IMSK Final MK Review Flashcards
ID parts of the ear
External: pinna, vertical canal, horizontal canal, tympanic membrane
Middle: tympanic bulla (bony septum, 2 compartments in cats), ossicles, vestibular window
Inner: vestibular organ (balance), cochlea (hearing organ)
describe the phases of the hair growth cycle
Anagen: growth phase; cells mitotically active, melanin production increases
Thyroid and growth hormones increase the activity of this phase; glucocorticoids and estrogen decrease the activity of this phase
Catagen: regressive/resting phase; mitotic activity decreases and then ceases
Caspase activity and keratinocyte apoptosis increases and melanin production decreases
Telogen: resting phase; follicle eventually cycles back to mitotically active
Small dermal papilla and no mitotic activity
Exogen: shedding before returning to anagen
list the layers of the skin and what they contain
Epidermis: primary envelope containing water, electrolytes, and macromolecules like protein, carbohydrates, and fat; also melanocytes, intraepidermal macrophages, merkel cells
Dermis: fibers (mainly collagen) + polymers (proteoglycans and hyaluranan)
Fibers resist pull/tensile forces and polymers resist push/compression forces
Subcutis/hypodermis: protective padding of skin, mainly adipose tissue
Same thing as midterm just adjusted, same label pic- Layers of skin: epidermis, dermis, subcutis
describe the cell membrane
phospholipid bilayer, hydrophobic molecules can diffuse right through but charged molecules like ions require channels
describe membrane potential and what contributes to it/how ions move
cell resting potential is more negative, so potassium (K+) is kept inside by attraction to the negative;
there is usually more K+ inside the cell than outside and it wants to move out of the cell via its channels;
There is usually more sodium (Na+) outside of the cell than inside and it wants to move inside the cell via its channels
There is usually more chloride outside the cell than inside (Cl-)
There is not much calcium inside or outside of the cell at rest. Since it is Ca2+, it really really wants to move inside the cell. It is a very large molecule though so it can sometimes block sodium channels (how some anesthetics work)
describe voltage and ligand gated ion channels
Voltage gated channels open and close in response to changes in membrane potential
Ligand gated channels open when a chemical ligand binds to the protein
describe depolarization
Leaky sodium channels slowly bring membrane potential to threshold
Once threshold reached, voltage-gated sodium channels fly open, rapid (+) influx, membrane depolarizes and action potential is propagated
K+ channels open and rapid efflux of (+) leaving cell hyperpolarizes
describe absolute refractory period
Absolute refractory period is when the membrane cannot produce another action potential because sodium channels are inactivated or blocked; is important because when an AP is propagated, it sets up a local current that could travel both forward and backward bc physics, so the absolute refractory period ensures that the AP only moves forward
describe hypokalemia
If have low extracellular potassium, the excess potassium would rush out of the cell, causing the cell to hyperpolarize and decreasing excitability; can be caused by diuretics, vomiting, diarrhea, and diabetes
describe major differences in skeletal/cardiac/smooth muscle in the context of myasthenia gravis
myasthenia gravis only affects the skeletal muscle and in very rare cases will affect the cardiac muscle
Myasthenia gravis destroys the communication network between muscles and nerves in skeletal muscle
Acetylcholinesterase typically breaks down acetylcholine in the synapse, allowing responses only when there is an action potential
If a drug blocks acetylcholinesterase, acetylcholine will stay in the cell and the muscle will continue to contract, which can be useful for myasthenia gravis patients (acetylcholinesterase inhibitors)
describe the effects of monoamine oxidase
Monoamine oxidase
Degrades epinephrine, norepinephrine, and dopamine
When inhibited via MAOIs, there is an increased amount of neurotransmitters left in the synapse
Since there is an increase in norepinephrine, looks like there’s sympathetic activation
Because there is more norepi available to bind to adrenergic receptors and cause a response. Same mechanism as acetylcholinesterase inhibitor effect on acetylcholine.
describe generation of skeletal muscle tension
Contracting from resting length will generate the most muscle tension
If contract from an extended position, not as much interaction between thin and thick filaments
If contract from already somewhat contracted position, thin and thick filaments have too much interaction and can’t shorten farther than their capacity
what is stringhalt and how is it fixed?
Stringhalt- high stepping gait and abnormal and exaggerated flexion of the hock due to neuropathy of the lateral digital extensor
Remove the entire belly of the lateral digital extensor and allow long digital extensor to take over to fix
describe fibrotic myopathy in equines
Damage to the semi-muscle complex (biceps femoris) leads to
Scar tissue formation that limits extension;
decreased range of motion, will see foot swing forward and then snap back on/to ground
what structures connect the femur to the tibia?
Medial and lateral collateral ligaments
Medial, intermediate, and lateral patellar ligaments
describe the trochlear groove of the femur
This groove is significant because the patella can get stuck on top of the medial trochlear ridge during movement, can cut the medial patellar ligament to unlock patella and return motion
describe the reciprocal aparatus
Peroneus tertius originates from femur and extends across the tibia to metatarsal region
Works with the SDF to ensure that hock and stifle are either synchronously flexed or extended
give the major flexors of the stifle joint
Biceps femoris- inserts on tuber calcanei
Semimembranosus- inserts on medial tibial condyle
Semitendinosus- inserts on tuber calcanei
gastrocnemius and SDF help too (tibial nerve)
All innervated by sciatic nerve
give the major flexors of the hip joint
Iliopsoas- inserts on lesser trochanter
Rectus femoris- inserts on tibial tuberosity through the patellar ligament
Both innervated by femoral nerve
describe the attachments of the cruciate ligaments
Cranial cruciate- attaches at the cranial aspect of tibial intercondyloid space
Caudal cruciate- attaches at the caudal aspect of tibial intercondyloid space
