Digestion 3 Flashcards

(99 cards)

1
Q

how much does the compound stomach of ruminants take up

A

3/4 of the abdominal cavity - fills almost the entire left half of the abdominal cavity and squashed intestines to the right

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2
Q

what are the four compartments of the compound stomach of ruminants and group them into glandular and non-glandular

A

The fore-stomach (or proventriculus) which is non glandular -
- Rumen -
- Reticulum -
- Omasum -
The Abomasum which is glandular - monogastric type digestion

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3
Q

what occurs in terms of the compound stomach from milk to forage diet

A
  • At birth, the abomasum is the largest compartment - on the milk diet not forage so much more like monogastric, don’t need large amount of bacteria to get nutrients; In the adult, the rumen is the largest
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4
Q

Reticulum where located in the abdomen and where will illicit pain response

A

Lies on the left side, opposite the 6th to 8th ribs; it is the most cranial compartment
- The reticulum reaches from the cardia to the most forward part of the diaphragm and occupies the full height of this shallower part of the abdomen.
lies above the xiphoid process of the sternum. External pressure applied in this position will elicit a pain response in cases of reticulitis (inflammation of the reticulum).

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5
Q

what does the internal surface of the reticulum look like and its function and what occurs when sharp objects fall into stomach

A

Has honeycomb areas with papillae - holds onto longest ends of fibres so with forcible contraction thrown back into rumen so can be further digested, the smooth paste like substances can move through the hole to the omasum
Sharp objects ingested fall into reticulum, if sharp can poke through the wall and into the diaphragm on the other side is the heart which can pierce the heart - traumatic reticuloperitonitis - can present as heart failure

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6
Q

list and describe the 3 opening in the reticulum

A

1) Cardia - is the slit like opening of the oesophagus positioned at the junction of the rumen and reticulum and opens into both chambers.
2) Ruminoreticular orifice - wide opening between the rumen and reticulum which communicate over the U-shaped ruminoreticular fold - separate reticulum and rumen (pillars)
3) Reticulo-omasal orifice - round exit into the omasum at the lower end of the reticular groove

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7
Q

functions of the reticulum

A

o Serves as a sieve for coarse material
o Absorbs fatty acids, water, salts, etc.
o Passes coarse material back to the rumen and fine material to the omasum by very forceful contractions.

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8
Q

correlation between treatment of bloat and dorsal sac of rumen

A

can use rumen - left fland area to palpate and relieve gas from dorsal sac

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9
Q

what are the two curvatures of the external rumen

A

o Dorsal curvature - is firmly attached to the sublumbar muscles on the left by peritoneum and connective tissue as far caudal as the 4th lumbar vertebrae.
o Ventral curvature - lies on the floor of the abdomen with the superficial wall of the omental bursae between.

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10
Q

describe the two surfaces of the rumen

A

1) parietal or left surface - right up against the body wall - convex - related to diaphragm has superficial wall of greater omentum between ventral sac and abdominal wall
2) visceral or right surface - right up against internal organs - has many grooves denoting the different sacs

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11
Q

List the 11 grooves found in the rumen

A

1) cranial
2) rumino-reticular
3) right longitudinal
4) left longitudinal
5) right accessory
6) left accessory
7) right dorsal coronary
8) left dorsal coronary
9) right ventral coronary
10) left ventral coronary
11) caudal

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12
Q

where does the cranial and rumino-reticular groove go to and from and the function in rumen

A

Cranial groove - transverse groove that divides the cranial end of the rumen into the cranial sac (ruminal atrium) and the cranial end of the ventral sac
o Rumino-reticular groove - is the line of separation between the ruminal atrium and the reticulum. It is deep ventrally but dorsally the wall of the reticulum and the rumen are continuous and form the dome-like ventricular atrium on which the oesophagus terminates. Muscular fold

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13
Q

where does the left/right longitudinal, left and right dorsal and ventral coronary and caudal groove go to and from and the function in rumen

A

longitudinal grooves - extend from the cranial to caudal grooves and indicate the division of the rumen into dorsal and ventral sacs.
coronary grooves - demarcates the caudodorsal blind sac from the dorsal sac - curve
ventral coronary grooves same thing but ventral
caudal groove - deep transverse groove that divides the rumen into the caudodorsal and caudoventral blind sacs

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14
Q

what is the Ruminal atrium and Tympany

A

Ruminal atrium is that part of the rumen caudal to the rumino-reticular fold.
when rumen is filed with gas

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15
Q

groove and pillars relationship

A

internally the grooves correspond to bands of smooth muscle known as pillars. These pillars bear the same name as the grooves: Form the different sacs

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16
Q

papillae of the rumen, where present and what stimulates the development of them

A
  • not found on the pillars
  • Are long and numerous in the ventral and dorsal caudal blind sacs.
  • Fewer and less prominent in the ventral sac.
  • Are short or absent on the roof of the dorsal sac - due to the presence of gas bubbles resulting from fermentation.
    Volatile fatty acids stimulate development of papillae.
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17
Q

functions of the rumen and the papillae

A

o Ruminal contractions (waves of contractions caudally) mix the ingesta and furthers the process of microbial fermentation releasing volatile fatty acids and gases - coordinated to push gas into oesophagus (eructation)
o The absorption of volatile fatty acids, sodium, water, etc.
o Papillae increase the surface area for absorption and assist mixing of ingesta.
o Papillae also serve as heating rods for speeding up the fermentation process.
o Rumination and eructation. Rumen gas - gas cap normal - left paralumbar fossa (last few ribs) where gas sits

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18
Q

the omasum what curvatures does it have, where attached to the abomasum and what is it covered with

A

greater and lesser curvature
o Lower pole of the omasum has an extensive attachment to the fundic region of the abomasum around the omaso-abomasal orifice.
o Much of the right surface of the omasum is covered by, and is partly connected to, the lesser omentum - between true stomach and the liver

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19
Q

what are the two openings of the omasum

A

1) Reticulo-omasal orifice is at the upper end of the omasal canal.
2) Omaso-abomasal orifice at the lower end of the omasal canal is large and oval and partly obscured by the prolapse of the abomasal folds.

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20
Q

what is the omasal groove and omasal laminae in the omasum

A

Omasal groove -
Runs between the two openings and is in fact the floor of the omasal canal.
Mucosa in this region is smooth except for a few low longitudinal ridges.
Omasal laminae - or leaflets
Many parallel folds of four different sizes that fill the omasum.
Arise from the sides and greater curvature and project towards the lesser curvature - site of the omasal canal.
Lots of smooth muscle - two types in longest folds - 1. inner portion tunica muscularis 2. differentiates mucosa from sub mucosa - lamina muscculars mucosa

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21
Q

what is the interlaminar recess, omasal canal of the omasum

Where are papillae and what type

A

Interlaminar recesses - spaces between the folds.
Omasal canal - central area not occupied by folds.
Papillae – The mucosa forms numerous projections or papillae that cover the surface of the laminae. Most are small and somewhat flattened but there are a few large conical projections.

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22
Q

functions of the omasum

A

o Absorbs fatty acids, water, salts.
o Serves as a two-stage pump for transfer of ingesta from the reticulum to the abomasum.
o It is a sieve for quality control separation - lots of folds

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23
Q

what problems can arise with the abomasum

A

abomasal displacement - left or right occurs often in dairy cows as it is not well attached

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24
Q

what are the two poles of the abomasum

A

o The larger cranial pole:
- Forms a pear-shaped sac equated with the fundus and body of the simple stomach - Connected by muscle bundles to the reticulum, ruminal atrium and the ventral sac of the rumen.
o The narrower caudal pole:
- Forms the pyloric region. This passes transversely to the right; Terminates at the pylorus just caudal to the lower part of the omasum

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25
what are the two opening of the abomasum
Omaso-abomasal orifice | Pylorus - opens into the duodenum
26
spiral folds of the abomasum where do they arise, how are they coordinated, their function
spiral folds that arise around the entrance and course over the walls of the fundus and body, decreasing as they approach the flexure they serve to increase the mucosal surface area. In the region of the omasal-abomasal orifice these folds help to form a mucosa "plug" that limits reflux of ingesta into the omasum.
27
structure of the wall in the compound stomach
o Mucosa - is smooth pink and glandular; a thick muscularis mucosa is present o Submucosa o Muscularis externa - smooth muscle thicker inner (circular around length of organ) and a thin outer (longitudinal outer length) layer. o Serosa is absent from the surface only along the origin of the omentum
28
function of the abomasum
Is rich in glands that produce digestive enzymes and HCl for digestion and mucus for protection.
29
torus - where is it what does it do
abomasum - The lighter mucosa of pylorus bears a few low rugae but is marked by a large swelling that projects from the lesser curvature to narrow the pyloric passage. The vascular structure of the torus suggests it is capable of engorgement, but its functional significance is unknown.
30
oesophageal groove what is its function and the 3 segments
Serves as a conduit for conveying milk from the oesophagus into the abomasum without having to go through the rumen 1) Reticular groove - - From the cardia to the reticulo-omasal orifice - Bounded by two prominent muscular folds - It is open along its left side facing the cavity of the reticulum and rumen - Muscular folds roll into a tube when a young animal drinks milk 2) Omasal groove - - From reticulo-omasal orifice to omaso-abomasal orifice on floor of omasum - Muscular folds are not very prominent - It is open along its right side facing the cavity of the omasum 3) Abomasal groove - - Not a proper groove, just an area without gastric folds - It extends along the lesser curvature of the abomasum
31
blood and nerve supply to the compound stomach
Blood and nerve supply to the compound stomach Blood Supply - branches of the celiac artery; veins are satellites to the arteries eventually draining into the portal vein which then goes to liver - volatile fatty acids gets turned into energy there. Nerve supply - branches from the dorsal and ventral trunks of the vagus nerve.
32
differences for small ruminants such as sheep and goat for the reticulum, ventral sac of rumen, caudovenral blind sac of ruen, omasum and abomasum
o Reticulum - Is relatively larger (7-8% of total stomach capacity). - Contact with the ventral abdominal floor is subject to much variation. o Ventral Sac of Rumen - Is relatively larger. - Extends more to the right of the midline. o Caudoventral Blind Sac of Rumen - Extends more caudally than the dorsal blind sac. o Omasum - Is the smallest compartment (~5% of total stomach capacity) o Abomasum - Is relatively larger. - Due to smaller size of the omasum is usually in direct contact with the liver.
33
what are the two parts of the simple stomach
1) Cardiac, fundic and body regions form the larger part - into which the oesophagus opens - lies mainly to the left of the median plane - is well forward under cover of the ribs - is in direct contact with the liver and diaphragm - is relatively distensible 2) Pyloric region is the second part which is narrower - Has thicker walls and is more constant in appearance - It passes to the right to continue into the duodenum at the pylorus
34
what are the two surfaces of the simple stomach and what are they in contact with
1) Cranial or parietal surface (body wall) - is mainly in contact with the liver and diaphragm 2) Caudal or visceral surface (organs) - is in contact with the intestinal mass, the left kidney, the pancreas and the greater omentum
35
what are the two extremities of the simple stomach (openings)
1) Cardia - the oesophageal orifice into the stomach | 2) Pylorus - the opening of the stomach into the intestine
36
position of the simple stomach which way does it lay, when distends where does it move
transverse position | moves back caudally
37
What is the larger left side of the simple stomach divided into
1) Cardiac region - usually around the cardiac sphincter 2) Fundic region (or Fundus) - is large and rounded and usually the most dorsal part of the stomach (above the level of the cardia) 3) Body - usually extending from level of the cardia to the ventral angle
38
what is the smaller right pyloric region of the simple stomach divided into
1) Pyloric antrum - the more proximal portion 2) Pyloric canal - the more distal portion 3) Pyloric sphincter - the outlet of the stomach into the duodenum
39
list and describe the 2 supporting membranes of the stomach
1) The greater omentum - An often extensive serous membrane attached to the greater curvature of the stomach - It is rich in fat - It has a parietal and visceral layer which encloses a cavity – the omental bursa. - The opening of the cavity is the epiploic foramen - It functions as a storage organ for fat and provides protection 2) The lesser omentum - Is a serous membrane that extends from the lesser curvature of the stomach and the initial part of the duodenum to the hilus of the liver. - Has two parts - 1. Hepatogastric ligament 2. Hepatoduodenal ligament contains the portal vein, hepatic artery, bile duct produced by liver released into duodenum and lymphatic duct
40
blood and nerve supply of the simple stomach
blood - share with spleen and liver Branches of the celiac artery branch off aorta - gives one branch to spleen branch again to greater omentum, one to liver supply blood to the stomach The gastric veins drain into the portal vein Nerve Supply - Branches of the vagus (parasympathetic - main ones that stimulate motility) and sympathetic nerves
41
structure of the simple stomach wall
composed of the usual 4 layers however different in different areas of the stomach to lining is divided into different zones or regions
42
what are the two main regions of the stomach based on structure of the wall
1) nonglandular region | 2) glandular region
43
nonglandular region of the simple stomach what is the wall structure and what is it prone to
similar to the oesophagus but muscularis mucosa is usually present. There are NO GLANDS present in the wall. - Epithelium - keratinized squamous epithelium - Mucosa - smooth mouth - Submocosa - loose connective tissue - Muscularis - spindle shape smooth muscle cells - Serosa - squamous on outside secreting peritoneal fluid Prone to gastric ulcers - as acid build up in stomach and spillage into oesophagus onto non protected non glandular area
44
glandular region of the simple stomach wall structure
1) Mucosa: thrown up into longitudinal folds - gastric folds or rugae and the surface epithelium invaginates to form gastric pits -lined by constantly mucus secreting simple columnar surface epithelium. - Function is to protect the gastric mucosa (may produce bicarbonate as well, especially in cardiac and pyloric gland regions) - Tubular Glands are present in the laminar propria, which extend to the muscularis mucosa. They open into the base of the gastric pits.- May also see lymphoid follicles in the lamina propria. 2) Submucosa: - No glands; Rich in blood vessels and nerves, mainly collagen fibres. 3) Muscularis externa: - Has 3 incomplete layers of smooth muscle, which also contributes to the cardiac and pyloric sphincters. 1. Inner- oblique - fibres don't run in same orientation so contract in different directions 2. Middle- circular- helps form the thick ring of the pyloric sphincter and the weaker ring of the cardiac sphincter \3. Outer- longitudinal- is a very thin layer. 4) Serosa: - A serous membrane- reduces friction.
45
List the 3 zones the lumenal surface of the glandular region of the simple stomach is divided into and what they secrete what do you need to be careful of
1) cardiac zone - mucus 2) fundic zone - mucus, enzymes, HCl and hormones 3) plyoric zone - mucus need to be careful as in different species besides dog and human the cardiac zone isn't in the cardiac area of the stomach etc.
46
describe the cardiac zone of the simple stomach
- Gastric pits are lined by simple columnar epithelium- produce mucus. - At base of the pits there are glands - Glands are short branched and coiled, composed of mainly mucous cells - usually cuboidal to low columnar
47
describe the fundic zone of the simple stomach
- Gastric pits are lined by simple columnar epithelium- produce mucus - Glands -tubular and branched and divided into neck, body and base regions - all the way down to muscularis mucosa - Cells in gland wall- 1) mucus neck cells 2) chief cells 3) parietal cells 4) endocrine cells
48
mucus neck cells and chief cells what zone of the simple stomach are they present and their position of the gastric pit and what they secrete and type of cell
Fundic zone 1. Mucous neck cells - in the neck region of the fundic glands - cuboidal to low columnar cells, lining the lumen in the upper 1/3 of gland. - These cells produce mucus. They have flat basal nuclei, cytoplasm slightly more basophilic than surface epithelium. 2. Chief cells - - These line the lumen in body and base of gland. They produce enzymes (pepsinogen) - converted to pepsin - They are the most numerous cells in fundic glands, are cuboidal to pyramidal in shape, with a spherical basal nucleus. - Their basal cytoplasm is basophilic (stains blue/purple on base - due to high protein output so lots of mRNA)- due to extensive RER, and they have an apical cytoplasm- 'lacy' vacuolated appearance
49
parietal and endocrine cells what zone of the simple stomach are they present and their position of the gastric pit and what they secrete and type of cell
Fundic zone 3. Parietal cells - are present in neck body and base of gland; these produce HCl. Acid secreting - They are large and occur singularly (less numerous). They have spherical nuclei, and a deep eosinophilic cytoplasm - due to extensive mitochondria. Pyramidal shape - (narrow apex of cell, base of cell bulges from the outer surface of the gland). 4. Endocrine cells - Produce hormones such as gastrin, secretin etc; difficult to identify with H&E. - Also includes ECL (enterochromaffin-like) cells: secrete histamine.
50
describe the pyloric zone and what it secretes
- Gastric pits are much deeper- maybe 1/2 the thickness of the mucosa; glands are branched, coiled and short - Cells in gland wall - mucous cells – (flat basal nuclei, pale staining apical cytoplasm).
51
the mucosa contains three distinct regions in the dog simple stomach what are they and what does the mucosa look like
1) Cardiac glands are found in a very narrow pale zone around the cardiac opening and scattered along the lesser curvature 2) The Fundic gland region has a thick reddish brown mucosa which lines about 2/3 of the stomach and has prominent longitudinally orientated rugae 3) The Pyloric mucosa is thin and pale and is often stained by regurgitated bile at post-mortem.
52
what shape is the dog and cut simple stomach
C-shape cat is more elongated
53
the horse stomach what shape, what parts are large, and what extra sac does it contain and its boundary
curved J-shape with less curvature narrow and tight and more extensive greater curvature Fundus is extensive, forms a large non-glandular sac - the saccus caecus - surface is smooth white or yellowish in colour. - Internally, the saccus caecus is separated from the rest of the stomach by a mucosal fold- the margo plicatus - marks the boundary between the non-glandular and glandular regions of the gastric mucosa (may see craterlike perforations caused by the larvae of bot flies in this region)
54
what are the two reasons horses can't vomit
1) The cardiac sphincter is very strong | 2) oesophagus enters at an acute angle such that the cardia closes when the stomach expands
55
what is the size and orientation of the greater omentum in the horse
relatively small in the horse and is usually not visible when the abdomen is opened - it is usually folded up in the space between the stomach and the intestine
56
torus pyloricus structure and function
is a projection of tissue from the wall of the lesser curvature into the pylorus. It is highly glandular and has a strong fibromuscular/ muscular/fat layer. It assists the pyloric sphincters to close the pyloric opening.
57
pig stomach shape, and extra area
- Irregular J-shape - more open less curvature than the horse but still narrow - Is relatively large (~ 9 litres) - The left extremity - the fundus - has a flattened conical pouch the diverticulum (= diverticulum ventriculi) the apex of which projects caudally
58
pig has an extra region in its stomach what is it
1) The proventricular region - - Lies around the crdia - Is oesophageal in character - Presents a number of folds - Is non-glandular - Sharp line of demarcation between it and the rest of the stomach
59
bird stomach what are the two distinct parts their sub-parts and what separates them
1) proventriculus 2) gizzard (ventriculus) 1. craniodorsal blind sac 2. body 3, caudoventral blind sac separated by the isthmus
60
shape, mucosa and function of the proventriculus and ventriculus
small cranial glandular stomach - mixed with HCl - Elongated spindle-shaped organ - Mucosa is reddish in colour - Papillae secret the HCl - very acidic ven - large caudal muscular (smooth muscle) stomach - Large biconvex oval shaped very thick muscular organ - Mucosa is thick, glandular and thrown into folds
61
what do the three regions of the gizzard severe
1. Craniodorsal blind sac receives the opening of the proventriculus and the duodenum 2. Body - main part 3. Caudoventral blind sac - where stones and rocks can sit if swallow to aid mechanical digestion - grit - need a special protective layer
62
the structure of the wall of the small intestine
Mucosa - Secretory cells - mucus and enzymes - columnar - Absorptive surface villi and microvilli Submucosa - Secretory glands - goblet - mucus and paneth - enzymes Muscle layers - Complex motility patterns
63
what digestion function are highly regulated and what aren't
``` Highly regulated - Motility - Secretion Little regulation - can't switch off - Digestive - Absorption ```
64
what type of activity is involved with regulation of the gastrointestinal tract
1) Autonomous activity - take piece of gut and provided it has what it needs it will continue to generate spontaneous activity 2) Local (intrinsic) reflexes - reflexes occurring within gut - Neural (enteric plexuses) - Neuroendocrine (enterogastrones) - gut hormones 3) Long (extrinsic) reflexes - most not under conscious control
65
characteristics of smooth muscle
* A functional syncytium - multiple cells but connected by tight junctions - electrical activity will spread from one cell to another * Tight junctions * Autonomous (intrinsic) activity * Depolarised by stretch - and contract
66
describe the autonomous nature of smooth muscle and what modulates it
Membrane potential is not stable - tends to fluctuate due to Na constantly being pumped out so drifts back in down concentration gradient 1) intrinsic nerves 2) local hormones 3) extrinsic nerves
67
intrinsic nerves in the gastrointestinal system what is it called and what are the areas in which they originate called
The enteric nervous system (ENS) - more nerves than in spinal cord Submucous plexus- in submucosa Myenteric plexus- in muscle layers
68
what are local gut hormones called, what produced by, where carried, when released, what modulated by
enterogastrones Produced by enterochromaffin cells in gut wall • Carried in blood stream to act in same or other areas of the gut • Released in response to local changes particularly in lumen ( eg fat pH etc) • Release modulated by intrinsic and extrinsic nerve pathways • Can work in stomach or small intestine but released from stomach
69
extrinsic nerves in gut where originate, what nervous system involved, how does it modulate secretion
originate outside the digestive tract and innervate digestive organs autonomic nervous system - Modifying activity of intrinsic plexus (intrinsic nerves) – Altering level of hormone secretion – Direct effect on muscle (and glands)
70
what are they different type of receptors within the gut wall
``` • Chemoreceptors: – sense pH, protein, fat levels of luminal content • Mechanoreceptors – Sense stretch, particulate matter • Osmoreceptors – Sense osmolality ```
71
list the 3 steps that require control in terms of gastric motility
1) gastric filling 2) gastric storage/mixing 3) gastric emptying
72
what occurs during gastric filling and what controls this
Receptive relaxation of stomach as it fills: a vago-vagal reflex - as stomach fills stimulates relaxation of the stomach - first step in motility - due to vagus nerve
73
what occurs with gastric storage and mixing where, and what stimulus
Pacemaker activity initiated in upper fundus and cardia - Waves of depolarisation sweep towards pylorus - increase pacemarker increase mixing and physical digestion stimulus - stretch, gastrin and vagus nerve
74
gastric emptying generally what leads to an increase
- Increased pyloric antral peristaltic contraction leads to increased gastric emptying - Duodenal and gastric factors alter gastric emptying • Particularly the chemical and physical properties of chyme
75
what specific factors in the stomach and duodenum modify emptying
stomach - increase emptying - stretch and fluidity of chyme | duodenum - decrease emptying - fat, acid, hypertonicity, distension
76
what hormones control gas emptying and nerve pathways
– Gastrin ( G cells of pyloric antrum (stomach) and duodenum (small intestine)) – Secretin - duodenum – Cholecystokinin - duodenum – Gastric inhibitory peptide - duodenum
77
gastric emptying increase or decrease for sympathetic and parasympathetic
sympathetic - decreased emptying | parasympathetic - increase emptying
78
stimuli for release of gastrin
• Distension of stomach • Presence of protein or amino acids in pyloric region of stomach --> gastrin stimulates increased gastric motility and emptying
79
stimuli for release of intestinal enterogastrones
* Distension of duodenum * Low pH in duodenum * Increased protein in duodenum * Increased fat in duodenum * Increased osmolality of duodenal chyme
80
what are the 3 types of motility in the small and large intestine and describe the movement
1) Segmentation: circular muscle constricts, forward and back migration of motility so mixing occurs – responsible for mixing of chyme and increased contact with absorptive surfaces 2) Migrating motor complexes (MMC) – Peristaltic waves that propel food down GI tract - need relaxation ahead of peristaltic wave 3) Giant peristaltic contractions – Longer duration and greater intensity than MMC – Distal SI and colon
81
spasmolytics what do they do and why are they bad sometimes
blocks the action of the parasympathetic neurotransmitter acetyl choline at the receptor on smooth muscle cells. reduce gi tone and motility can stop gut motility and not specific to areas of the gut there is also direct smooth muscle relaxants
82
prokinetics what do they do and example
- “normalise” gastrointestinal motility so restore motility in “injured” gut eg after gastric distension - More complex mechanism of action involving other neurotransmitters in the ENS such as dopamine dopamine antagonists and cisapride which increase release of ACh from gut
83
series of experiments into vomiting found what
in the blood stream chemicals can stimulate the chemoreceptor trigger zone in the stomach can stimulate via the neural pathways to the brain stem
84
what is nausea in terms of vomiting
on the continuum of vomiting so if nausea then probably stimulating vomiting pathway just not at the threshold of vomiting yet.
85
where does the stimuli for vomiting converge and list the stimuli for vomiting
emetic center NK1 - receptor CRTZ - outside blood brain centre and indirectly stimulus the emetic centre - Unpleasant smells - - Unpleasant sights - Abnormal motion - travel sickness important for dogs - puppies - Intense pain - Tactile stimulation to back of throat - Distension of stomach or intestine - Toxins -urea build up, lots of drugs - GIT irritation……. - dietary indiscretion - dogs eating what they shouldn’t
86
what are the receptors and effects for the vomiting reflex
chemo-, stretch in multiple organs | effectors - skeletal muscles, salivary glands and gastrointestinal tract
87
list the 7 steps of vomiting
1) Preceded by salivation, increased HR, pallor etc - autonomic nervous system signs - part of the reflex of vomiting 2) Deep inspiration and closure of glottis 3) Contraction of diaphragm and abdominal muscles (skeletal muscles) --> increase intraabdominal pressure 4) Relaxation of sphincters and stomach 5) Gastric contents forced into oesophagus 6) Increased pressure leads to relaxation of pharyngo-oesophageal sphincter 7) Passage of vomitus to mouth
88
what is regurgitation when and why does it occur and differences with vomiting
* Regurgitation involves a reverse peristaltic wave in the oesophagus * Generally occurs shortly after eating * Undigested or poorly digested material * Not preceded by salivation, increased HR etc
89
what are the drugs called that used to treat vomiting, why are they given and what is important
anti-emetics given because associated with: - Nausea - suffering not necessarily painful - distress, - fluid loss and electrolyte imbalance - exhaustion - always important that the underlying disease is identified and addressed
90
how do pharmacologists group drugs and what is a class of drugs
1) by their effect 2) by their mechanisms A CLASS of drugs is a group of drugs that shares a common mechanism of action
91
List the 6 classes anti-emetics
1) Anti-histamines - block histamine receptor 2) Phenothiazines 3) Dopamine receptor antagonists 4) 5HT3 receptor antagonists 5) Neurokinin 1 receptor antagonists 6) (Anticholinergics)
92
anti-histamines what does it treat and what is the side effect
anti-emetic - Treatment of motion sickness (receptors in semi circular canals - only area of body histamine is useful) - Side effect is sedation - The sedation can sometimes be useful as part of alleviating the stimulus to vomiting - anxiety - such as puppy during travelling
93
phenothiazines - what is its mechanism and side effects
anti-emetic - dopamine antagonist @CTZ (chemoreceptor trigger zone), Ach receptor antagonist @ vomiting centre - not specific as range of receptors that it acts upon Side effects: anti muscarinic, extrapyramidal effects (eg tremor, incoordination) and sedation
94
neurokinin 1 receptor antagonists - what is the mechanism
anti-emetic | target NK1 receptors in both CTZ (chemoreceptor trigger zone) and vomiting centre
95
Dopamine receptor antagonists - what is the mechanism, when useful and what side effects
- dopamine antagonism @CTZ, - peripheral effects due to increased activity of ACh --> increased gastric emptying - restore normal motility - This is very useful in situations of gastric irritation where gastric emptying is delayed, providing a continuing stimulus to vomiting - Side effects due to dopamine antagonism: motor effects (partic metoclopramide) - in-coordination effect
96
5HT3 antagonists and Anticholinergics mechanism of action, and when used
5HT3 - - activity at CTZ and periphery - Nausea and vomiting associated with cancer chemotherapy and post operatively Anticholinergics - - is often present in drug mixtures of limited value as an anti-emetic - not a precise form of treatment due to presence of acetylcholine
97
List the 3 drugs that modify intestinal motility and secretion
1) prokinetics 2) antispasmodics 3) Laxatives
98
laxatives what is the aim
Aims in treatment of constipation – To increase bulk of large bowel content - stimulates motility – To soften large bowel content To increase water in large bowel – To increase propulsive contractions of the colon
99
what are the drugs for diarrhoea and what are side effects
– Short term use only | – May have adverse (opioid) side effects and cause habituation - constipation which is why it is used for diarrhoea