Exam 4: GI 6-10 Flashcards
What are the 2 control systems of the GI tract?
- intrinsic control sys.
2. Extrinsic control sys
Component of the autonomc nervous system, located w/i the GI wall and enables autonomic regulation of GI functions
enteric nervous system
What are the 2 plexuses of the enteric nervous system
- plexus submucosus
2. Plexus myentericus
plexus of the enteric NS located b/t submucosa and circular muscullature.
plexus submucosus
Plexus of the enteric NS located in the muscularis externa, between longitudinal and circular musculature.
Plexus myentericus
Which Plexus of the ENS regulates mucus secretion and food absorption?
Plexus submucosus
Which plexus of the ENS controls the muscular activity
Plexus myentericus
Unlike typical neurons, enteric neurons secrete their neuroT from ______, or bulge like structures located on axonal collaterals or branches
varicosities
What is imortant about enteric neurons varicosities
can spread effect to wide area
What are the 3 types of enteric neurons?
- dogiel type 1
- dogiel type 2
- dogiel type 3
What are dogiel type 1 neurons?
have a small cell body with short dendrites and are motor neurons
what are dogiel type 2 neurons
have large cell bodies with one or two long dendrites and are sensory
what are dogiel type 3 neurons
show multiple shapes and functions
What are the 3 types of neurons based on function?
- sensory nerve cells
- interneurons
- motoneurons
detect changes/stimuli and are used to regulate funtion
Sensory nerve cells
What are the 2 types of sensory nerve cells?
- mechanosensitive cells
2. chemosensitive cells
Sensory nerve cells that recognize stretching of intestinal wall or volume changes
mechanosensitive cells
sensory nerve cells that detect the presence of nutrients in the GI lumen, changes in osmolarity, and changes in Ph
chemosensitive cells
Process signals coming from other cells or from the CNS and propagate them to other neurons
interneurons
induce a change in the GI tract as an answer to stimulus
motor neurons
What are the 3 types of motor neurons?
- muscle MN
- Secreto MN
- Vaso MN
MN primarily located in the plexus myentericus
Muscle MN
MN primarily located in plexus submucosus
Secreto MN
MN in both the mhyentericus and submucosus
Vaso MN
What are 3 examples of NANC substances?
- NO
- VIP
- Substance P
What is NANC?
Non-noradrenergic, non-cholinergic substances
substances, alnong with conventional transmitters, that are released by enteric neurons
Sympathetic nervous system uses noradrenaline which has an stim/inhib effect on the GI tract.
Inhibitory
What are the two basic types of electrical waves in the gI tract
- slow waves
2. spikes
What are the slow waves of the GI tract?
rhythmical GI contractions
electrical pacemakers for smooth muscle cells
Interstitial cells of Cajal (ICC)
True AP of the GI tract that occur automatically when the resting membrane potential of the GI smooth muscle becomes more positive than -40mV
Spike potentials
concerning GI smooth muscle cells which one is true?
a. their contraction cannot be extrinsically influenced
b. spike potential do not conduce to a contraction
c. they show spontaneous undulations in the membrane potential
c.
What are the 3 types of GI reflexes essential to GI control.
- reflexes integrated within the gut wall
- reflexes from the gut to the prevertebral sympathetic canglia and back
- reflexes from the gut to the spinal cord/brain stem and back
What are the 3 types of the Reflexes from the gut to the ganglia and back?
- gastrocolic reflex
- enterogastric reflex
- colonoileal reflex
signal from the stomach that causes evacuation of the colon
Gastrocolic reflex
signal from the colon and SI to inhibit stomach motility and stomach secretion
enterogastric reflex
Signal from the colon to inhibit emptying of ileal contents into colon
colonoileal reflex
Which reflex is responsible for controling GI secretions , peristalsis, mixing contractions, and local inhibitory effects?
reflexes integrated within gut wall
Which reflex is responsible for transmitting signals long distances to other areas of the GI tract
reflexes from the gut to prevertebral sympathetic ganglia and back
Which reflex is responsible for controlling gastric motor and secretory activity
from gut to spinal cord
which reflex is responsible for pain
from gut to spinal cord
which reflex is responsible for defecation reflex?
gut to spinal cord
Stretching of the intestinal wall during the passage of a bolus triggers this reflex to constrict the lumen behind the bolus and dilate in front
peristaltic reflex
In order to move bolus through GI, areas proximal to the bolus are stimulated by _____ causing _____
excitatatory MN, Smooth muscle contraction
In order to move bolus through GI, areas distal to the bolus are stimulated by _____ causing ______.
inhibitory motor neurons, smooth muscle relaxation
Which kinds of sensory neurons will be stimulated during the peristaltic reflex?
a. chemosensitive neurons
b. mechanosensitive neurons
b. mechanosensative neurons
GI tract reflex circuts where afferent and efferent fibers of the vagus n. coordinate responses to gut stimuli via the dorsal vagal complex in the brain
vagovagal reflex
This reflex controls contraction of the GI m. layers in response to distension of the tract by the chyme
vagovagal reflex
the vagovagal reflex is active during _______ of the stomach in response to mastication of food.
Receptive relaxation
What does the vagovagal reflex do to the stomach
active relaxation
What are the 3 parts of the stomach based on function?
- gastric store- tonix relaxation and contraction
- gastric pump- peristaltic wave
- grinder- mixing and breaking down
inflow into the gastric pump happens due to the following sequences:
- tonic contraction of fundus
- peristaltic waave in corpus
- passage into grinder then pylorus
- emptying into duodenum
What are the 3 relaxation signals of the stomach?
- receptive relaxation
b. adaptive relaxation
c. feed-back relaxation
What reflex control receptive relaxation of the stomach?
vagovagal reflex
Which reflex controls adaptive relaxation of the stomach?
gastro-gastric reflexes
What are the 3 purposes of intestinal motility?
- mixing of food with GI juices
- inc. contact b/t food and walls
- peristalsis
What are the 2 distinct phases of SI motility?
- digestive period
2. interdigestive period
Which phase of SI motility occurs when food is present in the stomach?
digestive period
Which phase of SI motility occurs when little food is present in the gut?
interdigestive period
Which phase of SI motility occurs when little food is present in the gut?
interdigestive period
What are the two contraction patterns of the SI?
- Propulsive pattern
2. non-propulsive pattern
Motility pattern of SI during interdigestive period.
migrating motoric complex (MMC)
What are the two function of MMC in the SI during the interdigestive period
- helps pushing undigested material out of the intestine
2. controls bacterial pop.
What are the 3 phases of the MMC of the sI during the interdigestive period.
Phase 1- no contractions Phase 2- intermitent contractions
Phase 3- strong peristaltic contractions starting from the stomach and moving distally
What are the 2 motility patterns of the large intestine?
- peristaltic waves
2. antiperistaltic waves
Motility pattern of the LI that impedes the movement of ingesta, causing a more intense mixing
antiperistaltic waves
Giant contractions
pathologic contractions
What are 2 exapmles of pathologic contractions
- vomiting
2. diarrhea
Where is vomiting coordinated in the body?
brainstem
T/F. vomiting contains only ingesta of gastric origin.
F
An inc. in frequency of defecation or fecal volume
Diarrhea
what are 3 reasons for water in the gut?
- ingested water
- water secreted by glands
- water secreted or lost directly through the mucosal epithelium
Diarrhea occurs when there is a mismatch between ____ and ____.
secretion and absorption
What are the 2 types of Diarrhea
- malabsorptive
2 secretory
D that occurs when absorption is inadequate to recover all secreted water
malabsorptive diarrhea
D that occurs when rate of intestinal secretion increases and overwhelms the absorptive capacity
secretory diarrhea
What Type of diarrhea is caused by viral, bacterial, or protozoal infections?
malabsorptive
In which type of diarrhea would you see shortened villi?
malabsorptive
in which type of D would you see opening of the Cl channels?
secretory
Is the internal sphincter sympathetic or parasympathetic?
both
sympathetic stimulation causes contraction/relaxation of the sphincter.
constriction
Parasympathetic stimulation causes constriction/relaxation of the sphincter
relaxation
the internal/external sphincter is normally tonically contracted
internal
What is the retrosphincteric reflex?
When poo accumulates in the rectum, peristaltic movement of poo into the rectum and relaxation of internal anal sphincter, urge to defecate
What are the 2 suborders of ruminants?
- ruminantia
2. tylopoda
digestion that occurs in specialized compartments localized before the stomach or after the stomach an SI
fermentative digestion
3 microbes that are responsible for fermentation?
- bacteria
- fungi
- protozoa
What side of the animal is the abomasum located on?
Right
The ______ is the largest compartment of the newborn’s stomach
abomasum
most protozoa in the rumen belong to the genus ____ or ____
isotricha or entodinium
what is the ph of the ruminants stomach?
5.5-7
carbohydrates, proteins, and lipids in the ruminants stomach is digested by microbes to become ______.
VFA
propionate in the rumen goes to the _____ to procuce _____
liver, glucose
Acetate in the rumen goes to the ______ to procuce ____
all tissues, energy
adipose tissue, fatty acid
Butyrate in the rumen goes to the ______ to produce ____
all tissues, energy
Indigestible plant component
lignin
what are the 3 primary VFAs
- acetic acid
- propionic acid
- butyric acid
product of microbes that form short chain peptides as end products which are absorbed in to the microbial cell bodies
endopeptidases
AA contribute to what 2 things?
- synthesis of microbial protein
2. metabolized to VFA and ammonia
To enter the VFA pathway an AA must first be ______
deaminated
what happens in deamination?
NH3 group removed, carbon skeleton remains
What are the exception to the deamination rule
Branch chain AA
(BCAA)
carbon skeleton cannot be used
nitrogen waste product of prtotein catabolism
urea
What are the 2 sources of urea?
- urea from deamination of AA
2. nitrogen absorbed as ammonia from the rumen
What are the 4 types of fats and lipids?
- triglycerides
- glycolipids
- phospholipids
- free fatty acids
major lipid type found in cereal grains, oilseeds, animal fats, and byproduct of feeds, also in milk
triglycerides
major lipid type found in forages
glycolipids
minor compnent of most feeds, forms the cell memb. of all animal cells, and the surface of milk fat globules
phospholipids
Lipid that is important in fat digestion in the SI of cows
phospholipids
minor component of dairy feeds, but major component of certain fat supplements
free fatty acids
microorganism that digests triglycerids
A. lipolytica
microorganism that digests phospho and glycolipids
B. fibrisolvens
ruminants eating high forage will have a acetic/propionic/butyric ratio of:
70:20:10
Ruminants eating high grain diets will have an acetic/propionic/butyric ratio of:
60:30:10
What 3 vitamins do microbs synthesize?
- vit. C
- vit. K
- Vit. B (B1 and B12)
Vitamin B1
Thyamin
Bitamin B12
Cobalamin
When do you see a vit. B1 deficiency
sudden change of feed from roughage to concentrate
When do you see a vit B12 deficiency
cobalt poor soils or diets with too much grain
What are the 2 main mechanisms for absorption of VFA in rumen epithelium?
- ionized VFA- need carrier
2. non-ionized VFA- lipophilic- diffuse through apical memb
how does rumen acidosis occur?
fast-fermentable carbohydrates lead to an inc. in VFA production
ph in rumen dec.
what is the pK of VFA?
4.8
What are the 3 ways sodium is absorbed in the rumen
- Na channel
- Na/H exchanger
- basolat. Na/K ATPase
What 2 ways are Cl absorbed in the rumen
- Cl/HCO3 exchanger
2. basolateral channel
what is the highest mineral found in the rumen?
Na
what are the 2 buffers found in the rumen?
H2PO4-
HCO3-
What 2 ways is potassium absorbed in the rumen?
apical and basolateral channels
how is magnesium absorbed in the rumen?
Mg channel (affected by high K)
what are the clinical signs of pasture grass tetany?
irritability, muscle twitching, incoordination staggers, collapse
What two ways are Ca absorbed in rumen?
- Ca/H exchanger
2. basolat. Na/Ca exchanger and Ca ATPase
compartment of the stomach with muscular folds that project into the lumen, the canal connects reticulum to abomasum
omasum
What are the 3 functions of the omasum?
- concentration of ingestia (absorption of H2o)
- SCFA absorption
- Na Cl absorption
- HCO3 reabsorption
What are the two motility patterns in the rumen?
- mixing (primary contractions)
2. erucation (secondary contractions)
The two major motility patterns observed in the rumen are:
a. Peristaltic and antiperistaltic waves
b. Segmentation andpropulsive contractions
c. Mixing and erucation contractions
c.
T/F. Deglutition, eructation, and regurgitation can be observed on the left side of a cow?
T
What is the function of primary contractions?
reduce particle size
What is the function of secondary contractions
force gas toward cranial part of rumen
What are the main compnents of the gas produced in the rumen?
carbon dioxide and methane
where is the eructation center located?
medulla
bloating that occurs in cattle when the eructation mechanism fails
tympanism
When cattle feed on lush, rapidly growing alfalfa or clover pastures, gas becomes trapped in tiny bubbles and normal gas bubble cannot accumulate on top of dorsal sac
legume bloat
occurs most frequently in high producing dairy cows
ruminant ketosis
Where is the control center for reticulorumen motility located
brainstem
a gutterlike infagination transversing the wall of the reticulum from the cardia to the reticulo-omasal orfice
esophageal groove/ reticular groove
What is the importance of the reticular groove?
diverts milk away from the rumen to the abomasum
all of the glucose available to ruminants originates from _______.
gluconeogenesis
The most important precrsor of glucose in ruminants is the VFA ______
propionate
Bloat in cattle is caused by
a. inc. in the volume of cas produced
b. failure of the erucation lmechanism
b.
proprionate enters the krebs cycle as ____
succinate
succinate leads to the formation of ______ which is the entry metabolite for gluconeogenesis.
oxyloacetate