Alimentary - Malabsorption & Maldigestion (PDF)

4.1 Malabsorption & Maldigestion Digestive pathology: ​ Ingestion & breakdown of food particle ○​ Physical breakdown ○​ Salivary enzyme ○​ Gastric acid ​ Digestion ○​ Pancreas ○​ Gut mucosal enzymes ○​ Bile acid ​ Abso...

4.1 Malabsorption & Maldigestion Digestive pathology: ​ Ingestion & breakdown of food particle ○​ Physical breakdown ○​ Salivary enzyme ○​ Gastric acid ​ Digestion ○​ Pancreas ○​ Gut mucosal enzymes ○​ Bile acid ​ Absorption ○​ Small intestine ​ Utilisation → X work properly: ​ Malassimilation ○​ Maldigestion ​ Impaired normal digestion ​ Pancreatic function ○​ Malabsorption ​ Digest normally, but X absorb ​ Gut function ​ Malutilisation ○​ Digest & absorb normally, but utilise abnormally / lost Pancreas: ​ Exocrine ○​ Secretion, transported through pancreatic duct into small intestine ○​ Enzyme: digestion for all major types of food ​ Lipase, protease, amylase ○​ HCO3- & water: secreted by epithelial cell of ductile ​ Neutralise HCl from stomach ​ Suitable environment for pancreatic enzyme ​ X function properly: ○​ Protein (eg. chymotrypsin) / carb / fat (transported into lacteal → lymphatic → colon) maldigestion ○​ Impaired assimilation of fat-soluble vitamin A D E K Retina, eyesight Ca metabolism Protection from toxin (esp. liver) Clotting factor activation ○​ Impaired absorption of cobalamin (vitamin B12) ​ Intrinsic factor: permit absorption (synthesised by pancreas & small amount @ stomach) ○​ Increase bacterial growth @ small intestine (upper small intestinal tract) ​ Chyme: undigested in upper GIT ​ X broken down by enzyme ​ Growth media  ​ → Antibiotic treatment ​ Increase cobalamin uptake → use up Maldigestion: ​ Exocrine pancreatic insufficiency ○​ Most common ○​ → Pancreatic enzyme production ○​ → HCO3-: neutralise HCl ○​ → Large reserve capacity ○​ Clinical sign: 90% pancreatic function loss ○​ Cause: ​ Pancreatic acinar atrophy ​ Chronic pancreatitis ​ Pancreatic hypoplasia (under / incompletely developed): uncommon ​ Pancreatic neoplasia (total loss of function): rare ○​ Clinical sign: ​ Weight loss, w/ normal / increased appetite ​ Increase faecal volume ​ Abnormal faeces: grey / yellow, greasy, increase water content ​ Flatulence 腸胃氣漲: bacteria break down undigested food @ colon → produce gas ​ Coprophagia: eat faeces ○​ Diagnosis: ​ Clinical sign: X pathognomic, can occur w/ small bowel disease ​ Blood test: trypsin-like immunoreactivity (species specific assay, low lv = EPI) ​ Faeces: may contain fat & starch (under microscope) ○​ Treatment: ​ W/ pancreatic acinar atrophy: X high fat / very fat-restricted diet ​ Normal → moderately restricted fat, high calorie & digestible, low fibre (impair pancreatic enzyme activity, soluble: absorb enzyme) ​ ≥ 2 meals / day ​ W/ pancreatitis: low fat diet ​ Pancreatic enzyme replacement (food): life long ​ Antimicrobial (oral): 1-3 weeks  ​ Supplement of vitamin A, B12, D, E, K: weekly injection (6-8 weeks / life long) ​ X antibiotics ​ Secondary enzyme deficiency ○​ Luminal condition: X optimal for pancreatic enzyme function ​ Bile acid deficiency ​ X brush border enzyme Pancreatic acinar atrophy: ​ Autoimmune disease → selective destruction of digestive enzyme-producing acinar cells ​ Unaffected endocrine function ​ 2 phases: ○​ Subclinical (X clinical sign): ​ Inflammation: T lymphocyte infiltration ​ Particle acinar atrophy ○​ Clinical: ​ Severe end stage atrophy ​ Dog: many breeds ○​ Inherit & increase prevalence: German Shepherd, rough coated collie ○​ Suspect to be inherited: English Setter ○​ Over represent: Chow Chow ○​ Under represent (protected from): Labrador, Golden retriever, ​ Cat: X common Chronic pancreatitis: ​ Cat: uncommon, cause exocrine pancreatic insufficiency ​ Dog: middle age → older, small-medium ​ Fibrosis: destruct exocrine & endocrine pancreas ​ Clinical sign of exocrine pancreatic insufficiency, diabetes (insulin deficiency) Malabsorption: ​ Impaired absorption in small intestine ​ GI disease: ○​ Primary: structural (most common) ​ Infiltrative disease of gut wall ​ → Parasitic ​ → Inflammatory bowel disease: impaired function ​ → Lymphangiectasia: X absorb fat ​ → GI lymphoma (blood cancer): impaired function ​ → Severe small intestinal bacterial overgrowth ​ → Dry feline infectious peritonitis (FIP): coronavirus ​ → Deep mycosis (fungal infection): endemic area (eg. US) ○​ Secondary: metabolic, more difficult absorption ​ Luminal ○​ W/ digestion ○​ Hyperthyroidism (make too much thyroid hormone) → dysmotility 食道動力障礙 ○​ Gastric acid hypersecretion → pancreatic enzyme deficiency / inactivation  ○​ Fat maldigestion: ​ EPI ​ Ileal / liver disease → loss / impaired bile salt activity ​ Mucosal ○​ Enterocyte defect ​ Eg. inflammatory bowel 腸道 disease ○​ Brush border Enzyme Protein transport Congenital 先天 Cat: trehalase Relative lactose deficiency Acquired 後天 intrinsic factor deficiency Small intestinal disease ​ Transport ○​ Lymphatic obstruction 阻塞 ​ Primary / secondary (most common) lymphangiectasia (pathologic dilation of lymph vessel) ​ Due to neoplasia, infection, inflammation ○​ Vascular compromise (alternative): glucose & amino absorption ​ Vasculitis (blood vessel inflammation): infection, immune mediated ​ Portal hypertension (high blood pressure): hepatopathy, right sided heart failure ​ Clinical sign: ○​ Weight loss ​ W/ normal / increased appetite ○​ Diarrhoea ○​ Coprophagia ​ Treatment: depend on cause ○​ Inflammatory → diet, immunosuppressive ○​ Infectious ​ Bacteria → antimicrobial ​ Fungi → antifungal ○​ Parasitic → antiparasitic ○​ Neoplastic → chemotherapy 化療 Secondary GI disease: treatment Hepatic disease Right sided cardiac disease Hyperthyroidism Depend on pathology Depend on cause ​ Anti-thyroid drug: tablet, oral ​ Inflammatory ​ Valvular liquid, transdermal cream ​ Infectious ​ Cardiac muscle ​ Diet ​ Neoplastic ​ Pericardial ​ Surgery ​ Toxic ​ Radioactive iodine (I131) ​ Fibrosis 4.2 Overview of Liver Function Function: ​ Metabolism ○​ Carb: store (glycogen), breakdown ○​ Fat: break down → produce energy ○​ Protein: ​ → Amino acid / fat / carb (energy) ​ NH3: absorb from gut, detoxify & produce through urea cycle ​ Synthesis ○​ Albumin ○​ Some globulin ○​ Clotting factor (& activate) ○​ Bile ​ Storage → nutrient release & assimilation ○​ Vitamin, mineral (Fe, Cu) ○​ Carb (in form of glycogen) ​ Detoxification ○​ Drug ○​ Toxin ​ Reticuloendothelial system ○​ Kupffer cell: resident macrophage in liver ​ Destroy WBC & RBC ​ Haemoglobin (from old RBC) → bilirubin ​ RBC production ​ Store excess Fe ○​ → Inflammation, immunity ​ Immune system, neuroendocrine regulation, lymphoid cell development Disease: ​ Cause: ○​ Infection  ​ Bacterial, viral (feline, canine), fungal ○​ Parasite ​ Eg. liver fluke ○​ Vascular disorder ​ Eg. portal systemic shunt ○​ Toxicity ​ Plant (eg. cocoa) ​ Drug, chemical ​ Aflatoxin (eg. sugar-free gum) ○​ Neoplasia ○​ Degeneration, fibrosis ○​ Genetic ​ Clinical sign: ○​ Inappetence (X appetite), anorexia 厭食 ○​ Vomiting, diarrhoea ○​ Jaundice 黄疸病: high bilirubin lv ○​ Depression, lethargy (X energy) ○​ Polydipsia (excessive thirst), polyuria (excessive urination) ○​ Neurological encephalopathy ​ Build up of NH3 → smaller brain size ○​ Coagulopathy (difficult for blood clotting) → bleeding tendency ○​ GI ulceration ​ → Digestive blood in faeces 血便: black faeces, fresh blood ○​ Photosensitisation ​ Ulcerative skin lesion ​ Chemical: accumulate in blood & skin, activate by UV ​ Chemical reaction → damage skin cell ​ Pathology change: ○​ Increase: ​ Liver enzyme ​ Bilirubin ​ Bild acid (abnormal: liver X take back, stay in blood) ​ Blood NH3 ​ Globulin (protein): inflammation ○​ Decrease: ​ Blood glucose ​ Albumin (protein) ​ Clotting factor ○​ Increase / decrease: cholesterol (regulation) ○​ Dysfunction: platelet ○​ X ​ Esp. cat: lower magnitude Case: 1.​ Fred: 6 months, entire male, DSH cat History ​ Last 2 weeks: depressed, reduced appetite, lethargic ​ X grooming Clinical sign ​ Depressed, lethargic ​ Mucus membrane, sclera: jaundiced (yellow) ​ Dehydrated System / location ​ Pre-hepatic: ○​ Haemopoietic (blood) system ​ RBC breakdown ​ Anaemia ​ Liver ​ Post-hepatic: ○​ Biliary tract (gall bladder, duct) ○​ Pancreas: pancreatitis ​ Sepsis (severe inflammation) ○​ Extreme response to infection ○​ → Organ failure, shock, death Diagnosis Feline infectious peritonitis 貓傳染性腹膜炎 (FIP) ​ Viral ​ Before 2022: incurable ​ Treat w/ remdesivir (cure early COVID-19) Clinical sign → ​ Liver, pancreas inflammation / cancer ​ Liver / bile duct bacterial infection Post mortem 驗屍 ​ All tissue: severely jaundiced ​ Serosal surface of all abdominal organ: small white plaque ​ Liver: pale, rounded margin ​ Mesenteric lymph node: necrosis Histopathology: ​ Severe, chronic, multifocal arteritis (arterial wall inflammation) ​ Liver: contain scattered granuloma 2.​ Bertie: 18 y/o, male, Irish Draft cross horse Clinical sign ​ Press head against wall ​ 1 week ago: wound → tetanus anti-toxoid vaccination (lax 不嚴格) ​ Ataxic: loss of muscle control, clumsy movement & poor balance ​ Central blindness, circling Diagnosis Theiler’s disease ​ Acute equine serum hepatitis ​ Rare, but fatal Treatment ​ Hypertonic saline (high conc. NaCl water) ​ Intravenous fluid  ​ Glucose ​ Antibiotic: penicillin, gentamicin 3.​ Jessie: 15 y/o, female (neutered), cat History ​ 3 days: intermittent 斷斷續續 weakness ○​ X stand ○​ Interval: normal ​ Good / increased appetite Clinical sign ​ Flaccid 鬆軟 paralysis: affect all limbs ○​ X stand, walk, hold head still ○​ Paroxysmal (sudden worsening) ​ Pinpoint pupil (abnormally small & constricted) ​ X aware of surrounding ○​ Altered consciousness ​ Thin → 4 hours after: seem to be recovered completely Diagnosis ​ Enzyme increase → liver damage ​ Hypoglycaemia (low blood glucose lv) ​ Ultrasound: altered liver density → Exploratory laparotomy (open abdomen, examine organ): ​ Orange-size tumour: @ middle lobe of liver ​ Hepatocellular carcinoma 肝細胞癌 4.​ Blossom: 15 y/o, cob (pony) horse Clinical sign ​ Icteric (yellow) mucous membrane ​ Poor body condition ​ Ulcerative skin lesion (photosensitisation): around eye & muzzle Diagnosis ​ Liver biopsy (small sample, examination) → pyrrolizidine alkaloid toxicity ○​ W/ fibrosis (little) ○​ Ingest toxic plant ○​ Photosensitisation: blue-green algae (cyanobacteria), fungi Treatment ​ X sunlight for months 5.​ Bruce: 10 m/o, male, chihuahua dog History ​ 2-3 days: intermittent vomiting, inappetence ○​ Vomitus: contain bile, mucus ​ Month: intermittent anorexia, vomiting ​ X diarrhoea ​ Water intake, abdominal palpation: normal ○​ Dehydration Clinical sign ​ Rectal temp.: 39.5 °C ○​ Pyrexia (slightly higher than normal) ​ Mucus: pink, tacky (sticky) ​ Abdominal palpation: normal ​ Depression Progression Exploratory laparotomy: ​ Abnormal caudate lobe of liver ​ Purulent 膿 discharge through capsule ​ Pancreas: grossly (naked eye) normal ​ Biliary (bile) drainage: normal Diagnosis Histopathology, microbiology: ​ Caudate lobe: suppuration (form & release pus), microabscessation 潰瘍 ​ ‘Normal’ lobe: chronic active cholangiohepatitis (liver & bile duct) ○​ Klebsiella pneumoniae (bacteria) Treatment (3 days: intravenous fluid, antibiotic → X improvement) ​ Abscess: surgery ​ Antibiotic: amoxicillin clavulanate 6.​ Roger: 12 y/o, male (neutered), miniature schnauzer dog History ​ 1-2 week: Watery small bowel diarrhoea ○​ X tenesmus (bowel cramping & straining → pain), blood ​ 3 days: intermittent vomiting, less active ​ 2 days: anorexia Clinical sign ​ Mucus membrane: slightly pale, tacky ​ Skin elasticity: slightly reduced ​ Sclera (eye): mild jaundice ​ Abdominal palpation, thorax auscultate 聽診, rectal temp.: normal Diagnosis ​ Gall bladder mucocoele 黏液囊腫 ​ Cholecystitis ○​ Gall stone: block gall bladder duct → inflammation ○​ Block bile flow Management ​ Cholecystectomy ○​ Surgery ○​ Remove gall bladder ​ → Low fat diet 7.​ Rocky: 2 y/o, male, Rottweiler dog History ​ 1 month: weight loss ​ Variable appetite ​ X vomit, diarrhoea  ​ Water intake: unchanged Clinical sign ​ Emaciation (abnormally thin / weak) ○​ 33 kg ○​ Appropriate: 55 kg ​ Coat: dull, dry ​ Quiet ​ Mucus membrane: pink ​ Abdominal palpation: fluid ​ Rectal temp. (38.5 °C), heart rate, respiration rate, chest sound: normal Diagnosis Test: ​ Liver enzyme, bile acid: increase ​ Albumin: decrease ○​ Produced by liver ○​ → Fluid leakage Ultrasound: ​ Diffuse change through liver Fine needle aspiration: ​ Remove small amount of cell / tissue / fluid from lump w/ thin needle ​ Sample: examine under microscope ​ Lymphosarcoma (malignant 惡性 cancer) Treatment ​ Chemotherapy: cytotoxic (toxic to cell) drug ○​ Prednisolone ○​ Vincristine ○​ Cyclophosphamide → 6 months survival 4.3 Diarrhoea Small intestine structure: villi ​ Jejunum: longer ​ Ileum: shorter, denser (more numerous) ​ → Surface area of small intestinal mucosa ○​ Villi: increase 10X ○​ Microvilli: increase 20X Structure: ​ Villus tip: ○​ After 3-5 days: die, shed into lumen ○​ Develop absorptive & surface digestive capacity ​ Brush border enzyme, carrier protein ​ Crypt: ○​ Continuous cell division → formation ○​ Inward projection ​ Cell migrate: crypt → villus tip Intestinal pathology on digestion & absorption: ​ Carb & protein: ○​ Brush border enzyme: ​ @ Mature enterocyte ​ Final digestion (→ monosaccharide, amino acid, peptide) ○​ Absorption: ATP dependent ○​ → Hamper: destroy mature enterocyte ​ Fat: ○​ Uptake of monoglyceride, free fatty acid ○​ Diffusion across villi, into lymph lacteal ○​ → Hamper: increase villi width (distance) Fluid: ​ Normal balance (20 kg dog): ○​ Species diff. ○​ Eg. hindgut fermenter (horse, rabbit): larger role of large intestine in fluid absorption Secretion: → lumen (ml) Absorption: → blood (ml) Diet 600 Jejunum 1350 (50 %) Saliva 300 Ileum 1000 (75% of rest) Gastric 600 Colon 315 (90 % of rest) Bile 300 Pancreatic 600 Small intestine 300  Total 2700 2665 (98 %) Faecal water 35 ​ Dynamic in small intestine: ○​ Villus tip: ​ Mature enterocyte (absorptive, tight intercellular junction) ​ Absorb Na, glucose, amino acid ​ Across brush border, on apical (highest point) surface ​ Na pumped out of cell (basolateral: below & side) → net fluid absorption ○​ Crypt base: ​ Stem cell (secreting, leaky intercellular junction) ​ Na leak back into lumen → net fluid secretion ○​ Normal: net absorption > net secretion ○​ Diarrhoea: decrease absorption, increase secretion ​ Increase volume & fluid content of faeces ​ Common clinical sign of intestinal tract disease Basic mechanism: ​ Secretory diarrhoea ○​ Altered epithelial cell transport (change in movement: secrete too much fluid) ○​ Bacteria infection ​ Produce toxin → block electrolyte (Na) pump ​ Net loss of Na into lumen ​ Eg. E. coli, Vibrio cholerae ○​ Profuse (abundant), watery diarrhoea ○​ Self-limiting: villus epithelial cell shedding Increased fluid content Later of adherent bacteria (black) ​ Altered villus (mucosal) structure / permeability ○​ Most common ○​ Cytotoxin: ​ Bacterial infection ​ Cell death ​ Blood, fluid, protein: leak into lumen ​ Villi X absorptive ​ → Dysentery 痢疾: appearance of blood, intestinal tissue shred ​ Eg. Salmonella spp. Irregular surface of damaged intestinal mucosa Microscopic: extensive destruction Bloodstained fluid in lumen ○​ Cellular infiltration into villi: ​ Widening & shortening of villi ​ Reduction in surface area (absorption of nutrient) ​ Malabsorption ​ Unabsorbed nutrient: remain in lumen ​ Overgrowth of bacteria ​ Alter osmotic gradient: draw fluid into lumen ​ Cause: neoplasia, chronic inflammation & (lytic) infection Neoplastic disease (dog): ​ Intestinal lymphoma ​ Infiltration → thickening ○​ ‘Cobblestone gut’ ​ Villi shape: altered Immune-mediated disease (dog): ​ Inflammatory bowel disease ○​ Inappropriate immune response ○​ Dietary / bacterial antigen ​ Lymphocyte + plasma cell Infectious disease (cow): ​ Paratuberculosis (Johne’s disease) ○​ @ Crypt ​ Poor BCS (rib, vertebral process, pelvic bone) ​ Thickened, corrugated (parallel ridge & groove) mucosa ○​ ‘Cobblestone gut’ ​ Microscopic: ○​ Shortening & widening villi ○​ Macrophage infiltration ○​ Intracellular bacteria (red)  ○​ (Lytic) viral infection: ​ Specific target Coronavirus (piglet): Parvovirus (cat): ​ @ Villus epithelium ​ Feline infectious enteritis ​ Viral antigen (brown) ​ @ Crypt ○​ Destruction ○​ Collapse of mucosa ​ Intestinal mucosa, fluid content: red / brown discolouration ​ Osmotic diarrhoea ○​ X specific brush border enzyme ○​ X absorb small osmotic solute → accumulation ○​ Pull water from bloodstream into intestine ○​ Eg. milk intolerance ​ X lactase ○​ → Laxative 瀉藥: induce (mild) ​ Altered motility ○​ Hypermotility: ​ Decrease intestinal transit time ​ Reduce digestion & absorption time ​ Cause: infection (eg. parasitic disease) ○​ Hypomotility: ​ Increase intestinal transit time ​ Bacterial overgrowth in lumen ​ Cause: recent abdominal surgery (post-operative ileus) 4.4 GIT Histopathology (DL) Equine gastric ulcer syndrome: ​ Region: ○​ Epithelium (separated from stomach) ​ Non-glandular (dorsal): keratinised stratified squamous ​ Glandular (ventral): simple columnar ○​ → Separated by Margo Plicatus ○​ Mucosa, can perforate entire wall ​ Protective mechanism: ○​ Non-glandular: X mucus production ○​ Glandular: secretion → splash over ​ Damage to non-glandular ​ Clinical sign: ○​ Vomiting ○​ Lots of pain → X eat, weight loss, low BCS Canine parvovirus: ​ Virus: tropism (affinity) for rapidly dividing cell ○​ Replication → destroy enterocyte from source (crypt of Lieberkuhn) ○​ Chronic onset: villi X repair fast enough ○​ → Scar ​ X divide → reduce absorption ​ Clinical sign: ○​ Acute onset of diarrhoea ○​ Inappetence, weight loss ○​ Death (puppy) ​ Prevention: vaccination Paratuberculosis (Johne’s disease): ​ Cause: mycobacterial infection ​ Accumulation of cell in mucosa ○​ Lamina propria of small intestine ○​ Persist & infect macrophage → proliferate, accumulate ​ Smaller surface area → reduce absorption ​ Clinical sign: ○​ Lose nutrient (malabsorption), fluid (diarrhoea) ○​ Weight loss, lower BCS ○​ Less energy production → reduce milk yield ​ Less productive / 4.5 Glucose Homeostasis meeting Metabolism 4.6 Glucose Tolerance Test Design (DL) Diabetes: Type 1 Type 2 ​ Congenital 先天: inherit ​ Acquired ​ X produce insulin ​ Insulin resistance / insensitivity ​ Eg. young dog ○​ Too much intake ○​ Overproduction of antagonist ○​ Eg. glucagon, adrenaline (fatty acid synthesis) ○​ → Obesity: triggering factor ​ Gestational diabetes ​ Eg. cat ○​ X exercise ○​ Reversible Insulin antagonist: ​ Glucagon ​ Adrenaline ​ Steroid Diagnosis of diabetes (mellitus): setup ​ Fast overnight ​ Take blood sample: control ​ Give bolus of glucose ​ Take blood samples @ interval ​ Measure glucose conc. ○​ Chromogen reagent: ​ Glucose oxidase (oxidation: glucose → H2O2 + gluconic acid) ​ Chromogen ​ Peroxidase ○​ → Pink ​ Intensity: proportional to initial amount of glucose ​ Spectrophotometer: absorbance (15 min incubation, 505 nm wavelength) Standard data: ​ Equation: y = 0.04x Absorbance Glucose conc. (nM) 0 0 0.2 5 0.4 10 0.6 15  0.8 20 Result: Time (min) Blood glucose conc. (mM) Pearl Dean 0 9 5 10 20 16 30 18 13 60 16 9 120 14 4.8 240 12 5 → Diagnosis: ​ Diabetic cat: pearl ○​ High blood glucose lv ○​ Decrease more slowly ​ X only base on hyperglycaemia ○​ Stress response ​ Hormone: steroid ○​ Over / underweight, thirsty → more urine ​ Esp. cat Solution: insulin injection 4.7 Ruminant Anatomy & Physiology Stomach development: ​ Single tube → organ development Structure: 1.​ Oesophagus 2.​ Developing rumen 3.​ Reticulum 4.​ Omasum 5.​ Abomasum 1. Rumen 毛肚: ​ Anatomy: ​ Caudal ​ Pillar: separate reticulum & rumen ○​ X affect circulation ​ Mechanical digestion, X secretion ○​ Epithelium: keratinised stratified squamous ​ Histology: Ruminal papillae: Tunica muscularis: ​ Finger like projection ​ Very thick ​ Hold food for fermentation ​ Contraction: mix food for fermentation ​ Newborn: short, undeveloped ○​ Milk diet, X need ​ Rumination: ○​ Regurgitation → re-mastication  ○​ Reticulum contraction: flood cardia w/ food, → oesophagus ​ Big chunks filtered ○​ → Antiperistaltic contraction: move up to mouth ​ Rely on thorax expansion ​ Closed upper airway ​ Motility (reticuloruminal movement): ○​ → Refer to ch 1.2.2 ○​ Innervation: vagus nerve (CN 10) ​ Dorsal vagal nucleus brainstem: parasympathetic ​ Branches ​ Damage → bloating (emergency, compress diaphragm → breathing difficulty / respiratory insufficiency, death) ○​ Stimulation: ​ Distention (stretch receptor) ​ Ingesta consistency ​ pH ​ VFA (volatile fatty acid) conc. ​ → Afferent @ ruminoreticular lumen: chemo & mechanical receptor, monitor Primary movement: ​ Mixing cycle: follow biphasic (primary → secondary) contraction of reticulum (power: 2nd) ○​ Contract tgt ​ Every 60 sec Secondary movement: ​ Caudal → cranial ​ Eruct ○​ Eg. CH4 ○​ Burping ​ Every 20 sec (vary) ​ Paralumbar fossa (hole): ○​ X ribs, depressed area ○​ Can feel / hear ​ Layering matter: ○​ Slurry & liquid: resting, X active movement ○​ Absorbed gas: VFA ​ Propionate, butyrate, acetate ​ Fermentation product ​ Transport: → blood → liver, convert into energy 2. Reticulum 金錢肚:  Anatomy: ​ Ventral ​ ‘Honeycomb’ structure ​ Mechanical digestion, X secretion ○​ Epithelium: keratinised stratified squamous ​ Less fermentation Histology: ​ Lamina propria, lamina muscularis mucosae ○​ Same in carnivore 3. Omasum 牛百葉: Anatomy: ​ Ventral ​ Epithelium: keratinised stratified squamous ​ Water resorption @ base 4. Abomasum: 1.​ Omasoabomasal opening 2.​ Abomasal fold 3.​ Fundus 4.​ Body 5.​ Pyloric part 6.​ Torus pyloricus 7.​ Pylorus Anatomy: ​ Ventral, midline ​ ‘True’ stomach: secrete pepsinogen, HCl, mucus ○​ Resemble carnivore stomach ○​ Epithelium: simple columnar ○​ Break down protein (eg. from milk → enlarged in newborn) ○​ Receive drier food Histology: ​ Gastric pit, lamina muscularis mucosae ​ Rugae: fold Blood supply of stomach: gastric artery ​ Coeliac artery: ○​ 1st branch of abdominal artery ○​ All foregut  ​ Splenic artery: ○​ Spleen & part of pancreas Newborn calf: ​ Diff. diet → small gut ​ Gastric (/ reticular / oesophageal) groove: ○​ Muscular channel ○​ Next to reticulum ○​ Contract: form cup / tube ○​ Transport milk: oesophagus → abomasum ​ Bypass (X into) rumen, reticulum, omasum ○​ X: milk enter 1st 3 chambers (X digest) ​ Diarrhoea, malabsorption Intestine: ​ Big caecum: bacterial fermentation ​ Colon: ○​ Spiral (90° turn): allow small & large intestine to compartmentalise 1.​ Pyloric part of abomasum 2.​ Duodenum 3.​ Jejunum 4.​ Ileum 5.​ Caecum 6.​ Ileocaecal fold 7.​ Proximal loop of ascending colon 8.​ Centripetal turn of spiral colon 9.​ Centrifugal turn of spiral colon 10.​ Distal loop of ascending colon 11.​ Transverse colon 12.​ Descending colon 13.​ Rectum 14.​ Jejunal lymph node 15.​ Cranial mesenteric artery Liver: ​ Anatomy: ○​ 1st organ behind diaphragm ○​ Central midline (slightly towards RHS) ○​ 4 lobes ​ Caudate lobe: 2 processes 1.​ Left lobe a.​ Omasal impression 2.​ Quadrate lobe 3.​ Right lobe 4.​ Papillary process of caudate lobe a.​ Caudate process of caudate lobe 5.​ Round ligament 6.​ Left triangular ligament 7.​ Right triangular ligament 8.​ Caudal vena cava 9.​ Right kidney 10.​ Portal vein 11.​ Hepatic lymph node 12.​ Bile duct 13.​ Cystic duct 14.​ Gall bladder Pancreas: ​ Mid-ventral, RHS ​ Next to duodenum ○​ Secretion: via pancreatic duct Spleen: ​ Elongated ​ LHS, above rumen Abdominal musculature: ​ Bloating: emergency surgery A.​ Cutaneous trunk line muscle B.​ External oblique muscle C.​ Internal oblique muscle D.​ Transverse (2) & rectus (3) abdominus muscle Topography (organisation of organ): ​ Reticulum: ○​ Close to diaphragm ○​ Hardware disease / traumatic reticuloperitonitis: ​ Metal piece in feed: may pierce reticulum wall → abdominal wall ​ → Ingest magnet (lifetime) ​ Omenta: 1.​ Dorsal sac of rumen 2.​ Ventral sac of rumen 3.​ Superficial wall of greater omentum: attach to central pillar 4.​ Deep wall of greater omentum 5.​ Omental bursa 6.​ Descending duodenum: between 2 walls of greater omentum 7.​ Intestinal mass 8.​ Right kidney 9.​ Aorta 10.​ Caudal vena cava 11.​ Supraomental recess: site of intestine 12.​ Retroperitoneal attachment of rumen ​ Abdomen: 1.​ Right atrioventricular valve 2.​ Lung basal border 3.​ Diaphragm 4.​ Field of liver percussion (technique: estimate liver size & shape) 5.​ Omasum 6.​ Field of omasum percussion & auscultation (listening w/ stethoscope) A.​ Newborn B.​ Young, towards maturity C.​ Pregnant After birth: ​ Uterus shrink ​ Abomasum can move freely → displace ○​ Gas trapped, X release ​ → Diagnosis: flick → metallic ‘ping’ sound ​ → Solution: ○​ Surgery: abomasopexy ○​ Place cow on plank of wood → toggle & roll side-to-side (X permanent) 4.8 Equine & Swine Anatomy & Physiology Horse Stomach: ​ Small, simple ​ Glandular (ventral) & non-glandular ○​ Separated by Margo Picatus ​ Sphincter: ○​ Cardiac: connect w/ oesophagus, very thick ○​ Pyloric: connect w/ duodenum, small angle ​ → X vomit Small intestine: ​ Similar to dog ​ Papillae: ○​ Lesser: connect w/ lesser pancreatic duct ○​ Greater: connect w/ greater pancreatic duct & bile duct ​ Borborygmus Caecum: ​ Anatomy: ○​ RHS, blind sac ○​ Enlarged: hindgut fermenter ○​ Base: connect w/ ileum & (right ventral) colon ○​ Apex: point cranially ​ Development: ​ Strippled: homologous (same) w/ other species ​ Non-strippled: annexed (subordinate, extra) 1st part of colon ​ Caecocolic orifice: constriction of ascending colon ​ Taenia: ○​ Smooth muscle ​ W/ connective tissue ○​ Hold structure in place ​ Haustra: sacculation Ileocaecocolic junction: ​ Separate → ileocaecal & caecocolic orifice (hole) ○​ Carnivore: ileocaecal fold (ligament, external) Colon: ​ Ascending: enlarged, complex → well-developed ○​ Maximise absorption after fermentation (eg. VFA)  ​ Borborygmus ​ Structure: A.​ Ileum B.​ Caecum C.​ Right ventral colon ○​ Twist: right → left ○​ Via sternal (/ ventral diaphragmatic) flexure D.​ Left ventral colon ○​ Go caudally → near pelvis E.​ Pelvic flexure ○​ Twist: ventral → dorsal F.​ Left dorsal colon ○​ Twist: left → right ○​ Via (dorsal) diaphragmatic flexure G.​ Right dorsal colon H.​ Transverse colon ○​ Centre I.​ Descending (small) colon C-G: ascending colon Liver Spleen ​ 4 lobes, 1 process ​ LHS, elongated & wide shape ​ Coeliac trunk: hepatic artery ​ Renosplenic (/ nephrosplenic) ligament: ​ X gall bladder ○​ Connect tissue: spleen & left kidney ○​ Bile acid: secrete, X store ○​ Ascending colon: twist upward ​ Bile duct: release to duodenum ○​ → Prevent: fall in between Pancreas Kidneys ​ Major & minor duodenal papilla ​ Left: can palpate ○​ Connect w/ small intestine ​ Right: more cranial → secretion ○​ Pushed by caecum Foal GIT: ​ Caecum & ascending colon: undeveloped Topography: LHS: 1.​ Diaphragm a.​ Ribs 2.​ Stomach 3.​ Liver 4.​ Spleen 5.​ Transverse & descending colon  6.​ Small intestine 7.​ Left dorsal colon 8.​ Left ventral colon RHS: 1.​ Diaphragm a.​ Ribs 2.​ Liver 3.​ Right kidney 4.​ Transverse colon 5.​ Caecum 6.​ Right ventral colon 7.​ Right dorsal colon Transverse: 1.​ Spleen (LHS) 2.​ Stomach 3.​ Pylorus 4.​ Duodenum: cranial 5.​ Duodenum descending 6.​ Duodenum: caudal flexure 7.​ Pancreas 8.​ Right kidney 9.​ Left kidney 10.​ Left adrenal gland 11.​ Cranial mesenteric artery & vein 12.​ Portal vein 13.​ Liver 14.​ Falciform ligament: remnant of umbilical vessel, connect liver & abdominal wall ​ Rectal palpation: ​ Descending colon ○​ Ball of faeces ​ Spleen: caudal ○​ LHS ​ Nephrosplenic ligament ○​ Next to spleen ​ Left kidney: caudal ○​ Medial / ventral: mesentery root ​ Caecum ○​ Base & ventral taenia ○​ RHS ​ Pelvic flexure ​ Distended (swollen, bloated) small intestine ​ → Colic: ○​ (Any sort of) abdominal pain: esp. around large intestine  ○​ Cause: ​ Blockage → build up of gas → gut wall stretching ​ Torsion (twist) → mesentery tension → ischaemia (X blood supply to organ) ​ Inflammation ○​ Symptom: roll on ground Pig Digestive tract: ​ ~ Human → organ xenotransplantation ○​ Eg. islets of Langerhans Pharynx: ​ Teeth: brachydont ○​ Except tusks (canine teeth): continuous growth 1.​ Nasal concha: dorsal 2.​ Nasal concha: ventral 3.​ Ethmoidal conchae 4.​ Soft palate: elongated 5.​ Tongue 6.​ Oropharynx 7.​ Nasopharynx 8.​ Mental hair 9.​ Geniohyoideus 10.​ Basihyoid 11.​ Laryngeal ventricle 12.​ Larynx 13.​ Pharyngeal diverticulum: trap medicine pill, X swallow 14.​ Atlas 15.​ Axis 16.​ Oesophagus 17.​ Trachea 18.​ Thyroid gland 19.​ Sternohyoideus Stomach: ​ Simple: 1 chamber 1.​ Non-glandular ○​ Very small, around cardiac region 2.​ Glandular a.​ W/ cardiac gland b.​ W/ proper gastric gland c.​ W/ pyloric gland Intestine: ​ Caecum: enlarged ○​ Omnivore: X fermentation ​ Ascending colon: complex ○​ Spiral (pyramid): able to fit ○​ → Ansa spiralis: flat disc, optimise space 1.​ Descending duodenum 2.​ Duodenum: caudal flexure 3.​ Jejunum 4.​ Ileum 5.​ Caecum 6.​ Ascending colon 7.​ Transverse colon 8.​ Descending colon 9.​ Descending mesocolon 10.​ Mesoduodenum 11.​ Mesentery LHS RHS Dorsal Ventral Caecum: ileocaecal orifice, X caecocolic Liver: ​ 5 lobes, 1 process 1.​ Left lateral lobe 2.​ Left medial lobe 3.​ Right lateral lobe 4.​ Right medial lobe 5.​ Quadrate lobe 6.​ Caudate process 7.​ Porta 8.​ Gall bladder: big 9.​ Median plane 10.​ Caudal vena cava Uterus: turn & twist ​ ~ Small intestine 3.1 Metabolic Concepts & Cellular Energy & 3.2 Catabolic Core of Metabolism Metabolic pathway: ​ Series of steps ​ Catalysed by enzymes ​ → Catabolism: break down, release energy ​ → Anabolism: build, consume energy Common intermediate (activated, limited no.): 3 ​ Glucose-6-phosphate ​ Pyruvate ​ Acetyl CoA Rule of thermodynamics: ​ Spontaneous: exergonic (-ve delta G: Gibbs free energy) ○​ Delta G = G product - G reactant ○​ Create chaos (heat) → release ○​ Only show spontaneity, X indicate reaction rate ○​ Inherent free energy: under same conc., forward / reverse reaction? ​ Set condition: 1M reactant, 25 °C, pH 7 ​ More substrate: delta G more -ve → more spontaneous ​ More product: delta G more +ve → less spontaneous ​ Run towards eqm (delta G = 0) ​ Endergonic (+ve delta G): energy input to drive reaction ○​ Through linked (coupled) exergonic reaction ​ Substrate:product ratio: affect dynamic ​ Essentially irreversible: too exergonic → very favourable Biological reaction: ​ Unfavourable (endergonic, anabolic) driven by favourable (exergonic, catabolic) reaction ​ Overall delta G: -ve ​ Common energy transducer: ATP ○​ Carrier of energy: link catabolism to anabolism ○​ ATP → ADP + Pi: spontaneous, release energy ○​ Pi bond: intermediate amount of free energy ​ 1. PO4 3-: X full resonance → need more energy to maintain shape ​ Taken off → full resonance ​ 2. -ve charge of O2: stressful ​ Break down → release energy ○​ Eg. NADH, NADPH Enzyme: ​ Bind substrate (ligand) @ active site → convert into product ○​ Lock & key model: complementary ○​ Induced fit model: similar shape → change ​ Can de-induce ​ Alternative pathway ​ Lower activation energy (Ea) & delta G → energy input ​ Increase reaction rate ​ Time: direct activity < allosteric < reversible covalent ​ → Allosteric: ○​ Regulatory site: away from active site ○​ Small molecule: bind ○​ → Change conformation of active site ○​ → Promote / inhibit activity ​ → Reversible covalent modification ○​ Regulatory mechanism ○​ Inorganic phosphate (PO4 3-): enzyme phosphorylation → de-phosphorylation ​ Phosphorylation: kinase ​ De-phosphorylation: phosphatase ​ 17000 active genes: 1000 for kinase ○​ → Stimulate / inhibit activity  ○​ Reversible ○​ Hormone: control Key catabolic pathway (respiration): ​ Generate required energy ​ Maintain appropriate energy charge in cell ○​ ~ 70% ATP ○​ ~ 30% ADP ​ ADP → ATP: ~ 5 secs ○​ ATP: exported from matrix ○​ ADP: imported via transmembrane translocase protein ○​ 1 H+ / nucleotide exchanged ​ 4 H+ / P bond generation ​ Enzyme: control flux → Glycolysis: 1. Substrate lv phosphorylation ​ Glucose + 2 (ADP + Pi + NAD+) → 2 (pyruvate + ATP + NADH + H+) ○​ 4 ATP produced ○​ Net production of 2 ATP & 2 NADH ​ Operate most of time in most tissues ○​ Liver & muscle: more control (mass action, allosteric regulation) → more adaptive ​ Liver: metabolism hub ○​ More pathways w/ more control ○​ Eg. hormone ​ Enzyme: ○​ Phosphofructokinase ​ Stimulate: AMP ​ Inhibit: ATP, citrate, H+ (skeletal muscle, pyruvate produce lactic acid → feedback) ○​ Pyruvate kinase ​ Stimulate: fructose-1,6-bisphosphate ​ Inhibit: ATP ​ Emergency reaction: 2 ADP → ATP + AMP ○​ Enzyme: adenylate kinase ○​ AMP: signal for low energy lv 2. Link reaction: ​ Pyruvate → acetyl CoA (→ fatty acid) ​ Enzyme: pyruvate dehydrogenase ○​ Stimulate: pyruvate, Ca2+, insulin ○​ Inhibit: ATP, NADH, acetyl CoA ​ End product regulation ​ Essentially irreversible ​ Cytosolic NADH: donate e- to electron transport chain (ETC) → generate more ATP 3. Citric acid (Krebs) cycle: ​ 2 (acetyl CoA + 3 NAD+ + FAD + GDP + Pi + 2 H2O → 2 CO2 + 3 NADH + FADH2 + GTP → 2 H+ + CoA) ○​ Net: acetyl (2-C) → 2 CO2 ​ 4 redox: 4 pairs of e- ○​ 3 pairs: 3 NAD+ + 6 e- → 3 NADH ○​ 1 pair: FAD → FADH2 ​ Aerobic: FAD supply → carry e-s to O2 via ETC ​ Tight regulation: ○​ Allosteric effect on 3 regulated enzymes ○​ Regulate pyruvate dehydrogenase → control of acetyl CoA supply 4. ETC ​ Accept e-s from matrix NADH → gradual release of energy → pump H+ into inner mitochondrial membrane (intermembrane space) ○​ NADH: oxidation of 1 pair of e-s → pump 10 H+s ○​ FADH2: 1 pair → pump 6 H+s ​ pH gradient & transmembrane electric potential → H+ motive force ​ O2: final e- acceptor 5. Chemiosmosis (ATP synthesis) ​ ADP + Pi → ATP ​ Enzyme: ATP synthase ​ ATP synthesis: oxidative phosphorylation ○​ Coupled by H+ gradient ​ 26 (out of 30) ATP generated from 1 glucose Complete oxidation: 30 ATP ​ Glycolysis: 5 (2 direct) ○​ + Cytosolic NADH: 3 ​ 1.5 each ​ pump 6 H+ each ​ Pyruvate dehydrogenase: 5  ​ Citric acid cycle: 20 ○​ Matrix NADH: 15 ​ 2.5 each ○​ Matrix FADH2: 3 ​ 1.5 each ​ pump 6 H+ each ○​ GTP direct: 2 Brain: pump ions (Na+, K+, Ca2+) → burn ATP No. of H+ needed to flow across intermembrane: range ​ Depend on conc. of H+ & ATP Oxidation & phosphorylation: tightly coupled → Uncoupling oxidation: ​ Disrupt H+ gradient → generate heat ​ Eg. non-shivering thermogenesis ○​ Hibernating animal, neonate 嬰兒, mammals adapted to cold ○​ Inner mitochondrial membrane of brown adipose: copies of thermogenin (transmembrane protein) ○​ → Transfer H+ down conc. gradient ○​ Cytosol → matrix ○​ Controlled by hormone ​ Eg. 2.4-dinitrophenol (DNP) ○​ Carry H+ over inner mitochondrial membrane ○​ Dissipate 消散 H+ motive force ○​ Uncoupler: permeable to proteins ○​ Speed up metabolism, use more fat → more energy release ○​ Toxic → used in war as weapon ​ Eg. valinomycin ○​ Inner membrane: K+ permeable ○​ Electrochemical H+ gradient: push K+ into mitochondria ○​ Dissipate change gradient ○​ Much weaker H+ gradient force ○​ Partially affect → X toxic 3.3 Organising Metabolism (DL) Glycolysis: 8 reactions Phosphorylation: ​ Increase chaos (achieve unstable state) → further break down reactions ​ X go back to original cell: locked w/in liver / skeletal muscle / adipose De-phosphorylation: liver, X skeletal muscle ​ Raise blood glucose lv ​ Skeletal muscle: store glycogen (→ glycogenolysis), but X change blood glucose lv Liver: ​ Integrate metabolism → ensure provision of appropriate metabolites under diff. conditions ​ Eating: ○​ Absorb: vitamins ABDK ○​ Metabolise: carb, fat, protein ○​ Alter: glycogenesis, protein → amino acid, fat → fatty acid & glycerol ​ Fasting: ○​ Glycogenolysis: glycogen → glucose ○​ Lipolysis ○​ Beta oxidation ○​ Eg. sleeping Control of metabolic pathways: 3 main tiers ​ Mass action (substrate:product ratio) ○​ Substrate: +ve relationship ○​ Product: -ve ​ Enzyme amount: +ve ​ Enzyme activity: stimulate / inhibit ○​ Allostery ○​ Hormone: insulin secretion after meal → glycogenesis Gluconeogenesis: ​ Convert non-carb → glucose ​ Produce energy ​ Precursor: lipid (fatty acid), protein (amino acid), acetyl CoA, pyruvate, alpha ketoglutarate, oxaloacetate Strict carnivore: ​ Characterised by ketosis state, increased protein oxidation, gluconeogenesis ​ Urea cycle: ○​ Convert NH3 → urea ○​ Remove toxic byproduct (NH3) 3.4 Animals with Simple Stomach Peritoneum, mesentery, omentum: ​ Same structure ​ Diff. region → diff. name GIT development: ​ Single tubular structure ​ In mother’s body: X specialisation ​ Grow & expand → organ ​ Blood supply: aorta → ○​ Coeliac artery (foregut) ○​ Mesenteric artery ​ Cranial (midgut) / caudal (hindgut) Abdominal cavity boundary: line abdomen space ​ Upper: diaphragm ○​ Affect respiration ○​ Bird: thoracoabdominal / coelomic cavity ​ Lower: upper plane of pelvic cavity (floor) ​ Vertical: vertebral column, abdominal muscle Peritoneal cavity / peritoneum: ​ Serous membrane: lining ​ Cover most of intra-abdominal organs ○​ Retro-peritoneum: organ created after peritoneum formation → X cover ○​ Eg. kidneys, pancreas, rectum, part of stomach ​ Composition: ○​ Mesothelium layer ○​ Thin layer of connective tissue (support) ​ Function: ○​ Support organs ○​ Conduit: blood vessels, lymphatic vessels, nerve ​ → Visceral: wrap around organ ​ → Parietal: outer layer, line abdominal & pelvic wall Stomach: ​ Internal anatomy: rugae ○​ Stomach fold ○​ Increase surface area → speed up digestion ○​ Glandular: simple columnar epithelium ​ Wrapped by omentum (peritoneum of stomach) ○​ Extend beyond organ ○​ Double / multiple layer ○​ Greater / lesser curvature → greater / lesser omentum ○​ → Greater: stomach & proximal duodenum → transverse colon & mesocolon  ​ Transverse mesocolon, anterior of intestines: hang down freely ​ Gastrosplenic ligament: connect stomach & spleen ​ Extend: omental bursa → allow stomach to move freely ○​ → Lesser: stomach & proximal duodenum → liver ○​ Only attach to stomach & spleen ​ Benefit surgery ○​ Produce growth factor, increase blood flow, recruit immune cell ​ Cover wound after surgery: speed up healing Coeliac artery: ​ Blood supply to foregut ○​ Liver (hepatic), stomach (gastric), pancreas (pancreatic), spleen (splenic) ○​ → Cranial mesentery ​ Anastomosis (branches connect to each other) ○​ 1 cut off → blood supply still functional ○​ Benefit surgical removal ​ Drainage: hepatic portal vein ○​ Nutrients: small intestine (absorb) → liver → heart → rest of body ○​ Detoxification Liver: Duodenal papilla: ​ Most cranial of abdomen ​ Major: ​ Behind diaphragm ○​ Small opening ​ More towards right ○​ Allow bile & pancreatic juice ​ 6 lobes, 2 processes to flow into small intestine ​ Lobule: hexagon ​ Minor (dog, X cat): ○​ Portal vein ○​ Accessory pancreatic duct ○​ Portal triad ○​ X bile ​ Produce bile ○​ Storage: gall bladder (carnivore) ○​ CCK (hormone): gall bladder contract → release bile Intestine: ​ Small: ○​ Duodenum ​ Lining: secrete mucous & fluid ​ Bile & pancreatic duct ○​ Jejunum & ileum ​ Secrete fluid ​ Digestive & absorptive ​ Large: ○​ Caecum ○​ Ascending / transverse / descending colon ​ Mesentery (peritoneum of intestines) ○​ Double layer ○​ Net of conduit: blood supply ​ Ileocaecocolic junction: ○​ Formed by ileum junction, into ascending colon @ caecocolic orifice ○​ Canine: caecocolic (connect to colon directly) & ileocolic orifice ○​ Feline: ileocaecocolic junction (merge) ​ Everything meet @ once Mesenteric artery: ​ Blood supply to midgut (cranial) & hindgut (caudal)  ○​ Cranial: small intestine, caecum, ascending & transverse colon ○​ Caudal: much smaller, mainly for descending colon (& rectum) ​ Carnivore: longer ​ Anastomosis: ○​ X 1 single vessel / area ○​ Diff. branch → can remove part of intestine Venous drainage: ​ All veins from GIT & spleen: combine into portal vein → liver ​ Filter nutrients: detoxify ​ Distribution into body circulatory system Abdominal wall: muscle ​ External abdominal oblique ○​ Outermost layer ○​ Origin: ​ Costal cartilage ○​ Insertion: ​ Wide aponeurosis (connective tissue: connect muscle & bone) ○​ Fibre direction: ​ Caudoventral ○​ Function: ​ Compress abdominal cavity ​ Trunk rotation ​ Form inguinal ligament ​ Internal abdominal oblique ○​ Origin: ​ Coxal tuberosity ​ Transverse process of lumbar vertebrae ​ Iliac fascia ○​ Insertion: ​ Linea alba ​ Final rib costal arch ○​ Fibre direction: ​ Ventrocranial ​ Perpendicular of external ○​ Function: ​ Compress abdomen (opposite of diaphragm) ​ Oppose external → rotation ○​ Location: ​ Below external, above transverse abdominal muscle ○​ Male: become Cremaster muscle (caudal) ​ Go inside scrotum ​ Maintain temp.: too high → contract → pull away, too low → relax ​ Transversus abdominis ○​ Innermost layer ○​ Origin:  ​ Transverse process of lumbar vertebrae ​ Ribcage ○​ Insertion: ​ Linea alba ○​ Fibre direction: ○​ Transverse ○​ Function: ​ Compress ribs ​ Provide stability ​ Rectus abdominis (6 pack 腹肌) ○​ Origin: ​ Sternum (xiphoid process) ​ Sternal rib cartilage ○​ Insertion: ​ Prepubic tendon ​ Pubic bone (public symphysis) ○​ Fibre direction: ​ Longitudinal on both sides of linea alba ○​ Function: ​ Assist breathing ​ Abdominal stability ○​ Rectus sheath: ​ Tendinous ​ Enclose rectus abdominis ​ Surgery: need to be sutured → provide tension ○​ → Abdominis + sheath → linea alba (white line) ​ Surgery: X blood vessel → place for incision Inguinal ring: ​ Connective tissue opening ​ Between abdominal muscle & aponeurosis ​ (Diff. sex) form passage for vaginal process / descent of testis ○​ Small testicle: pass through → grow → ring close ​ X go back into abdominal cavity ○​ Uterus & cervix: w/in abdominal cavity ​ X use ○​ → Spermatic cord / round ligament ​ X close → hernia (internal of body push through muscle / surrounding tissue wall weakness) ○​ Lobes of intestine can go through ​ Cryptorchidism: ‘missing’ / undescended testicle(s) ○​ Inguinal ring X open enough to allow passage of testicles ○​ Remain inside of abdominal cavity ​ 2 in cavity / 1 in scrotum 1 in cavity ○​ Sometimes fertile ○​ Genetical condition: inherit ​ Remove from breeding pool Abdominal wall: blood supply → Cranial / caudal superficial epigastric artery & vein ​ Very close to skin ​ Cranial: blood supply to mammary gland ○​ Mammary cancer removal: X cut blood vessel Topography (distribution of parts / features w/in organism): 3.5 Gluconeogenesis, Nitrogen Metabolism & Amino Acid Balance Gluconeogenesis: ​ Tissue protein ​ @ liver (+ kidney) ​ Body: glucose deficient ○​ Fasting: amino acid (protein: 3rd energy source), glycerol ○​ Strenuous exercise: lactate ○​ Convert absorbed nutrient: propionate (ruminant) ​ 2nd pathway to increase glucose lv (boost blood glucose lv) ○​ From X CHO metabolic intermediate ​ X simple reversal of glycolysis ○​ Bypass essentially irreversible steps w/ new reaction ​ Consume 6 ATP → need reciprocal control in hepatocyte ​ Enzyme: ○​ Glucose-6-phosphatase: ​ Fructose-6-phosphate → glucose-6-phosphate ○​ Fructose-1,6-bisphosphatase: ​ Fructose-1,6-bisphosphate → fructose-6-phosphate ○​ PEP carboxykinase: ​ Oxaloacetate (4-C in Krebs cycle) → phosphoenolpyruvate ​ Reciprocal ​ Stimulate: glucagon ​ Inhibit: insulin ○​ Pyruvate carboxylase: ​ Pyruvate → oxaloacetate ​ Turn on by acetyl CoA ​ Amino acid: ○​ Glucogenic (pair w/ alpha-keto acid): ​ Alanine: → pyruvate + NH4+ ​ Aspartate: → oxaloacetate + NH4+ ​ Glutamate: → alpha-ketoglutarate (5-C in Kreb cycle) + NH4+ ○​ Ketogenic: ​ → acetyl CoA ​ Regulate: hormone ​ → Neonatal pig:  ○​ Glycogen: supply ~ 1 day of CHO ○​ X gluconeogenic potential for 2-3 days after birth ○​ Suckle milk: fresh glucose ​ X → hypoglycaemic Nitrogen metabolism: ​ Important for health ​ Issue: toxicity ​ Intake as protein (amino acid) ​ → Balance: intake = excretion ​ → +ve: intake > excretion ○​ Eg. growth, pregnancy ​ → -ve: intake < excretion ○​ Eg. starvation ​ Healthy adult: 1 g protein input / day / kg (bodyweight) ○​ Good quality: nutritionally essential amino acid Amino acid pool: ​ Amino group (NH2-) ​ Input: ○​ Endogenous (internal origin) protein ○​ Dietary protein ​ Output: ○​ Endogenous protein ○​ X protein nitrogenous compound ​ Eg. neurotransmitter, catecholamine (stress-responding hormone), nucleotide, heme ○​ Alpha-keto acid ​ Carbon skeleton amphibolic (both cata- & anabolic) intermediate ​ Transamination: amino acid → ​ Deamination: → anabolic synthesis (gluconeogenesis), catabolic energy production ○​ NH3 (toxin) → excretion ​ NH3 (g): ammonotelic (eg. fish) ​ Uric acid: uricotelic (eg. bird, reptile, Dalmatian 斑點狗) ​ Urea (H2N – CO – NH2): ureotelic (eg. mammal) Transamination: ​ Swap R group ​ Form glutamate ○​ Alpha-ketoglutarate →  ○​ Transport into liver ​ Tissue: glutamate + NH4+ ​ Blood (solid transport): → glutamine ​ Liver: → glutamate + NH4+ (deamination) ​ → Urea (urea synthesis / cycle) Urea cycle: ​ Use 4 ATP ​ Produce urea: excretion ​ → Other animal: slow down when fasting ​ → Cat: all time NH3 toxicity: ​ Urea cycle X function → blood NH3 lv rise ​ → NH3 intoxication ○​ Reverse glutamate dehydrogenase ​ Glutamate + NAD+ + H2O ← alpha-ketoglutarate + NH4+ + NADH ○​ Use up alpha-ketoglutarate (Kreb cycle) ○​ Promote: glutamate → glutamine ​ Enzyme: glutamine synthase ​ Clinical sign: ○​ High protein food intolerance, vomiting, mental retardation, coma, death ○​ Genetic defect of urea cycle enzyme, liver disease / damage ​ Treatment: ○​ Lower blood NH3 lv ○​ Low protein diet, small amount & frequent interval 3.6 Energy Stores: Glycogen & Fats Glycogen: ​ Deposit from excess glucose ​ Breakdown: ○​ Liver (80%): buffer blood glucose ○​ Muscle (20%): generate energy during strenuous exercise ​ Storage, X produce ​ Local use ​ Same pathway, diff. hormone: adrenaline (promote phosphorylase) ​ Enzyme: ○​ Glycogen synthase: branching ○​ Phosphorylase: take away 1 glucose ​ Control: reciprocal (1 side on & 1 side off) ○​ Prevent futile (useless) cycle ○​ Allostery ​ AMP (low energy): promote phosphorylase → produce glucose ​ Ca: break down glucose ​ Glucose: promote glycogen synthase ○​ Hormone ​ Pancreas → liver ​ Act on cell-surface receptor → intracellular signal ​ Activate: kinase / phosphatase Insulin Glucagon ​ Promote glycogen synthase ​ Promote phosphorylase ​ Glucose → glycogen ​ Glycogen → glucose ​ Decrease blood glucose lv ​ Increase blood glucose lv Lipid: ​ Triacylglycerol (triglyceride) ○​ 3 long chain fatty acid + glycerol backbone ​ Fatty acid: CH3 – (CH2)n – COOH ​ All single bond: saturated ​ W/ double bond: unsaturated ○​ Primary storage form ​ Predominant: adipose tissue  White Brown ​ Store triglyceride Neonate 嬰兒, small animal ​ Secrete multiple adipokine: ​ Highly oxidative cell-signalling, for body energy ​ Non-shivering thermogenesis status (obesity, inflammation) (uncoupling) Fat droplet Single Multiple, small Mitochondria Few Many Storage Multiple Less (eg. periscapular: shoulder blade) ​ Small amount: liver, muscle ○​ High energy density ○​ Non-polar, X toxic ​ Disease: Species Aberrant 異常 fat: disease All Obesity Cow, sheep Pregnancy toxaemia: body burn fat (X glucose) Cat, horse Hepatic lipidosis: triglyceride accumulate in liver cell Dog, cat Diabetes Human Atherosclerosis (narrowed artery), metabolic syndrome Lipid transport: ​ Liver: metabolism ​ → Fatty acid: bound to albumin (most abundant blood protein), in circulation ​ → Lipoprotein ○​ Classify: size, lipid & protein composition ​ Very low density: newly synthesised triglyceride (liver → adipose tissue) ​ Low density: mixture of lipid (around body) ​ High density: return lipid (other tissue → lipid) ​ Triglyceride: ○​ Absorbed from gut ○​ Chylomicron: facilitate transport through lymphatic system, into blood ​ → Peripheral tissue: metabolism ​ → Adipose tissue: storage (broken by lipoprotein lipase) ○​ Chylomicron remnant: processed in liver ​ Make triglyceride Lipase: ​ Adipose hormone-sensitive lipase: rate control ○​ Promote: glucagon / adrenaline ○​ Inhibit: insulin  Location Function Pancreatic → Small intestine Food lipid digestion Lipoprotein Endothelial cell Hydrolysis Triglyceride Aid tissue uptake Adipose Triglyceride Adipocyte, other (Lipolysis: Stored triglyceride → diglyceride lipid-storing cell release + fatty acid free fatty Hormone-sensitive Diglyceride → monoglyceride + acid) fatty acid Monoacylglycerol Monoglyceride → fatty acid + glycerol Glycerol: ​ → Liver ​ For metabolism Fatty acid: ​ → Cells ​ Free = X esterified (bound) ​ Break down: oxidation ○​ Produce energy ​ Esp. actively metabolising tissue (eg. skeletal muscle) ○​ @ Mitochondrial matrix ○​ → Across membrane: reciprocal regulation ​ Acyl carnitine: facilitate transport via CPT1 transporter ​ Inhibit: malonyl CoA (fatty acid synthesis intermediate) → acyl CoA X transport into mitochondria ○​ → Matrix: beta-oxidation ​ Repeated removal of acetyl CoA ​ Fatty acyl CoA broken down ○​ Palmitate (16-C fatty acid): ​ 7 cycle ​ Generate 8 acetyl CoA (2-C) ​ Net production: 106 ATP / mole (3X of glucose) ​ Synthesis: ○​ @ Liver, adipose tissue ○​ Repeated condensation of acetyl CoA → palmitic acid ​ Acetyl CoA + 7 malonyl CoA + 14 NADPH → palmitic acid + 8 CoA + 14 NADP+ + 6 H2O + 7 CO2 ​ Enzyme: fatty acid synthase (cytoplasmic multi-enzyme complex) ○​ Reciprocal regulation ​ Unique path & enzyme (X reverse beta-oxidation) ​ Site: cytosol (X matrix) ○​ Rate limiting step:  ​ Acetyl CoA + HCO3- + ATP → malonyl CoA + ADP + Pi + H+ ​ Enzyme: acetyl CoA carboxylase Stimulate Inhibit Hormone Insulin: dephosphorylation Glucagon / adrenaline: phosphorylation Allosteric Citrate: feedforward (from external Palmitoyl CoA environment) stimulation AMP: -ve feedback ​ Co-factor: biotin (vitamin B7) ○​ 8 acetyl CoA + 7 ATP + 14 NADPH → palmitate + 8 CoA + 14 NADP+ + 6 H2O + 7 ADP + 7 Pi Lipogenesis: ​ Fatty acid & glycerol → triglyceride ○​ Oppose to adipogenesis (adipose expansion) ○​ Fatty acid: from new synthesis, diet, adipose tissue ​ Mainly @ liver, adipose tissue ​ Pathway: step-wise acylation of glycerol-3-phosphate (from glycolysis) 3.7 Cat Metabolism (DL) Case study ​ 6 months old Persian kitten ○​ Small for its age ​ Poor condition ​ Listlessness 無精打采, walk in circle ○​ After meal ​ Examination: dazed, normal functional cranial nerve Dysfunctional organ system: ​ Digestive ​ Neurological Blood NH3 lv: extremely high ​ Liver deficient ​ Affect urea cycle (deamination & transamination) ​ NH3 intoxication → lower ATP production → listlessness Arginine: ​ Essential amino acid ○​ X fish: excrete NH3 gas ○​ X bird & reptile: excrete uric acid ​ Assist urea cycle (nitrogen metabolism): NH3 → urea Fasting bile acid lv: extremely high ​ Production: break down cholesterol ​ Emulsify lipid ​ Lipolysis: lipid → glucose, produce energy ○​ X produce fatty acid → X beta oxidation ​ Resorption issue Inherited anatomical cause: ​ Portosystemic shunt (PSS) ○​ Blood from portal circulation bypass liver, flow into systemic circulation ○​ Treatment difficulty: depend on type of shunt (tube, allow fluid to move between parts of body) ​ Inter (more difficult) / extra ​ Single / double (more difficult) ​ Hypertension: more difficult ​ X hepatic encephalopathy (structural defect) ​ Diagnosis: ultrasound (muscle) ○​ Bone: X ray Prognosis 預知: bad ​ Depends on type of shunt Treatment: ​ Surgical intervention ○​ Band (metal): slowly close shunt off ○​ Cat: smaller in size → harder ​ Diet: low protein ○​ Omnivore: deal w/ low protein diet more easily ​ Lactulose ○​ Synthetic ○​ Change absorption of protein ​ Antibiotic ○​ Gut flora bacteria ○​ Help w/ protein digestion ​ Low success rate → animal welfare problem Conditionally essential amino acid: ​ Major trauma, stress ​ → Stop production of specific amino acid ​ Need to consume from food 3.8 Oral Cavity & Foregut Point-to-Point Tongue function: ​ Grooming, lapping, prehension, deglutition, vocalisation ​ Taste bud: taste, temp. sensation, mix food w/ saliva Ovine Porcine Canine ​ Main papillae: vallate, fungiform, filiform, foliate ​ Root / body / apex Tongue muscle: ​ Intrinsic ​ Extrinsic ○​ Hyoglossus ​ Attachment: arise from hyoid bone, insert into side of tongue ​ Function: depress & retract tongue ​ Innervation: motor, via hypoglossal nerve (CN 12) ○​ Styloglossus ​ Attachment: originate @ styloid process of temporal bone, insert into side of tongue ​ Function: retract & elevate tongue ​ Innervation: motor, via hypoglossal nerve (CN 12) ​ Lyssa: cup water → drinking Major salivary gland in carnivore: ​ Parotid ○​ Around ear canal ​ Zygomatic ○​ Near eye ​ Mandibular ○​ Behind jaw bone ​ Sublingual ○​ Under tongue Diff. w/ sheep (herbivore): Dog Sheep Size Small Parotid: largest (4 lobes: cranial, middle, caudal, accessory) Zygomatic gland Present X Soft & hard palate: ​ Soft: ○​ Cartilage ○​ Separate oral & nasal pharynx ○​ Breathing, swallowing, speaking ​ Hard: ○​ Bone ○​ Separate oral & nasal cavity ○​ Swallowing, speaking Passage: Food: Air: ​ Upon hard palate ​ Under hard palate ​ Through soft palate ​ Through soft palate ​ Into trachea ​ Into larynx & oesophagus Larynx: ​ Innervate: branches of vagus nerve ​ Laryngeal nerve: ○​ Cranial: 2 branches ​ Internal: innervate mucosa ​ External: innervate cricothyroid muscle → constrict pharynx ○​ Caudal: innervate intrinsic muscle of larynx ​ Except cricothyroid muscle ​ Damage → laryngeal paralysis (horse ‘roaring’) Hyoid muscle: Bone Muscle Cartilage ​ Basihyoid ​ Ceratohyoideus ​ Arytenoid ○​ Single ​ Cricoarytenoid ​ Cricoid ○​ @ base of tongue ○​ Dorsal ​ Epiglottis ​ Ceratohyoid ○​ Lateral ​ Thyroid ○​ Paired ​ Cricothyroid ○​ Rod-shaped ​ Thyrohyoid ​ Epihyoid ​ Hyoepiglotticus ○​ Paired ​ Stylohyoid ○​ Paired ​ Thyrohyoid ○​ Paired ○​ Attach to thyroid cartilage of larynx Muscle of mastication: ​ Digastricus ○​ Jaw opening ○​ Innervation: facial (CN 7) & mandibular branch of trigeminal (CN 5) ​ Temporalis ○​ Jaw closing ​ Masseter ○​ Jaw closing ​ Pterygoid ○​ Lateral (protrude) & medial ○​ W/ masseter: swing motion Teeth: Brachydont: Hypsodont: ​ Crown: above gingiva ​ Erupt throughout life ​ Constrict neck @ gumline ○​ Horse: permanent teeth ​ Root: embedded in jaw bone ○​ Ruminant: cheek teeth ​ X wear → harder ​ Aradicular ​ More spiky ○​ Open root ○​ Continued growth ○​ Eg. rabbit ​ Radicular ○​ Close root ○​ Growth decrease w/ age ○​ Eg. horse ​ Occlusal plate: flat Bird (some species): spike of teeth Diastema: ​ Gap between canine & incisor ○​ Hypsodont: X canine → larger ​ X shorten: ○​ Space for nasal cavity ○​ Muscle attachment ○​ Food move to back when chewing → X need ​ Risk: food get stuck → infection Jaw: bilaterally symmetrical Dental formula: ​ Left → right: ○​ Incisor → canine → premolar → molar ​ Up: maxillary arcade (upper jaw) ​ Down: mandibular arcade (lower jaw) Dog Cat 3142 3131 3143 3121 3.9 Canine Abdomen Dissection: Skin & Body Wall, Topography & Viscera Canine abdomen quiz Aponeurosis: ​ Flat sheet of tendon ​ Collagen fibre: run in same direction Fascia: ​ Flat sheet of connective tissue ​ Collagen fibre: random direction Rectus abdominis: ​ Muscle: ○​ Origin: xiphoid process of sternum ○​ Insertion: public symphysis (public bone) ​ Sheath: ○​ Formed by connective tissue extension of 3 muscles: ​ Transversus abdominis ​ Internal abdominal oblique ​ External abdominal oblique Visceral peritoneum: wrap stomach Epiploic (omental) foramen: ​ Small opening ​ Bounded by hepatic portal vein (central) & caudal vena cava (dorsal) ​ Connect greater & lesser peritoneal cavity ​ Link omental bursa to remainder of peritoneal cavity Coeliac: ​ Ganglion: ○​ Nerve bundle @ upper abdomen ○​ Part of autonomic nervous system  ○​ Innervate digestive tract & abdominal visceral tissue ​ Artery: ○​ Supply oxygenated blood to liver, stomach, abdominal oesophagus, spleen, cranial half of duodenum & pancreas Cisterna chyli: ​ Sac-shaped lymphatic structure ​ Receive lymph from jejunum, ileum, pancreas ​ Through mesenteric lymph node Stomach: 4 regions ​ Cardia, fundus, body, pyloris Oral → ab-oral: ​ Stomach → duodenum → jejunum → ileum → colon → caecum Gall bladder: ​ Between right medial & quadrate lobe of liver Portal vein: ​ Receive venous drainage from spleen, stomach, pancreas, entire GIT ​ Transport to liver for processing