Digestive system Flashcards
1
Q
Why does the tongue have grooves on it
A
because of how it developed - fusion of embryo
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
3
Q
What does the front area of the tongue contain
A
taste buds
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
5
Q
What do intrinsic muscles of the tongue do
A
shortens/widens/curls the tongue
6
Q
What do extrinsic muscles of the tongue do
A
protrudes/retracts the tongue. Frenulum – stops tongue from flipping backwards.
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.
8
Q
Function of transverse mucosal ridges
A
stop the front of the tongue slipping so food goes backwards
9
Q
Name the 3 salivary glands
A
parotid, submandibular, sublingual
10
Q
What do parotid salivary galnd secrete
A
serous (watery saliva)
11
Q
Where are the parotid salivary galnds located
A
in the cheeks around ear
12
Q
What do submandibular salivary glands secrete
A
thin seromucous
13
Q
Where is the submandibular gland found
A
Below the jaw - long duct
14
Q
What does the sublingual salivary gland secrete
A
mucous
15
Q
Where us the sublingual gland located
A
under the tongue - lots of short ducts
16
Q
What keeps the mouth moist
A
hundreds of minor salivary glands
17
Q
Function of the pharynx
A
channels food into the esophagus
18
Q
Function of the larynx
A
separates what you swallow from what you are breathing
19
Q
What are the 3 pharyngeal constrictors
A
superior, middle and inferior constrictor muscles
20
Q
Location and function of pharyngeal constrictors
A
encircle the larynx and pharynx, they constrict the airway to help with swallowing. (
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
22
Q
Stomach location
A
below the diaphragm
23
Q
Cardiac sphincter function
A
prevents the backflow of stomach acids and content into the esophagus
24
Q
Pyloric sphincter function
A
controls the release of chyme from the stomach into the duodenum
25
Fundus function
stores gas that is a by product of digestion
26
The cardiac region contains a valve - what is its function
preventing food from backing up into the stomach
27
What facilitates the passage of saliva/liquids when swallowing
curvatures
28
What is pylorus and what is its function
a valve that allows partly digested food to enter the small intestine.
29
Rugae in stomach function
some protein digestion (pepsin), reduction of solid food to loose, semisolid chyme, delivery of chyme to duodenum
30
Rugae acting as a hopper
receives material irregularly, stores and delivers them regularly to duodenum until empty
31
What intrinsic factor does rugae make
one that is needed for absorption of vitamin B12 in intestine.
32
What does the jejunum absorb
absorbs sugars, amino acids and fatty acids
33
What are the parts of the small intestine and what is the length
Duodenum (25cm) , jejunum (1m) and ileum (2m)
34
Small intestine4 location
tightly folded within the abdomen
35
Small intestine function
Completes digestion, absorbs its products into blood and lymph streams
36
What does the duodenum recieve
acid material from stomach; protected by mucus glands. Receives products of pancreas and bile from liver – common duct.
37
What is the shape and location of the duodenum
C shaped, bent around the head of pancreas, on back wall of abdomen
38
Where is bile secreted to
intermittent secretion from pancreas: both to common duct, sphincter to duodenum. Bile stored in gall bladder until pancreatic secretions released.
39
When is bile released
when chyme enters duodenum; sphincter relaxes, gall bladder contracts, bile and pancreatic juice mixes with chyme.
40
Function of bile
allows mixing of pancreatic enzymes and fatty food material: lowers surface tension and emulsifies fat
41
What is the role of mesenterys in tyhe small intestine
to make sure it is highly folded and to keep it in place
42
What are mesentaries
folds of peritoneum
43
What are the 2 peritoneum
visceral and parietal
44
Where is the mesentary attached to
posterior abdomen wall
45
What are the moevments of the small intestine
Peristaltic movements propel food along
Intermittent churning movements for mixing – segmentation
46
What controls the movements of the small intetsine
myenteric plexus of nerves within muscle layers of gut wall.
47
What is the at the end of the small intestine
the ileo-caecal valve
48
Length of the appendix
2-20cm
49
What is the total length of the large intetsine
1.6m
50
Sections of the large intetsine
caecum, colon, rectum and anal canal
51
Does the large intetsine contain mesentaries
yes - lots of them
52
What are the 4 colons in order
ascending colon, transverse colon, descending colon and sigmoid colon
53
Which parts of the colon do not have mesentaries
ascending and descending colon - attached to rear abdominal wall
54
What is the sigmoid colon also called
pelvic colon
55
When does material reach the small intestine after ingestion
3-4 hours
56
Large intestine function
water and ion absorption, formation of faeces
57
When does material reach the sigmoid colon
12 hours after ingestion
58
Peristalsis contractions
Large intestine undergoes peristalsis and churning to mix contents
59
What does a strong peristaltic wave do
pushes gut contentsto pelvic colon; after about 24h, contents move to rectum – immediate desire to defecate
60
mass movement of gut contents
set off by gastro-colic reflex from stomach; strongest stimulus with first meal of the day
61
What triggers defecation
disintention of rectum walls. Contraction of colon, relaxation of involuntary sphincter. Voluntary sphincter gives conscious control.
62
What is the oral cavity lining
the oral mucosa
63
What are the 3 layers of the oral mucosa
masticatory mucosa (bashed about when chewing), specialised muscosa tongue (top surface of the tongue), ordinary lining mucosa
64
Where is the masticatory mucosa found
gingiva and hard plate
65
What epithelium is found in the masticatory mucosa
stratified squamos keratinized
66
What anchors the epithelium in the masticatory mucosa
collagen fibres in the submucosa. Attached to basal lamina
67
Why does the masticatory mucosa have a wavy epitherlium
greater surface area for anchorage- hard palate is where epithelium is strongly attached
68
masticatory mucosa fatty zone
provides cushoining for chewing
69
masticatory mucosa galndular zone
contains secretory cells so its moist
70
Where is the lining mucosa found
nside of lips, underside of tongue, soft palate, gums away from gingiva
71
Epithelium in lining mucosa
stratified squamos non-keratinised epithelium
72
What does the lining mucosa contain
lots of minor salivary glands in the submucosa
73
What is the posterior part of the tongue
tonsils
74
what does the anterior 2/3 of the tongue4 contain
lingual papillae which make up specialised mucosa
75
What are the 4 types of lingual papillae
filiform papillae (sharp), fungiform papille (tastebuds), foliate papillae (tastebuds), valiate papillae (form inverted v shape separating posterior from anterior).
76
What is the foramen caecum
site of which thyroid gland developed
77
Filiform papillae features
point, covered in stratified squamos keratinised epithelium giving abrasive surface to the tongue. Good for when chewing.
78
Fungiform papillae features
rounded, have taste buds in the wall, central core made of loose connective tissue containing blood vessels and nerves
79
Vallate papillae features
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
Structure of taste buds
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
4 types of taste buds
sweet, bitter, acid, salt.
82
What are the 4 layers of the gut wall
1. mucosa
2.submucosa
3. muscularis externa
4.Adventitia/serosa
83
Muscularis externa 2 smooth muscle layers
inner circular layer (contraction narrows the tube), outer longitudinal layer (contraction scrunches it up)
84
Where is the nerve plexus located
in mucosa and muscularis externa
85
What makes up the serosa
connective tissue
86
Esophagus lining
stratified squamos non keratinised epithelium
87
Mucus in the esophagus
lubrication - helps pass food into stomach. Protects lining from acidic splashback
88
Why are various muscle types needed in the esophagus
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
What is the additional layer to the muscularis externa in the stomach
an oblique muscle layer
90
Function of rugae
helps stomach expand because they can be pulled out straight, prominent when stomach empty. Large easily visible to naked eye.
91
Function of the mucous in the stomach
protects epithelium while still allowing you to absorb minerals. Every cell secretes mucous - protective mechanism
92
What is the epithelium in the sgtomach
simple epithelium
93
What makes HCl and pepsinogen
gastric glands - once released HCl etc enters the bottom of gastric pits
94
What are plicae circulares and where are they found
circular folds of the submucosa - in duodenum
95
What epithelium is found in the intetsine and advantage to that
simple columnar absorptive epithelium - allows for more cytoplasm containing more golgi
96
What are microvilli
projections of plasma membrane supported by cytoskeleton
97
What creates crypts of lieberkuin
villi poking outwards into interior gut causing tubular depressions
98
why do gut cells need to be continuously replaced
it is a hostile environment so cells only live a few days - retains ability to absorb nutrients
99
Where are stem cells located in the intetsine
at the bottom of the crypts of lieberkuhn - move upwards to replace damaged cells
100
What are taenia coli
the longitudinal smooth muscle split into 3 ribbons that run longitudinally along colon 120 degrees from each other
101
What are haustrae/sacculations
contraction of the longitudinal smooth muscle layer creating bulges
102
function of haustrae
pushes chyme from one sac to the next - aided by the appendices epipcloe
103
What part of the anal canal is under voluntray and involuntary control
inside - involuntary.
103
What part of the anal canal is under voluntray and involuntary control
inside - involuntary. outside - voluntary
104
Which muscle is present in the anal canal
skeletal muscle
105
What are longitudinal folds in the anal xanal
helps stomach expand because they can be pulled out straight, prominent when stomach empty. Large easily visible to naked eye.
106
Where is the stronger epithelium in the anal canal
at the end
107
What are the 3 phases of gastric secretion
cephalic, gastric and intestinal
108
cause of cephalic phase
sensation and thoughts (to either increase or decrease appetite)
109
Cephalic phase effect
cerebral cortex/hypothalamus
110
Transmission of signals in cephalic phase
Parasympathetic - vagus ( x cranial nerve)
111
Neural negative feedback in the gastric phase
stretch receptors and chemoreceptors routed via the submucosal plexus – peristalsis stimulated
112
What is the result of the hormonal negtaive feedback mechanism
emptying
113
When is gastrin secretion inhibited
when pH < 2, stimulated when pH rises
114
Where is gastrin transported to
the gastric glands, travels through the blood stream
115
Function of gastrin - motility
stimulates gastric secretions, contraction of lower eosphageal (cardiac) sphincter, increases motility, relaxes pyloric sphincter.
116
Function of gastrin - controls of HCl secreting parietal cells
stimulated by 3 signal chemicals: gastrin, acetylcholine, histamine (additive response, all 3 needed for strong H+ secretion)
117
What is the intestinal phase
food entering the intestine and having an effect on the stomach
118
Intestinal phase events
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
what do enteroendocrine cells release and inhibit
cholecystokinin (CCK), gastric inhibitory peptide (GIP), secretin. They inhibit gastric secretion.
120
What stimulates the pancreas
food entering the duodenum, neuronal input, secretion of secretin and GIP from duodenum
121
What stimulates bile production in liver
parasympathetic impulses along vagus (X)
122
What stimulates secretion of CCK into blood stream
fatty acids and amino acids in chyme entering the duodenum
123
What stimulates secretion of secretin
acid chyme entering the duodenum
124
What does CCK cause
contraction of gallbladder causing bile to enter the duodenum to emulsify fats for digestion and absorption. Makes you feel full
125
What does secretin do
enhances flow of bile rich in HCO3- from liver. Promotes production and secretion of bile from liver to gall bladder
126
What causes gastrin to be secreted
food in stomach
127
Gastrin function and effect on motility
stimulates secretion of HCl and pepsin - increases motility of stomach
128
CCK - hunger signals
reduces appetite and inhibits eating - hypothalamus is the neurotrabsnitter to inhibit eating
129
What is the 'illeal brake'
slows all gastric emptying - not as hungry
130
What other compounds transmit satiety (not hungry) signals
Glucagon - like peptide - 1 and peptide YY (PYY) - from intestine in response to food
131
Ghrelin function
increases hunger, growth hormone secretion and fat store
132
What secretes ghrelin
endocrine cells in gastric mucosa
133
Ghrelin's neural pathway
binds to GHSR in hypothalamus - growth hormones secretagogue receptors
134
What are the long term satiety signals
leptin, insulin and estrogen - act to lower body weight
135
what do the long term satiety signal compounds target
anorexigenic pro-opiomelanocortin (POMC) neuron
136
Function of leptin
increases activity of melanocortin pathway, both hormones and receptors - suppresses appetite
137
What signals control appetite
Arcuate nucleus (ARC), Pro-opiomelanocortin (POMC), cocaine-amphetamine regulated transcript (CART)
138
Where in the hypothalamus does the melanocortin system occur
arcuate nucleus
139
What activates the melanocortin system
POMC and CART
140
What inhibits the melanocortin system
NPY and AgRP
141
What hormones are part of the melanocortin syystem
Peptides adrenocorticotropin and melanocyte stimulating (MSH) hormones
142
What does the melanocortin system do
decreases food intake (anorexigenic) - integrates short and long term signals
143
What supresses NPY/AgRP
insulin and leptin
144
Where are the neurotransmitters for NPY and AgRP
hypothalamus
145
Function of NPY
activates its receptor which are GPCR. Stimulates eating
146
Function of AgRP
binds to and inhibits MC4R, inhibits anorexigenic effects of alpha – MSH
147
How much does the rumen account for of an animals body weight
10-20%
148
What increases the surface area of the rumen
finger like projections
149
What is the contents and function of the rumen
85-93% water (large vessel containing aqueous environemnt)(fermentation vessel)
150
How much slaiva do cows produce a day
150L
151
Function of ruminal papillae
increase surface area - helps absoprtion occur in rumen
152
Epithelium in rumen
stratified squamos epithelium - keratinised
153
Food being reswallowed
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
Where are microorganisms for fermentation found
in the rumen and reticulum
155
What relationship occurs between microorganisms in the rumen and the bacteria
symbiotic
156
What kind of microoganisms are found in the reticulo-rumen
anaerobic bacteria and fungi. Heterotophic and autotrophic
157
How are there complex interrelationships in the rumen
methanogens reduce efficiency but impact on growth of other species
158
What is a chemostat
fresh medium is continuously added - waste products are continuously removed. Helps regulate the growth rate - rumen is one
159
How many microorganisms does each mm of rumen contain
10 to 50 billion bacteria, 1 million protozoa + yeasts + fungi
160
What does fermentation in rumen produce
volatile fatty acids (VFAs) which are absorbed, gas and more microorganisms (more than 30L/hr)(~40% CO2, ~30-40% CH4. ~5% H2)
161
Structural changes of the rumen during development
At birth the abomasum is the largest chamber
At 18 months the reticulorumen occupies > 90% of the stomach
162
Structure of the reticulum
hexagonal structures - each structure is a ring of muscle that contracts
163
Reticulum epithelium
keratinised stratified squamos epithelium
164
Function of reticulum
particle sorting
165
Muscularis mucosa in the reticulum
around top of each compartment. Aid separation, mixing and breakdown
166
Omasum location
gateway between fermentation vessel and stomach
167
Omasum function
Regulates entry to food into the abomasum
May return food to the reticulo-rumen
Water and VFA absorption
168
Abomasum function
true stomach (like fundus) - same digestive functions as humans
169
Compartments of the abomasum
Oesophagael groove, Glandular, Gastric pits, Parietal and chief
170
Epithelium in the abomasum
simple columnar epithelium
171
Monomer of cellulose and bonds
glucose units bound by beta 1-4 linkages
172
Hydrogen bonds in cellulose
decreases flexibility, high tensile strength, low solubility in water of dilute acid. Allows development of crystalline lattice
173
What is hemicellulose
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
What is lignin
poorly defined polymer of phenylpropane
175
What does lignin do
Binds to hemicellulose only, forms a matrix around cellulose, increased strength under compression
176
What is the effect of lignification
reduces digestibility
177
Where does cellulose digestion occur
in the reticulorumen
178
Cellulose digestion - step 1
Transport of bacteria to fiber (slow, dependent on number of bacteria)
179
Cellulose digestion - step 2
Nonspecific adhesion (binds to glycocalyx, most commonly at cut or macerated areas)
180
cellulose digestion - step 3
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
What does the cellulose binding domain do
brings cellulose into contact with hydrolases
182
Structure of starch
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
Where is starch digested
majority digested in rumen
184
What enzyme breaks down starch
by alpha-amylase to oligosaccharides which degrade to glucose
185
Where is alpha amylase found
d in cell-free rumen fluid, but 70% associated with paticulate bound microorganisms. Activity increases in high grain diets
186
protozoa uptake in starch digestion
stabilises fermentation and less readily passed from rumen
187
bacteria uptake in starch digestion
storage polysaccharide. May account for as much as 50% of carbohydrate leaving rumen
188
What produces volatile fatty acids
end product of microbial carbohydrate digestion
189
What factors increase propionate
1. Decreased forage and increased concentrate
2. Decreased physical form of diet
3. Unsaturated fatty acids
190
Where are proteins digested in cows
microorganisms in the reticulorumen
191
Protein digestion
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)
