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Structure And Function Of Living Organisms > Digestive system > Flashcards

Digestive system Flashcards

1
Q

Why does the tongue have grooves on it

A

because of how it developed - fusion of embryo

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2
Q

What can the posterior area of the tongue do and contain

A

bends back into the throat and contains tissue that is involved in the immune system

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3
Q

What does the front area of the tongue contain

A

taste buds

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4
Q

Why does the tongue contain tissue that is involved in the immune system

A

protects against organisms that may get through the epithelium

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5
Q

What do intrinsic muscles of the tongue do

A

shortens/widens/curls the tongue

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6
Q

What do extrinsic muscles of the tongue do

A

protrudes/retracts the tongue. Frenulum – stops tongue from flipping backwards.

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7
Q

Function of the palate of the mouth

A

separates the oral cavity from the nasal cavity. Hard plate – front. Soft palate – shuts off nasal from oral when you swallow.

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8
Q

Function of transverse mucosal ridges

A

stop the front of the tongue slipping so food goes backwards

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9
Q

Name the 3 salivary glands

A

parotid, submandibular, sublingual

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10
Q

What do parotid salivary galnd secrete

A

serous (watery saliva)

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11
Q

Where are the parotid salivary galnds located

A

in the cheeks around ear

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12
Q

What do submandibular salivary glands secrete

A

thin seromucous

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13
Q

Where is the submandibular gland found

A

Below the jaw - long duct

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14
Q

What does the sublingual salivary gland secrete

A

mucous

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15
Q

Where us the sublingual gland located

A

under the tongue - lots of short ducts

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16
Q

What keeps the mouth moist

A

hundreds of minor salivary glands

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17
Q

Function of the pharynx

A

channels food into the esophagus

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18
Q

Function of the larynx

A

separates what you swallow from what you are breathing

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19
Q

What are the 3 pharyngeal constrictors

A

superior, middle and inferior constrictor muscles

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20
Q

Location and function of pharyngeal constrictors

A

encircle the larynx and pharynx, they constrict the airway to help with swallowing. (

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21
Q

Oesophagus location and function

A

muscular tube, pharynx to stomach, passes through diaphragm. Carries food and liquid from your throat to your stomach

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22
Q

Stomach location

A

below the diaphragm

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23
Q

Cardiac sphincter function

A

prevents the backflow of stomach acids and content into the esophagus

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24
Q

Pyloric sphincter function

A

controls the release of chyme from the stomach into the duodenum

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25
Q

Fundus function

A

stores gas that is a by product of digestion

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26
Q

The cardiac region contains a valve - what is its function

A

preventing food from backing up into the stomach

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27
Q

What facilitates the passage of saliva/liquids when swallowing

A

curvatures

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28
Q

What is pylorus and what is its function

A

a valve that allows partly digested food to enter the small intestine.

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29
Q

Rugae in stomach function

A

some protein digestion (pepsin), reduction of solid food to loose, semisolid chyme, delivery of chyme to duodenum

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30
Q

Rugae acting as a hopper

A

receives material irregularly, stores and delivers them regularly to duodenum until empty

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31
Q

What intrinsic factor does rugae make

A

one that is needed for absorption of vitamin B12 in intestine.

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32
Q

What does the jejunum absorb

A

absorbs sugars, amino acids and fatty acids

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33
Q

What are the parts of the small intestine and what is the length

A

Duodenum (25cm) , jejunum (1m) and ileum (2m)

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34
Q

Small intestine4 location

A

tightly folded within the abdomen

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35
Q

Small intestine function

A

Completes digestion, absorbs its products into blood and lymph streams

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36
Q

What does the duodenum recieve

A

acid material from stomach; protected by mucus glands. Receives products of pancreas and bile from liver – common duct.

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37
Q

What is the shape and location of the duodenum

A

C shaped, bent around the head of pancreas, on back wall of abdomen

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38
Q

Where is bile secreted to

A

intermittent secretion from pancreas: both to common duct, sphincter to duodenum. Bile stored in gall bladder until pancreatic secretions released.

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39
Q

When is bile released

A

when chyme enters duodenum; sphincter relaxes, gall bladder contracts, bile and pancreatic juice mixes with chyme.

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40
Q

Function of bile

A

allows mixing of pancreatic enzymes and fatty food material: lowers surface tension and emulsifies fat

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41
Q

What is the role of mesenterys in tyhe small intestine

A

to make sure it is highly folded and to keep it in place

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42
Q

What are mesentaries

A

folds of peritoneum

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43
Q

What are the 2 peritoneum

A

visceral and parietal

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44
Q

Where is the mesentary attached to

A

posterior abdomen wall

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45
Q

What are the moevments of the small intestine

A

Peristaltic movements propel food along

Intermittent churning movements for mixing – segmentation

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46
Q

What controls the movements of the small intetsine

A

myenteric plexus of nerves within muscle layers of gut wall.

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47
Q

What is the at the end of the small intestine

A

the ileo-caecal valve

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48
Q

Length of the appendix

A

2-20cm

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49
Q

What is the total length of the large intetsine

A

1.6m

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50
Q

Sections of the large intetsine

A

caecum, colon, rectum and anal canal

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51
Q

Does the large intetsine contain mesentaries

A

yes - lots of them

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52
Q

What are the 4 colons in order

A

ascending colon, transverse colon, descending colon and sigmoid colon

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53
Q

Which parts of the colon do not have mesentaries

A

ascending and descending colon - attached to rear abdominal wall

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54
Q

What is the sigmoid colon also called

A

pelvic colon

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55
Q

When does material reach the small intestine after ingestion

A

3-4 hours

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56
Q

Large intestine function

A

water and ion absorption, formation of faeces

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57
Q

When does material reach the sigmoid colon

A

12 hours after ingestion

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58
Q

Peristalsis contractions

A

Large intestine undergoes peristalsis and churning to mix contents

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59
Q

What does a strong peristaltic wave do

A

pushes gut contentsto pelvic colon; after about 24h, contents move to rectum – immediate desire to defecate

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60
Q

mass movement of gut contents

A

set off by gastro-colic reflex from stomach; strongest stimulus with first meal of the day

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61
Q

What triggers defecation

A

disintention of rectum walls. Contraction of colon, relaxation of involuntary sphincter. Voluntary sphincter gives conscious control.

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62
Q

What is the oral cavity lining

A

the oral mucosa

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63
Q

What are the 3 layers of the oral mucosa

A

masticatory mucosa (bashed about when chewing), specialised muscosa tongue (top surface of the tongue), ordinary lining mucosa

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64
Q

Where is the masticatory mucosa found

A

gingiva and hard plate

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65
Q

What epithelium is found in the masticatory mucosa

A

stratified squamos keratinized

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66
Q

What anchors the epithelium in the masticatory mucosa

A

collagen fibres in the submucosa. Attached to basal lamina

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67
Q

Why does the masticatory mucosa have a wavy epitherlium

A

greater surface area for anchorage- hard palate is where epithelium is strongly attached

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68
Q

masticatory mucosa fatty zone

A

provides cushoining for chewing

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69
Q

masticatory mucosa galndular zone

A

contains secretory cells so its moist

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70
Q

Where is the lining mucosa found

A

nside of lips, underside of tongue, soft palate, gums away from gingiva

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71
Q

Epithelium in lining mucosa

A

stratified squamos non-keratinised epithelium

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72
Q

What does the lining mucosa contain

A

lots of minor salivary glands in the submucosa

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73
Q

What is the posterior part of the tongue

A

tonsils

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74
Q

what does the anterior 2/3 of the tongue4 contain

A

lingual papillae which make up specialised mucosa

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75
Q

What are the 4 types of lingual papillae

A

filiform papillae (sharp), fungiform papille (tastebuds), foliate papillae (tastebuds), valiate papillae (form inverted v shape separating posterior from anterior).

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76
Q

What is the foramen caecum

A

site of which thyroid gland developed

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77
Q

Filiform papillae features

A

point, covered in stratified squamos keratinised epithelium giving abrasive surface to the tongue. Good for when chewing.

78
Q

Fungiform papillae features

A

rounded, have taste buds in the wall, central core made of loose connective tissue containing blood vessels and nerves

79
Q

Vallate papillae features

A

large (size of the head of the match), back surface of the tongue, pressed into the surface and surrounded by a groove. Taste buds are in the side walls. Blue things - specialised salivary glands that pump saliva into the back of the groove.

80
Q

Structure of taste buds

A

occupy whole thickness of epithelium. Nerves at the bottom and carry taste information. Hollow ball made up of cells round the outside. Supporting cells and sensory cells. Basal cells at the bottom that can grow up to replace other cells.

81
Q

4 types of taste buds

A

sweet, bitter, acid, salt.

82
Q

What are the 4 layers of the gut wall

A
  1. mucosa
    2.submucosa
  2. muscularis externa
    4.Adventitia/serosa
83
Q

Muscularis externa 2 smooth muscle layers

A

inner circular layer (contraction narrows the tube), outer longitudinal layer (contraction scrunches it up)

84
Q

Where is the nerve plexus located

A

in mucosa and muscularis externa

85
Q

What makes up the serosa

A

connective tissue

86
Q

Esophagus lining

A

stratified squamos non keratinised epithelium

87
Q

Mucus in the esophagus

A

lubrication - helps pass food into stomach. Protects lining from acidic splashback

88
Q

Why are various muscle types needed in the esophagus

A

swallowing is a voluntary activity, so we need skeletal muscle but once we have swallowed we want our auomatic system to take over which is smooth muscle, mixed in the middle for the transition.

89
Q

What is the additional layer to the muscularis externa in the stomach

A

an oblique muscle layer

90
Q

Function of rugae

A

helps stomach expand because they can be pulled out straight, prominent when stomach empty. Large easily visible to naked eye.

91
Q

Function of the mucous in the stomach

A

protects epithelium while still allowing you to absorb minerals. Every cell secretes mucous - protective mechanism

92
Q

What is the epithelium in the sgtomach

A

simple epithelium

93
Q

What makes HCl and pepsinogen

A

gastric glands - once released HCl etc enters the bottom of gastric pits

94
Q

What are plicae circulares and where are they found

A

circular folds of the submucosa - in duodenum

95
Q

What epithelium is found in the intetsine and advantage to that

A

simple columnar absorptive epithelium - allows for more cytoplasm containing more golgi

96
Q

What are microvilli

A

projections of plasma membrane supported by cytoskeleton

97
Q

What creates crypts of lieberkuin

A

villi poking outwards into interior gut causing tubular depressions

98
Q

why do gut cells need to be continuously replaced

A

it is a hostile environment so cells only live a few days - retains ability to absorb nutrients

99
Q

Where are stem cells located in the intetsine

A

at the bottom of the crypts of lieberkuhn - move upwards to replace damaged cells

100
Q

What are taenia coli

A

the longitudinal smooth muscle split into 3 ribbons that run longitudinally along colon 120 degrees from each other

101
Q

What are haustrae/sacculations

A

contraction of the longitudinal smooth muscle layer creating bulges

102
Q

function of haustrae

A

pushes chyme from one sac to the next - aided by the appendices epipcloe

103
Q

What part of the anal canal is under voluntray and involuntary control

A

inside - involuntary.

103
Q

What part of the anal canal is under voluntray and involuntary control

A

inside - involuntary. outside - voluntary

104
Q

Which muscle is present in the anal canal

A

skeletal muscle

105
Q

What are longitudinal folds in the anal xanal

A

helps stomach expand because they can be pulled out straight, prominent when stomach empty. Large easily visible to naked eye.

106
Q

Where is the stronger epithelium in the anal canal

A

at the end

107
Q

What are the 3 phases of gastric secretion

A

cephalic, gastric and intestinal

108
Q

cause of cephalic phase

A

sensation and thoughts (to either increase or decrease appetite)

109
Q

Cephalic phase effect

A

cerebral cortex/hypothalamus

110
Q

Transmission of signals in cephalic phase

A

Parasympathetic - vagus ( x cranial nerve)

111
Q

Neural negative feedback in the gastric phase

A

stretch receptors and chemoreceptors routed via the submucosal plexus – peristalsis stimulated

112
Q

What is the result of the hormonal negtaive feedback mechanism

A

emptying

113
Q

When is gastrin secretion inhibited

A

when pH < 2, stimulated when pH rises

114
Q

Where is gastrin transported to

A

the gastric glands, travels through the blood stream

115
Q

Function of gastrin - motility

A

stimulates gastric secretions, contraction of lower eosphageal (cardiac) sphincter, increases motility, relaxes pyloric sphincter.

116
Q

Function of gastrin - controls of HCl secreting parietal cells

A

stimulated by 3 signal chemicals: gastrin, acetylcholine, histamine (additive response, all 3 needed for strong H+ secretion)

117
Q

What is the intestinal phase

A

food entering the intestine and having an effect on the stomach

118
Q

Intestinal phase events

A

Stretch receptors respond

Chemoreceptors detect fatty acids and glucose in the chyme in the duodenum

Entereoendocrine cells in the stomach release gastrin

Increases gastric peristalsis and gastric emptying

119
Q

what do enteroendocrine cells release and inhibit

A

cholecystokinin (CCK), gastric inhibitory peptide (GIP), secretin. They inhibit gastric secretion.

120
Q

What stimulates the pancreas

A

food entering the duodenum, neuronal input, secretion of secretin and GIP from duodenum

121
Q

What stimulates bile production in liver

A

parasympathetic impulses along vagus (X)

122
Q

What stimulates secretion of CCK into blood stream

A

fatty acids and amino acids in chyme entering the duodenum

123
Q

What stimulates secretion of secretin

A

acid chyme entering the duodenum

124
Q

What does CCK cause

A

contraction of gallbladder causing bile to enter the duodenum to emulsify fats for digestion and absorption. Makes you feel full

125
Q

What does secretin do

A

enhances flow of bile rich in HCO3- from liver. Promotes production and secretion of bile from liver to gall bladder

126
Q

What causes gastrin to be secreted

A

food in stomach

127
Q

Gastrin function and effect on motility

A

stimulates secretion of HCl and pepsin - increases motility of stomach

128
Q

CCK - hunger signals

A

reduces appetite and inhibits eating - hypothalamus is the neurotrabsnitter to inhibit eating

129
Q

What is the ‘illeal brake’

A

slows all gastric emptying - not as hungry

130
Q

What other compounds transmit satiety (not hungry) signals

A

Glucagon - like peptide - 1 and peptide YY (PYY) - from intestine in response to food

131
Q

Ghrelin function

A

increases hunger, growth hormone secretion and fat store

132
Q

What secretes ghrelin

A

endocrine cells in gastric mucosa

133
Q

Ghrelin’s neural pathway

A

binds to GHSR in hypothalamus - growth hormones secretagogue receptors

134
Q

What are the long term satiety signals

A

leptin, insulin and estrogen - act to lower body weight

135
Q

what do the long term satiety signal compounds target

A

anorexigenic pro-opiomelanocortin (POMC) neuron

136
Q

Function of leptin

A

increases activity of melanocortin pathway, both hormones and receptors - suppresses appetite

137
Q

What signals control appetite

A

Arcuate nucleus (ARC), Pro-opiomelanocortin (POMC), cocaine-amphetamine regulated transcript (CART)

138
Q

Where in the hypothalamus does the melanocortin system occur

A

arcuate nucleus

139
Q

What activates the melanocortin system

A

POMC and CART

140
Q

What inhibits the melanocortin system

A

NPY and AgRP

141
Q

What hormones are part of the melanocortin syystem

A

Peptides adrenocorticotropin and melanocyte stimulating (MSH) hormones

142
Q

What does the melanocortin system do

A

decreases food intake (anorexigenic) - integrates short and long term signals

143
Q

What supresses NPY/AgRP

A

insulin and leptin

144
Q

Where are the neurotransmitters for NPY and AgRP

A

hypothalamus

145
Q

Function of NPY

A

activates its receptor which are GPCR. Stimulates eating

146
Q

Function of AgRP

A

binds to and inhibits MC4R, inhibits anorexigenic effects of alpha – MSH

147
Q

How much does the rumen account for of an animals body weight

A

10-20%

148
Q

What increases the surface area of the rumen

A

finger like projections

149
Q

What is the contents and function of the rumen

A

85-93% water (large vessel containing aqueous environemnt)(fermentation vessel)

150
Q

How much slaiva do cows produce a day

A

150L

151
Q

Function of ruminal papillae

A

increase surface area - helps absoprtion occur in rumen

152
Q

Epithelium in rumen

A

stratified squamos epithelium - keratinised

153
Q

Food being reswallowed

A
  1. Material drawn back into the oesophagus and muscle contractions return it to the mouth
  2. Liquid rapidly re-swallowed, coarse material chewed again before swallowing
  3. Each bolus chewed 40-50 times
154
Q

Where are microorganisms for fermentation found

A

in the rumen and reticulum

155
Q

What relationship occurs between microorganisms in the rumen and the bacteria

A

symbiotic

156
Q

What kind of microoganisms are found in the reticulo-rumen

A

anaerobic bacteria and fungi. Heterotophic and autotrophic

157
Q

How are there complex interrelationships in the rumen

A

methanogens reduce efficiency but impact on growth of other species

158
Q

What is a chemostat

A

fresh medium is continuously added - waste products are continuously removed. Helps regulate the growth rate - rumen is one

159
Q

How many microorganisms does each mm of rumen contain

A

10 to 50 billion bacteria, 1 million protozoa + yeasts + fungi

160
Q

What does fermentation in rumen produce

A

volatile fatty acids (VFAs) which are absorbed, gas and more microorganisms (more than 30L/hr)(~40% CO2, ~30-40% CH4. ~5% H2)

161
Q

Structural changes of the rumen during development

A

At birth the abomasum is the largest chamber

At 18 months the reticulorumen occupies > 90% of the stomach

162
Q

Structure of the reticulum

A

hexagonal structures - each structure is a ring of muscle that contracts

163
Q

Reticulum epithelium

A

keratinised stratified squamos epithelium

164
Q

Function of reticulum

A

particle sorting

165
Q

Muscularis mucosa in the reticulum

A

around top of each compartment. Aid separation, mixing and breakdown

166
Q

Omasum location

A

gateway between fermentation vessel and stomach

167
Q

Omasum function

A

Regulates entry to food into the abomasum

May return food to the reticulo-rumen

Water and VFA absorption

168
Q

Abomasum function

A

true stomach (like fundus) - same digestive functions as humans

169
Q

Compartments of the abomasum

A

Oesophagael groove, Glandular, Gastric pits, Parietal and chief

170
Q

Epithelium in the abomasum

A

simple columnar epithelium

171
Q

Monomer of cellulose and bonds

A

glucose units bound by beta 1-4 linkages

172
Q

Hydrogen bonds in cellulose

A

decreases flexibility, high tensile strength, low solubility in water of dilute acid. Allows development of crystalline lattice

173
Q

What is hemicellulose

A

Mixture of: pentose, hexose, uronic acids bound to a beta – 1,4 linked core composed primarily of xylose

Closely bound to lignin than cellulose

174
Q

What is lignin

A

poorly defined polymer of phenylpropane

175
Q

What does lignin do

A

Binds to hemicellulose only, forms a matrix around cellulose, increased strength under compression

176
Q

What is the effect of lignification

A

reduces digestibility

177
Q

Where does cellulose digestion occur

A

in the reticulorumen

178
Q

Cellulose digestion - step 1

A

Transport of bacteria to fiber (slow, dependent on number of bacteria)

179
Q

Cellulose digestion - step 2

A

Nonspecific adhesion (binds to glycocalyx, most commonly at cut or macerated areas)

180
Q

cellulose digestion - step 3

A

Specific adhesions of bacteria with digestible cellulose: cellulososme (large, multienzyme complexes for adhesion and hydrolysis of cellulose) Fimbriae (attatchemnt pilli) (small (5-7 x 100-200nm) structure in gram + and – bacteria.

181
Q

What does the cellulose binding domain do

A

brings cellulose into contact with hydrolases

182
Q

Structure of starch

A

amylose (glucose units bound by alpha 1,4 – linkages) and amylopectin (glucose units by alpha 1,4 – linkages with alpha 1,6 – branch points)

183
Q

Where is starch digested

A

majority digested in rumen

184
Q

What enzyme breaks down starch

A

by alpha-amylase to oligosaccharides which degrade to glucose

185
Q

Where is alpha amylase found

A

d in cell-free rumen fluid, but 70% associated with paticulate bound microorganisms. Activity increases in high grain diets

186
Q

protozoa uptake in starch digestion

A

stabilises fermentation and less readily passed from rumen

187
Q

bacteria uptake in starch digestion

A

storage polysaccharide. May account for as much as 50% of carbohydrate leaving rumen

188
Q

What produces volatile fatty acids

A

end product of microbial carbohydrate digestion

189
Q

What factors increase propionate

A
  1. Decreased forage and increased concentrate
  2. Decreased physical form of diet
  3. Unsaturated fatty acids
190
Q

Where are proteins digested in cows

A

microorganisms in the reticulorumen

191
Q

Protein digestion

A

Most of the protein that reaches the abomasum will be of microbial origin

There is an optimum level of ammonia in the reticulorumen (can add urea to the diet from which they can make amino acids)

Structure And Function Of Living Organisms (10 decks)

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