Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Digestion > Digestion > Flashcards

Digestion Flashcards

(74 cards)

Start Studying
1
Q

Receptive relaxation in proximal stomach dependent on

A

Vagus n.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Parts of stomach and functions

A

Fundus and body store food
Antrum grinds, mixes, and empties
Pylorus prevents particles >2mm from leaving

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

3 phases of gastric acid secretion

A
  1. cephalic
  2. gastric
  3. intestinal
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Cephalic phase of gastric acid secretion

A

Vagovagal reflex and endocrine release of gastrin prepare stomach for digestion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Gastric phase of gastric acid secretion

A

2 mechanisms:

1) distention (Vagovagal reflex (Ach) )
2) stimulation of protein-sensitive musocal receptors

pepsinogen->pepsin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Stimulation of parietal cells

A

Stimulated by acetylcholine, gastrin, histamine to produce HCl

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Why do gastric secretions not digest gastric mucosa?

A

Secretion of bicarbonate protects stomach

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Canine gastric acid and pepsin secretion after a meal

A

Peaks 1 hour after feeding

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Gastric emptying

A

When intragastric pressure exceeds duodenal pressure and pyloric resistance

Emptying is influenced by physical and chemical composition of a meal, food type, pH, osmolarity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Osmolarity of stomach contents before release into duodenum

A

Must be isotonic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Factors that influence pH of proximal small intestine

A

H+ input (from gastrin)/H+ absorption
HCO3 (from pancreatic duct cells, biliary duct cells, duodenal mucosa)
Buffers: dietary protein, peptides, fatty acids, bile acids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Secretory function of pancreas

A

Acini: digestive enzymes and cofactors
Ducts: HCO3, buffers
Islets of Langerhans: hormones

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Secretin

A

Released from wall of duodenum

Causes copious secretion of bicarb and pancreatic fluid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Swallowing

A

Swallowing control center in medulla
Upper esophageal sphincter relaxes and pharyngeal contraction propels bolus into proximal esophagus
Peristaltic waves moves food down esophagus
Lower esophageal sphincter (cardiac) relaxes and food enters stomach

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

CCK

A

Cholecytokinin:

  1. Fat and protein products stimulate secretion of CCK from duodenum to bloodstream
  2. Relaxes sphincter of Oddi
  3. Contracts gall bladder

Delays gastric emptying and controls rate at which stomach contents are delivered to duodenum
Most potent stimulus for pancreatic enzyme (protease, amylase, lipase) secretion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Enterohepatic circulation of bile salts

A

Bile salts enter small intestine via bile duct, passively absorbed in jejunum, actively reabsorbed in distal ileum, and then are returned to liver via portal vein and are re-secreted

About 6% lost in feces

Not enough bile salts to last a whole meal, so they are recirculated 5-6 times per meal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Pancreatic Enzymes

A

Amylase: starch, glycogen -> small sugars
Lipase: long-chain triglycerides -> monoglycerides and fatty acids
Trypsin: secreted into duodenum as trypsinogen (zymogen) and functions in protein break-down

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Trypsin activation

A

Secreted into duodenum as trypsinogen (zymogen), activated by enteropeptidase, activates other enxymes, breaks down proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Major function of large intestine

A

salt and water absorption

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Types of salivary glands

A

Serous- parotid
Mucous - buccal
Both- mandibular, sublingual

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Composition of saliva- species differences

A

Ruminants- high in HCO3
Horse- high in Ca
Pig- amylase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Functions of saliva

A
  1. Mastication and deglutition
  2. Evaporative cooling
  3. Buffering forestomach digestion
  4. Starch and fat digestion (minor)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Control of saliva secretion

A

ANS- cholinergic stimulation increases flow rate
Sight and smell of food
Mastication (horse)
Mechanical stimulation

Inhibited by rumen distention

Continuous secretion (cat)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Urolithiasis in goats

A

Male, castrated goats
High P:Ca ratio in grain causes inc. urine pH (alkaline)
Low roughage, high grain diets decrease saliva production and P in urine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Loss of one (of each type) salivary gland
Other gland will compensate
26
Lining of esophagus
Squamous mucosa with longitudinal folds
27
Muscle composition of esophagus
All striated muscle- dog, ruminants, pig Proximal striated, distal smooth- horse, cat
28
primary vs secondary peristalsis
Primary: initiated by the act of swallowing Secondary: not initiated by swallowing, occurs if primary peristalsis fails to empty esophagus or when gastric contents are refluxed
29
Why horses rarely vomit
Not due to strong LES, they have poorly developed vomiting centers in brain
30
Choke in horses
Impaction of food items in proximal esophagus, no known causes
31
Functions of biliary secretion
1. Provides a source of bile acids for fat digestion and absorption 2. Provides excretory route for metabolites and some drugs 3. Provides additional buffer to neutralize H+ in duodenum
32
Composition of bile
``` 50% bile salts Bilirubin Lecithin Cholesterol Electrolytes of plasma Water ```
33
Function of bile salts
Absorption of fat and fat soluble vitamins
34
Conjugation of bile salts
Precursor cholesterol converted to cholic and chenodeoxycholic acid, then combine with glycine and taurine to form glyco- and taur-conjugated bile salts LOWERS pKa and improves solubility *Cats are OBLIGATE taurine-conjugators*
35
Primary vs. secondary bile salts
Primary converted to secondary by enteric bacteria in colon by deconjugation and dehydroxylation Also in small intestine if bacterial overgrowth Precipitate and bind to bacteria
36
Absorption of fat
Micellar solubilization | Chylomicrons take fat to lymphatics
37
Formation of bilirubin
Separation of red blood cells = heme and free iron | Heme oxygenase converts it to biliverdin -> biliverdin reductase -> bilirubin
38
Unconjugated bilirubin
"Idirect" or "free" Highly hydrophobic Released from macrophages
39
Conjugated bilirubin
Hydrophilic Secreted actively into bile (is the rate limiting step in bile secretion) Easily secreted into urine (makes urine dark color)
40
Stercobilin
Conjugated bilirubin converted to stercobilin in colon (via urobilinogen, which can be recycled by liver and used by kidneys)
41
Clinical causes of icterus
Increased production of bilirubin (hemolysis) Impaired bilirubin uptake and conjugation Impaired bilirubin secretion (bile duct obstruction)
42
Features of squamous gastric mucosa
Presence is species-dependent, function unknown
43
Features of cardiac gastric mucosa
Musouc, HCO3- secretion
44
Features of fundic gastric mucosa
HCl, pepsin, lipase, histamine, somatostatin
45
Features of pylorica gastric mucosa
Gastrin, somatostatin, pepsin, lipase
46
Parietal secretory cells
Secrete HCl Stimulated by receptors for Ach, Gastrin, and H2* *most important pathway
47
G cells
Secrete gastrin Stimulated by Ach, AA, gastric distention Inhibited by somatostatin
48
D cells
Secrete somatostatin Important inhibitor of acid secretion* Suppresses gastrin release by G cells and histamine release by ECL cells Stimulated by gastric lumen pH
49
Enterochromaffin-like (ECL) cell
Secretes histamine Stimulated by Ach, gastrin Inhibited by somatostatin
50
Important stimulators of gastric acid secretion
AA Protein Gastric distention Helicobacter pylori (species dependent)
51
Important inhibitors of gastric acid secretion
Luminal acid | pH
52
Pepsin
Secreted as pepsinogen by chief (zymogen) cells | Converted to pepsin if pH
53
Gastric Lipase
Found in all species Secreted in active form by chief (zymogen) cells Active in acid medium Hydrolyzes long chain fatty acids
54
Prostaglandin E2
Induces bicarb secretion Induces mucous secretion Induces mucosal blood flow Suppresses acid secretion
55
Function of mucins
Lubrication Diffusion barrier Binding (to foreign substances, pathogens) Interaction with immune surveillance system
56
Gastric mucosal protection and repair
Protection: vasodilation, mucous/bicarbonate secretion Enhanced by: PGE2, CGRP, nitric oxide, bradykinin Inhibited by: NSAIDs, tachykinin
57
Two events of gastric smooth muscle activity
1. Slow wave: does not cause muscle contraction by itself, freq determines max. AP freq 2. Action potential (spike): causes contraction
58
Interstitial Cells of Cajal (ICC)
Pacemaker cells responsible for slow wave
59
Trituration of gastric contents
Increased pressure in antrum causes retropulsion of contents
60
Function of HCO3
``` Neutralizes pH in duodenum Inactivates pepsin Protects duodenal mucosa provides functional pH for enzymes Increases solubility of bile and fatty acids ```
61
Amylase
Secreted into duodenum in active form | Digests starch and glycogen into smaller sugars
62
Lipase
Secreted into duodenum in active form | Digests ingested long-chain triglycerides into monoglycerides and fatty acids
63
Trypsin
Secreted into duodenum in its inactive form, trypsinogen (zymogen) Trypsin -> trypsinogen by enteropeptidase Activates other enzymes Proteolytic- breaks down proteins
64
Intestinal phase inhibition
Trypsin inhibits secretin and CCK release (negative feedback)
65
Pancreatic exocrine insufficiency (PEI)
Decreased digestion of macronutrients -> caloric deficiency, steatorrhea, diarrhea Clinical signs: weight loss
66
Pancreatic protection
Enzymes secreted in vesicles Enzymes secreted as zymogens Trypsin activated by eneteropeptidase (and then activates other enzymes) Trypsin inhibitor in acinar cell *Failure of these will cause pancreatitis
67
Equine pancreas
``` Continuous, profuse secretion HCO3- concentration always low Low enzyme activity Gastrin can take the place of secretin *HCO3 in ileum ```
68
Function of HCO3 in equine ileum
buffer acid production of microorganisms in cecum
69
4 functions of digestive system
1. Secretion 2. Digestion 3. Absorption 4. Motility
70
Small intestinal diarrhea
Excess secretion "washes out" lumen Stimulated by enterotoxin or inflammatory mediators from immune stimulation Mucosal epithelial damage -> malabsorption
71
E.coli enterotoxin
Inc. intracellular cAMP -> blocks transporter for NaCl and water, stimulates secretion of Cl- -> diarrhea
72
Treatment of enteroxigenic diarrhea
Oral or IV fluids to replace lost electrolytes and restore plasma volume Stimulate the unaffected glucose/Na transporter Give water solution with salt and sugar (Gatorade)
73
Prostaglandins
Produced in large amounts by intestinal mucosa Several functions-secretion, proliferation, "cytoprotection" Produced by equine colonic mucosa
74
CFTR
Cystic Fibrosis Transmembrane Conductance Regulator Genetic defect in channel that secreted Cl- Occlusion by mucous plugs

Digestion (6 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions