GI System Flashcards
1
Q
What is prehension?
A
Movement of food into the oral cavity using tongue, lips and teeth
2
Q
What is mechanical breakdown?
A
Mastication to reduce the size of food
3
Q
What is muccin?
A
Mixture of mucous and water
4
Q
What is salivation for?
A
Mucous for lubrication, some contain enzymes for digestion
5
Q
Where is saliva produced?
A
parotid/ serous gland
6
Q
What is the composition of saliva?
A
Mucin, amylase (omnivores), bicarbonate, phosphate (ruminants), lysosome, antibodies, protein binding tannins, urea (ruminants)
7
Q
What effects the composition of salivary in non-ruminants?
A
Secretion comp effected by blood flow- primary secretion isotonic with blood, at low flow secretion hypotonic, at high rates remains isotonic
8
Q
How is a ruminants composition of saliva affected?
A
Secretion is always isotonic to blood, at low flow PO4 predominates, at high HCO3 predominates
9
Q
How is secretion of saliva regulated?
A
Regulated by neural control, sympathetic reduced, parasympathetic increased, can be congenital (taste), conditioned (pavlov)
10
Q
What are the different types of motility in the abdomen?
A
Segmental- breakdown/mix, peristaltic- aboral direction
anti-peristaltic- oral direction
11
Q
What is used for chemical breakdown in digestion?
A
ions, mucous, enzymes
12
Q
What happens to chemicals after chemical breakdown?
A
reabsorbed
13
Q
What are the 4 muscles of the abdominal wall?
A
Rectus abdominus, external abdominal oblique, internal abdominal oblique and transverse abdominal
14
Q
What is the insertion and origin of the rectus abdominis?
A
O- ventral surface of ribs
I- cranial pubis
15
Q
How are the left and right side of the rectus abdomens separated?
A
Line alba
16
Q
What is the outermost abdominal wall muscle?
A
External abdominal oblique
17
Q
What are the origins and insertions of the external abdominal obliques?
A
O- lateral caudal surface of ribs 4+/lumbodorsal fascia
I- linea alba/ pre-pubic tendon
18
Q
What direction do external abdominal oblique muscle fibres run?
A
caudo-ventral
19
Q
What is the order from outside to inside of transverse abdominal muscles?
A
External abdominal oblique, Internal abdominal oblique, Transverse abdominal
20
Q
What is the origin and insertion of the internal abdominal oblique?
A
O- coxal tuber/lumbodorsal fascia
I- linea alba, last rib and cartilages of caudal ribs
21
Q
What direction do fibres of the internal abdominal oblique run?
A
Cranio-ventrally
22
Q
What is the origin and Insertion of the transverse abdominal?
A
O- medial ventral ribs/ deep lumbosacral fascia
I- linea alba
23
Q
How do fibres of the transverse abdominal run?
A
Transversely
24
Q
How is the linea alba formed?
A
Tendons of lateral abdominal wall muscles pass above and below the rectus abdominis to join milling forming aponeurosis and the linea alba
25
What section of the spinal cord innervates the abdominal wall muscles?
T13 and L1-L5
26
How does the dorsal and ventral routes innervate the abdominal wall?
```
Dorsal roots- dorsal muscle
Ventral roots- 3 branches
1) medial between TA and IAO to RA
2) lateral between IAO/EAO to midway
3) lateral cutaneous perforates EAO to skin
```
27
What in the embryo does the epithelial lining and exocrine glands develop from?
Endoderm
28
What does muscle and connective tissue develop from in the embryo?
Splanchnic mesoderm
29
What does the foregut in the embryo develop into?
pharynx, oesophagus, stomach and initial duodenum
30
What does the mid gut from the embryo develop into?
Rest of the duodenum, jejunum, ilium, caecum and ascending and transverse colon
31
What does the hindgut from the embryo differentiate into
descending colon and rectum
32
What is the peritoneum?
A serous membrane that line the abdominal cavity and envelope abdominal organs
33
What does the parietal membrane of the peritoneum cover?
Lines the abdominal wall and extends through inguinal canal
34
What does the visceral peritoneum cover?
Lines organ surface and envelopes organs
35
What are the different ways the peritoneum be connected?
Mesenteric, Omentum, Fold, Ligament
36
What is a mesenteric part of peritoneum?
Bowel to body wall (SI/LI)
37
What is a omentum connection of peritoneum?
Stomach to something
38
What is a fold in the peritoneum?
Connects bowl/organ to one-another
39
What does a ligament of the peritoneum connect?
Organ to body wall
40
What does the diaphragm define in the abdomen?
The cranial border
41
How does the oesophagus pass through the diaphragm?
Oesophogeal hiatus
42
What is the diffecence between the abdominal and peritoneal cavity?
Abdominal cavity contains all abdominal organs and structures, peritoneal cavity is potential space between parietal and visceral peritoneum
43
How many lobes does a liver have?
4 lobes
left and right (split medial/lateral in dog)
caudate and quadrate
44
What are the three ducts of the gall bladder?
Common bile, hepatic and cystic
45
What are the peritoneal attachments of the liver?
coronary ligament, R and L triangular ligament, falciform/round ligament
46
What are the three areas of the stomach?
Fundus = blind ending, Corpus- body, Pylorus
47
What are the peritoneal attachments of the stomach?
greater/lesser omentum, gastro-splenic ligament
48
Where is the spleen found in the abdomen?
left side of the abdomen
49
What are the peritoneal attachments of the spleen?
Gastro-splenic ligament
50
What are the three parts of the small intestine in order?
Duodenum, jejunum, ilium
51
What three ducts exit into the duodenum?
Bile duct, pancreatic duct and accessory duct
52
What are the peritoneal attachments of the duodenum?
mesoduodenum, duodeno-colic fold, hepato-duodenal ligament
53
How many lobes does a pancreas have?
2
54
What direction does the right lobe of the pancreas run in?
Cranio-caudal
55
What direction is the left lobe of the pancreas running in?
Medio-laterally
56
What are the peritoneal attachments of the pancreas?
right lobe mesoduodenum
| left lobe greater omentum
57
Which is the largest part of the small intestine?
jejunum
58
What is covered by the greater omentum?
jejunum
59
What are the peritoneal attachments of the jejunum?
meso-jejunum
60
Where does the ilium enter the large intestine?
cacao-colic junction
61
What are the peritoneal attachments of the ileum?
ilio-ceacal fold, meso ileum
62
What is the first part of the large intestine?
Caecum
63
What are the peritoneal attachments of the caecum?
ileo-caecal fold, cacao-colic fold
64
What are the 4 parts to the colon?
Acending, transverse, descending, rectum
65
What are the peritoneal attachments of the colon?
Meso-colon
66
What causes short reflex arcs in the digestive tract?
Enteric nervous system (sensory and motor with in GI)
67
What causes long reflex arcs in the digestive tract?
Autonomic nervous system
68
What do the sensory neurones respond to in the enteric system?
Content of lumen and stretch
69
What do enteric motor neurones stimulate?
Smooth muscle or secretion
70
How are complex arcs formed in the GI?
Simple arcs connected by interneurons
71
What main neurotransmitter do short arcs use?
Acetylcholine
72
What do inhibitory neurotransmitters mainly do in the GI?
Relax sphincters
73
Where do the parasympathetic pre and post ganglionic neurones run and what neurotransmitter do they use?
Pre-ganglionic in vagus
Post-ganglionic in wall of GI tract
Both acetyl choline
74
Where do the sympathetic pre and post ganglionic nerves run and what neurotransmitter do they use?
Pre-ganglionic run in splanchnic nerves- acetylcholine
| Post-ganglionic run along arteries to organ or hypogastric nerves- adrenergic
75
How does the ANS have a connection to the central nervous system?
Enters-enteric reflexes- coordinate activity between different parts of the GI
76
What 4 hormones are secreted for regulation of the GI tract?
Gastrin, Secretin, Cholecystokinin, Gastric inhibitory peptide
77
Where are the gastrin, secreting cholecystokinin, GIP hormones produced?
Gastrin- caudal stomach
Secretin/CCK- duodenum
GIP- cranial small intestine
78
What stimulates the production of gastrin?
Peptides/amino acids and acetyl choline
79
What are the effects of gastrin?
Stimulates HCL
80
What stimulates secretin?
HCL
81
What effect does secretin have?
Stimulates pancreatic HCO3-
82
What stimulates CCK?
Fatty acids, monoglycerides, amino acids, peptides
83
What does CCK effect?
Pancreatic enzymes production and contraction of gall bladder
84
What stimulates GIP?
Fat, glucose, amino acids
85
What are the effects of GIP?
Inhibits HCL, stimulates insulin production
86
What are the different phases of digestion?
Cephalic, Gastric, Intestinal
87
What coordinates each phase of digestion?
Cephalic- ANS
Gastric- ANS/ENS and hormones
Intestinal- ANS/ENS and hormones
88
What controls the regulation of appetite?
Hypothalamus
89
Where is the appetite centre in the hypothalamus?
Ventro-lateral
90
What effects does the appetite centre go the hypothalamus have?
Food searching and eager to eat (behaviour)
91
What is the satiety centre of the hypothalamus?
Causes refusal of food and inhibits appetite
92
Where is the satiety centre in the hypothalamus?
Ventro-medial
93
What is the mechanism of action for the hypothalamus?
Unknown- hypothesised Glucose, CCK or fat
94
What causes motility of the digestive tract?
Smooth muscle
95
What are the 4 different types of contraction?
Segmental, Peristalsis, anti-peristalsis, mass movement
96
How is contraction controlled in the GI tract?
Pacemaker cells give repetitive, spontaneous oscillations which only reach threshold with stimulus
97
Where are pacemaker cells located?
Between circular and longitudinal smooth muscle
98
How is synchronisation of smooth muscle achieved?
Transfer of oscillations by gap junctions
99
Describe the anatomy of the oesophagus
Mucosal- stratified squamous
Sub-mucosal
Mucular- inner circular/outer longitudinal, smooth muscle
Serosal- Adventia- (loose CT) only in neck
100
How is food swallowed?
Food moulded into bolus by tongue, moved up by pharynx, epiglottis closes of trachea, upper sphincter opens, contraction, lower sphincter opens
101
What happens after food reaches the stomach to the oesophagus?
Upper oesophageal sphincter closes, epiglottis opens, lower oesophageal sphincter closes
102
What are the 4 functions of the stomach?
Digestion- starch/protein
Protection- acid kills bacteria
Storage- food held for SI
Mechanical breakdown- chyme
103
What are the 4 regions of the stomach?
Cardia
Fundus
Corpus
Pylorus
104
Which region of the stomach forms the entrance and valve?
Cardia
105
Which region of the stomach forms the main body?
Corpus
106
Which region of the stomach is blind ending?
Fundus
107
Which region of the stomach forms the exit?
Pylorus
108
What are the 4 types of cells of the stomach and what do they secrete?
Mucous
Parietal- secrete HCL
Chief- secrete pepsinogen
Entero-endocrine- secretes hormones
109
Which two embryological regions secrete mucous only?
Pyloric- pylorus
| Cardiac- fungus
110
Which embryological region secretes mucous and gastric juices?
Fundic region- corpus
111
What does the oesophageal embryological region form?
Cardia
112
What are the 4 things the motility of the stomach controls?
Preparing to receive a meal
Mix and mechanically breakdown
Prevent regurgitation
Empty contents
113
What does the stomach do when the animal begins eating?
Initial relaxation to accommodate- regulated by vagus (neurotransmitter= vasoactive inhibitory peptide)
114
What is the main type of contraction of the stomach?
Peristalsis
115
Describe contraction in the stomach
Starts with weak contractions at fundus, propogated down corpus, pyloric sphincter opens, allowing chyme into duodenum, when contraction reaches pylorus the pyloric sphincter closes
116
What regulates stomach emptying?
Strength of contraction
| open/closing of pyloric sphincter
117
What stimulates the stomach emptying?
neural- expansion of stomach wall increases contraction
| hormonal- release of gastrin increases contraction and relaxes pyloric sphincter
118
What causes inhibition of emptying?
Duodenum can inhibit due to increased pressure, low pH, high fat/osmolarity
119
What is used for neural and hormonal stimulation?
Neural-sympathetic/ parasympathetic system
| Hormonal- secretin, CCK, GIP
120
How is starch digested in the stomach?
Initiated by amylase in the mouth, but swallowed food enters the centre of the stomach, the secreted acid from the periphery slowly lowers ph allowing more digestion
121
What is the optimum pH for Amylase and what bonds can it break?
pH 6
| alpha-glycosidic bonds
122
Which two species have adapted stomach to allow more starch digestion?
Horses and pigs
123
How much salivary amylase are in the following species?: Horse, Pigs, Carnivore and ruminants
Horses- low
Pigs- high
Ruminants- absent
Carnivores- absent
124
Why is the stomach resistant to HCL?
Large amounts of mucosa
125
What causes ulcerations?
Breech of the mucosa
126
How is pepsinogen converted to pepsin?
HCL converts
127
How does HCL prevent fermentation?
Killing microbes
128
Why does pepsin need to be inactive inside cells?
To prevent the cell protein being broken down
129
What does HCL help in breaking down?
Degrades connective and muscle tissue
130
What cells secrete HCL?
Parietal cells
131
When is the maximum secretion of HCL and wha tis the pH?
2-3 hours after meal (dogs/pigs)
| pH- 2-2.5
132
What produces and secretes pepsinogen?
Chief cells
133
How does pepsin initiate protein digestion?
Breaks peptide links adjacent to aromatic acids
134
Other then HCL what activates pepsinogen?
Pepsin
135
How is HCL secreted?
CO2 from capillary and H2O converted to H2CO3, converted to bicarbonate and H+, exchanged for Cl-, H+ exchanged for K+ using ATP, Cl- diffuses into gland lumen
136
Why does ph of urine increase after a meal?
Production of HCL produces bicarbonate before usage in the SI
137
What three substances stimulates secretion?
Acetyl choline, histamine, gastrin
138
How do long and short reflex arcs run in the stomach to control protein digestion?
Long via vagus
| Short locally
139
What is the difference between acetyl choline/gastrin and histamine causing secretion?
Acetyl choline and histamine directly
| Gastrin uses ECL to produce histamine
140
What cells do histamine and felty choline stimulate?
Chief, parietal and mucin cells
141
What cells does Gastrin stimulate?
Mainly parietal
142
What stimulates acetyl choline and gastrin in the blood for secretion in stomach?
Smell, sight, taste and presence of food
| Stomach expansion and peptides
143
Once the food in the duodenum what does stimulation of inhibition depend on?
Acidity of food contents
144
What mediates hormonal stimulation?
Gastrin via blood
145
Other than mucous layer what protects stomach from HCL?
Epithelial cell membrane and interconnecting tight junctions impenetrable
