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Anatomy 2 > Digestive System > Flashcards

Digestive System Flashcards

1
Q

digestive system

A

responsible for providing raw materials to support life: food molecules catabolized energy and building blocks to supply anabolic reaction

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2
Q

anabolism

A

uses raw materials to synthesize essential compounds

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3
Q

anabolic processes

A

cell division, repair, secretions, etc.

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4
Q

catabolism

A

decomposes substances to provide energy cells need to function

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5
Q

catabolic reactions require two essential ingredients to break down macromolecules

A

oxygen and organic molecules broken down by intracellular enzymes (ex. carbohydrates, fats and proteins)

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6
Q

components of the alimentary canal/gastrointestinal tract (G.I.)

A

oral cavity, pharynx, esophagus, stomach, small intestine, large intestine, rectum, anus

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7
Q

accessory digestive organs

A

teeth, tongue, salivary glands, liver, gallbladder, pancreas

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8
Q

digestive tract

A

gastrointestinal (GI) tract or alimentary canal
is a muscular tube
extends from oral cavity to anus

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9
Q

7 functions of the digestive system

A

ingestion, propulsion, mechanical processing, chemical digestion, secretion, absorption, excretion

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10
Q

ingestion

A

occurs when materials enter digestive tract via mouth

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11
Q

propulsion

A

move food through GI swallowing and peristalsis

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12
Q

mechanical processing

A

chewing, churning, mixing, compacting
makes materials easier to propel along digestive tract

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13
Q

chemical digestion

A

enzymatic chemical breakdown of large food molecules into small organic fragments (building blocks) for absorption by digestive epithelium

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14
Q

secretion

A

release of water, acids, enzymes, mucus, salts, and cell waste by epithelium of digestive tract and glandular organs

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15
Q

absorption

A

movement of organic substrates, electrolytes, vitamins, and water from the gut, into interstitial fluid, lymph, and blood

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16
Q

excretion

A

removal of cell waste products, secretions, indigestible foodstuffs from the body
defecation of feces

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17
Q

digestive activity (gland secretions or lumen movement) is controlled by

A

chemical or mechanical stimuli:
1. stretching
2. osmolarity (osmotic concentration)
3. pH

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18
Q

osmolarity measures

A

solute concentrations-> osmoles of solute particles per unit volume in secretion
substrate concentration
end product concentration

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19
Q

control of digestive function

A
  1. neural mechanisms
  2. hormonal mechanisms
  3. local mechanisms
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20
Q

neural mechanisms

A

enteric (or intrinsic) nervous system (ENS)
input from ANS (in CNS)

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21
Q

hormonal mechanisms

A

at least 18 hormones produced by enteroendocrine cells in GI: target may be same organ or distant organ
specific hormones for specific foods

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22
Q

local mechanisms

A

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

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23
Q

the lining of the digestive tract safeguards surrounding tissues against

A
  1. corrosive effects of digestive acids and enzymes
  2. mechanical stresses, such as abrasion
  3. bacteria either ingested with food or that reside in digestive tract
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24
Q

peritoneal cavity

A

most organs- in peritoneal cavity of abdomen
is located within two layers of serosa

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25
Q

cavity

A

lined with serosa, parietal peritoneum

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26
Q

organs

A

covered with serosa, visceral peritoneum

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27
Q

both serous membrane lining (parietal and visceral) secrete

A

peritoneal fluid

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28
Q

peritoneal fluid function

A

provides essential lubrication
allows sliding without friction or irritation

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29
Q

mesenteries

A

sheets of peritoneum
support a bulk of the digestive system

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30
Q

peritoneal organs

A

supported by mesenteries
double sheets of peritoneum serous membrane

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31
Q

retroperitoneal organs

A

anchored to body wall

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32
Q

functions of mesenteries

A

connect parietal peritoneum with visceral peritoneum
provide an access route to and from the digestive tract for passage of blood vessels, nerves and lymphatic vessels
stabilize positions of attached organs
prevent intestines from becoming entangled

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33
Q

mesentery development during embryonic development

A

digestive tract and accessory organs are suspended in peritoneal cavity by dorsal and ventral mesentery

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34
Q

special mesentery folds

A

lesser omentum, falciform ligament, greater omentum

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35
Q

lesser omentum

A

stabilizes position of stomach
provides access route for blood vessels and other structures entering or leaving liver

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36
Q

falciform ligament

A

helps stabilize position of liver

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37
Q

greater omentum

A

holds intestines hanging like an apron from lateral and inferior borders of stomach

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38
Q

adipose tissue in greater omentum

A

pads and protects surfaces of abdomen
provides insulation to reduce heat loss
stores lipid energy reserves

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39
Q

blood supply

A

digestive organs receive 1/4 cardiac output
this can increase following a meal
liver processes or absorbs nutrients from gut before blood returns to circulation

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40
Q

all venous return from GI enters

A

hepatic portal circulation
delivered to liver

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41
Q

disorders of peritoneal cavity

A

ascites
peritonitis

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42
Q

ascites

A

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

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43
Q

peritonitis

A

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

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44
Q

4 major layers along entire length of digestive tract

A
  1. mucosa
  2. submucosa
  3. muscularis externa
  4. serosa
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45
Q

mucosa

A

is the inner lining of digestive tract

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46
Q

mucosa functions to

A
  1. secrete mucus, digestive enzymes, and hormones
  2. absorb end products of digestion
  3. provide protection from pathogens
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47
Q

mucosa layers

A

A. epithelium
B. lamina propria
C. muscularis muscosae

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48
Q

mucosa epithelium

A

continuously renewed, surface cells last 2-6 days
stratified squamous-> mechanical stresses- oral cavity, pharynx, esophagus, anus
simple columnar-> absorption- stomach, intestines with goblet cells (mucus) and enteroendocrine cells (hormones)

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49
Q

lamina propria

A

loose areolar connective tissue with-> blood vessels, lymphatic vessels, nerves, mucous glands
lymphoid tissue (extending from submucosa)
MALT (mucosa associated lymphatic tissue e.g. Peyer’s patches) and tonsils

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50
Q

muscularis muscosae

A

bands of smooth muscles and elastic fibers
one layer circular, one layer longitudinal
functions to change shape of plicae and villi

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51
Q

villi

A

finger-like projections on the mucosa layer
increase surface area

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52
Q

plicae (small intestine)

A

permanent folds of mucosa and submucosa
increase surface area

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53
Q

rugae (stomach)

A

pleats of mucosa and submucosa
expand to accommodate volume

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54
Q

enteroendocrine and goblet cells

A

are scattered along columnar cells of digestive epithelium

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55
Q

enteroendocrine cells secrete hormones that

A

coordinate activities of the digestive tract and accessory glands

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56
Q

goblet cells secrete

A

gel-forming mucins

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57
Q

submucosa

A

layer of dense irregular connective tissue
surrounds muscularis mucosae
houses the submucosal nerve plexus

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58
Q

submucosa contains

A

large blood vessels and lymphatic vessels
exocrine glands: secrete digestive enzymes and mucus into digestive tract

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59
Q

submucosal nerve plexus

A

autonomic nervous system control of glands and smooth muscle of mucosa
also called the plexus of Meissner
innervates the mucosa and submucosa

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60
Q

submucosal plexus contains

A

sensory organs
parasympathetic ganglionic neurons
sympathetic postganglionic fibers

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61
Q

muscularis externa

A

is dominated by smooth muscle cells
is arranged in inner circular layer and outer longitudinal layer
contains the Myenteric Nerve Plexus

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62
Q

functions of smooth muscle

A

mixing and moving lumenal contents
circular layer thickened to create sphincters at junctions to prevent backflow

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63
Q

Myenteric Nerve Plexus

A

enteric nervous system- ENS
control GI mobility via local reflex arcs and ANS stimulation (mostly parasympathetic)

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64
Q

serosa

A

membrane covering muscularis externa
visceral peritoneum- areolar connective tissue plus mesothelium (simple squamous epithelium)
covers all abdominal/peritoneal GI tract organs except oral cavity, pharynx, esophagus and rectum

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65
Q

adventitia

A

covers muscularis externa of oral cavity, pharynx, esophagus and rectum
dense irregular connective tissue sheath of collagen fibers
function to anchor organs to surrounding tissues

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66
Q

movement of digestive materials

A

movement from visceral smooth muscle tissue
coordinated by short reflex arcs of ENS
peristalsis and segmentation

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67
Q

peristalsis and ENS

A

ENS also innervated by ANS allowing extrinsic control of digestive activity

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68
Q

parasympathetic

A

increase muscle activity and secretion
most ANS to the gut is parasympathetic

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69
Q

sympathetic

A

decrease muscle activity and secretions

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70
Q

peristalsis

A

waves of contraction
move food bolus along length of gut

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71
Q

segmentation

A

single point contractions
chop up bolus
allow enzymes to access inner regions

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72
Q

peristaltic motion

A
  1. circular muscles contract behind bolus- while circular muscles ahead of bolus relax
  2. longitudinal muscles ahead of bolus contract- shortening adjacent segments
  3. wave of contraction in circular muscles- forces bolus forward
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73
Q

oral cavity/mouth/buccal cavity

A

connects environment to pharynx
lined with stratified squamous epithelium
walls- muscular cheeks
floor contains tongue
roof- hard palate (anterior)
soft palate (posterior) with uvula- close off nasopharynx while swallowing

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74
Q

functions of the oral cavity

A
  1. analyze food: taste buds
  2. mechanically process food: chew
  3. lubricate food: saliva- mixing with mucus and salivary gland secretions
  4. digest starches: amylase- limited digestion of carbohydrates and lipids
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75
Q

oral cavity/mouth/buccal cavity accessory organs

A

tongue
salivary glands
teeth

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76
Q

tongue

A

muscular
surface covered by papillae
provide friction, house taste buds

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77
Q

salivary glands

A

produce 1-2 L saliva/day
saliva=99% water plus enzymes, electrolyte buffers, mucins, antibodies, antimicrobials

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78
Q

three pairs of salivary glands

A
  1. parotid salivary glands
  2. sublingual salivary glands
  3. submandibular salivary glands
    each pair produces saliva with different properties
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79
Q

parotid salivary glands

A

25% of saliva
inferior to zygomatic arch
produce serous secretion- enzyme salivary amylase (breaks down starches)

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80
Q

sublingual salivary glands

A

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

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81
Q
  1. submandibular salivary glands
A

posterior floor of mouth
secrete buffers, glycoproteins (mucins), and salivary amylase

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82
Q

salivary glands sympathetic vs parasympathetic

A

low levels saliva produced continuously
parasympathetic stimulate increase secretion: food cue
sympathetic stimulate decrease secretion: “dry mouth”

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83
Q

teeth

A

mastication, mechanical digestion
structure: pulp cavity, dentin, above and below gums

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84
Q

pulp cavity

A

soft center that receive blood vessels and nerves in CT from the root canal-> called pulp

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85
Q

dentin

A

bone like, surrounds pulp cavity, contains odontoblasts which secrete and maintain dentin throughout life

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86
Q

above and below the gums

A

crown- covered in enamel
root- covered in cementum, attached to periodontal ligaments

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87
Q

contain 4 types of teeth

A
  1. incisors
  2. cuspids (canines)
  3. bicuspids (premolars)
  4. molars
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88
Q

incisors

A

blade-shaped teeth, located at front of mouth
8 total used for clipping or cutting
have a single root

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89
Q

cuspids (canines)

A

conical shaped
4 total used for tearing and piercing
single root

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90
Q

bicuspids (premolars)

A

2 ridges/cusps
8 total used for crushing, mashing, grinding
one or two roots

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91
Q

molars

A

4-5 ridges/cusps
12 total used for crushing and grinding
three or more roots

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92
Q

under age 12

A

you have 20 deciduous/milk teeth
primary dentition
replaced by age 13-21-> you get 32 permanent teeth- secondary dentition

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93
Q

disorders of teeth

A
  1. impacted tooth
  2. dental caries
  3. periodontal disease
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94
Q

impacted tooth

A

fails to erupt
remains in jaw causing pain
surgical fix

95
Q

dental caries

A

demineralization of enamel and dentin by bacteria
exposes nerves-> pain

96
Q

periodontal disease

A

infection of gingiva (gums)
immunes response erodes bone around teeth-> teeth fall out

97
Q

the pharynx

A

a common passageway for solid food, liquids and air
connects oral cavity to esophagus
shared space with respiratory system
stratified squamous epithelium
lamina propria has tonsils and mucus glands
skeletal muscles surround for swallowing

98
Q

oropharynx

A

back of mouth

99
Q

laryngopharynx

A

superior to voice box

100
Q

esophagus

A

a hollow muscular tube, connects pharynx to stomach
about 25 cm long and 2 cm wide
passes through diaphragm to abdomen
at rest superior and inferior regions constricts to keep air out and stomach contents in

101
Q

inferior constriction point of esophagus

A

gastroesophageal sphincter

102
Q

“heartburn”

A

gastroesophageal reflux disease (GERD)
gastric juice regurgitates into esophagus causing erosion

103
Q

histology of the esophagus

A

stratified squamous epithelium
large folds in mucosa and submucosa to keep lumen closed during rest
esophageal glands in submucosa secrete mucus to reduce friction
upper 2/3 of muscularis externa contains skeletal muscle
adventitia anchors esophagus

104
Q

pharynx and esophagus

A

function in food propulsion from mouth to stomach

105
Q

deglutations (swallowing)

A
  1. buccal phase- voluntary
  2. pharyngeal phase- involuntary reflex
  3. esophageal phase- involuntary reflex
106
Q

stomach functions

A
  1. storage of ingested food (~1L)
  2. mechanical breakdown of ingested food- churning
  3. chemical breakdown of food- denature and digest proteins, disrupt chemical bonds in food by acids and enzymes
  4. produce intrinsic factor for vitamin B12 uptake- vitamin B12 necessary for erythropoiesis- glycoprotein required for absorption of vitamin B12 in small intestine
107
Q

chyme

A

stomach holds acidic mixture of enzymes and food
typically 1L but up to 4L

108
Q

four major regions of the stomach

A

fundus
cardia
body
pylorus

109
Q

fundus

A

superior region, contact diaphragm

110
Q

cardia

A

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

111
Q

body

A

majority of stomach
holds chyme
gastric glands secrete enzymes and acids for digestion

112
Q

pylorus

A

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

113
Q

features of the stomach

A

muscularis externa has 3 layers (+ oblique) assist mixing chyme
when empty mucosa and submucosa folds into rugae- can expand for large volume
mucosa has simple columnar epithelium with goblet cells that secrete alkaline mucus
mucosa perforated by deep gastric pits which connect to gastric glands in lamina propria
stem cells in gastric pits replace stomach epithelium every 3-6 days

114
Q

gastric glands

A

produce 1-3L gastric juice/day
secretions vary per region

115
Q

cardia gastric glands

116
Q

fundus and body gastric glands

A

digestive enzymes and acids

117
Q

two types of gastric cells

A

parietal cells & chief cells

118
Q

pyloric gastric glands

A

mucus and hormones

119
Q

2 important hormone producing gastric cells

A

G cells and D cells

120
Q

parietal cell secretions

A

intrinsic factor (Vitamin B12 uptake)
H+ and Cl- ions combine to make HCl in stomach

121
Q

chief cell secretions

A

pepsinogen
rennin

122
Q

pepsinogen

A

converted to pepsin by acid in stomach; hydrolyzes proteins

123
Q

rennin

A

infants only, curdles milk protein to aid digestion

124
Q

acid production important to gastric function

A
  1. kill microbes
  2. denature proteins- digestion, destroy enzymes in food
  3. break down plant cells walls and animal CT
  4. activate pepsin
125
Q

G cells

A

produce gastrin hormones
stimulates secretion by parietal and chief cells
promote contraction of gastric wall
secreted in response to food or parasympathetic stimulation

126
Q

D cells

A

produce somatostatin hormone
inhibits release of gastrin
thus inhibits gastric activity
secreted in response to sympathetic stimulation

127
Q

stomach disorders

A

gastritis
peptic ulcer

128
Q

gastritis

A

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

129
Q

peptic ulcer

A

erosion of stomach lining
caused by: too much acid and not enough mucus
most common: helicobacter pylori (bacteria)

130
Q

secretion and motility of gastric activity controlled by 3 factors

A
  1. innervation from CNS (ANS)
  2. reflexes of the ENS
  3. hormones
131
Q

mechanisms of gastric activity rely on stimuli from 3 regions

A

head, stomach, and small intestines

132
Q

3 phases of gastric regulation

A

cephalic, gastric, and intestinal phases
may all act simultaneously to alter gastric activity

133
Q

digestion in stomach

A

much digestion occurs in the stomach but not much absorption- except alcohol and drugs
food does not usually remain in the stomach for more than 4 hours, but total time depends on the chemical makeup of food

134
Q

how long it will take to digest in the small intestines

A

carbohydrate rich: pass quickly
fatty foods can cause chyme to remain in the stomach for 6+ hrs

135
Q

small intestines

A

major digestive organ
chemical digestion completed
90% of nutrients absorbed- remaining absorbed in large intestine
20 ft long, 3 major subdivisions

136
Q

3 major subdivisions of small intestines

A

duodenum
jejunum
ileum

137
Q

duodenum

A

first 10 inches
retroperitoneal (behind the peritoneum)
receives chyme from stomach through pyloric sphincter
receives digestive secretions from pancreas and liver through duodenal ampula controlled by hepatopancreatic sphincter
mixing pot

138
Q

jejunum

A

peritoneal
is the middle segment of small intestine-> 2.5 meters (8.2 ft) long
is the location of most: chemical digestion, nutrient absorption

139
Q

ileum

A

peritoneal
last 12 ft
mucosa rich in lymphoid tissue
connects to cecum at ileocecal valve

140
Q

small intestines histology

A

same 4 layers, but adapted for absorption
plicae, villi, microvilli

141
Q

plicae in small intestine

A

mucosa and submucosa folded into circular plicae
cause chyme to spiral slowly

142
Q

villi in small intestine

A

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

143
Q

microvilli of small intestine

A

simple columnar epithelial cells have microvilli on apical surface
membrane called brush border of intestines

144
Q

small intestines histology

A

plicae + villi + microvilli = 2200 ft2 surface area (compare to 3.6 ft2 for flat wall)
lamina propria of each villus contains capillaries- carry small nutrient molecules to liver via hepatic portal vein
larger molecules that cannot enter capillaries (lipid-protein complexes) are connected by special lymphatic capillary called a lacteal
contractions of muscularis mucosae: move villi to expose surface to new chyme, squeeze lacteal to more lymph

145
Q

glands of small intestine

A

goblet cells
intestinal glands

146
Q

goblet cells of small intestine

A

between columnar epithelial cells
secrete mucus (mucin)

147
Q

intestinal glands of small intestine

A

variety of cells in the crypts
located in the lamina propria at the base of each villus
produce many products- intestinal juice, lysozyme, hormones

148
Q

intestinal juice

A

(1-2L/day)
watery mucus, aids solubilization and absorption of nutrients

149
Q

lysozyme

A

from Paneth cells, lyse bacteria

150
Q

hormones

A

from enteroendocrine cells
all control GI activity
intestinal gastrin, cholecystokinin, secretin, gastric inhibitory peptide, vasoactive intestinal peptide, somatostatin, enterocrinin

151
Q

intestinal cell regeneration

A

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

152
Q

brush border enzyme

A

complete digestion of carbohydrates and proteins

153
Q

small intestinal movements

A

chyme arrives in duodenum
weak peristaltic contractions move it slowly toward jejunum
Myenteric reflexes- not under CNS control
parasympathetic stimulation accelerates local peristalsis and segmentation

154
Q

Myenteric reflexes (ENS)

A

peristalsis to move chyme slowly through the small intestine

155
Q

parasympathetic reflexes (stretch receptors)

A

accelerate movement
gastroenteric reflex
gastroileal reflex

156
Q

gastroenteric reflex

A

stimulates motility and secretion along entire small intestine

157
Q

gastroileal reflex

A

relaxes ileocecal valve
materials pass from ileum to cecum

158
Q

pancreas

A

retroperitoneal
inferior to stomach
regions of the pancreas
head- broad, in loop of duodenum
body- slender, extends toward spleen
tail- short and rounded

159
Q

lobules of the pancreas

A

are separated by connective tissue (septa)
contain blood vessels and tributaries of pancreatic ducts

160
Q

in each lobule of pancreas

A

ducts branch repeatedly
end in blind pockets (pancreatic acini)

161
Q

pancreatic acini (exocrine)

A

acinar cells= simple cuboidal epithelium
produce digestive enzymes and buffers-> pancreatic juice

162
Q

pancreatic islets (endocrine) 1%

A

cells secrete insulin (increase storage of glucose-> decreases blood sugar levels) and glucagon (increase blood sugar levels) to control blood sugar

163
Q

pancreatic juice

A

~1-1.5L/day in response to parasympathetic and hormonal control
water + electrolytes (buffer)
contain pancreatic enzymes: pancreatic alpha-amylase, pancreatic lipase, nucleases, proteolytic enzymes

164
Q

pancreatic enzymes

A

~70% secreted as proeznymes, activated in the gut
1. pancreatic alpha-amylase- hydrolyzes starch
2. pancreatic lipase- hydrolyzes lipids and fatty acids
3. nucleases- hydrolyzes nucleic acids (RNA, DNA)
4. proteolytic enzymes- MAJORITY

165
Q

proteolytic enzymes

A

many, each digests specific peptide bonds
2 main classes- proteases, peptidases
all proteolytic enzymes are secreted inactive
MUST be activated in the gut, this prevents autolysis

166
Q

proteases

A

hydrolyze large proteins into peptides

167
Q

peptidases

A

hydrolyze peptide chains into amino acids

168
Q

pancreas exocrine secretions

A

pancreatic juice is released into pancreatic ducts-> joins with the common bile duct-> enters duodenum at duodenal ampula-> controlled by the hepatopancreatic sphincter

169
Q

disorders of the pancreas

A

pancreatitis
diabetes mellitus

170
Q

pancreatitis

A

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

171
Q

diabetes mellitus

A

destruction of islet cells
cause-> pancreatitis or autoimmune attack
result-> loss of regulation of blood sugar levels

172
Q

the liver

A

is the largest visceral organ (1.5 kg)
right side, inferior to diaphragm
four lobes
anterior- large right and left lobes- separated by falciform ligament= fetal umbilical vein
posterior: tiny caudate lobe and quadrate lobe

173
Q

lobules

A

hexagonal function units
separated by interlobular septa
central vein in the middle
six portal triads on hexagonal corners

174
Q

hepatic artery

A

oxygen rich blood

175
Q

hepatic portal vein

A

nutrient rich blood from small intestine

176
Q

bile duct

A

collect bile produced by hepatocytes

177
Q

hepatocytes

A

function in nutrient regulation and bile production
arranged in rows around central veins with sinusoids between rows

178
Q

blood flow in lobule

A

blood from arteries and veins of triads flows through sinusoids
allows molecule exchange with hepatocytes
blood flows out through the central vein

179
Q

Kupffer cells

A

sinusoids also contain Kupffer cellls (fixed macrophages)
functions to remove pathogens cell debris, damaged erythrocytes
remove and store ion
remove and store lipids
remove and store heavy metals

180
Q

bile flow

A

bile secreted by hepatocytes-> flows through bile canaliculi between cells-> bile ducts of triads-> merge into common hepatic duct-> exits the loiver-> joins cystic duct from gallbladder creating common bile duct-> connects to duodenum at duodenal ampula controlled by hepatopancreatic sphincter

181
Q

3 functions of liver

A
  1. metabolic regulation
  2. hematological regulation
  3. digestive: bile production and secretion
182
Q

metabolic regulation of liver

A

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

183
Q

carbohydrates metabolism

A

too much glucose-> hepatocytes store glucose an glycogen
too little glucose-> hepatocytes break down glycogen or perform gluconeogenesis (synthesis from non-card) to release glucose

184
Q

hepatocytes also carry out

A

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

185
Q

composition of circulating blood

A

all blood leaving absorptive surfaces of digestive tract: enters hepatic portal system, flows into the liver
liver cells extract nutrients or toxins from blood: before it reaches systemic circulation through hepatic veins
liver removes and stores excess nutrients: corrects nutrient deficiencies by mobilizing stored reserves or performing synthetic activities

186
Q

hematological regulation

A

liver serves as blood reservoir
kupffer cells- recycle RBCs and perform antigen presentation to lymphocytes
hepatocytes- remove/recycle hormones, remove antibodies, produce plasma proteins
hepatocytes and kupffer cells remove, inactivate, or store toxins, drugs, and heavy metals

187
Q

bile components

A

water, bilirubin, phospholipids, electrolytes, cholesterol, bile salts (lipids)

188
Q

bile functions

A

buffer chyme with electrolytes
emulsify fats- break large lipid globs into small droplets of phospholipids and bile salts

189
Q

functions of emulsification

A

allow enzymes to access lipids
promote solubilization and absorption of lipids in blood and lymph

190
Q

disorders of the liver

A

hepatitis
cirrhosis

191
Q

hepatitis

A

inflammation of liver
cause-> viral infection
result-> restricts blood flow to liver
six known viruses with different severity

192
Q

cirrhosis

A

chronic inflammation
cause-> severe hepatitis or alcoholism
result-> damaged hepatocytes are replaced by fibrous tissue and adipose
results in portal hypertension-> veins swell and rupture

193
Q

the gallbladder

A

anterior and inferior to liver
functions to concentrate and store bile produced by liver

194
Q

cholecystokinin (CCK) from duodenum causes:

A
  1. release of bile by stimulating contraction of gallbladder
  2. relaxation of hepatopancreatic sphincter
195
Q

disorders of the gallbladder

A
  1. gall stones- crystalizations of over concentrated bile
  2. cholecystitis- inflammation caused by large gall stones that block or damage the gallbladder
196
Q

the large intestine

A

~5 feet long
less than 10% of nutrient absorption
prepares fecal matter for ejection from the body
no digestion, except by microbes
water absorption important to feces consistency
too much water = diarrhea
too little water = constipation

197
Q

functions of large intestine

A
  1. reabsorb any remaining water and compact feces
  2. absorb vitamins and electrolytes
  3. storage of feces and defection
198
Q

3 parts of large intestine

A
  1. cecum- the pouchlike first portion
  2. colon- the larges portion
  3. rectum- the last 15 cm of digestive tract
199
Q

cecum

A

attached to ileum via ileocecal valve
function-> begin compaction of feces
appendix on side- has lymphoid nodules that are part of the MALT

200
Q

appendicitis

A

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

201
Q

colon

A

absorbs water, vitamins, electrolytes
four major regions: ascending colon, transverse colon, descending colon, sigmoid colon

202
Q

diverticulitis

A

pockets form in the colon wall
site of recurrent inflammation and infection
due to lack of fiber

203
Q

rectum

A

stores feces
has 3 valves to separate feces and flatus
exits at anal canal
lined with stratified squamous epithelium

204
Q

defecation controlled by two sphincters

A
  1. internal anal sphincter- involuntary control, smooth muscle from muscularis externa
  2. external anal sphincter- voluntary control- skeletal muscle under voluntary control
205
Q

bacteria of large intestine

A

~2 lb bacteria in gut
some produce vitamins
vitamin K, biotin, vitamin B5

206
Q

vitamin K

A

clotting factor synthesis

207
Q

biotin

A

glucose metabolism

208
Q

vitamin B5

A

steroid hormone and neurotransmitter synthesis

209
Q

histology specialization of large intestines

A

muscularis externa made up of three longitudinal bands of smooth muscle called-> taeniae coli
contraction of taeniae coli produces pouches called-> haustra
mucosa has deep crypts with intestinal glands that produce mucus
no plicae and vili
lamina propria has large lymphoid nodules
epithelium is simple columnar with abundance of goblet cells

210
Q

large intestine movements

A
  1. haustral contractions
  2. mass movements
  3. defecation reflex
211
Q

haustral contractions

A

local, slow segmenting contractions
shift feces for water absorption

212
Q

mass movements

A

powerful peristaltic contractions
force feces toward rectum
occur few times/day
can trigger defecation reflex via stretch receptors in rectum

213
Q

defecation reflex

A

stretch receptors-> parasympathetic stimulation->
1. contraction of sigmoid colo
2. relaxation of internal anal sphincter
voluntary control of external anal sphincter controls timing of defecation

214
Q

time in colon controls water absorption

A

movement too fast-> too much water in feces = diarrhea
movement too slow-> too little water in feces = constipation

215
Q

chemical digestion

A

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

216
Q

a balanced diet contains:

A

carbohydrates, lipids, proteins, vitamins, minerals, water

217
Q

carbohydrate digestion method

A

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

218
Q

carbohydrate absorption method

A

facilitated diffusion or cotransport of monosaccharides
cellulose not digest: “bulk” fiber, aids intestinal mobility

219
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

220
Q

lipid digestion method

A

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

221
Q

lipid absorption method

A

micelles form-> monoglycerides, fatty acids and bile salts
micelles absorbed by intestinal epithelium
proteins added = chylomicron (water soluble)
chylomicrons exocytosed into lumen
chylomicrons absorbed by lacteal

222
Q

protein digestion method

A

mastication (mouth)
churning (stomach)
pepsin + acid (stomach)- protein-> polypeptide
protease + peptidases (pancreas, brush border)- polypeptide-> amino acids

223
Q

protein absorption method

A

facilitated diffusion or cotransport of amino acids

224
Q

nucleic acid digestion method

A

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

225
Q

nucleic acid absorption method

A

active transport of nitrogenous bases + sugar + phosphate ions

226
Q

water digestion method

A

no digestion required
2L from food, 7L from secretions

227
Q

water absorption method

A

osmosis (95% in small intestine)
~150 mL lost in feces

228
Q

ions

A

from food and secretions
must be regulated for homeostasis
control osmosis and pH, needed for enzyme function

229
Q

ions digestion method

A

no digestion required
Na+, Ca++, K+, Mg++, Fe++, Cl-, I-, HCO3-

230
Q

ions absorption method

A

diffusion, cotransport. active transport

231
Q

vitamins digestion method

A

no digestion required
fat soluble: A, D, E, K
water soluble: most B vitamins, C, vitamins B12

232
Q

vitamins absorption method

A

fat soluble: mixed with fats in micelle-> chylomicrons
water soluble B and C: diffusion
water soluble B12: bound to intrinsic factor-> binds receptors-> endocytosed

233
Q

aging on the digestive system

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

Anatomy 2 (8 decks)

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