Week 2 Flashcards
what does the carnivore digestive system consist of?
stomach small intestine - duodeumun, jejuenum, ileum large intestine - ceacum, colon, rectum liver pancreas
what are the 4 layers on oesophagus?
mucosa, submucosa, muscalaris externa, serosa/adventitia
where does the osphogaus begin and finsih?
starts dorsal to cricoid cartilage and runs medial dorsal to trachea enters at Cardia of stomach.
what is the aortic arch and where does it belong?
a section of the aorta running between descending and ascedmning limbs of the aorta. runs along side part of the trachea and oesophagus.
what is peristalsis? and its uses?
basic propulsion of digestive tract contents. 1. constriction of lumen - by angular muscle fibres 2. propulsion - longnitidual muscle fibres 3. stimulation - external nerves and distension
what happens when a oesophageal obstruction occurs?
foreign body due to ingested material leads to suffocation of trouble swallowing
what is the mesentery?
where the peritoneum extends into cavity to wrap and GIT. provided access for vascular, nervous and lymphatic structures.
what are the 5 names of the mesentery attachments to. the GIT of carnivore
mesodurodemun mesojejunum mesoileum mesocolon mesorectum
what is the peritoneum and what does it do?
layer os mesothecila cells with a serous membrane and used to wrap around organs. contains two layer; parietal peritoneum visceral peritoneum includes; GIT, spleen, liver, pancreas, bladder, reproductive
what is the omentum (gastric mesentery)?
forms a ‘sac’ between folds = momentum bursa and causes fat deposition, momentum = serous membrane and used to isolate infection areas.
what blood vessels are involved in the digestive system?
aorta - Arteile supple to digestion system venous drainage - systematic vein to caudal vena cava - liver, terminal rectum hepatic portal system to liver includes GIT, pancreas and spleen.
explain the arterial supply craniely from abdominal aorta?
involves cranial mesenteric activity with pancreas, caudal duodenum, jejunum, ileum, caecum, Ann ascending and transerve colon.
explain the artier supply caudally form abdominal aorta?
C.D mesenteric activity, descending colon and rectum.
how is the systemic drainage system used for arterial supply?
systemic veins in terminal recturm = caudal vena cava, liver = caudal vena cave all other organs via hepatic portal system.
what is the Hepatic Portal system?
carries blood from digestive system to liver. connects systematic veins at periphery. Multiple potential routes for blood through portal system
what are the routes leading to the portal vein to liver?
Splenic vein - spleen, stomach Cranial Mesenteric Vein - DJI in small intestine Gastroduodenal Vein - pancreas, stomach, D Caudal Mesenteric Vein - colon, caecum, ileum
what is portosystemic shunting?
abnormal connecting between portal system and systemic circulation, bypasses the liver.
explain the sympathetic nerve supply for the digestive system?
via ganglia - coeliac craniale mesenteric caudal mesenteric the post ganglionic fibres run with artery decreased GIT activity
explain the parasympathetic nerve supply for the digestive system?
vagus (X) - craniel structures pelvic nerve - colon and rectum Increased GIT activity
what is the stomach?
consists - greater omenteum, lesser ometum gastrophetic ligament, lesser curvature and greater curvature
what are the different sections of the stomach?
fundus, cardia, pylorus, body and oesophagus
what are the 3 mucosal gland regions of the stomach?
gastric gland region pyloric gland region gland region
what is the need for the submucosa and mucosa?
submucosa = vascular plexuses and is very elastic mucosa = columnar epithelium covered in mucus
what is the pyloric sphincter?
makes a sharp transition in GI mucosa
how is the canine intestine layout?
S.I = Duodenum, Jejunum, Ilieum L.I = Caecum, colon, rectum
if you were to ultrasound the canine intestine what would you see?
intestine wall has 4 layers, Serosa, muscularis, submucosa, mucosa.
explain the features of the small intestine (DOG)
consists of DJI, for absorption and digestion products, lined with muscosa and submucosa up into plicate circulares. (especially in jejunum)
what is mucosa made up of?
finger like villi (V) with mucosa between called Crypts of Leiberkuhn (C) Microvilli are present at surface of columnar enterocytes (E)
what is the reason for microvilli and villi in mucosa in the S.I?
used to increase surface area for absorption
what is muscaularis mucaosae (MM)?
smooth muscle lined with villi, separated mucosa and submucosa.
what is muscularis external?
responsible for peristaltic activity in small intestine.
describe the Duodenum?
starts at the Pyloric sphincter, supported by mesoduodenum, first part of S.I, neutralises stomach acid and pepsin to allow for further digestion
what is the bottom of the descending called in the Duodenum?
caudal flexure
describe the Jejunum?
longest section, suspended by greater mesentery Histolgy - longer villi present, increase SA, greater absorption/ bulk absorption.
describe the Ileum?
shortest part of S.I, supported by greater mesentery and ileocaecal fold. contains ‘islands’ of villi that float in the lumen. contains lymphatic nodes and also has immunoprotection
explain the Large intestine?
used for recovery of water and salt from faeces. Propulsion of faeces to rectum for dedication. Fat soluble molecules/vitamines absorbed as-well. consists of Caecum, colon and rectum with 4 layers aswell, Serora, muscularis externa, submucsoa and mucosa.
what are the main differences between S.I and L.I?
L.I - has crypts but NO vili present Increased number of goblet cells (needed to secrete mucous)
how is the caecum positioned in the body?
small pouch at side of the colon Ileum carries to the colon.
describe the Colon?
supported by mesocolon, absorption of water and electrolytes. thinner walls that small intestine, does NOT have villi. muscular and serosal layers.
Name the 3 parts of colon?
ascending - short section between duodenum and mesenteric root transverse - runs right to left, caudal to stomach descending - longest part runs to pelvic canal, left of abdomen.
describe the Rectum?
intrapelvic part od L.I, supported by mesorectum. serosa reflects laterally into perietal peritoneum, stores faeces prior to excretion.
describe the Anal canal?
invagination of ectoderm,, very narrow lumen, internal anal sphincter - narrowing pf circular muscle of gut external anal sphincter - striated muscle under voluntary nervous control.
describe the Anal Glands?
small glands in mucosa and skin, paranal sacs, that contain small secretion expelled via single duct during defection. carnivores have them.
what is a disease that can occur due to last of opening/closing of anus?
Atresia, failure of a orifice or passage to develop or open. anal membrane/anal canal fails to open no faeces passed.
describe the Spleen functions?
storage of blood, lysis of RBCs, production of lymphocytes
what is red pulp and white pulp?
Red pulp - contains cellular blood, reservoir of blood cells. White Pulp - lymph nodules in reticuloendotheila frame.
what is the capsule in the spleen?
extends trabeculae into pulp, muscular in carnivores, some lymph vessels, contraction of capsule exiles blood cells into circulation (Stitch)
what supplies blood and nerves to Spleen?
Splenic artery and splenic vein sympathetic n.s and parasympathetic runs with arteries and veins.
describe the carnivore Spleen?
elongated, flattened, “dumbbell” shape. left cranial abdomen. head, body and tail of spleen sits to left of kidney and tail is ventral abdomen.
what is Halsted’s Principles?
be gentle to tissue, preservation of blood supply, min tension of tissue, accurate tissue appostose, dead space obligation.
what are the key factors when clipping for surgery?
sharp, clean on flat surface, clip 15-20cm around incision area, use white sticky roller to remove extra hair.
what solitons should be used for skin preparation for surgery?
chlarhexidine gluconate 2-3min contact time povidone iodine isopropyl alcohol sterilium
what method should be used for skin preparation for surgery?
use a target pattern. to and fro, work outward to drive bacteria away from incision site.
how should a surgeon approach getting into abdomen?
skin - contrious trunk muscle - external/internal abdominal oblique muscle - transverse oblique muscle peritoneum.
what are the five ways of entering the abdomen?
midline laparotomy paramedian laparotomy parainguinal laparotomy flank laparotomy laparoscopy
how should the abdomen wall be closed in surgery?
simple continuous suture - fast, easy to do simple interrupted - slower, multiple knots cruciate - slower, can be benefit with tension. subcutaneous closure - needs a simple continuous suture
what will happen if tissue layers are not closed properly?
meticulous haemoatisis
describe mastication?
reduces size of food particles moistens and lubricated food mixes with saliva food stimulates by pressure - sensory cells
what is the different between carnivore and herbivores mastication?
carnivores - allows cutting action herbivores - allows grinding action
what is saliva and what releases it?
saliva is 98% water, ions, enzymes used for lubrication, pH regulation, antibacterial, enzyme digestion. secreted form ACINUS, released form a salivary duct. saliva is hypotonic.
explain how swallowing occurs and where?
Oral cavity, pharyngeal and peristalsis food clumps together, stimulation of palate, swallowing reflex, causes opening of upper osphigeal sphincter and enters oesophagus, lower osphgeal sphincter relaxes and food moves into stomach. wave like contractions.
describe the stomach and the functions?
food storage, food with gastric juice, protein and starch, HCL kills bacteria, intrinsic factor secreted by gastric musical cells.
name the cells in the stomach?
mucin-producing cells-prodsate for HCL parroted cells - HCL intrinsic factor chief cells - pepsinogen neuroendocrine cells - histamine release
explain Hydrochloric acid secretion?
H+ ions formed in parietal cells, CO2 + H20 converted into HCO3- by enzyme carbonic anhydrase HCL contains pepsinogen.
why does the conversion of H2O + CO2 to HCO3- causes HCL to be secreted?
when HCO3- is produced it causes Cl- to pass into parietal cells, this causes H+ ions to move by A.T out into the gland lumen creating a concentration gradient in the lumen which causes K+ to move back into the parietal cells. CL- moves into gland lumen via diffusion and CL- + H+ bind to create HCL.
what is the purpose fo Chief cells?
store and release pepsinogen, pepsin is a stomach acid and hydrolyes proteins and breaks peptide bonds.
name the 3 substances that stimulate glandular cells?
ACh by cholingeric neurones Gastrin - from goblet cells Histamine - ECG cells stimulates Hydrogen pump.
explain gastric juice secretion?
vagal nerve stimulated of sight of food - triggers secretion of gastric juice via gastrin and secretory cells - food enters, distention + peptide stimulation by parietal and goblet cells
what is stomach churning?
food churned by waves in stomach, made into chyme, food mixes thoroughly, peristatlic weaves, force chyme formed
how is chyme expelled by stomach?
propulsion, grinding, retropulsion.
what are pacemaker cells?
interstitial cells of Cajal - produce spontaneous oscillators in stomach and intestine
what are the 2 types of signal for pacemakers?
Reflexes - short reflexes wall of stomach long reflexex by vagus nerve - EACh released - contractions - stomach expands - rapid emptying Gastrin hormone - secreted by epithelium cells of goblet cells - gastric contractions - reflex pyloric sphincter - gastric emptying.
what normally protects lining of stomach form HCL acid?
HCO3- and mucous form a protective barrier.. BUT if HCL breaks down barrier then stomach will produce ‘gastric ulcers’ common in equine and dogs
label this diagram
A-caudate process of caudate lobe B-left lateral lobe C-left medial lobe D-quadrate lobe E-right medial lobe F-right lateral lobe
label this organ
A - left lobe B - C - gall blader
label this section
A-sinusoids B-hepatocytes C-centr
label this image
A-papillary process of caudate lobe B-caudate process of caudate lobe with renal fossa C-right lateral lobe D-right medial lobe E-hilus or porta hepatis F-quadrate lobe G-left medial lobe
label this image
A-portal vein B-artery C-bile canuliculi D-hepatic vein
label this region of the abdomen
A-body of stomach B-small intestine and omentum C-liver
A-hepatic vein B-caudal vena cava
A-stomach B-L limb of pancreas C-pancreas body D-descending duodenum E-right limb pancreas
describe fatty degeneration of hepatocytes.
this is when instead of the fatty droplets within liver cells being transient, they are pernament - loss of functional liver tissue
describe what the liver is used for?
what is the liver capsule for?
explain the blood supply to the liver?
hepatic artery = 1/3
portal vein = 2/3
enters at hilus and both discharge into hepatc sinusoids
descibe what the Hepatic Lobules do?
hexagnoal shape, used for movement of blood form outside in.
what are hepatocytes?
chief functional cells of the liver and perform an astonishing number of metabolic, endocrine and secretory functions. Roughly 80% of the mass of the liver is contributed by hepatocytes.
how is Bile transported from hepatocytes?
transported to pheriphery of the lobule in the OPPOSITE direction of blood flow
what are the 4 major cell types in liver?
hepatocytes (HCs), hepatic stellate cells (HSCs), Kupffer cells (KCs), and liver sinusoidal endothelial cells (LSECs)
desicbe what Kepfter cells do?
descibe what Hepatic Stellate cells do?
store Vit A,
producytion of extracellular matrix + collagen.
describe what the Billary System does?
liver, gall bladder and bileducts, and how they work together to make, store and secrete bile
describe the Gall Bladder
sac lined by non-secretaory simple columnar epithiulum
what does the presence of lipids cause in duodenum?
release of cholecystokinin is the presence of fat in the duodenum. Once released, it stimulates contractions of the gallbladder and common bile duct, resulting in delivery of bile into the gut.
describe the Pancreas?
exocrine - digestive system
endocirne - humoral priduced by Islets cells
L shaped organ, soft and slighly lobular
explain what the pancretic duct does?
and the arterial/venous supply?
smaller duct, joins bile and runs into pudeuanl papillae
somtimes abscent in dogs
what are hindgut fermentors and foregut fermentors?
Equine = hindgut (caecocolic)
ruminant = foregut (gastric)
what does the Ruminant stomach consist of?
large, 4 chambers, take up most of abdomen, vascualr supply via coelic artery
Reticulum
Rumen
Omasum
Abomasum
60-100 litres in cow
descibe the Reticulum?
take drainage from oespsphagus, opening into omasum,
muscosa - 1cm ridges with HONEYCOMB appearence small papillae
what is the reticular grove?
- conveys milk from oesophagus - omasum - abosmasum
- bypasses reticulum + rumen (milk would sit and curdle in rumen)
descirbe the Rumen?
largest chamber, subdivided into sacs by pillars
dorsal and ventral sacs. Craniel seperation of dorsal sac - Artium Ruminis.
Mucosa - papillated surface, increased SA for absorption of microsial digestion
what contratcion occurs in the rumen and what is it controlled by?
Primary contraction - biphasic reticular contrtacion allows for mixing!
Secondary contraction - caudal - cranialm, RUMEN only, gas into oesphagsi and excrued.
controlled by Vagus nerve.
how are ruminanats able to eat forgein bodies and not b affected?
forgein bodies can be forced through ruminorectiular wall by contraction.
but can cause abseces and infection e.g) pericarditis
what is Suppurative Pericarditis
indiscriminate feeding of cattle. Objects become lodged in the rumen and are then forced by ruminal contractions into the reticulum and cranially into the diaphragm and pericardium. They may also penetrate the liver.
describe the Omasum?
the ‘Bible’ - 100 laminae layers sheets (thin like paper)
covered in papillae, assit in movement of ingestion move and squeeze
describe the Abomasum?
sits on abdominal floor, feeds the omaso-abdominal opening,
smooth, slimly lining, has a doubel layer of muscle present
which part of the stoamch is glandular?
only glandular part of stomach
what is the greater omentum?
dorsal of oesophagus, attaches to reticulum, abomasum and proximal deuoduemum.
what is the lesser omentum?
passes from visceral surface of liver to reticular groove, proximal dueodemum
explain the nerve supply for the omentum?
vagus nerve (cranial nerve X) parasymtoathic, dorsal vagal trunk - rumen wall, reticular groove, omasum, abomasum
descibe the Intetsines?
situated left of abdomen, complex coiling
s.intestine and l.intestine
describe the Ruminent DJI?
Duodenum - runs vertically behind liver, supported by greater omentum
Jejunum - multiply short coils, deep in stomach
Ileum - short, joined to caecum by ileocaecal fold.
describe the ruminant Lage intestine?
Caecum - widest part, blunt, bind-ending sac into canal
Colon - ascending transverse and descending colon, centrifugal and centperhieal aganist right flank.
Rectum - wider and more muscleuar than desceding colon
limits movement possible.
Anal canal - mucsosal folds assist in closure, pelvic ‘diaphram’
describe the vascular supply for intestines?
Cranial mesenteric artery - proximal duodemun for coelic artery, descending colon from mesenetric artery.
describe the venous drainage of intetsines?
portal system, mainly cranial mesenteric vein
describe the lymphatic draiange of intestines?
giant jejunal chains, with multipul nodes.
describe the Ruminant Liver?
left quadrate and rigjt caudal lobes.
contains Gall bladder,
vascualr supply = 1/3 hepatic artery (O2)
2/3 portal vein - rich blood for interstinal tract. blood drians via hepatic veins to vena cava
describe the Ruminant pancreas?
ventral to liver
cows = one pancreatic duct enters duodenum distal to to bile duct.
smaller ruminants = pancreatic duct enetrs with bile duct
describe how post-natal devopelment works for a milk diet?
ABOMASUM = 60% of stomach = biggest at birth.
means milk must get to the abomasum via the reticular groove which transports milk bypassing rumen and omasum.
at 2-3 weeks old - abomasum gets smaller, ruemn, reticulum and omasum 2x size.
solid food adaptation from 3-8 weeks old
explain the equine GIT?
stomach, large and small intetstines, covered by ribcage, cardia - string sphincter and makes vommiting very diffuclt in horses.
Margo Plicatus - gap between glandular and non-glandular areas.
name the 3 parts of the equine stomach?
fundas, body, pylarus
describe the S.I in equine?
short dueodenum, attached via mesentrary.
major pancreatic and bile dutcs with surronding ampulla
minor pancratic ducts, small papillae and concave margin.
describe the Equine Jejunum?
long mesentrary, left dorsal abdomen loops may lue between L.I
describe the equine Ilueum?
Very short, thicker wall that jejumn, opens into base of caecum.
describe the large intetsine (hindgut)
caecum
ascending colon
transverse colon
descending colon
rectum
describe the equine caecum?
Distal to ileocaecal junciton, caecocolic orifce - construction of colon, 1m long 30L capacity in large intetsine
what are Tenial bands/funciton?
external longnitudal muscle and elastic fibres into circumferal bands.
gives L.I a sacculated appearance
allows firm control of fermentaion
what are the 4 limbs of the large colon?
four limbs - right ventral colon, left ventral colon, left dorsal colon, right dorsal colon.
to remeberr RVC comes first (like the vet school)
describe the pelvic flexure in the large colon in equine?
Narrowing of colon
- Separation into sacs
- Small particles pass
- Water resorbed
- Site of impaction
- Palpable per rectum
describe the transverse colon and how it joins onto the small colon?
arises from right dorsal colon, passes in fornt of mesnetric root,
small colon, Small sacculations form faecal balls
describe the Rectum and Anal canal in equine?
rectum become retroperitoneal, losses sacculation and widens before anal canal.
anal canal closed by longnitdunal musocal folds
describe the arteial supply for the colon in equine?
all leads from the aorta -
coelic artery - liver,spleen,stomach,pancreas etc
cranial mesenteric artery - ileocolic artery, right colic artery (ascending colon), middle colic artery(transverse), jejunal and cd pancreaticoduodenal artery (pancreas and the lesser curvature of the duodenum)
caudal mesenetric artery - left colic artery, craniel rectal artery.
internal illiac artery - caudal rectal artery.
describe the equine liver?
in cranial abdomen, 2/3 midlien 1/3 otherside less dividied
4 lobes- left lobe, quadrate lobe, right lobe, caudate lobe
NO GALL BLADDER pressent
bile opens into major duodenal papilla.
describe the equine Pancreas?
largely right side of abdomen, attached to caecal base and right dorsal colon, has two opeings into dueodenum.
describe the Porcine GiT?
omnivores - very similar sturtures to dogs.
elongated cone-shaped ascending colon and large caecum.
GIT fairly lossly achored. lies in caudaventral abdomen.
describe the Porcine Liver?
simialr to dogs,
Left lateral lobe
L medial lobe
Quadrate lobe
R medial lobe
R lateral lobe
Caudate lobe
what are the 4 ways for CHO breakdown?
small intestine - pancreatic amylase
enzymatic breakdown of dissaccarides into monosaccarides - enzymes on brush border of S.I
Monosaccharides from enthrocytes into blood by facillaited diffusion.
transport and upatke of glucose by target cells.
describe emulsificaiton of lipids?
triglycerides, phosopholipids and cholesroles.
lipids = hydrophobic, lump together in S.I,
broken down and held in suspension = emulfification
how are lipids broken down?
fat(lipids) broken down by bile acting as a detergent, lipids become coated in bile salts/phosopholipids.
Chylomicrons - lipoprotein complexes (lipid+protein)
describe the breakdown of TAGs?
lingual lipase - seceted in mouth, lipid digestion in mouth.
Gastric lipase - secreted in stomach
Lipprotein lipase - releases fatty acids from lipids (TAGs) to tissues.
how does TAG digestion occur?
Pancreatic lipase attacks TAGs via gaps in chylomicrons = partial degernation. the TAGs are now bound to chylomicrons and can be taken up.
TAGs are resynthesized with choletsrol + phosplipids = chylomicrons
chylomicrons move by exocytosis into lymphatic system.
Hydorlysised by lipoprotein lipase (LPL)
LPL hydoryles TAGs to free fatty acids + glycerol (lipolysis)
descibe the exocrine pancreas structure and fucntion and how it contirbutes to digestion?
produces pancreatic juice for dogetsion.
2main cell types - interclated cells - secretion rich in HCo3- nutralises acidic content, provdes optinla pH for pancretaic enzymes
- acinar cells - produces enzymes for breakdown of macromolecules.
what does pancreatic juice contain?
Proteases, endopeptidases, amylase, nucleases, lipase, bile salts
descibe the phases of pancreatic secretions?
cephalic phase - increases as food increwases, vagal activty increases for gastric release from stomach
gatric phase - distention of stomach casues a relfex stimulating further secretion.
intersital phase - chyme enters duodeum, causes vagal and hormonal signals depending on compostion of food
describe what secretin is and what its function is?
regualtes duodenum pH, inhitits gastric acid secretion from parietal cells, stimulates liver to produce bile. HCO3- production.
what is Cholecystolcinin (CCK)?
increased fatty acids and pepties, increase CCK.
stimulates enzyme-pattened cells
enzymes enhance prodiction - increases release
describe some difffernces betwene species in pancreas?
Ruminants - continually release pancreatic secretion after feeding at a constant rate
Horses - contoinous 35L/day but increases after feeding, low enyme conc
Cats/Dogs - little jouce secreted in S.I but increases vastly after feeding
descibe what the liver does?
produces bile by hepatocytes, and bile is stored in gall bladder.
contaisn kupffer cells - star shaped macrophages
bile secreted into S.I via bile canaliculi, nessasory for degenertaion and abosorption of fat.
explain the regulation of bile secretion?
conc of bile salts in portal blood ⬆️
⬆️ in bile salt secretion
⬆️ bile production
epxlain why horses and ruminants do NOT have a gall bladder?
constantly digesting food and grazing, requires a constant supply of bile salts so gall bladder not required for storage.
explain how the small intestine motility occurs?
mix, ensure contact with membrane of epithial cells, transport chyme along digestive tract.
types of movement = mix and segmentation
= propulsive movements (peristalsis)
explain the regulation of motility?
interstitial cells of Cajal - pacemaker cells of inststial tract, produce action potenicals, which propogate from muscle cells via gap juncitons.
Ileocaecal sphincter - ensuring expansion of L.I causes sphincter to close, emptying is a highly contolled process.
explain the large intetsine motility?
segmentation, peristalsis, retoperistalsis, mass movement (propel chyme to reaction)
contractions regualted by instertial cells of cajal.
what happens when rectum is full?
distention stimulates stetch recpectors in the wall, can cause rectum to contract propusivily = mass movement
what is hindgut fermentation?
anerobic breakdown of fatty acids, high fibre feeds, pectin etc
hind gut = caecum and colon.
Hindgut functionally akin to the reticulo-rumen – importance of the microbiome!
Hindgut = 85% efficiency cf. the rumen
–Digestive efficiency in the hindgut of the horse:
- 75-85% cell-wall CHOs
- 15-30% soluble CHOs
- 30% dietary protein
what inflences the passage rate?
physical form of food, forage v grain
physical form of food - parical size processing, growth stage
