ into lumen, wheras they release ____ into blood

Back 54

HCI into lumen
HCO3 (bicarb) into blood

Front 55

-gastrin
-histamine
-NTs
-exercise
-caffiene
what do these all stimulate?

Back 55

gastric secretion

Front 56

______ & _____stimulate:
-parietal cells (weak)
-ETC cells (strong)

Back 56

gastrin from G cell
Ach from PNS via vagus nerve

Front 57

cell that inhibits digestion:

Back 57

D cells secrete somatostatin that inhibit digestion

Front 58

___ functions to:
-denature proteins
-activates pepsinogen>>pepsin
-provides optimal pH for pepsin (to begin protein digestion
-kills microbes

Back 58

the high concentration of HCL in gastric juice (stomach acid)

Front 59

4 stomach lining protection mechanisms from stomach acid & pepsin?

Back 59

-mucous layer
-bicarb (alkaline) secreted from apical cells in epithelium
-tight junctions betw epithelium
-stem cells (replace epithelium every 3 days)

Front 60

gastric mucosa produces _____, which stimulate mucous & bicarb production that form the mucosal barrier

Back 60

prostaglandulins

Front 61

within this organ:
-little digestion & absorption
-proteins partially digested
-starch digestion halted
-alcohol, aspirin, very lipid soluble substances absorbed

Back 61

stomach

Front 62

erosions in stomach/duodenal muscous mb due to HCI:

Back 62

peptic ulcers

Front 63

-gastrin secreting tumor (often pancreatic)
-mainly duodenal ulcers

Back 63

Zollinger Ellison Syndrome

Front 64

ulcers that involve failure of protective lining:

Back 64

stomach ulcers

Front 65

-resides in GI (50% population)
-cause of most gastric & duodenal ulcers

Back 65

helicobacter pylori

Front 66

treatment of gastric & duodenal ulcers caused by helicobacter pylori

Back 66

antibiotic & proton pump inhibitor (prilosec/prevacid)

Front 67

NSAIDS inhibit ______ causing a stomach ulceration

Back 67

prostaglandulins

Front 68

stomach ulcerations are caused by ______, whereas duodenal ulcerations are caused by ____or ____

Back 68

stomach- failure of protective lining
duodenum- high gastric acid secretion or inadequate bicarb

Front 69

gastrin is normally secreted in the stomach, but a _____ can secrete gastrin in duodenum, known as ____ Syndrome, & can cause a duodenal ulcer

Back 69

tumor (usually pancreatic) Zoolinger Ellison Syndrome

Front 70

prilosec & prevacid are:

Back 70

proton pump inhibitors

Front 71

zantac & tagament are:

Back 71

H2 blockers

Front 72

protection gastric acid in _____ include:
-mucosal cells >bicarb
-brunners glands> bicarb
-pancreatic juice >alkaline

Back 72

duodenum

Front 73

protection from gastric acid & pepsin in _____ include:
-prostaglandulins
-mucosal layer (epithelium bicarb secretion)

Back 73

stomach

Front 74

____ulcers can be treated by
-antacids
-H2blockers
-proton pump inhibitors

Back 74

duodenal ulcers

Front 75

stomach ulcers can be treated by _____

Back 75

H2 blockers (zantac/ tagament)

Front 76

acute gastritis can cause a ____ ulcer in the stomach

Back 76

peptic

Front 77

most absorption occurs in the _____& _____

Back 77

duodenum & jejunum

Front 78

absorption of carbs, lipids, & amino acids occurs primarily in ______

Back 78

duodenum & jejunum

Front 79

absorption of B12, water, bile salts, & electrolytes occurs in ____

Back 79

ileum

Front 80

absorption in SI occurs rapidly due to:

Back 80

folded intestinal mucosa that greatly increases surface area (plicae circulares & villi)

Front 81

the mucosa & submucosa form large folds called _______ in SI that are visible by the eye

Back 81

plicae circulares

Front 82

microscopic folds in SI are ____

Back 82

villi (of mucosa) & microvilli (of epithelial cells)

Front 83

microscopic fold in SI:
-fingerlike fold-projects > lumen
-covered by columnar epithelium
-goblet cells interspersed
-lymphocytes
-blood capillaries
-central lacteal (lymph vessels)
-intestinal crypts

Back 83

villi

Front 84

In villi of SI, carbs & amino acids enter _____

Back 84

blood capillaries

Front 85

In villi of SI, absorbed fat enters ______

Back 85

central lacteals (lymph vessels)

Front 86

-narrow pouches
-open thru pores of intestinal lumen
-produce new epithelial cells

Back 86

intestinal crypts (villi)

Front 87

-foldings in apical cell mb of SI
-only visable by electron microscope
-brush border enzymes

Back 87

microvilli

Front 88

-enzymes in SI
-not secreted into lumen
-attached to pm
-contact with mb required for action (active site exposed to chyme)

Back 88

brush border enzymes

Front 89

brush border enzyme required to active trypsin

Back 89

enterokinase

Front 90

-brush border enzyme digests lactose
-kids under 4
-inactive in most adults
-deficiency results in diarrhea or cramps

Back 90

lactase

Front 91

-muscular contractions of lumen
-slow in SI
-kneads chyme
-simultaneous contractions
-more frequent in proximal end SI (for contact with bb enzymes & churning)

Back 91

segmentation

Front 92

-occur during fasting
-prevents bacterial growth in intestines
-clears SI (leftover)
-stopped by eating

Back 92

migratory motor complexes

Front 93

contractions in SI occur automatically in response to ______

Back 93

pacemaker activity

Front 94

-pacemaker/cajal cell depolarizations
-mediated via gap junctions
-faster at proximal end
-only spread short distance

Back 94

slow waves

Front 95

-cells of Cajal
-non neuronal/muscle cells
-long processes (connect cells to cells & cells to muscle)
-gap junctions

Back 95

pacemaker cells

Front 96

____ do not initiate contractions, they just make it easier for them to occur

Back 96

slow waves

Front 97

if ANS or ENS are active simultaneously with slow waves, it will cause ________

Back 97

VGCCs open>AP> contraction>push GI contents along tract

Front 98

______ contractions moves bolus along esophagus & intestine, whereas ______ contractions are constrictions of the lumen that knead chyme

Back 98

peristalsis- bolus, esophogus & intest
segementation- knead chyme, constrict lumen

Front 99

how does ANS influences slow waves to increase amplitude & duration?

Back 99

1.PNS: Ach binds muscarinic receptors>>increases production of APs>>promotes contraction & motility

Front 100

segmentation declines when _____ & peristalsis begins

Back 100

most nutrients have been absorbed

Front 101

after esophagus & stomach, peristaltic wave begins in _____

Back 101

duodenum

Front 102

peristaltic waves travel 10-70 cm & die. next wave begins a little further down tract. this creates ______

Back 102

successive overlapping waves

Front 103

chyme enters the LI from the ____ to the ______

Back 103

ileum to cecum (blind pouch)

Front 104

mucosa of ____ (organ):
-lymphocytes & lymph nodules
-columnar epithelium
-goblet cells
-NO villi

Back 104

LI

Front 105

Diverticulitis is inflammation of distended _____ (pouches of the LI that bulge outward)

Back 105

haustra

Front 106

functions of this organ:
-absorbs water, electrolytes, & vitamin B & K
-intestinal microbiota (many functions)

Back 106

LI

Front 107

functions of ____ in the LI:
-ferment indigestible chyme
-vitamin K & folic acid
-out-compete pathogens
-antinflammatory- protect mucosa

Back 107

intestinal microbiota (commensal bacteria)

Front 108

inflammatory bowel disease, chrohn's disease, & ulcerative colitis are associated with increased use of _______

Back 108

antibiotics

Front 109

absorption:
most (7-9L/day) in ___
less (1-2L/day) in ___
remaining 10% (200mL) leftover in feces

Back 109

SI- most
LI- less

Front 110

water absorption in the intestine is passive due to:

Back 110

osmotic gradient due to active transport reabsorption of ions

Front 111

excessive fluid in feces _____. caused by:
-enterotoxin from cholera (keeps Na+ & water in lumen)
-lactose intolerance (exerts OSMP, pulls water into lumen)
-many others

Back 111

diarrhea

Front 112

the involuntary anal sphincter is _____, whereas the voluntary anal sphincter is ______

Back 112

internal-involuntary
external-voluntary

Front 113

how does urge to defecate occur?

Back 113

waste passes thru rectum>> increases rectal pressure>> relaxes internal anal sphincter

Front 114

act of defecation:

Back 114

sphincters relax>> rectal muscle contracts, abdominal & pelvic skeletal muscles assist (push feces out) by contracting

Front 115

-largest organ
-hepatocytes form hepatoplates separated by sinusoids
-regenerative ability

Back 115

liver

Front 116

-fenestrae (lg pores)
-very permeable
-apoproteins (fats & cholesterol pkg'd)
-keep blood & hepatocytes close
-kupfer cells (macrophages)

Back 116

sinusoids

Front 117

the ability for the liver to regenerate is due to:

Back 117

mitotic division of hepatocytes

Front 118

liver fibrosis can lead to _____

Back 118

liver cirrhosis

Front 119

what is liver fibrosis?

Back 119

accumulation of collagen fibers (scar tissue) due to alcohol & viral hepatitis

Front 120

what is cirrhosis?

Back 120

large numbers of liver lobules destroyed by inflammation & permanently replaced with scar tissue less functional

Front 121

the intestine delivers ____ blood to the liver, whereas the hepatic artery delivers (oxygen rich) _____ blood.

Back 121

intestine> venous blood> liver
hepatic arteries> arterial blood> liver

Front 122

flow of intestinal absorption products in liver:

Back 122

products> digestive caps> hepatic portal veins> liver caps> hepatic vein> general circulation

Front 123

first pass effect:

Back 123

drugs taken orally go to liver first to be metabolized

Front 124

bioavailability (amount of active drug) decreased if:

Back 124

large first pass: extensively metabolized by liver

Front 125

causes of ______:
-chronic alcohol use
-biliary obstruction
-viral hepatitis
-hepatoxic chems

Back 125

liver cirrhosis

Front 126

2 treatments for liver cirrhosis:

Back 126

remove inflammatory cause by: antiviral drugs & ant-inflammatory drugs

Front 127

bile is produced by hepatocytes & then
secreted into _______

Back 127

bile canaliculi

Front 128

bile flow:

Back 128

produced by hepatocytes>
bile canaliculi>
bile ducts (periphery of lobules)> hepatic ducts

Front 129

when bile enters SI to aid fat absorption, bile salts are absorbed & returned to liver, reenter bile duct, & recirculate, conserving bile salts. this is called:

Back 129

enterohepatic circulation

Front 130

functions of the ____:
-detoxifies blood
-produces bile, plasma proteins, glycogen, tryglycerides, & cholesterol (micelles)

Back 130

liver

Front 131

biles pigments are aka:

Back 131

billirubin

Front 132

-derivative of heme
-produced by spleen, liver, & bone marrow
-not water soluble

Back 132

bile pigments (billirubin)

Front 133

contains:
-bile pigment
-bile salts
-phospholipids
-cholesterol
-inorganic ions

Back 133

bile

Front 134

conjugation of billirubin (bile pigment)

Back 134

liver>> billirubin>> adds glucuronic acid= more water soluble & can now be secreted into bile

Front 135

conjugated billirubin can enter bile & then the intestine where it is converted to _____ by bacteria

Back 135

urobillirubin

Front 136

-gives feces its brown color
-filtered by kidneys also
-provides amber color to urine

Back 136

urobillirubin

Front 137

___(condition) occurs if:
-gallstones
-erythroblastosis fetalis (high RBC destruction)
-immature liver
Treat: blue UV lamp

Back 137

jaundice

Front 138

-cholesterol derivatives
-form micelles (emulsification)
-recirculated via enterohepatic circulation

Back 138

bile salts

Front 139

liver removes _____ from the blood by:
-excreting through bile
-chemically altering in hepatocytes
-phagocytic kupffer cells (sinusoids)

Back 139

drugs, hormones, etc

Front 140

why do the liver hepatocytes chemically alter a drug/hormone?

Back 140

inactivate compound solubilizing for renal excretion,
exceptions: sometime make it more active

Front 141

-enzymes that metabolize steroid molecules
-differences in drug sensitivity
-certain drugs can induce/ inhibit, accounts for interractions

Back 141

Cytochrome P450