Week 3 Flashcards
What are the differences in their muscularis mucosa
How is keratin replaced in keratinised stratified squamous mucosal epithelium of rumen, reticulum & omasum?
Keratin broken down by microbial population
They contain enzymes (keritinases) that degrade keratin
Why is a keratinised epithelium needed in ruminant forestomachs
What are these and describe them
Vary in shape & size depending on age, diet & location
High concentrations of VFA’s and fibre promote growth
Which digestive products are absorbed in rumen papillae
label the rumen papillae
How do ruminal papillae change with diet
Label the rumen
What is this & describe it
Reticulum
Why do solid objects end up in the reticulum
What is hardware disease and which structures are involved
Label the reticulum
What do we think the omasum does
water absorption
mechanical breakdown of ingested material
absorption of small nutrients
Label the omasum
Which groups of ruminants dont have an omasum
camelidae
Label the omasum
Apart from water, what else does saliva contain
Proteins
amylase
sodium ions
chloride ions
potassium ions
bicarbonate
Which of these statements about rumen is correct:
a. food storage to allow large meals to be eaten
b. allows fermentation to occur
c. allows water absorption
d. allows mixing of gastric enzymes
B
Briefly describe how small intestinal epithelium is regenerated under normal conditions
which nerve(s) supply most of the parasympathetic supply to the gastrointestinal tract?
a. lumbar splanchnics
b. dorsal vagus
c. dorsal and ventral vagus
d. perineal
e. pelvic ganglia
C
When assessing health of teeth from a radiograph, which of these signs indicate healthy teeth:
a. even radiolucent band between alveolar bone and tooth
b. radiolucent halo at apex of root
c. narrow pulp cavity
d. sclerosis of alveolar bone
e. radiolucent region around all roots of a tooth
A
Which are radiographic signs of dental disease:
a. even radiolucent band between alveolar bone and tooth
b. radiolucent halo at apex of root
c. narrow pulp cavity
d. sclerosis of alveolar bone
e. radiolucent region around all roots of a tooth
B, D, E
When performing a double-contrast gastrogram, why is the animals position important?
Why does a right-sided aortic anomaly cause megaoesophagus
What is choke in horses?
Label the liver
Label the organs and blood supply
Describe the liver blood supply
Describe regeneration of liver
What is hepatic parenchyma
What is hepatic stroma
Structural tissue of liver
Label the liver histology
Label the pig hepatic lobule
Pigs have more connective tissue in liver than other species
What is a liver lobule
Hepatocytes are organised in radial cords forming a 6 sided prism with portal triads at each corner and a single central vein
Label the liver lobule
Describe the histological organisation of the a liver lobule
How does blood flow in a liver lobule
centripetally to central vein
Label the portal tract
What is the limiting plate of a liver lobule
Label the liver lobule
Sinusoids: Region where blood is flowing where there is either absent, or very few endothelial cells
What are the 4 liver cell types
Label the liver cell types
Label the liver cell types
Fill in the liver cell types table
Label the liver under TEM
Label the liver
What is the role of HSC/Ito cells in liver
What liver cell in this
Fill in the hepatocyte organelles functions
Label the hepatocyte organelles
What are bile canaliculi
Label the liver
What is the function of the gall bladder
storage, concentration and release of bile
What are the functions of bile
fat digestion
hepatic excretion
Label the gall bladder
Label the gallbladder
Label the blood and bile flow diagram
What is a hepatic acinus
What is a portal lobule
label the hepatic parenchyma
What are the zones of hepatic acinus
Zone 1 closest to portal tract and receives most oxygenated blood and zone 3 the least
Zone 3 has higher biotransformation/detoxification activity
In toxic diseases, zone 1 suffers first (perilobular necrosis)
In hypotensive/congestive diseases zone 3 suffers first (centrilobular necrosis)
Which is the liver
B
Describe detoxification of foreign chemicals in liver
Xenobiotics
Phase I - cytochrome P450 modifies the chemical to allow phase II
Phase II - glucuronidation
Describe haem breakdown
Occurs in macrophages (mainly in spleen but also liver & bone marrow)
Iron toxic so important to remove
Damanged RBCs phagocytised by macrophages
Haemoglobin broken down into Fe2+, bilirubin (from haem) and amino acids
Amino acids enter blood stream
Bilirubin travels to liver to be excreted in bile
Fe2+ travels to bone marrow for erythropoeisis and to the liver to be stored as ferritin
Fill in the urea metabolism diagram
In ruminants urea is food source for microbial proteins
In mammals amino part of amino acid turns into NH4+
Fill in the energy metabolism table
1. amino acid 2. glucose 3. triglyceride 4. VFA
Where are liver enzymes in healthy and diseased livers
When liver is healthy, enzymes stay intracellular (wont be able to measure them)
If found in blood test there is liver damage
What are the liver enzymes involved in energy metabolism?
Aspartate aminotransferase (AST)
Alanine aminotransferase (ALT)
What is the function of aspartate aminotransferase (AST) in energy metabolism in the liver?
Glycolysis (Role in the malate-asparate shuttle)
AST catalyses the conversion between aspartate and oxaloacetate
What is the role of alanine aminotransferase (ALT) in energy metaolism in the liver?
Gluconeogenesis
Amino acid catabolism
Alanine reacts with alpha-ketoglutarate to form glutamate and pyruvate (catalyzed by ALT)
Pyruvate can be used to produce glucose or enter the Kreb’s cycle
What are some plasma proteins
Serum Albumin - highly abundant
- carrier protein
- maintains osmotic pressure
- Important so plasma is at same osmotic pressure as cells to prevent water transfer
VLDL
HDL
Fibrinogen & Prothrombin – coagulation cascade
Transferrin – iron transport
Complement proteins
Describe lipoproteins
Lipoproteins move insoluble fat around e.g., triglycerides, cholesterol esters
Describe according to density e.g, VLDL, HDL
Linked to proteins (apolipoproteins)
What are apolipoproteins
Each lipoprotein has own set of apolipoproteins
- e.g. Major protein in chylomicrons is apolipoprotein B, specifically apoB-48
- Give it its characteristics
Apolipoprotein functions:
- Activate enzymes
- Bind receptors
- Stabilise lipoprotein
Describe bile salts
Bile acids are cholesterol derivatives
Main bile acid is cholic acid
What are micelles
Bile salts in aqueous solution tend to form aggregates or micelles
These are amphiphilic i.e. inside +ve & outside –ve
Therefore internalised lipid core, water soluble exterior
The –ve external charge prevents them from coalescing.
Describe the action of bile
Emulsification: Bile acts like a detergent to break down fats into smaller droplets, increasing their surface area for better digestion.
Mechanism: Bile has hydrophobic sides that bind to fats and hydrophilic sides that mix with water, helping to mix fats into the watery digestive juices.
Nutrient Absorption: By emulsifying fats, bile aids in the absorption of fat-soluble vitamins (A, D, E, K).
Enzymatic Action:
Phospholipids: Broken down by pancreatic phospholipase A2.
Cholesterol: Broken down by cholesterol esterase.
Describe the synthesis of cholesterol in the liver
- Acetyl-CoA + actetoacetyl-CoA
- Carbon chain lengthens
- Decarboxylation => cholesterol
- Cholesterol can then be converted to bile salts in the liver or moved to endocrine glands to become steroid hormones
Describe the route of bile acids
Absorbed in ileum
- travel to liver via hepatic portal vein
- conjugate with cholesterol
- travel to gall bladder then into the duodenum where they cause fat absorption
- travel down to ileum and reabsorbed
How is fat absorbed in the small intestine
- Bile salts and pancreatic lipase break large fat droplets down
- Micelles formed as bile salts form aggregates, conjugated with phospholipids and cholesterol
- Micelles release into epithelial cells/enterocytes
- Free fatty acids and monoglycerides within mycelle diffuse into enterocyte
- Triglycerides resynthesised and chylomicrons formed in enterocyte (chylomicrons are exocytosed into lymph vessel)
Describe the urea cycle in the liver
- Ammonium reacts with CO2 => carbamoyl phosphate in the mitochondria
- Carbomoyl phosphate reacts with ornithine to produce citrulline
- Citrulline reacts with aspartate in the cytoplasm => arginine
- Arginine reacts with water to form urea and ornithine
describe the immunoregulation function of the liver
Kupffer cells (sit in sinusoids between liver cells)
Complement synthesis & metabolism
What does the liver store
Glycogen
Water-soluble vitamins
Fat-soluble vitamins
Iron
- Gives it dark color
- Too much iron being stored can cause damage
Define toxicology
study of harmful properties, actions & effects of chemicals on biological systems
Define toxin
antigenic poison/venom of plant or animal origin
Define toxicant
any toxic substance
Define poison
substance capable of causing illness or death of living organism
Define venom
Define xenobiotic
a chemical substance within an organism that is not naturally expected or foreign
Define toxicosis
any disease or condition caused by poisoning
Define no observable effect level (N.O.E.L)
Define developmental toxicology
Describe ways in which toxicants may produce toxicosis
When does a chemical become toxic
How can we measure how dangerous a toxin is
List the key information in the investigation of a suspected case of intoxication
How can toxicants be absorbed
How can toxicants be distributed
Where do toxicants go (storage)
How are toxicants eliminated
What is lethal synthesis and give an example of it
Describe the main metabolic pathways for elimination of fat soluble toxicants
What factors effect toxicity?
- dose of toxin
- environmental factors (e.g. temperature, humidity)
- duration & frequency of exposure
- inability to vomit
- age & health of patient
- seasonal or climatic changes
- route of exposure
- isomer of toxin
Compare acute to chronic toxicosis
What is chronicity factor
Duration of exposure can affect toxicity
CF is ratio of acute to chronic LD50 dose
- e.g. a compound may have low acute toxicity but if it accumulates in tissue it can lead to chronic toxicity = cumulative poisons
- CF of >2 suggests drug is relatively cumulative
Chronicity factor gives indication of cumulative danger (but could be affected by body developing tolerance)
What is tolerance and how does it develop?
What is resistance and how does it develop
Outline therapeutic options for management of toxicosis
Fill in the urea cycle
What is NH4+ used for in mammals
feeds the Krebs cycle
What is nitrogen converted to in fish, mammals, birds and reptiles
mammals: urea
Fish: NH4+ (because they are in water)
Birds and reptiles: uric acid
Fill in the table
What pathways can lead to an excess of nitrogenous compounds in animals body
What is deamination
NH4+ removed from amino acid
How is excess ammonia removed in the absence of amino acids?
formation of glutamate and glutamine from a-ketoglutarate
Describe the amino acid catabolism
What happens if ammonia builds up
hyperammonemia
damages brain cells => abnormal behaviour, dizziness, coma and death
What conditions cause hyperammonemia
Liver dysfunction
Abnormality in hepatic portal flow
abnormality in urea cycle enzymes
starvation (body breads down skeletal muscle for energy -> more amino acid catabolism)
What is the fate of a-keto acids (product of deamination)?
recycled into the TCA/Kreb’s/Citric acid cycle or used in lipid metabolism
Ketogenic amino acids - will feed lipid metabolism
Glucogenic amino acids will feeds gluconeogenesis
What is first pass metabolism of a drug
Liver metabolism once drug is ingested
Liver protects body from drugs
Metabolism prior to drug entering systemic circulation
How are polar drugs excreted
Polar drugs are more likely to be excreted
How are non polar drugs excreted
If drug is not water soluble it must be metabolised by CYP450 to be excreted in urine
Describe phases of drug transformation (polar drugs)
Phases occur in liver
Phase 1. catabolic
- oxidation
- reduction
- hydrolysis
If phase 1 not sufficient then to phase 2
Phase 2. anabolic
- synthetic conjugation (makes it more water soluble so it can be excreted in urine)
What is the location of CYP450 enzymes
in endoplasmic reticulum of cells
What is pharmacokinetics
How the drug enters, is transported and eliminated
What is pharmacodynamics
effect drug has on body
What is the role of CYP450
metabolise lipophilic/non-polar drugs into hydrophilic/polar compounds to allow excretion
How can multiple drugs affect activity of each other
The product of one drug reacting with a CYP450 may decrease or increase the expression of another CYP450
So the activty of the drug the affected CYP450 acts on could increase or decrease
Interactions are less likely if drugs can be metabolised by more than 1 CYP450 enzyme
Two positive contrast radiographs from the same patient are provided.
A catheter (marked by the arrow) has been placed in one of the tributaries of the hepatic portal vein and in each case a positive contrast medium has been injected into the vein to demonstrate the flow of blood from the intestinal tract to the liver. These are known as portal venograms.
Questions:
Which image shows a normal hepatic portal vascular pattern? Given the images are from the same patient, what has changed?
In one of the images blood from the GIT is by-passing the liver, into which vessel is blood from the GIT emptying? Which embryological structures could be involved?
Why do patients with this abnormality exhibit neurological signs?
Why would a patient with a urea cycle enzyme deficiency show similar signs?
Why is paracetamol dangerous in cats
Because, compared to other species, they have limited capacity for glucoronidation of paracetamol metabolites (to make “safe” metabolites for excretion) and so “unsafe” metabolites accumulate which cause tissue damage through reactive oxidation including oxidation of haemoglobin and red cell damage. Glutathione, which is protective against oxidation, is quickly consumed leaving cells and tissue unprotected.
Most of the metabolic enzymes used by the liver remain contained within the cells of the liver and we don’t learn anything about the livers activity by trying to measure those metabolic enzymes in the circulation.
However, there are some enzymes that will leak out of liver cells into the circulation if the liver cells are compromised or damaged. We measure these in the circulation, not because they are particularly interesting enzymes for liver function but because they are markers of cell damage.
Fill in the table
Give examples of primary liver disease
Hepatitis
Parasitism (fluke)
Biliary obstruction (e.g. gall stone)
Give examples of secondary liver diseases
Energy metabolisation disorders
- diabetes mellitus
- fatty liver
Systemic inflammation/sepsis
- e.g. pyometra
Pathology of GI tract or pancreas
Why do we measure bile acids before and after a meal to assess liver function in dogs and cats but not in horses?
By providing a meal, we should stimulate a gall bladder contraction causing bile to enter the GI tract and bile acids to be resorbed back into the circulation from the gut. How well the liver recaptures these bile acids from the blood flowing through it gives an idea of how well it is functioning. We expect the liver to have recaptured this pulse of bile acids within 2 hours of the gall bladder contraction. In horses, without a gall bladder, we can’t stimulate this “challenge pulse” of bile acids into the enterohepatic circulation and just have to rely on the baseline concentration as measure of function.
Patient 1 is more likely to have the bile duct obstruction and the impact on the biliary lining is reflected in the relatively higher activity of AlkPhos (a biliary enzyme). Patient 2, more suggestive of toxic insult directly to the hepatocytes (the increase in ALT is relatively greater (15x URL) than the increase in ALKP (<5xURL))
The liver synthesises all of the coagulation factors except Factor VIII. Among these are vitamin K-dependent factors – which clotting factors are vitamin K-dependent?
2, 7, 9, 10
In a patient with a coagulopathy resulting from hepatic failure, which of the following tests of the coagulation mechanism would be likely to be abnormal?
* Platelet count
* Von Willebrand Factor
* Whole blood clotting time
* Activated partial thromboplastin time
* One stage prothrombin time
* Fibrin degradation products
* Fibrinogen
Why do some animals with liver disease have yellow mucous membranes and sclera
Why do some animals with advanced liver disease have ascites? What is a transudate?
How does avian metabolism & GI tract compare to mammals
high metabolism due to energy demands of flight
Short GI tract with low volume to keep weight low
Label the bird
Compare GI tract of seed/green leaf eating birds to carnivorous birds
Label the bird GI tract
Describe the structure of the beak
Label the bird skull
What muscles open and close the beak
Name the birds and their beak adaptations
Describe the avian oropharynx
oropharynx instead of soft palate, oral cavity & pharynx
Choana = connection between oropharynx & nasal cavity
infundibular cleft (caudal to choana) = common opening for pharyngotympanic tubules
Hyoid apparatus supports keratinised tongue
No teeth
Tubular salivary glands release mucin +- amylase
How do birds swallow while eating
How do birds swallow while drinking
Describe the avian oesophagus
Describe the avian crop
What is sour crop
Describe the mechanisms of the crop
Label the avian GI tract
Describe the avian proventriculus and gizzard
Label the avian GI tract
Describe egestion in birds
Compare the function of gizzard thin and thick muscles
What is grit
Describe the avian liver & pancreas
Describe the avian small intestine
Describe avian small intestine physiology
Describe avian caeca
Describe the avian large intestine
Describe the avian cloaca
Describe the 3 compartments of the cloaca
Describe avian excretion
Define laparotomy
surgical procedure that involves making incision through abdominal wall
Define laparoscopy
minimally invasive technique that uses laparoscope to view inisde abdominal cavity
Define coeliotomy
surgical incision through abdominal wall
define paralumbar fossa
hollow area located on side of lumbar vertebrae in animals (esp. cattle).
Site is commonly used to access abdominal cavity
Define linea alba
fibrous band of tissue in midline of abdomen that serves as attachment site for abdominal muscles
Define pre-pubic tendon
fibrous band of connective tissue in pelvic region that provides support to abdominal wall
Define parietal, visceral and mesenteric peritoneum
Where do crura arise from
lumbar vertebrae
Where are costal and sternal attachments
What are the 3 openings of the diaphragm
aortic hiatus
oesophageal hiatus
inferior vena cava
What is the innervation of the diaphragm
phrenic nerves
What are the muscular boundaries of the abdominal cavity
Label the limits of the abdominal cavity
Describe the directions in which the muscles of the abdominal wall run?
Why are they in a crossed pattern?
contributes to strength and stability of abdominal wall
Describe the location of the paralumbar fossa
Describe the peritoneum
peritoneum is serous membrane which lines abdominal cavity
3 sections
- parietal
- visceral
- mesenteric
Sac between each section is called peritoneal cavity (contains peritoneal fluid)
Peritoneum can excrete and resorb fluid and resorb gas
Diseases include peritonitis, neoplasia, haemorrhage
Label the layers of the lateral abdomen
What are the arrows pointing at
Describe the Ligamentum teres
Extra ligament in horses holding hip joint together
comes from head of femur
attaches to acetabulum of hip bone
Prevents excessive adduction and extension
What is the arrow pointing at
Why are abdominal surgeries done on the left side in ruminants
everything can be reached easily from the left
describe the inguinal canal
Do females have inguinal canals
yes but its smaller and less well defined
it doesnt transmit a spermatic cord but does allow for passage of round ligament of uterus
Describe the innervation of the abdominal wall
What is a paravertebral nerve block
Describe the vasculature of the abdominal wall
Fill in the intestinal anatomy table
What are the layers of the small intestine
- lumen
- mucosa
a. single epithelial layer
b. lamina propria - submucosa
- tunica muscularis
- serosa
Label the small intestine
What are the adaptations of the SI to increase surface area for absorption
ridges/folds
villi
microvilli
Label and describe their function
Label and describe their function
Label red and blue arrows
Label
What are Brunner’s glands
What is the arrow pointing at
Ileum
Last bit of small intestine
What are the 6 cell types of the small intestine
Label
where are cells of small intestine produced and how long does it take
stem cell zone at neck of crypts
Takes 3-4 days for cells to travel from crypts to tip of villus
What are the functions of enterocytes
Label the villus
Describe entero-endocrine cells
produce hormones
Label the small intestine
Describe paneth cells
What is this showing
Paneth cell granules
Describe peyers patches
Describe lymphoid follicles and lymph nodes
Label the ileum
Describe M cells
Label the M cell
Describe tuft cells
Sparse cells
sit between epithelial cells so still columnar
Have long fingers which project sideways into neighbouring epithelial cells
Produced by stem cells
Modulate immune system responses (esp. against protists and metazoa)
Label
How does venous blood from pancreas drain
Describe cat and dog pancreatic lobes and ducts
Both have dorsal (left, accessory) and ventral (right, main) lobe
Dogs have dorsal and ventral ducts
Cats only have ventral duct because they fuse
What are the secretions of the pancreas
Label the pancreas
Describe pancreatic stimulation
Describe Islets of Langerhans
Describe blood supply to GIT
Describe Coeliac artery branches
only those in bold
Label the arteries
Describe enteric nervous system supply to GIT
What do enterocyte enzymes break down and absorb
What are the arrows pointing at
crypts
In which parts of the GIT are villi found
duodenum, jejunum, ileum
Where do you find goblet cells and what is their purpose
epithelium of small and large intestines
purpose is to lubricate & protect lining of GIT, trap foreign particles & pathogens & facilitate movement of materials
Inflammatory signals stimulate them to produce more mucus in case of inflammation
What kind of feedback mechanisms operate to tell crypts to re-form villus if they had been destroyed
What is the ingredient in rat poison that is poisonous
How would you treat a patient that consumed rat poison
What clinical signs would you expect in a sheep with rhododendron poisoning and how would you treat it
abdominal pain
bruxism (grinding teeth)
regurgitation
death
loss of appetite
lethargy
nausea
salivation
vomiting
bradycardia
Why might a toxin affect 2 patients differently
Assuming the effective doses of the substances below are the same, which is more dangerous ?
A. LD50 of 20mg/kg
B. LD50 of 50mg/kg
A
What is photosensitisation
common in horses
caused by impaired liver function due to ingesting plants toxic to liver
chemicals from toxic plant are not excreted due to impaired liver function so they build up in blood
They are activated by sunlight and cause irritation
clinical signs: sore muzzle (cracking & crusty), yellow tinged mucous membranes, not eating
What clinical signs would you see in a cat that consumed ethylene glycol (antifreeze)
How would you treat a cat that consumed ethylene glycol (antifreeze)
How would a buzzard ingest lead and what would the clinical signs be
What organs are affected by lead toxicity and what tests would you do to confirm it
What would be the likely causes of lead toxicity in a parrot? what clinical signs would you notice and how would you treat it?
What would be likely causes of lead ingestion in a pet rabbit
toys
lead paint
cage
things around house if let out
