digestive system Flashcards
1
Q
What are the gingiva?
A
gums
2
Q
How do baby teeth become looser and fall out?
A
osteoclasts eat the roots of the baby teeth - when the root has been completely digested then the tooth can fall out
3
Q
What stops the tongue flipping backwards?
A
frenulum
4
Q
What does the soft palate shut off?
A
nasal cavity from oral cavity when you swallow
5
Q
What are the three salivary glands?
A
parotid, submandibular, sublingual
6
Q
What are features of the parotid gland?
A
runny, serous secretion which enters mouth by upper second molar. very long duct
7
Q
What are features of the submandibular gland?
A
long duct. thin sero-mucous secretion
8
Q
What are features of the sublingual gland?
A
lots of short ducts. thick mucus secretion
9
Q
Where is the pharynx?
A
at the top of the stomach. muscular tube
10
Q
What does the pharynx contain?
A
superior, middle and inferior constrictor
11
Q
What does the larynx do?
A
separates what you swallow from the air you breath
12
Q
What are the parts of the stomach?
A
fundus, body, pylorus
13
Q
Where does any air swallowed go?
A
into the fundus
14
Q
What are the functions of the stomach?
A
some protein digestion, reduction of solid food to loose, semisolid chyme, delivery of chyme to duodenum
15
Q
What are the parts of the small intestine?
A
duodenum, jejunun and ileum
16
Q
What are the rugae for in the stomach?
A
to increase surface area
17
Q
What is the mesentery?
A
a fold of membrane that attaches the intestine to the abdominal wall and holds it in place
18
Q
What lines the main abdominal cavity?
A
parietal peritoneum
19
Q
What surrounds the small intestine?
A
visceral peritoneum
20
Q
What are folds of peritoneum called?
A
mesenteries
21
Q
Why does intermittent churning occur in the small intestine?
A
mixing
22
Q
What shape is the duodenum?
A
c-shaped, bent around the head of the pancreas, on the back wall of the abdomen
23
Q
What is the function of the duodenum?
A
receives acid material from stomach; protected by mucus glands, receives produces of pancreas and bile from liver + pancreatic juices from pancreas with digestive enzymes
24
Q
Where is bile stored?
A
gall bladder
25
What is secreted to the duodenum?
bile from liver and pancreatic juice from pancreas with digestive enzymes
26
When are both secretions released?
when chyme enters the duodenum
27
What is the function of bile?
allows mixing of pancreatic enzymes and fatty food materials: lowers surface tension and emulsifies fat
28
Where is the ileo-caecal junction?
end of the small intestine - guarded by the ileo-caecal valve
29
When does food arrive at the ileo-caecal junction?
3-4 hours after swallowing
30
What is the total length of the large intestine?
1.6m
31
What are the structures present in the large intestine + after?
caecum -> colon -> rectum -> anal cavity
32
What are the parts of the colon?
ascending, descending and sigmoid
33
What are the functions of the large intestine?
water & ion absorption, formation of faeces
34
What triggers defecation?
distension of its walls
35
What are the three basic regions of the oral cavity?
masticatory mucosa, ordinary lining mucosa, specialised mucosa (tongue)
36
What are features of the masticatory mucosa?
gingiva & hard palate. stratified squamous keratinised epithelium
37
How is the masticatory mucosa firmly anchored to the bone?
by collagen fibres in the submucosa
38
What is the shape of the gingiva?
wavy
39
Where is the lining mucosa?
anywhere other than the top surface of the tongue, the gingiva and the hard palate
40
What epithelium is in the lining mucosa?
stratified squamous non-keratinised
41
What is the tongue divided into?
two anterior thirds and a posterior one third
42
What does the anterior two thirds have on it?
lingual papillae
43
What are the fungiform papillae?
tastebuds
44
What are the shape of filiform papillae?
sharp and pointed
45
What occurred at the foramen caecum?
the site from which your thyroid gland developed as an embryo
46
What is the order of things in the tongue from front to back?
filiform papillae -> fungiform papillae -> foliate papillae -> vallate papillae -> foramen caecum
47
What do the nerves associated with taste buds interact with?
sensory glands
48
What are the four types of taste bud?
sweet, bitter, acid, salt
49
What is the first layer of the hollow tube of the gut?
mucosa - lamina propria is underneath, then the muscle lining
50
What is the second layer of the hollow tube of the gut?
submucosa - has lots of lymphatics and blood vessels
51
What is the third layer of the hollow tube of the gut?
muscularis externa - contracts to make gut narrow, peristaltic movement is controlled by the Auerbach's plexus
52
What is the outermost layer of the hollow tube of the gut?
adventitia
53
What is the Meissner's plexus?
a neural network located within the submucosa
54
What epithelium lines the oesophagus?
stratified squamous non-keratinised
55
What glands as present in the oesophagus?
mucus-secreting
56
What types of muscle are present in the oesophagus?
three types due to both voluntary and involuntary control
57
How many muscle layers are in the M. externa of the stomach?
three
58
Why is mucus produced in the stomach?
to keep acidic conditions away from the epithelium of the stomach
59
What is made in the gastric glands?
HCl and pepsinogen
60
What do parietal cells do?
make HCl
61
What do chief cells do?
make pepsin
62
What folds run circular around the duodenum?
plicae circulares - folds to submucosa
63
What are the villi folds of?
mucosa
64
What are the Crypts of Lieberkuhn?
they are tubular glands formed from the mucosa of the small intestine in between the bases of the villi. The cells of these glands secrete intestinal juice.
65
Where are the Crypts of Lieberkuhn present?
small intestine but there are also crypts in the large intestine
66
What do the taeniae coli do?
slightly contracted so make gut scrunch up
67
What are the taeniae coli?
they are three separate longitudinal ribbons of smooth muscle on the outside of the ascending, transverse, descending and sigmoid colons
68
When is the rectum relaxed?
when is it empty
69
What lines the anal canal?
goblet cells
70
What are the three phases of gastric secretion?
cephalic, gastric, intestinal
71
What is the cause of the cephalic phase?
sensation & thoughts
72
What is the effect of the cephalic phase?
cerebral cortex/hypothalamus + parasympathetic system stimulated
73
What can distension stimulate?
G cells
74
When is gastric secretion inhibited?
pH < 2 + so is stimulated when pH rises
75
What does gastrin stimulate when transported to gastric glands?
stimulates gastric secretion, contraction of lower oesophageal sphincter, increased motility & relaxes pyloric sphincter
76
How are HCl secreting parietal cells stimulated?
by gastrin, acetylcholine and histamine
77
What happens during the excitatory phase of the intestine?
stretch receptors respond, chemoreceptors detect fatty acids and glucose in the chyme, enterendocrine cells release gastrin, increases gastric peristalsis and emptying
78
What happens during the inhibitory phase of the intestine?
enteroendocrine cells in the small intestine release cholecystokini (CCK), gastric inhibitory peptide (GIP), secretin
79
What happens in the pancreas?
parasympathetic impulse along vagus nerve, stimulate secretion of pancreatic enzyme, acidic chyme, CCK and secretin enter blood, stimulates secretion of pancreatic juice rich in bicarbonate ions, stimulates secretion of pancreatic juice rich in digestive enzymes
80
What happens in the liver?
parasympathetic impulse along vagus nerve stimulates bile production by liver, fatty acids + amino acids in chyme stimulate secreting of CCK, when acid chyme enters duodenum secretin is secreted into blood, CCK causes contraction of the gallbladder, secretin enhances flow of bile rich in HCO3- from liver
81
What does CCK do to appetite?
reduces appetite and inhibits eating
82
What is released from the intestine in response to food?
glucagon-like peptide-1 and peptide YY (PYY)
83
What are peripheral hunger signals mediated by?
ghrelin - increases food intake
84
What is ghrelin secreted by?
endocrine cells of the gastric mucosa
85
What does ghrelin do?
increases hunger, growth hormone & fat stores
86
What does ghrelin bind to in the hypothalamus?
growth hormone secretagogue receptors (GHSR)
87
What are long term satiety signals?
leptin, insulin, oestrogen
88
What may leptin, insulin + oestrogen target?
anorexigenic pro-opiomelanocortin neuron (POMC)
89
What are POMC and CART stimulated by?
leptin
90
What does leptin suppress?
long-term appetite
91
What peptides are present in the melanocortin system?
anrenocorticotropin & melanocyte-stimulating hormones (MSH)
92
Where does the melanocortin system occur?
in the arcuate nucleus hypothalamus
93
What is the melanocortin system activated by?
POMC and CART
94
What is the melanocortin system inhibited by?
NPY and AgRP
95
What stimulates NPY and AgRP?
ghrelin
96
What are NPY and AgRP neurones suppressed by?
insulin and leptin
97
What receptors are on NPY?
GCPR
98
What does NPY stimulate?
eating
99
What does AgRP bind to?
binds and inhibits MC4R
100
What does AgRP inhibit?
anorexigenic effects of alpha-MSH
101
What epithelium is in the rumen?
stratified squamous keratinised
102
How many hours a day do cows spend ruminating?
8 hours
103
What percentage of water is in the rumen?
85-93%
104
How does rumination work?
material drawn back into the oesophagus and muscle contractions return it to mouth, liquid rapidly re-swallowed, coarse material chewed again, each bolus chewed 40-50 times
105
How much bacteria is in each millimetre of rumen?
10-50 million bacteria
106
What does fermentation produce?
volatile fatty acids (VFAs)
107
What is the epithelium is the reticulum?
stratified squamous keratinised
108
What occurs in the reticulum?
particle sorting
109
What mucosa surrounds the reticulum?
muscularis - aids separation, mixing and breakdown
110
What does the omasum do?
regulates entry of food into the abomasum
111
What is absorbed in the omasum?
water and VFA absorption
112
What does the abomasum do?
broadly the same digestive functions as humans
113
What is the oesophageal groove?
when the head is incline up, allows food straight into the abomasum
114
Why do they ruminate?
animals don't produce enzymes to digest cellulose
115
What is hemicellulose closely bound to?
lignin
116
What is lignin a polymer of?
phenylpropane
117
What does lignin do?
binds to hemicellulose only, forms a matrix around cellulose
118
Where does 90% of cellulose digestion occur?
reticulorumen
119
What does bacteria bind with?
glycocalyx
120
What is cellulosome?
large, multicellular enzyme complexes for adhesion and hydrolysis of cellulose
121
How much starch is digested in the rumen?
47-95%
122
What is starch digested by?
alpha-amylase to oligosaccharides
123
What are the oligosaccharides degraded to?
glucose
124
What does protozoa uptake do?
stabilises fermentation and is less readily passed from the rumen
125
What does bacterial uptake do?
may account for as much as 50% of carbohydrate leaving rumen
126
What percentage of glucose required comes from VFAs?
70%
127
How can methane be decreased?
if you feed cows more corn and less grass
128
What is the origin of most protein that reaches the abomasum?
microbes
129
What are advantages of ruminant digestion?
utilises feed too fibrous for non-ruminants, uses the most abundant carbohydrate, produces high-quality microbial protein for NPN, produces vitamin B complexes
