Digestion 4

Question 1

ruminants and herbivores association

Answer 1

all herbivores ruminate but not all herbivores are ruminants

Question 2

ruminant motility - what type of contractions occur which one more important

Answer 2

Intrinsic contractions
- consist of low amplitude waves travelling in the smooth muscle wall of the reticulo-rumen
- occur even when the nerves to the reticulo-rumen are severed
- Limited in ruminants as very localised contractions - not across the whole rumen - occurs more in the abomasum
Extrinsic contractions
- occur only when the vagal or splanchnic nerves are intact - main one for ruminants
- Initiated by a burst of activity in the vagal nerves - which originate in the gastric centres of the medulla
- Main contractions within the rumen so if cut vagal nerves then paralysed rumen essentially

Question 3

oesophageal groove what formed from and between what openings

Answer 3

• Specialised region of the reticulum which is formed from reticular and omasal smooth muscle and oesophageal muscles.
• can be formed into a tube between the oesophageal orifice and the reticulo-omasal orifice, by contraction of the muscles forming the two lips

Question 4

How to move material from dorsal sac rumen into the retirculum and steps in regurgitation and what makes the animal stop chewing

Answer 4

contract rumen-reticular pillar (lower it) and fluid will flow into reticulum

1) The material will be in the raft that flows into reticulum then all you have to do is raise the liquid level in the reticulum up until the rough raft is level with oesophageal opening
2) Will now be aligned with the oesophageal opening so reflex opening
3) Tense the abdominal muscles
4) Breath in against closed glottis - lower pressure in oesophagus - material move into the oesophagus
5) once in oesophagus reverse peristalsis
- possible that chew until buccal receptors detect that particles are smaller than when brought up once finished fall back into reticulum

Question 5

steps in moving food from reticulum to the omasum and step in eructation

Answer 5

1) Rough stuff floating on top and fine stuff on the bottom
- Know how fine the material is by mechanoreceptors in the reticulum lining - detect no rough stuff then can move onto step 2
2) Close oesophageal opening and raise the liquid level up by contracting base of reticulum
3) Get the liquid level with omasal orifice then relax omasal orifice then material will flow in and will be the finest material if you raise the liquid level up high enough
open the oesophageal sphincter and allow gas pressure to send the gas up the oesophagus

Question 6

what are the 4 main functions of the parotid gland

Answer 6

1) Recycling salt absorbed from gut
2) Recycling water from gut
3) Maintaining the pH (7.4) of the reticulo-rumen
4) Maintaining an optimal electrolyte concentration in the reticulo-rumen
Effectively reduces the amount of water and electrolytes which have to be ingested by recycling

Question 7

Name the 6 ruminant families and which one doesn’t ruminate

Answer 7

Tragulidae, Giraffidae, Cervidae, Moschidae, Antilocapridae, and Bovidae
Tragulinidae - mouse deer primiative with 3 stomachs dont ruminate

Question 8

List 10 characteristics of ruminants

Answer 8

1) a complicated four-chambered stomach.
2) no incisors on upper jaw
3) a long diastema
4) incisor-like lower canines.
5) metapodial limb bones fused into a single, elongated cannon bone.
6) Large fermentative fore-stomach.
7) High yield metabolism of low-nutrient yield food - utilise ethanol as a food source - bi-product from micro bacteria which also produce a lot of methane
8) Water and electrolyte conservation mechanisms.
9) Control of complex digestive systems - rumen movement goes caudally and cranially
10) Control of complex digestive behaviours: – Rumination.

Question 9

origin of ruminants

Answer 9

• Assume evolutionary advantage in being a ruminant over ordinary herbivore
• Possibly the competition for reducing niches increased the chances of those animals with enhanced fermentation to do better than those without.
• Progressive development of more and more complicated digestive systems which increased the “yield” from poor quality food as rumination increases the efficiency of digestion

Question 10

strengths of ruminants - list 6

Answer 10

1) able to cope with diverse climatic conditions
2) efficient conversion of low quality feeds
3) great tolerance of dry conditions due to water and salt conservation in the rumen
4) reasonable reproductive capacity - twins
5) very rapid post-partum mobility - within few hours of birth high capability
6) capable of traveling extreme distances

Question 11

weaknesses of ruminants - list 6

Answer 11

1) birth-weight high
2) limited defenses beyond size and social behaviour
3) prolonged digestive processes - long time for nutrients to be available for the animal
4) require large areas of pasture for grazing
5) complicated digestive process can be disrupted
6) susceptible to parasite infection

Question 12

gastric secretion - what is secreted and from what cells and from where in the stomach

Answer 12

1) acid HCl - from parietal cell - fundic - gastric pits
2) pepsinogen (activated at low pH to pepsin - from chief cell - fundic
3) mucus - from surface mucosal cell and mucous neck cell

Question 13

characteristics of parietal cell

Answer 13

• huge membrane surface area
• secretory canaliculus
• tubulovesicles - within cell and become microvilli when secreting
• dense with mitochondria
• has a membrane lined H/K ATPase (proton pump) that actively secretes H+ into lumen

Question 14

differences between resting and secreting parietal cell

Answer 14

when resting have canaliculus that is small without microvilli as they are tubulovesicles that are within the cell
when secreting canaliculus moves deeper into cell and exposes microvilli on the surface which start secreting acid

Question 15

what enzyme is involved with making the H+ within the parietal cell and how does it work

Answer 15

Carbonic anhydrase
produces - Carbonic acid and H+ from CO2 - bicarbonate secreted out of cell into interstitular space and exchanged for chloride which is passively secreted, H+ is secreted through proton pump

Question 16

how is gastric acid secretion controlled

Answer 16

the one cell and two cell theories
One cell - Parietal cell can respond directly to vagus (ACh) and gastrin stimulation
Two cell - Mast cell/EC (enterochromaffin) cell releases histamine in response to gastrin or vagus (ACh) stimulation which acts on the parietal cell to release H+
Also - prostaglandins act directly on parietal cell to block the hydrogen pump

Question 17

stimuli for acid release - the different phases and what stimuli

Answer 17

1) cephalic phase: - stimuli coming from the head
- Sight/ smell of food
- Chewing/ taste of food
2) Gastric phase - stimuli from the stomach
- Stretch
- Mechanical stimulation
- Protein in stomach
- Certain drugs (eg caffeine)
3) Intestinal phase - stimuli from the intestines
Protein in intestine - suggests more digestion needs to occur in stomach

Question 18

what phases are nerves involved in and what hormones are involved in gastric acid release and their actions

Answer 18

vagus nerve with long reflexes
cephalic phase 
gastric phase 
hormones 
- Gastrin - excitatory 
- Secretin - inhibitory 
- Gastric inhibitory peptide - inhibitory 
- Cholecystokinin - inhibitory

Question 19

what is the source of the following enterogastrones

gastrin, histamine, secretin, cholecystokinin, gastric inhibitory peptide

Answer 19

1) GASTRIN from G cells in pyloric antrum & duodenum
2) Histamine from EC cells in lamina propria of stomach
3) SECRETIN from S cells in duodenal mucosa
4) Cholecystokinin from EC cells in intestinal wall
5) Gastric Inhibitory Peptide from EC cells in intestinal wall

Question 20

Ways in which the gastric mucosa protects against ulceration and where problems can occur

Answer 20

1) gastric mucus secretion
2) gastric bicarbonate secretion
3) epithelial cell turnover - lifespan 3-4 days and upward migration and replacement
4) gastric mucosal blood flow - wash away HCl - when in ICU circulatory shock reduce cardiac output reduce capacity to wash away H+
5) tight junctions between cells - lateral walls not protected by layer so important and gastric ulceration can occur
6) abundant mucus secretions from surface mucosal cells (glycocalyx layer) and mucus neck cell

Question 21

Helicobacter pylori what does it do, why is it an issue

Answer 21

bacteria that destroys gastric barrier and creates ulceration - human now given antibiotics against

Question 22

what are the 3 classes of drugs that are involved with gastric acid secretion

Answer 22

1) drugs that suppress acid secretion - H2 receptor antagonists and proton pump inhibitors
2) cytoprotective drugs - prostaglandin analogues and sucralfate
3) antacids

Question 23

name the two class of drugs that suppress acid secretion and how they do it

Answer 23

1) H2 receptor antagonists: - Histamine receptor type 2 - receptor found in stomach and heart
– Important drug- drug interactions involving liver metabolism and cytochrome p450 enzyme (these interactions also occur with grapefruit juice and alcohol!)
2) Proton pump inhibitors
– Irreversibly block active transport of H+ ions - persistent in action
– Used for unresponsive gastric ulcer
– Are tending to replace histamine antagonists

Question 24

what are the two class of drugs in the cytoprotective drug class and what they do

Answer 24

1) Prostaglandin analogues (synthetic prostaglandin) - as prostaglandins turn off acid secretion
– Increased mucus secretion, increased blood flow, increased cell turnover
– Decreased acid secretion
- Used when risk of gastric ulceration - ICU - reduced blood supply - Jack the Dog case-study
2) Sucralfate
– Sucrose octosulfate and aluminium hydroxide - ulcer band-aid - sticks to lesion and provides protection and neutralisation
– Dissociates –> sticky adherent gel + neutralising agent

Question 25

antacids how do they work, what do you use and what medicine used in

Answer 25

``` • Act to neutralise hydrochloric acid, bind bile acids and decrease pepsin activity • Provide symptomatic relief • Generally contain AlOH, CaCO3, Mg(OH)2, N HCO3 • Mg--> increased bowel motility, • Al---> decreased bowel activity Use together • Used only in human medicine ```

Question 26

what is the intestine in the dog and cat divided into and how to distinguish the two parts. what is the end of the small intestines called

Answer 26

proximal small intestine and distal large intestine distinguished by presence of blind diverticulum - the caecum at end of small and start of large ileo-colic orifice - start of colon

Question 27

What are the 3 parts of the small intestine and the large intestine in the dog and cat

Answer 27

``` small 1) initial duodenum 2) jejunum 3) ileum large 1) proximal blind ending caecum 2) colon 3) rectum ```

Question 28

List the 4 external features of the duodenum for cats and dogs

Answer 28

1) cranial flexure 2) descending portion 3) caudal flexure 4) ascending portion

Question 29

cranial flexure what does it run along and what separates it from the stomach for cats and dogs

Answer 29

runs from the pylorus, passes dorsally and right against the visceral surface of liver ventrally separated from the stomach by greater omentum

Question 30

descending portion of duodenum what does it follow and caudal flexure for dogs and cats

Answer 30

descending - follows the right body wall - fixed caudal - U bend going around blood vessels (root of mesentery) closely anchored to abdominal roof

Question 31

ascending portion of duodenum in cats and dogs, what anchored by what does it follow, what is it between

Answer 31

anchored by mesodudenum, passes cranially close to midline, between descending colon on left and root of mesentery on right

Question 32

what are the 3 supporting membranes of the duodenum in the dog and cat and what attach to

Answer 32

1) Mesoduodenum - - Attaches the duodenum to the abdominal roof - The mesentery of the descending duodenum begins fairly long but shortens towards the caudal flexure 2) Hepatoduodenal ligament - - Connects the duodenum to the liver - first part of the duodenum cranial flexure - Contains the bile duct, portal vein and hepatic artery 3) Duodenocolic fold - Fold with a free caudal border that attaches the caudal flexure of the duodenum to the descending mesocolon

Question 33

what are the 3 internal features of the duodenum in dogs and cats

Answer 33

1) The pyloric opening from the stomach 2) The major duodenal papilla - - Contains the opening of the bile duct and pancreatic duct secretions - A few centimetres distal to the pylorus 3) The minor duodenal papilla - - Contains the accessory pancreatic duct - Opens just distal to the major papilla

Question 34

external features of the pancreas in the dog and cat

Answer 34

yellow/pinkish colour - resembles sallivary gland but softer coarsely lobulated shape forms V which lies within cranial flexure divided into long slender right lobe and shorter thicker left lobe which unite at pancreatic angle which lies caudo-medial to the pyloric

Question 35

describe the left lobe of the dog and cat pancreas, what enclosed in and where does portal vein go through

Answer 35

- Is directed caudomedially, crosses the median plane behind the stomach and ends against the left kidney. - It is enclosed within the deep leaf of the greater omentum, where this passes dorsal to the transverse colon. - Dorsal surface of the pancreas, near the pancreatic angle, is crossed by the portal vein,

Question 36

describe the right lobe of the dog and cat pancreas

Answer 36

- Is directed caudo-dorsally and follows the dorsal surface of the descending duodenum within the mesoduodenum, near or in contact with the dorsal right flank. - Dorsally this lobe is related to the visceral surface of the liver and then to the ventral surface of the right kidney. It lies lateral to the ascending colon and dorsal to the small intestine.

Question 37

development of pancreas and what is special about cats

Answer 37

The pancreas arises from two primordia that bud from the proximal part of the duodenum. The buds later merge, but in many species evidence of the dual origin of the pancreas is provided by its duct system. Cat - only have one duodenal papillae so all bile and pancreatic secretions come through the one papillae

Question 38

what are the two ducts in the pancreas where are they located

Answer 38

The pancreatic duct - Commonly drains the part of the pancreas that arises from the ventral primordium. This ventral duct usually joins the bile duct just before it opens on the major duodenal papilla, 3-6cm distal to the pylorus. The accessory pancreatic duct (usually slightly larger) emerges from the part of the pancreas formed by the dorsal primordium (in embryo) and opens on the opposite aspect of the gut on the minor duodenal papilla, 3-5cm further distal.

Question 39

what are the pancreatic blood supply

Answer 39

The cranial pancreaticoduodenal artery - a branch of the celiac artery. The caudal pancreaticoduodenal artery - a branch of the cranial mesenteric artery. The veins drain to the portal vein

Question 40

the jejunum and ileum what part of the abdominal cavity do they occupy and what covered by in dogs and cats

Answer 40

the ventral part - first thing you see when dissect | ventrally and laterally covered by greater omentum

Question 41

external features of the jejunum and ileum when do they start and end in dogs and cats

Answer 41

- most convoluted part of small intestine and longest - It begins about level with the root of the mesentery at the duodeno-jejunal flexure. It is difficult to tell where the jejunum ends. - Long mesentery - how blood vessels and nerves reach intestines The main part of the ileum is straight and usually contracted. - The ileum ends by opening into the ascending colon at the ileo-caeco-colic junction at about the level of the 1st or 2nd lumbar vertebrae. - Ileum is firmer and straighter than the jejumum also has tiny blood vessel on opposite side of mesentery

Question 42

what is intussusception and what results

Answer 42

telescoping of the intestine into itself when happens blood vessels become compromised and can get death of intestinal wall - mainly jejunum

Question 43

what membrane supports the jejunum and ileum, what is its function and where is it gathered in dogs and cats

Answer 43

mesojejunoileum - long mesentery - Connected with the dorsal abdominal wall by a double layer of peritoneum, between which the vessels and nerves reach the intestine. - It allows the gut to slip freely over the abdominal floor in response to respiratory and other movements. - gathered at its root around the origin of the cranial mesenteric artery from the aorta and fans out to the length of the jejunum and ileum at its distal margin.

Question 44

internal features of jejunum and ileum in dogs and cats

Answer 44

velvety appearance due to presence of densely packed intestinal villi and mucus secretions from glands

Question 45

what is special about the ileocolic orifice and why

Answer 45

- is guarded by the ileocolic sphincter - thickening of smooth muscle. Due to presence of lots of bacteria so don't want back flow from large into small

Question 46

what are peyers patches and where found

Answer 46

the larger aggregations of lymphoid nodules - immune system monitor - may be visible on the luminal surface. In most species they become larger and more numerous in the ileum. (This is debatable in the dog).

Question 47

different segments in large intestine its function and what is special about dog

Answer 47

caecum, colon, rectum, anal canal It is largely responsible for the absorption of water, some microbial action on the ingesta and the secretion of mucus. The ileum and colon in the dog form a continuous tube that is joined to one side by the caecum.

Question 48

caecum in dog and cat function, where located, how long and what connects it to the ileum

Answer 48

Addition of new bacteria from caecum - reservoir for populations of bacteria right dorsal quarter of the abdominal cavity short (5cm) and twisted ileocecal fold - peritoneum attaching caecum to ileum

Question 49

in the cat and dog how does the caecum open into the colon

Answer 49

opens into ascending coln via the caecocolic orifice which is guarded by caecocolic sphincter

Question 50

what are the 3 parts of the colon in cats and dogs and describe them

Answer 50

1) Ascending colon (5 cm) - Short and tightly fixed, it lies to the right between the descending duodenum and the root of the mesentery - It generally makes contact with the pyloric part of the stomach 2) Transverse colon (7 cm) - Passes from right to left cranial to the root of the mesentery - Ventral to the left lobe of the pancreas - It is more loosely attached by its mesocolon and dips into the abdomen 3) Descending colon (12 cm) - Is the longest segment - Follows a nearly straight descent in the left flank - Enters the pelvic inlet dorsal to the bladder (and uterus) where it continued as the rectum - Only segment of the large intestine of the dog easily palpated

Question 51

supporting membrane for the colon of the dog and cat

Answer 51

The mesocolon and the duodenocolic fold

Question 52

the rectum in cats and dogs where begin and end, how long, what suspended by, what are internal features

Answer 52

begins at the pelvic inlet and ends at the anal canal 5cm long suspended by the short mesorectum mucosal surface smooth no permanent folds numerous solitary lymph nodules that form rectal pits on mucosa

Question 53

anal canal what connects and what glands present in dogs

Answer 53

connects the rectum (pelvic cavity) to the exterior environment sebaceous (secrete waxy substance) and sweat glands - can get tumours forming from these glands- the circumanal glands

Question 54

anal canal in dogs and cats lumen is constricted where and how and what are the two sphincters and what muscle made from

Answer 54

nstricted at the rectoanal junction - The mucosa is thrown into longitudinal folds, normally pressed together to occlude the orifice 1) Internal anal sphincter is a thickening of the inner circular smooth muscle layer of the rectum 2) External anal sphincter is composed of striated muscle and is under voluntary control

Question 55

anal sacs in dogs and cats where located how large, how many ducts and where open

Answer 55

Each sac is sandwiched between the internal and external anal sphincters 1cm in diameter A single duct from each sac opens near the anocutaneous junction

Question 56

functions of the anal sacs in dogs and cats and their clinical importance

Answer 56

- The sac is compressed at defaecation and the secretion is expelled; It serves as a territorial marker. clinical importance - Frequently become enlarged with accumulated secretion and may become abscessed and painful, causing "scooting", constipation. May rupture to the skin surface - 'anal fistulas'

Question 57

blood supply to the intestine

Answer 57

initial part of duodenum - hepatic branch of celiac artery majority small intestine - mid part of colon - cranial mesenteric artery descending colon and cranial part of rectum - smaller caudal mesenteric artery caudal part of rectum and anus - internal pudendal artery veins - portal vein drain into the liver

Question 58

lymphatic drainage of the intestine, when most prominant, describe movements from one duct to another and where located in the dog

Answer 58

Lacteals - intestinal lymphatic vessels in the mesentery. Lymphatic drainage of the small intestine is especially abundant - some of the products of digestion are absorbed through the lymphatics. Following a "fatty" meal the lymph is especially milky, making the intestinal lymphatic vessels in the mesentery especially prominent. mesenteric lymph node - cisterna chyli drainage area - thoracic duct (major lymphatic) in dog clustered around root of mesentery

Question 59

nerve supply to the intestine what for each part

Answer 59

sympathetic - reduce peristalsis and parasympathetic increase peristalsis sympathetic - celiac, cranial and caudal mesenteric parasympathetic vagus and pelvic nerves (rectum and distal colon) caudal rectum and anal canal come from the pudendal and caudal rectal nerves

Question 60

what is the exocrine and endocrine function of the pancreas

Answer 60

exocrine - tubuloacinar secretory units secrete enzymes, centro-acinar cells secrete electrolytes endocrine islets of langerhans secrete glucagon (alpha) and insulin (beta) cells

Question 61

what electrolytes and enzymes are secreted from pancreas and what is their function

Answer 61

NaHCO3 - neutralises acidic chyme to create optimal pH for pancreatic enzymes - Trypsinogen - cleaved by enterokinase (SI) to trypsin - Chymotrypsinogen - activated by trypsin - Procarboxypeptidase - activated by trypsin - Pancreatic amylase - secreted in active form - Pancreatic lipase * - secreted in active form *Pancreas is the only source of LIPASE

Question 62

list the 3 phases of control for pancreatic secretion

Answer 62

1) cephalic 2) gastric 3) intestinal

Question 63

what does the cephalic phase involve with pancreatic secretion control and what controlled by

Answer 63

– Ingestion of food (w/o swallowing) --> increased pancreatic secretion – Can be blocked by atropine ( blocking vagal nn) – Regulated by vagal efferent nerves to pancreas – Stimulation results in: can be modulated independently -Increased volume -Increased enzyme content

Question 64

what does the gastric phase involve with pancreatic secretion control, the 2 main stimuli and what controlled by

Answer 64

1) Stretching of stomach wall --> increased secretion - This response abolished by sectioning of vagus nn - Hence vago-vagal reflex - afferents from stomach and efferent from vagus nerve to pancreas 2) Presence of food in pyloric antrum --> increased secretion • This response persists after sectioning vagal nn - indicates - Another enterogastric reflex • Response can be simulated by I/V administration of pyloric cells extract indicate - Found to be mediated by GASTRIN

Question 65

what is involved with the intestinal phase in pancreatic secretion

Answer 65

– Stimuli associated with presence of CHYME in duodenum – Most potent stimuli to pancreatic secretion – Different substances instilled into the duodenum stimulate characteristically different pancreatic secretion

Question 66

enterogastrones mediating intestinal phase of pancreatic secretion

Answer 66

1) Secretin - Presence of acid in duodenum stimulates ○ Secretin release from S cells in duodenum - Stimulation of duct cells to secrete aqueous bicarbonate solution 2) Cholecystokinin (CCK) - Presence of fat or protein in duodenum - CCK released from duodenum and transported in blood stream to pancreas - Stimulation of acinar cells to secrete digestive enzymes ( with very little change in volume of secretion)

Question 67

what is the liver - define

Answer 67

- a metabolic organ - an exocrine gland - secreting into the intestine - a complex filter and detoxifier

Question 68

functions of the liver

Answer 68

- Important in fat digestion because of secretion of bile salts - Metabolic processing of nutrients following absorption - Detoxification and degradation of body metabolic waste, hormones, drugs, etc - Synthesis of plasma proteins & many clotting factors - Storage of glycogen, fats, iron, copper & many vitamins - Removal of bacteria, and effete RBC’s - Excretion of cholesterol and bilirubin

Question 69

Hepatocytes what do the excrete, secrete, store, detoxify, metabolise

Answer 69

``` Excretion - waste products Secretion- bile Storage- lipids, vitamins A & B, glycogen Detoxification- drugs Metabolism- proteins, CHO, lipids, Hb ```

Question 70

hepatocyte membrane specialisations and how are they arranged in the liver

Answer 70

- Two surfaces facing sinusoids- microvilli Lateral surfaces bile canaliculi (drains into bile duct) with microvilli tight junctions plates are orientated into plates that are one cell thick to resemble cords, plates are separated by sinusoids (discontinuous capillaries)

Question 71

what are the vessels supplying the hepatocytes and draining them

Answer 71

hepatic artery and portal vein which mix and bath the hepatocytes draining - hepatic vein back into vena cava and bile duct

Question 72

from hepatocytes to gallbladder - bile

Answer 72

canaliculi - ductule - hepatic duct - common hepatic duct - cystic duct - gallbladder

Question 73

gallbladder what is the function, how regulated and what species lack them

Answer 73

bile is stored and concentrated - increase efficiency of digestive process regulated by sphincter of Oddi which is where pancreatic and bile duct combine at duodenum as detects stretch horse, rat, elephant and some deer lack GB tend to be more continuous feeders but can still up-regulate bile production when needed

Question 74

what are the cells involved with creating bile and what do they add

Answer 74

Hepatocytes add: - Bile salts - only one important in digestion - Cholesterol - Lecithin - Bile pigments = Bilirubin - break down products of haemoglobin - secreted - diagnostic tool 2) Ductal cells add: - bicarbonate solution

Question 75

what is important in bile and what for and what is the primary function for bile

Answer 75

• Bile salts - Fat digestion • Cholesterol - Gall stones • Bile pigments - RBC breakdown primary function is absorption and digestion of fat

Question 76

Bile salts what derived from, how do they break up fat, what pH range needed and what are the two sources

Answer 76

derivatives of cholesterol - highly polar aggregate spontaneously with fat and break fat into micelles so increase contact between lipase in aqueous solution - more digestion many different bile salts active at different pH - evolutionary 1) hepatocytes from cholesterol 2) returning from liver following absorption in the ileum

Question 77

cholesterol how kept in bile salts and what problems can arise, Bile pigment how formed

Answer 77

keep cholesterol in supersaturated solution relative increase can result in precipitation of cholesterol (gallstones) bile pigment formed from breakdown of haeme - biliverdin - bilirubin then transported into hepatocytes where conjugate then transport to bile - important in diagnosis

Question 78

what do the bile pigments look like in monocyte macrophage system, systemic circulation, hepatocyte and intestine

Answer 78

• Monocyte macrophage – Breakdown of HB to biliverdin and bilirubin • Systemic circulation: – Bilirubin bound to albumin • Hepatocyte: – Bilirubin conjugated--> bilirubin glucuronide (soluble) and secreted (active process) to bile • Intestine: – Bilirubin converted to urobilinogen – Urobilinogen absorbed in ileum OR – Oxidised to stercobilin (brown) excreted - faeces brown colour contribute - can get change in faeces due to liver issues - pale or fatty and greasy

Question 79

what is jaundice and list the 3 reasons it occurs and how to tell clinically

Answer 79

- If circulating bilirubin concentration is >0.3-0.5mmol/l jaundice - once get to those levels can visibly see it 1) Prehepatic (increased production) - increase in unconjugated bilirubin 2) Hepatic (liver can’t keep up) - liver isn't functioning properly so not secreting enough 3) Post hepatic (obstructed bile ducts) - increase in conjugated bilirubin

Question 80

list the 3 secretory mechanisms for bile

Answer 80

1) chemical 2) hormonal 3) neural

Question 81

explain the chemical and neural mechanisms for bile secretion

Answer 81

Chemical: “Bile salt dependent flow” - During a meal bile salts digest fat and their return to the liver via the ileum increases production - processed by hepatocyte then secreted again - Between meals, secretion is low. Neural Vagus nerve plays minor role during cephalic phase before reaches the stomach or intestines

Question 82

Hormonal mechanisms for bile secretion

Answer 82

Secretin & CCK - Similar to pancreatic NaHCO3 secretion, secretin stimulates an increased aqueous alkaline bile secretion by duct cells without a corresponding increase in bile salt secretion. - i.e. helps neutralise gastric acid entering the duodenum. - Cholecystokinin: stimulates gall bladder to contract Stimuli • Cholecystokinin (CCK) - – Fat in the duodenum – Protein in duodenum • Secretin – Decreased pH in duodenum – Fat in duodenum

Question 83

enterophepatic circulation what does it involve, how important, what is recycled

Answer 83

liver, gallbladder, hepatic portal vein and ileum 98% of bile salts are reabsorbed so dysfunctional ileum alter fat absorption as major decrease in bile salts Also bile pigments reabsorbed and vitamins and drugs (contraceptive pill)

Question 84

Horse duodenum what shape of pylorus, where pancreas associated, how many papillae and pancreatic ducts

Answer 84

pyloric end forms S-shape curve instead of cranial flexure which is associated with the pancreas two duodenal papillae with two pancreatic ducts - accessory minor

Question 85

horse jejunum and ileum how long, what occupy, where terminates, what papillae are present and what is special about lymphs

Answer 85

20-25m occupy left dorsal region above the large intestines terminates at the caecum at the ileocaecal orifice mucus membrane form ileal papillae which protudes from ileum as moves into caecum and peyers patches are the largest in the ileum

Question 86

horse pancreas - what shape, where sits, what does caudal boarder contain and pancreatic ducts and what secrete

Answer 86

flat and irregular triangular shape - every horse different apex fits into concavity of duodenal flexure caudal boarder contains nothc or ring (amulus) for portal vein 1) pancreatic duct - larger duct opens with bile duct on hepatopancreatic ampulla (major duodenal papillae) 2) accessory pancreatic duct - smaller in horses opens on minor duodenal papillae

Question 87

large intestine of horse what mucosa made of and what two types of colon

Answer 87

- Mostly sacculated - haustra (sacs) - as the food moves along move from one sac into another - prevent backflow - External longitudinal bands - taenia - thickening of smooth muscle from muscularia externa - Chambers for bacterial fermentation • Great colon = ascending + transverse colon - need to keep food in their for as long as possible to ensure fermentation has time to occur • Small colon = descending colon

Question 88

caecum of the horse what shape, how big, where positioned, what divided into

Answer 88

comma shaped, takes up most of the ventral cavity 1) Base - attached by connective tissue and peritoneum to Pancreas and right kidney - Abdominal wall caudal to these 2 organs Has lleocaecal orifice - ileum flows into base of caecum and caecocolic orifice - near pelvic brim 2) Body– attached: - medially to transverse colon -lies between RVC and LVC - caecocolic fold attaches to RVC 3) Apex- free on the abdominal floor

Question 89

external features of the horse caecum and function

Answer 89

Has 4 longitudinal bands - 2 front and 2 back ○ Taenia - bands of smooth muscle - Cause 4 rows of sacculations – haustra • Haustra correspond to saccular cells in the lumen • Function to delay the passage of ingesta - help break down

Question 90

great colon list the parts of it in order from caecum to the end of the great colon any attachments in horses

Answer 90

RVC (right ventral colon) - sternal flexure - LVC (left ventral colon) - pelvic flexure - LDC (left dorsal colon) - diaphragmatic flexure - RDC (right dorsal colon) - transverse colon no attachments except at origin and end

Question 91

how many taenia and haustra and where runs for right ventral colon, left ventral colon, pelvic flexure

Answer 91

RVC - 4 rows of taenia and haustra runs ventrally and cranially on the right abdominal floor LVC - 4 rows of taenia and haustra - runs towards pelvis on left abdominal floor - caudally pelvic - 1 taenia and no haustra - very narrow and smooth (blockage) joins ventral to dorsal colon

Question 92

how many taenia and haustra and where runs for left dorsal colon, right dorsal colon and transverse colon

Answer 92

LDC - gradually widens increase to 3 teania and haustra runs cranially on the left above the LVC RDC - shortest and widest part of ascending colon - 3 taenia runs caudodorsally to base of caecum transverse - very short passes right to left infront of root of mesentery - 2 taenia

Question 93

descending colon in horse size, where does it lay, shape, supported by, how many taenia and haustra and when rectum

Answer 93

``` small, lies dorsal, caudal and left abdomen above small intestines narrow and thrown into coils supported by long mesentery 2 rows of taenia and haustra opens into rectum at pelvic rim ```

Question 94

where are the common sites for impaction for horse large intestines

Answer 94

1) Base of caecum 2) Pelvic flexure 3) Terminal end of RDC

Question 95

why is colic a big issue in horses

Answer 95

in order to get blood supply to pelvic flexure blood vessels must go along side the intestine so if twist can get disruption to blood supply also nothing to hold left dorsal and ventral colon so can get displacement - cut off blood supply - lots of bacteria within so get toxins into the peritoneum and blood supply

Question 96

duodenum for cows what flexure formed near pylorus, how many papillae and pancreatic ducts

Answer 96

- Near pylorus - forms a sigmoid flexure - to go to the dorsal side of the cow - Two duodenal papillae; one pancreatic duct - Single (Accessory) pancreatic duct: Opens on minor duodenal papilla 20-25 cm caudal to entry of bile duct on the major duodenal papilla

Question 97

cow jejunum and ileum where do they sit, pancreas what shape, where located, what does it have for blood supply

Answer 97

``` occupy right side of the abdomen cavity in supra-omental recess irregular shape (quadrilateral) located to right of median plane deep notch - opposite body for portal vein and cranial mesenteric artery to pass through ```

Question 98

large intestines of cow where sit caecum shape, where extend to

Answer 98

lies in supra-omental recess with small intestines | caecum -simple wide sac extends to right flank and seperated from it by greater omentum

Question 99

What are the parts and subparts of the colon of a cow

Answer 99

1) ascending colon - proximal loop - spiral loop - distal loop 2) transverse colon 3) descending colon

Question 100

describe the parts of the ascending colon in a cow

Answer 100

1) Proximal loop - - Runs cranially then doubles back - Turns R to L caudal to root of mesentery - Runs cranially then dips ventrally as spiral loop 2) Spiral loop - Centripetal coils - 2 full turns - spins into the middle - Central flexure - turns back own itself - Centrifugal coils - 2 full turns - spins into the outside 3) Distal loop - - Runs dorsally and caudally on proximal loop - Turns L to R caudal to root of mesentery - Runs cranially - continues as transverse colon

Question 101

describe the transverse and descending colon in a cow

Answer 101

Transverse colon - Very short; passes R to L cranial to Cranial mesenteric a. - Continues as descending colon • Descending colon - Runs caudally dorsal to ascending duodenum; inclines to right - Forms S - shape flexure near pelvic inlet - as seen on diagram - unsure about function

Question 102

small intestines of sheep - length, how many papilla, how many pancreatic ducts and what secrete

Answer 102

- Small intestine total length approx 25m - Only one duodenal papilla - Only one pancreatic duct ○ Opens on the single (major) duodenal papilla ○ Opens in conjunction with the bile duct - bile and pancreatic together

Question 103

pig duodenum how many papillae, how many pancreatic ducts, jejunum where located

Answer 103

two duodenal papillae and one pancreatic duct opens on the minor duodenal papillae jejunum - right of the abdomen

Question 104

pig pancreas - shape, where does it sit, where blood supply

Answer 104

Irregular triangular (tri-radiate - 3 arms) • 2/3 lies to left of median plane - sits in duodenal flexure • Two lobes and a middle portion (body) - Annular ring in middle portion Portal vein passes through

Question 105

pig large intestine positioned where, connected by what to what caecum where located, how many taenia and haustra

Answer 105

positioned between kidneys and connected by mesentery to dorsal abdominal wall caecum - dorsal and cranial part of left flank, apex on floor of abdomen near median plane 3 rows of taenia and haustra

Question 106

Pig colon divided into and what special how many taenia and haustra

Answer 106

1) Ascending - Coiled to form a cone shaped mass - 3D ○ Base is dorsal ○ Apex is ventral - Centripetal turns external - 2-3 coils - on the outside of the cone ○ Has 2 taenia and 2 haustra - Centrifugal turns internal ○ Calibre greatly reduced - much narrower and come up through the middle of the cone ○ No taenia or haustra 2) Transverse 3) Descending colon

Question 107

bird small intestine what shape, where located, how many pancreatic ducts and what other duct present large intestine what present and where terminates

Answer 107

- U-shaped duodenal loop on abdominal floor - 3 pancreatic ducts and 1 or 2 hepatic ducts - pancreas within the duodenum flexure large - Two ceca - paired (caecum) (most spp) + short colon - Terminates at the cloaca (instead of anus because common opening of reproductive, digestive and urinary tract