Term
| What is a skeletal muscle cell called? |
|
Definition
|
|
Term
| What is the plasma membrane of skeletal muscle called? |
|
Definition
| -sarcolemma or plasmalemma |
|
|
Term
| Where in myofibers is the nuscleus located? |
|
Definition
|
|
Term
| Why are satellite cells unique? Where are they located? |
|
Definition
-only cell that retains the ability to divide
-b/n the basal lamina and plasma membrane |
|
|
Term
| Regeneration of skeletal muscle is dependent on what? |
|
Definition
| -preservation of basal lamina or sarcolemmal tube |
|
|
Term
| Definition: Focal monophasic |
|
Definition
|
|
Term
Definition: Multifocal monophasic
-ex? |
|
Definition
-single insult, multiple sites
-ex: thrombus |
|
|
Term
Definition: Focal polyphasic
-ex? |
|
Definition
-repeated injury, one site
-ex: fibrotic myopathy |
|
|
Term
Definition: Multifocal polyphasic
-ex? |
|
Definition
-continued insults, many sites
-ex: nutritional myopathy |
|
|
Term
| What are some examples of common histologic artifacts seen with skeletal muscle? |
|
Definition
-formalin causes contraction bands
-glycogen release causes loss of cross striations |
|
|
Term
| Describe Type I myofibers in regard to contration rate, fatigue rate, and type of metabolism. |
|
Definition
-slow contraction
-slow fatigue
-oxidative metabolism |
|
|
Term
| Describe oxidative metabolism. |
|
Definition
-low myosin/APase
-high mitochondrial enzymes: SDH, NADH-TR |
|
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Term
| Describe Type IIA fibers in regards to contraction rate, fatigue rate, and metabolism type. |
|
Definition
-fast contraction
-slow fatigue
-mixed metabolism |
|
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Term
| Describe type IIB myofibers in regards to contraction rate, fatigue rate, and metabolism type. |
|
Definition
-fast contraction
-fast fatigue
-glycolytic metabolism |
|
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Term
| Describe glycolytic metabolism. |
|
Definition
-high myosin/ATPase
-few mitochondria |
|
|
Term
| Between Type IIA and IIB myofibers, which is favorable? |
|
Definition
|
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Term
| HOw are Type I myofibers innervated? Type II? |
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Definition
-Type I = ventral horn
-Type II = motor neuron from the brainstem |
|
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Term
| Are Type II or Type I myofibers in abundance at the periphery of a bundle? Which at the center? |
|
Definition
|
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Term
| Describe the general function of type I myofibers. Example? |
|
Definition
-repetitive, persistent, slow contraction
-ex: diaphragm, postural support, mastication |
|
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Term
| Describe the general function of type II myofibers. Examples? |
|
Definition
-rapid, bursts of contraction
-semimembranosus, semitendinosus, biceps femoris |
|
|
Term
| What are some different pattern types of skeletal muscle? |
|
Definition
| -streaks, focal, diffuse, multifocal, pathcy |
|
|
Term
| What are some examples of skeletal muscle character? |
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Definition
| -chalky, fatty, fibrous, gritty, liquefactive |
|
|
Term
| What are some examples of pigment in skeletal muscle and their corresponding colors? |
|
Definition
-LIpofusion: brown color due to wear and tear of age
-Melanin: shiny black in black face sheep
-Myoglobin |
|
|
Term
| What are some color variations seen in skeletal muscle? |
|
Definition
-Tetracyclines = yellow
-Penicillin G = chalky white
-Iron Dextran = Dark brown |
|
|
Term
Definition: Rigor mortis
-describe the onset time and order |
|
Definition
-fixed contraction of muscle following death
-2-6h max = 24-48h
-jaw => trunk => extremities |
|
|
Term
| What three factors can alter rigor mortis? How do they do so? |
|
Definition
-Glycogen reserve: dec glycogen = rapid rigor
-pH: dec pH = rapid rigor
-Temp of either environent or animal: inc temp = rapid rigor |
|
|
Term
| What happens after rigor mortis? |
|
Definition
| -release in the same order then autolysis |
|
|
Term
| What are the three major categories of skeletal muscle reaction to injury? |
|
Definition
| -atrophy, hypertrophy, degeneration |
|
|
Term
|
Definition
| -reduction in muscle size due to dec m fiber size (reduced cellular components) |
|
|
Term
| How does muscle atrophy appear histologically? |
|
Definition
| -fibers have angular margins and are dec in size |
|
|
Term
| What are the 4 types of atrophy? |
|
Definition
| -denervation atrophy, disuse atrophy, malnutrition, endocrine disease |
|
|
Term
| What is denervation atrophy? Which type of fibers are more severely affected? Examples? |
|
Definition
-loss of nerve supply
-RAPID atropy with type I fibers more severely affected
-Ex: Roarer, Sweeny, Avulsion of Brachial plexus |
|
|
Term
| What is disuse atrophy? Which type of fibers are more severely affected? Examples? |
|
Definition
-reduced stimulation or movement
-type II fibers more severely affected
-ex: Fracture, casting, Tenotomy, cage/Bed rest |
|
|
Term
| What is Malnutrition atrophy? Other names? HOw does it affect each fiber type? |
|
Definition
-negative energy state
-aka cachexia or senility
-slow process with Type II fibers depleted and type I fibers resistant or hypertrophied with type switching |
|
|
Term
| Which type of fibers is more severely affected by endocrine disease? Examples? |
|
Definition
-selective type II atrophy NOT as severe in most cases with no type I compensatory hypertrophy
-ex: canine hypothyroidism and hypoadrenocorticism |
|
|
Term
Definition: HYpertrophy
-what two mechanisms can cause it? |
|
Definition
-inc in diameter of muscle or myofiber
-caused in response to work or as a compensatory mech in response to degeneration |
|
|
Term
| Give an example of hypertrophy. |
|
Definition
| -X-linked muscular dystrophy in cats |
|
|
Term
|
Definition
-potentially reversible and segmental
-begins with vacuolar accumulation in cytoplasm of myofiber and is associated with cytoarchitectural changes on immunochem or EM |
|
|
Term
|
Definition
| -reduction of myofibrils to coagulum with Ca |
|
|
Term
| Definition: Zenker's degeneration |
|
Definition
| -severe, glassy-granular (Typhus) |
|
|
Term
| Definition: Discoid degeneration |
|
Definition
| -hypoxia, mild, cross-striatins intact, EM |
|
|
Term
| Definition: Vacuolar degeneration |
|
Definition
| -flocular/vacuolar change, storage diseases |
|
|
Term
| Definition: Fatty degeneration |
|
Definition
| -emaciated or anorectic animals |
|
|
Term
| Definition: Calcification |
|
Definition
-the initial mechanism for all types of degeneration
-Ca drives the process of degeneration in the reduction/absence of ATP and occurs within several hours |
|
|
Term
| How does calcification appear histologically? |
|
Definition
|
|
Term
| Is total necrosis common or rare? Examples? |
|
Definition
-rare
-ex: infarcts, massive trauma, large burns |
|
|
Term
|
Definition
| -segmental degeneration that causes damage to plasma membrane associated with cell leakage and elevation of serum enzymes (CK and AST) |
|
|
Term
| Skeletal muscle has a remarkable ability to regenerate IF what three things prove true? |
|
Definition
-nature of injury and magnitude not severe
-basal lamina remains intact
-satellite cells remain present and viable |
|
|
Term
| Skeletal muscle begins following degeneration or necrosis with the first microscopic changes at about ___ hours. |
|
Definition
|
|
Term
| Complete skeletal regeneration occurs in about __-__ days. |
|
Definition
|
|
Term
| What are the types of effects that degeneration has on skeletal muscle. |
|
Definition
-Type I: MYofibrils alone or myofibril + sarcoplasm (basal lamina, nuclei, satellite cells intact)
-II: satellite cells + basal lamina intact
-III: satellite cells destroyed
-IV: also destroys endomysial CT and blood vessels |
|
|
Term
| What happens in regards to skeletal muscle if regeneration is not possible? |
|
Definition
| -repair is by fibrosis with loss of function |
|
|
Term
| What are the two types of skeletal muscle regeneration? |
|
Definition
|
|
Term
| Describe optimum skeletal muscle regeneration. |
|
Definition
-basal lamina intact
-sarcoplasm contracts
-macrophage migration
-satellite cells: proliferate, migrate, fuse |
|
|
Term
| Describe budding skeletal regeneration. |
|
Definition
-basal lamina NOT intact
-sarcoplasm and satellite cell giant cells bulge out end of tube
-not effecient = can only bridge 2-4mm
-many times completed by fibrosis |
|
|
Term
|
Definition
-congenital articular rigidity due to denervation with muscle atrophy or agenesis and subsuquent fibrosis
-seen in lambs, calves, piglets, foals |
|
|
Term
| What are some of the causal associations seen with arthrogryposis? |
|
Definition
-Heritable genetic: Curley Calf Syndrome
-Toxic plants: Lupine & locoweed with cattle, sheep, and goats AND hybrid Sudan & Locoweed with horses
-Dietary deficiency: manganese with cattle, vit A with pigs
-viral infection: Akabane Bluetongue, Border dz, Cache Valley Feber
-linked to dysraphism |
|
|
Term
| Which domestic species are most commonly affected by congenital diaphragm clefts? Most common clefts? Issue? |
|
Definition
-dogs and rabbits
-left dorsolateral tendinous portion
-predisposes to diaphragmatic hernia |
|
|
Term
| What is Myofibrillar hypoplasia? |
|
Definition
-abduction of limbs
-aka splayleg in pigs and swimmer puppies
-also causes flattening of sternum and myofiber degeneration but transient and reversible |
|
|
Term
| Definition: Muscular Steatosis |
|
Definition
| -excess fat deposited in or replacing muscle fibers seen in old dogs/cattle/pig |
|
|
Term
| Describe muscular dystrophy. |
|
Definition
| -hereditary, progressive, degenerative disease of skeletal muscle |
|
|
Term
| Genes coding for which proteins are mutated in the case of muscular dystrophy? |
|
Definition
-Dystrophin: in most dogs, initial hypertrophy in cats/mice/rat terriers
-Laminin alpha 2 |
|
|
Term
| How is most muscular dystrophy passed? Exception being? |
|
Definition
-X-linked
-except in Laminin alpha 2 muscular dystrophy in cats |
|
|
Term
| Which dog breeds are more commonly affected by canine muscular dystrophy? Males or females are mroe affected? |
|
Definition
-Goldens, Irish terriers, Pembroke Welsh corgis
-Males > females |
|
|
Term
| How does canine muscular dystrophjy present? |
|
Definition
| -progressive limb weakness, muscle atrophy, stiff short-strided gait, exercise intolerance as young as 2 months |
|
|
Term
| Which domestic species are affected by myasthenia gravis? |
|
Definition
|
|
Term
| What is Myasthenia gravis? |
|
Definition
| -disorder of ACh receptors and NMJs |
|
|
Term
| Describe the acquired form of Myasthenia gravis. |
|
Definition
-autoimmune disease, anticholinesterase Ab
-association with thymoma or thymic hyperplasia |
|
|
Term
| Describe the congeital form of myasthenia gravis |
|
Definition
-endplate receptor defect
-Jack Russel Terriers, Smooth Fox Terriers, Springer Spaniels: pregressive weakness and recessive |
|
|
Term
| What are the clinical signs of myasthenia gravis? |
|
Definition
| -vomiting, coice change, exercise weakness, acute collapse, fatigue, dysphagia, at around 5-8w |
|
|
Term
| How do we diagnose myasthenia gravis? |
|
Definition
-edrophonium test
-serology: Ab to Anticholinesterase |
|
|
Term
| What are the common names for Congenital Muscular HYperplasia? Animals commonly affected? |
|
Definition
-double muscling and Culard
-Belgium Blue, Charolais, South Devron cattle |
|
|
Term
| What is congenital muscular hyperplasia? |
|
Definition
-inc muscle fiber numbers, inc type IIB fiber size, dec fat stores, thin skin of the thighs/rump/loin/shoulder
-causes the dystocia |
|
|
Term
| In which species are storage diseases described most commongly? |
|
Definition
| -horse, cattle, sheep, cats, and dogs |
|
|
Term
| What are the genetic bases for the 4 common types fo stworage diseases? |
|
Definition
-PSSM-1
-RER
-Glycogen branching enzyme disease
-Mucopolysacharidosis |
|
|
Term
| In regards to polysaccharide storage myopathy, where is there genetic mutation? What is the sigificance of this gene? |
|
Definition
-GYS-1
-causes a mutation in glycogen storage that was favorable in ancient times in that it produces horses that can ride all day and get by on very little forage |
|
|
Term
| Is polysaccharide storage myopathy autosomal or heterozygous dominant? Meaning what? |
|
Definition
| -autosomal dominant trai but irrelevant for clinical purposes b/c there are no carriers |
|
|
Term
| What are the clinical signs associated with PSSM-1? |
|
Definition
-reluctance to move
-stiff muscle
-very short choppy gait
-hunched appearance to loins |
|
|
Term
| How do we approach emergency care of PSSM-1 cases? |
|
Definition
-stop exercise, blanket or hose, call vet
-provide fluids, small amounts (+/- electrolytes)
-NSAID for pain relief
-remove grain from diet
=begin monitoring serum muscle enzyme levels |
|
|
Term
| IN what specifically is there a mutation in cases of hyperkalemic periodic paralysis (HYPP)? |
|
Definition
| -genetic mutation in sodium channel (SCN4A) |
|
|
Term
| How is Hyperkalemic Periodic Paralysis genetically passed? |
|
Definition
| -inherited as an autosomal dominant trait, thus everyone with the gene is clinically affected |
|
|
Term
| What are the clinical signs associated with HYPP? |
|
Definition
-muscle tremors
-muscle weakness
-sweating
-paralysis |
|
|
Term
| What are some of the causes of HYPP? |
|
Definition
| -stress, external stimulus (dietary change, fasting, anesthesia, illness, exercise, etc) |
|
|
Term
|
Definition
| -passive congestion/ localized blood stasis |
|
|
Term
|
Definition
| -deficiency of blood to an area or part |
|
|
Term
| What clinically occurs in the case of ischemia lasting 6-24 hours? What about cases of ischemia lasting more than 18-24 horus? |
|
Definition
-6-24 hours: death of myofiber and satelite cells = reduced regen and fibrosis
->18-24 hours = nearly total necrosis with phagocytosis and fibrosis repair |
|
|
Term
| In the case of a bloat line, on which side is the head of the animal? |
|
Definition
| -head is on the dark side |
|
|
Term
| What is the most common type of muscle ischemia? Describe it. Examples? |
|
Definition
-external pressure
-external physical pressure exceeds perfusion pressure of local capilaries in animals that are in good conidtion
-ex: Downer cows, Fibrotic myopathy in horses, Periparturient Abdominal obliques, all casts and bandage pressures |
|
|
Term
Definition: Vascular occlusive syndrome leading to muscle ischemia
-examples? |
|
Definition
-blockage of vessel with infarction
-size of infart determind by size of the occluded vessel and duration of blockage
-Ex: aortic-iliac thrombus in horses, saddle thrombus in cats, HW thrombus in dogs |
|
|
Term
| What does vascular occlusive syndrome look like grossly? |
|
Definition
| -zone of hyperemia around a pale center |
|
|
Term
| Briefly describe muscle ischemia due to swelling iwthin a non-expandible compartment. |
|
Definition
-vigorous exercise of muscle encased in a rigid fascia sheath
-more commonly seen in primates and avians |
|
|
Term
| What is the most common form of nutritional myopathy? What causes it? |
|
Definition
-White muscle disease
-related to Vit E and Selenium deficiency (plasma mem alts leaving basal lamina and satellite cels intact with rapid regen possible) |
|
|
Term
| What are the clinical signs of White Muscle Disease? What about the gross and microscopic lesions resulting? |
|
Definition
-recum, stiff gait, dyspnea, death
-diffuse or streaks of pale chalky mm of thigh, shoulder, etc with microscopic Zenker's degen |
|
|
Term
| What are the three major examples of Toxic Myopathy? |
|
Definition
| -Cassia (coffee senna) Toxicity, IOnophore Toxicity, GOssypol toxicity |
|
|
Term
| Which animals are commonly affected by Cassia (coffee senna) toxicity? Clinical signs? |
|
Definition
-cattle, goats, pigs: plant toxic after kiling frost "Anthra quinone"
-myoglobinuria, elevated CK, pale m (heart NOT usually affected) |
|
|
Term
| Which animals are commonly affected by IOnophore toxicity? Common causes? Gross lesions? |
|
Definition
-horses are very sensitive (alters mem transport of Na/K)
-Monensin, lasalocid, salinomycin
-pale areas or streaks in heart and skeletal m |
|
|
Term
| Which animals are most commonly affected by Gossypol toxicity? Causes? Gross lesions? |
|
Definition
-cattle (worse in pre-rums) and pigs
-phenolic present in Cottonseeds
-dose-related cardiac and hepatic necrosis |
|
|
Term
| What are some examples of exertional myopathy? |
|
Definition
-Rhabdomyolysis: RER, PSSM, Shivers, GBED
-Porcine Stress Syndrome: MH, Ryanodine Rc
-Capture myopathy in exotics |
|
|
Term
Definition: Myositis
-two categories of causes? |
|
Definition
-inflammation of muscle where inflammatory cells are responsible for initiating and maintaining myofiber injr
-caused by infectious agents (bacteria, virus, parasites) and immune-mediated causes |
|
|
Term
| What are the three major examples of Clostridial causes of myositis? |
|
Definition
-GAs gangrene and Malignant edema
-Blackleg
-Botulism |
|
|
Term
| How does gas gangrene and malignant edema occur? Which animals are affected? |
|
Definition
-wound infection/ penetrating wounds with Cl septicum, perfringens, novyi, or sordelli causes pdn of exoton with necross and destruction of blood supply (thus mm damaged are typically secondary)
-all animals but horse and sheep |
|
|
Term
| How does blackleg occur? Which animals are affected? |
|
Definition
-necrotizing myositis due to ingestion of Cl chauvoei spores that are distributed in tissues and released following trauma in an area of low oxygen tension
-affected cattle and sheep 9mo-2y |
|
|
Term
|
Definition
| -either ingestion of pre-formed toxin or toxico-nfectious botulism |
|
|
Term
| How do we tell the difference grossly b/n malignant edema and blackleg lesions? |
|
Definition
| -malignant edema is wet and blackleg is not |
|
|
Term
| IN addition to the clostridial organisms, what are some other examples of organisms that cause bacterial myositis? |
|
Definition
-Corynebacterium pseudotuberculosis" sheep/goat = caseous lymphadenitis & equine = pidgeon fever/dryland distemper
-Truepurella/ARcanobacterium pyogenes
-Actinobacillus lignieresi (wooden tongue)
-Actinomyces bovis (lumpy jaw)
-Staph aureus |
|
|
Term
| What are some common examples of viral myositis? What are their associated virus types? |
|
Definition
-Porcine encephalomyelitis: entero virus that causes necrosis of myofibers
-Foot and mouth disease: aphtho virus that causes segmental heart necrosis
-Bluetongue: orbi virus that causes infarction of mm and heart
-Akabane disease: Akabane virus that causes non-suppurative myositis of bovine fetus |
|
|
Term
| What are some examples of parasitic myositis caused by nematodes? |
|
Definition
-Trichinella spiralis: adults in SI of swine => larvae penestrate intestine and encyst in m
-Ancylostoma caninum
-T. canis |
|
|
Term
| What are some examples of parasitic myositis caused by cestodes? |
|
Definition
-Tainea soium
-Taenia saginata |
|
|
Term
| What are some examples of parasitic myositis caused by protozoa? |
|
Definition
-Sarcocystis: horses, cattle, birds (int stages in muscle)
-H. americanum: canine = IH
-Neospora caninum: dogs, bovine = pale streaks in m |
|
|
Term
| How do dogs get H. americanum? Clinical signs? |
|
Definition
-ingestion of tick
-leukocytosis, fever, anorexia, periosteal proliferation |
|
|
Term
| What are the three primary examples of Immune-mediated myositis and their associated clinical signs? |
|
Definition
-MAsticatory/eosinophilic/atrophic myositis (long-nosed dogs): acute pain, unwilling to open mouth, eosinophilia, progressive loss of muscle
-Strep-assoc in equine: rapid atrophy in young quarter horses |
|
|
Term
| Antibodies to what specifically occurs in cases of masticatory myositis? |
|
Definition
|
|
Term
| Autoantibodies to what specifically occurs in cases of Strep-assoc myositis? |
|
Definition
|
|
Term
| Are primary muscle tumors common or rare? |
|
Definition
|
|
Term
| What are the two more common primary muscle tumors? |
|
Definition
-Rhabdomyoma (benign): cardiac in pig/cow/sheep and laryngeal in dog
-Rhabdomyosarcoma (malignant): widely metastatic in the dog |
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