Flashcards in Digestive system Deck (95)
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1
List in sequence the sections of the digestive tract
1. Oral cavity (mouth/jaws/lips/tongue/teeth)
2. GI tract - Oesophagus, Stomach, SI, cecum, LI (colon), rectum, anus
2
Most important feeding structure of vertebrates?
Jaw
3
Define crown
Part of tooth visible above gum
4
Define dentin
mineralised substance
5
Define root
anchor
6
Define dental pulp
connective tissues, nerves & blood vessels
7
Define enamel
hard outer substance of tooth.
Inorganic crystals, irreplaceable
8
Dental formula of dog (upper & lower)?
3142
3143
9
Dental formula of sheep (upper & lower)?
0033
4033
10
Tongue properties...?
muscle mass covered in mucous membrane
stratified, squamous epithelium covered in papillae
11
Different forms of papillae?
filiform
fungiform
foliate
vallate
conical
12
Define prehension and structures involved
Act of getting food into mouth - lips, tongue
13
Define mastication
1st act of digestion
initiates mechanical breakdown
Motility of mouth enables slicing, tearing, grinding & mixing food
14
What does mastication stimulate?
Secretion of saliva, gastric juices, bile, pancreatic juices
15
Define deglutition
Swallowing - relaxed upper oesophageal sphincter & closed soft palate
16
Draw micro-anatomy of the SI
...
17
What are the 2 levels of control of the GIT?
Extrinsic - ANS
Intrinsic (enteric) - unique to GIT; nervous & endocrine components
18
T or F - ANS nerves form link with enteric NS
true
19
T or F - extrinsic nerves originate within the GIT
false - outside the GIT
20
ANS influences GIT motility how?
1. modifies ongoing activity thru intrinsic plexus
2. alters levels of GIT hormone secretion
3. Acts directly on SM & glands
21
Properties & functions of the oesophagus?
To push boluses of food from pharynx to stomach
Contains mucus -> prevents damage
22
Muscle type in dog & ruminant oesophagus
entirely striated
23
Muscle type in bird & human oesophagus
entirely smooth
24
Muscle type in horse, cat & pig oesophagus
striated at origin then to SM
25
Draw stomach & label
...
26
Learn and distinguish differences between GIT of ruminant & non-ruminant...
4 compartments vs 1 compartments
much greater number of bacteria to aid in digestion
See illustrations
27
List the structures in the horse large intestine
Caecum, ascending colon, transverse colon, descending colon, rectum
28
Name the accessory digestive organs
Salivary glands
Pancreas
Liver
29
Name the salivary glands
Parotid
Mandibular
Sublingual
Buccal
30
Endocrine portion of pancreas contains ... & secretes ...?
Islets of Langerhans & insulin/glucagon
31
Exocrine portion of pancreas contains ... & ... cells which secrete... & ...?
Acinar cells - digestive enzymes
Duct cells - sodium bicarb solution
32
Functions of the liver...?
Bile secretion
Metabolic processing
RBC breakdown
Waste elimination
Plasma protein synthesis
Secretion/modification of hormones/growth factors
Gluconeogenesis
33
Liver stores what?
glycogen, fat, iron, copper, vitamins
34
Know how to label structures of liver
... slide 47 & 48
35
Know components of the avian digestive tract
...slide 51 (lec objective)
36
Characteristics of motility?
Mixing ingested material with secretions
Peristalsis - circular muscle contracts & longitudinal muscle relaxes and vice versa
Rate of movement varies bwn feed/spp
37
Characteristics of secretion?
Release of useful substances in GIT lumen
Secretions: enzymes, buffers, bile, lubrication, solvent
38
Characteristics of digestion?
Breakdown into smaller molecules - mechanical/enzymatic
Aided by secretions
39
Characteristics of absorption?
nutrient uptake & use
uses specialised cells lining GIT lumen
passive or active
40
Segmentation (haustration) involves what?
Random, localised contraction of smooth muscle
Occurs in SI & colon
non-propulsive; instead mixes digesta
41
Most saliva secretion comes from where?
Parotid glands
mandibular glands
sublingual glands
42
2 types of saliva secretions?
viscous - mucous rich (small glands)
serous - (parotids)
43
Which salivary glands secrete both (viscous & serous) saliva?
madibular & sublingual
44
T or F - Starch digestion begins in mouth due to amylose
False - amylase
45
Amylase digestion is high, low and absent in which animals?
High - pigs
Low - horses
Absent - ruminants
46
T or F - saliva provides alkaline buffer & fluid bicarbonate in the rumen
True - very important for ruminant digestion
47
T or F - salive provides evaporative cooling and oral protection
true - oral protection is due to buffer, lysosomes & antibacterial properties
48
Salivary center in medulla is stimulated by which factors?
Pressure receptors & chemoreceptors (mouth)
Cerebral cortex (sight of food ->'mouthwatering')
49
Cascade of events to stimulate saliva secretion...?
Visual/chemo-/pressure cues -> + salivary center -> + ANS -> + salivary glands -> + saliva secretion
50
Mucous cells secretions & role?
Alkaline mucous & protect mucosa
51
Chief cells secretions & role?
pepsinogen & protein digestion
52
Parietal cells secretions & role (2 secretions)?
Hydrochloric acid & activates pepsinogen
Intrinsic factor & facilitates absorption of vit B12
53
Enterochromaffin like cells (ECL) secretions & role?
Histamine & stimulates parietal cells
54
G cells secretions & role?
Gastrin & stimulates parietal, chief & ECL cells
55
D cells secretions & role?
Somatostatin & Inhibits parietal, G & ECL cells
56
Pancreatic enzyme properties...?
Potent enzymatic secretions
Aqueous alkaline secretions
VERY important in non-ruminants
Synthesised as zymogens (inactive enzymes)
57
3 principle types of pancreatic enzymes?
proteolytic (protein catabolism)
amylase (starch catabolism)
lipase (fat catabolism)
58
Describe the control of pancreatic sodium bicarb secretion
+acid in duodenum -> + secretin release (mucosa) -> +secretion of bicarb (pancreatic duct cells) -> duodenal lumen -> neutralises acid in duodenum
59
Describe the control of pancreatic digestive enzyme secretion
Fats & proteins in duodenum -> +CCK (mucosa) -> + secretion digestive enzymes (acinar cells) -> digests fats & proteins
60
Bile...
Stored in gall bladder (not stored in horse)
Emulsifies fats
61
Know SI anatomy diagram on slide 22 (lec 2)
...
62
In the small intestine, what impairs digestion & absorption?
Loss of surface area (villous atrophy)
63
Why is physical breakdown of food important?
Reduces particle size
Enlarges surface area
64
Reduction of food particles occurs where?
stomach
65
Chemical digestion involves...?
Complex nutrients -> simple ones
Via hydrolysis
66
Chemical digestion of CHO breaks which bonds?
glycosidic linkages
67
Chemical digestion of proteins breaks which bonds?
peptide bonds
68
Chemical digestion of fats breaks which bonds?
ester bonds
69
Chemical digestion of nucleic acids breaks which bonds?
phosphodiester bonds
70
Describe luminal phase of monogastric digestion (non-fibrous CHO)
Dietary polysaccharides such as starch & glycogen broken down in GI lumen by salivary & pancreatic AMYLASE into maltose & sucrose.
71
Describe membraneous phase of monogastric digestion (non-fibrous CHO)
Maltose, sucrose & lactose -> monosaccharides by brush border enzymes -> glucose & galactose absorbed apical membrane by Na+ cotransport. Fructose by facilitated diffusion
72
Describe monogastric protein digestion & absorption (3 steps)
1. Dietary & endogenous protein ingested -> hydrolysed by pepsin & pancreatic proteolytic enzymes
2. AAs across apical membrane via Na+/K+ pump
3. Small peptides absorbed by different carrier -> AAs by aminopeptidases or intracellular peptidases
73
Consider drawing monogastric protein digestion (3 steps)
slide 27...
74
Consider drawing monogastric CHO digestion
slide 26...
75
Describe lipid digestion & absorption in monigatrics
1. TGs emulsified in SI by bile (duodenum)
2. Pancreatic lipases hydrolyse TGs -> monoglycerides & FFAs
3. Micelles formed by lipase & bile carry monoglycerides & FFAs -> luminal surface
4. Micelles release monoglycerides & FFAs near epithelial surface -> passive diffusion thru lipid bilayer
76
Consider drawing monogastric lipid digestion
slide 28...
77
Properties of large intestine...?
absorb water & electrolytes
microbial CHO & protein digestion
mucosal glands -> buffer & mucous
78
What does hind gut fermentation in horses produce?
VFAs = energy
79
Draw diagram of rumen and label compartments
slide 31-32...
80
Role(s) of the rumen...?
fermentation - anaerobic, pH, temp, removes indigestible material & products of digestion
81
Role of reticulum?
'Honeycomb' appearance - movement of material, fluid etc.
82
Role of omasum?
Spherical shape - laminae grind roughage & squeeze fluid out of ingesta
83
Role of abomasum?
True 'glandular' stomach - enzymatic digestion
84
2 main types of motility in the rumen?
Primary contractions - mixing
Secondary contractions - eructation of gas
85
T or F - regurgitation is not considered a motility pattern
true
86
3 main steps to ruminate...?
1. Regurgitate - rumen & reticulum contract -> recently eaten food away from oesophagus replacing it with semi-liquid partially fermented -> reverse peristalsis up oesophagus
2. Remasticate - only some matter ->reinsalivate
3. Reswallow
87
What is fermentation? Briefly describe...
Metabolic action of bacteria & other microorganisms
Microbial enzymes hydrolyse large molecules
88
What are the key features of ruminant & hindgut fermentation?
CHO most important E source
37 degrees
osmolality (ionic strength) optimum range
anaerobic (-ve red-ox potential)
removal of ingestible material
rate of microbial removal = microbial regeneration
VFAs buffered or removed
89
5 major groups of microbes?
Bacteria
Protozoa
Fungi
Archael (methanogens)
Bacteriophage
90
CHO digestion in the rumen...?
Microbial fermentation -> Acetate, Butyrate, Propionate
91
T or F - SCFA account for between 30 - 50% digestible E intake
False. 50 - 70%
92
Why is propionate important?
glucose production
93
Increased roughage -> ?
increased acetate
94
Protein digestion in the rumen...?
Proteins -> AAs -> microbial protein prod. & ammonia prod.
Can -> VFA prod.
95
