Digestion 3

Question 1

how much does the compound stomach of ruminants take up

Answer 1

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

Question 2

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

Answer 2

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

Question 3

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

Answer 3

• 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

Question 4

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

Answer 4

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).

Question 5

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

Answer 5

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

Question 6

list and describe the 3 opening in the reticulum

Answer 6

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

Question 7

functions of the reticulum

Answer 7

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.

Question 8

correlation between treatment of bloat and dorsal sac of rumen

Answer 8

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

Question 9

what are the two curvatures of the external rumen

Answer 9

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.

Question 10

describe the two surfaces of the rumen

Answer 10

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

Question 11

List the 11 grooves found in the rumen

Answer 11

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

Question 12

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

Answer 12

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

Question 13

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

Answer 13

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

Question 14

what is the Ruminal atrium and Tympany

Answer 14

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

Question 15

groove and pillars relationship

Answer 15

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

Question 16

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

Answer 16

• 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.

Question 17

functions of the rumen and the papillae

Answer 17

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

Question 18

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

Answer 18

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

Question 19

what are the two openings of the omasum

Answer 19

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.

Question 20

what is the omasal groove and omasal laminae in the omasum

Answer 20

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

Question 21

what is the interlaminar recess, omasal canal of the omasum

Where are papillae and what type

Answer 21

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.

Question 22

functions of the omasum

Answer 22

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

Question 23

what problems can arise with the abomasum

Answer 23

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

Question 24

what are the two poles of the abomasum

Answer 24

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

Question 25

what are the two opening of the abomasum

Answer 25

Omaso-abomasal orifice | Pylorus - opens into the duodenum

Question 26

spiral folds of the abomasum where do they arise, how are they coordinated, their function

Answer 26

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.

Question 27

structure of the wall in the compound stomach

Answer 27

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

Question 28

function of the abomasum

Answer 28

Is rich in glands that produce digestive enzymes and HCl for digestion and mucus for protection.

Question 29

torus - where is it what does it do

Answer 29

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.

Question 30

oesophageal groove what is its function and the 3 segments

Answer 30

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

Question 31

blood and nerve supply to the compound stomach

Answer 31

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.

Question 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

Answer 32

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.

Question 33

what are the two parts of the simple stomach

Answer 33

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

Question 34

what are the two surfaces of the simple stomach and what are they in contact with

Answer 34

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

Question 35

what are the two extremities of the simple stomach (openings)

Answer 35

1) Cardia - the oesophageal orifice into the stomach | 2) Pylorus - the opening of the stomach into the intestine

Question 36

position of the simple stomach which way does it lay, when distends where does it move

Answer 36

transverse position | moves back caudally

Question 37

What is the larger left side of the simple stomach divided into

Answer 37

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

Question 38

what is the smaller right pyloric region of the simple stomach divided into

Answer 38

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

Question 39

list and describe the 2 supporting membranes of the stomach

Answer 39

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

Question 40

blood and nerve supply of the simple stomach

Answer 40

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

Question 41

structure of the simple stomach wall

Answer 41

composed of the usual 4 layers however different in different areas of the stomach to lining is divided into different zones or regions

Question 42

what are the two main regions of the stomach based on structure of the wall

Answer 42

1) nonglandular region | 2) glandular region

Question 43

nonglandular region of the simple stomach what is the wall structure and what is it prone to

Answer 43

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

Question 44

glandular region of the simple stomach wall structure

Answer 44

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.

Question 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

Answer 45

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.

Question 46

describe the cardiac zone of the simple stomach

Answer 46

- 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

Question 47

describe the fundic zone of the simple stomach

Answer 47

- 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

Question 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

Answer 48

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

Question 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

Answer 49

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.

Question 50

describe the pyloric zone and what it secretes

Answer 50

- 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).

Question 51

the mucosa contains three distinct regions in the dog simple stomach what are they and what does the mucosa look like

Answer 51

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.

Question 52

what shape is the dog and cut simple stomach

Answer 52

C-shape cat is more elongated

Question 53

the horse stomach what shape, what parts are large, and what extra sac does it contain and its boundary

Answer 53

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)

Question 54

what are the two reasons horses can't vomit

Answer 54

1) The cardiac sphincter is very strong | 2) oesophagus enters at an acute angle such that the cardia closes when the stomach expands

Question 55

what is the size and orientation of the greater omentum in the horse

Answer 55

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

Question 56

torus pyloricus structure and function

Answer 56

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.

Question 57

pig stomach shape, and extra area

Answer 57

- 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

Question 58

pig has an extra region in its stomach what is it

Answer 58

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

Question 59

bird stomach what are the two distinct parts their sub-parts and what separates them

Answer 59

1) proventriculus 2) gizzard (ventriculus) 1. craniodorsal blind sac 2. body 3, caudoventral blind sac separated by the isthmus

Question 60

shape, mucosa and function of the proventriculus and ventriculus

Answer 60

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

Question 61

what do the three regions of the gizzard severe

Answer 61

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

Question 62

the structure of the wall of the small intestine

Answer 62

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

Question 63

what digestion function are highly regulated and what aren't

Answer 63

``` Highly regulated - Motility - Secretion Little regulation - can't switch off - Digestive - Absorption ```

Question 64

what type of activity is involved with regulation of the gastrointestinal tract

Answer 64

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

Question 65

characteristics of smooth muscle

Answer 65

* 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

Question 66

describe the autonomous nature of smooth muscle and what modulates it

Answer 66

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

Question 67

intrinsic nerves in the gastrointestinal system what is it called and what are the areas in which they originate called

Answer 67

The enteric nervous system (ENS) - more nerves than in spinal cord Submucous plexus- in submucosa Myenteric plexus- in muscle layers

Question 68

what are local gut hormones called, what produced by, where carried, when released, what modulated by

Answer 68

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

Question 69

extrinsic nerves in gut where originate, what nervous system involved, how does it modulate secretion

Answer 69

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)

Question 70

what are they different type of receptors within the gut wall

Answer 70

``` • Chemoreceptors: – sense pH, protein, fat levels of luminal content • Mechanoreceptors – Sense stretch, particulate matter • Osmoreceptors – Sense osmolality ```

Question 71

list the 3 steps that require control in terms of gastric motility

Answer 71

1) gastric filling 2) gastric storage/mixing 3) gastric emptying

Question 72

what occurs during gastric filling and what controls this

Answer 72

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

Question 73

what occurs with gastric storage and mixing where, and what stimulus

Answer 73

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

Question 74

gastric emptying generally what leads to an increase

Answer 74

- 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

Question 75

what specific factors in the stomach and duodenum modify emptying

Answer 75

stomach - increase emptying - stretch and fluidity of chyme | duodenum - decrease emptying - fat, acid, hypertonicity, distension

Question 76

what hormones control gas emptying and nerve pathways

Answer 76

– Gastrin ( G cells of pyloric antrum (stomach) and duodenum (small intestine)) – Secretin - duodenum – Cholecystokinin - duodenum – Gastric inhibitory peptide - duodenum

Question 77

gastric emptying increase or decrease for sympathetic and parasympathetic

Answer 77

sympathetic - decreased emptying | parasympathetic - increase emptying

Question 78

stimuli for release of gastrin

Answer 78

• Distension of stomach • Presence of protein or amino acids in pyloric region of stomach --> gastrin stimulates increased gastric motility and emptying

Question 79

stimuli for release of intestinal enterogastrones

Answer 79

* Distension of duodenum * Low pH in duodenum * Increased protein in duodenum * Increased fat in duodenum * Increased osmolality of duodenal chyme

Question 80

what are the 3 types of motility in the small and large intestine and describe the movement

Answer 80

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

Question 81

spasmolytics what do they do and why are they bad sometimes

Answer 81

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

Question 82

prokinetics what do they do and example

Answer 82

- “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

Question 83

series of experiments into vomiting found what

Answer 83

in the blood stream chemicals can stimulate the chemoreceptor trigger zone in the stomach can stimulate via the neural pathways to the brain stem

Question 84

what is nausea in terms of vomiting

Answer 84

on the continuum of vomiting so if nausea then probably stimulating vomiting pathway just not at the threshold of vomiting yet.

Question 85

where does the stimuli for vomiting converge and list the stimuli for vomiting

Answer 85

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

Question 86

what are the receptors and effects for the vomiting reflex

Answer 86

chemo-, stretch in multiple organs | effectors - skeletal muscles, salivary glands and gastrointestinal tract

Question 87

list the 7 steps of vomiting

Answer 87

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

Question 88

what is regurgitation when and why does it occur and differences with vomiting

Answer 88

* 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

Question 89

what are the drugs called that used to treat vomiting, why are they given and what is important

Answer 89

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

Question 90

how do pharmacologists group drugs and what is a class of drugs

Answer 90

1) by their effect 2) by their mechanisms A CLASS of drugs is a group of drugs that shares a common mechanism of action

Question 91

List the 6 classes anti-emetics

Answer 91

1) Anti-histamines - block histamine receptor 2) Phenothiazines 3) Dopamine receptor antagonists 4) 5HT3 receptor antagonists 5) Neurokinin 1 receptor antagonists 6) (Anticholinergics)

Question 92

anti-histamines what does it treat and what is the side effect

Answer 92

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

Question 93

phenothiazines - what is its mechanism and side effects

Answer 93

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

Question 94

neurokinin 1 receptor antagonists - what is the mechanism

Answer 94

anti-emetic | target NK1 receptors in both CTZ (chemoreceptor trigger zone) and vomiting centre

Question 95

Dopamine receptor antagonists - what is the mechanism, when useful and what side effects

Answer 95

- 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

Question 96

5HT3 antagonists and Anticholinergics mechanism of action, and when used

Answer 96

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

Question 97

List the 3 drugs that modify intestinal motility and secretion

Answer 97

1) prokinetics 2) antispasmodics 3) Laxatives

Question 98

laxatives what is the aim

Answer 98

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

Question 99

what are the drugs for diarrhoea and what are side effects

Answer 99

– Short term use only | – May have adverse (opioid) side effects and cause habituation - constipation which is why it is used for diarrhoea