Anatomy
The skeletal muscles which have muscle fibers (myocytes) angled in multiple directions are referred to as _____.
Multipennate
In a skeletal muscle, after leaving the binding site on actin, the myosin head immediately binds to ________.
ATP (adenosine triphosphate)
Binding of ATP to the head of the myosin heavy chain reduces the affinity of myosin for actin, causing the myosin head to release form the actin filament.
What lesion is responsible for the leakage of CK into blood after muscle injury?
Fragmentation of sarcoplasm
What mechanical class does ivermectin belong to?
Macrocyclic lactone
What stain is commonly used in histopathology to detect abnormal findings in polysaccharide storage disease?
PAS (Periodic acid Schiff reagent)
stains glycogen and other complex polysaccharides.
Amylase digests away normal glycogen deposits by breaking down 1-4 glucosidic bonds, inclusions that stain positively with PAS after amylase digested are regarded as abnormal.
What is the correct name for the connective tissue which surrounds skeletal muscle from the outside?
Epimysium
What provides information on muscle length and rate of stretch?
Muscle spindles
What is the definition of muscle hypertrophy?
Increased size of myocytes
True or False:
Agonists or ligands activate receptors by altering their confirmation which produces a physiologic or biochemical effect
True
An agonist is defined as a drug that combines with a receptor and initiates a sequence of events that lead to a response
Why may cardiomyocytes have residual bodies?
Because of the long life of the cardiomyocyte and their inability to divide (regenerate)
H-band
In a skeletal muscle at rest, what is the myosin head complexed with?
ADP (adenosine diphosphate) and Pi
In case of skeletal muscle damage, which specific cell will play a role in replacing damaged myocytes?
the satellite cells have the capability to divide and produce new myocytes.
What genotype would rise to a desirable autosomal recessive trait, (let A=undesirable dominant allele, and a = desirable recessive allele)
aa
homozygous recessive
In which type of muscle tissue are intercalated discs present?
Cardiac muscle
Contractile cells are connected cell to cell by intercalated discs
which muscle or group of muscles is LEAST likely to be affected by nutritional myopathy?
A. Diaphragm
B. Extraocular muscles
C. Intercostal musculature
D. Tongue
B. Extraocular muscles
What subunits of troponin bind to actin filament and calcium ions, respectively?
Troponin I and Troponin C
What is true about cachectic atrophy of muscle?
A. Back and thigh muscles are the last to atrophy.
B. Essential muscles are preserved and less essential muscles atrophy.
C. Type I fibers are depleted preferentially.
D. Type II fibers are more resistant to atrophy.
B. Essential muscles are preserved and less essential muscles atrophy.
Most immunoglobulins are found in what fraction of globulins in serum protein electrophoresis profiles?
Gamma globulins
What is the definition of a motor unit?
A single axon and a number of myocytes which it innervates
What is the function of the gracilis muscle?
Bonus: what is the innervation?
Adducts and flexes the thigh, assists in medial rotation of the thigh
Innervation: Obturator nerve
What is the ultimate intracellular signal that triggers and maintains contraction of all muscle cells?
Rise in intracellular calcium
In a horse, a diagnosis of myopathy would be supported by an increased serum concentration of _____ and _____.
Creatine kinase and AST
The major adverse effects of macrocyclic lactones in mammals occur in what organ?
The brain
a GABA-mediated action in the mammalian central nervous system may be responsible for the neurotoxicity observed when large toxic doses of different macrocyclic lactones are administered.
You are an equine veterinarian who is interested in looking at mortality statistics in a specific population of horses; 350 horses that reside at a local stable owned by one of your clients. There was a recent outbreak of equine influenza and you want to calculate the case fatality rate. What information would you need to complete this calculation?
The number of horses that died from equine influenza and the total number of horses what were diagnosed with equine influenza
What is the origin and insertion of the biceps brachii?
Origin: supraglenoid tubercle
Insertion: radial tuberosity
What hormone is important for glucose uptake in skeletal muscle?
Insulin
What is the diagnostic term for muscle spasm?
Myotonia
Which is true regarding the lifecycle of Parascaris equorum?
A. Larvae develop to the following stages in the intestinal lumen
B. Larvae develop in the stomach then migrate to the small intestine
C. Larvae migrate to the liver and throughout the abdominal cavity before migrating back to the small intestine
D. Larvae migrate from the liver to the lungs before returning to the small intestine
E. Larvae develop in the colon and then migrates back to the small intestine
D. Larvae migrate from the liver to the lungs before returning to the small intestine
What bacteria produces a toxin that can cause muscle tremors and rigidity in horses that might initially present similar to rhabdomyolysis myopathies?
Clostridium tetani
Where do the triceps brachii muscles insert?
What is the most energetically-expensive metabolic process that occurs within a skeletal muscle during the relaxation phase of an isotonic contraction?
Calcium transport into the sarcoplasmic reticulum
What is the name of the non-genetic condition of horses characterized by muscle stiffness, swelling and pain, after intense physical activity?
Exertional rhabdomyolysis
What is the etiologic diagnosis for vitamin E/selenium deficiency in small ruminants?
Nutritional myopathy
Where are the larvae of the small strongyles (Cyathostomes) located in the GI of the horse?
The walls of the cecum and colon