Osteocytes - Transformed osteoblasts that are surrounded by new bone tissue
Osteoclasts - The major reabsorptive cells of the bone (breaks down bone)
New bone is soft and hardens when it gets mineralized by _______ and _________ -
calcium and phosphate
Joints are also called _________ - articulations
The functional units of muscle contractions are _________. They are made of _______
and ________ - Myofibrils; actin and myosin
What do red muscles have that white muscles lack? - Myoglobin-a reservoir of oxygen
for the muscles (why white muscles fatigue quickly)
excitation-contraction coupling - events that link the action potentials on the sarcolemma
(the membrane of the muscle) to activation of the myofilaments, thereby preparing them
to contract
AP from LMN depolarizes muscle membrane at the motor end plate. That depolarization
spreads all over the sarcolemma
Depolarization increases the amount of calcium in the cytoplasm/sarcoplasm which
stimulates contraction
Physiologic Tetanus - occurs when motor units are stimulated again and the muscle unit
has not been able to relax between stimulation and the next contraction
Response to an AP is called a ______ - twitch
____________ gives the phosphoric group to ATP - Phosphocreatine
Isometric contraction - Muscle contracts but there is no movement, muscle stays the
same length
Same length, changing tension
Isotonic contraction - muscle shortens because muscle tension exceeds load
,Same tension, changing length
Tendons - •Attach muscle to bone
•Transfer forces from muscle to bone
•Act as a type of biologic spring for muscles to allow additional stability during
movement
Ligaments - •Attach bone to bone
•Stabilize joints against excessive movement
Sarcopenia - the loss of muscle mass, strength, and function that comes with aging
Rhabdomyolysis - breakdown of striated/skeletal muscle (caused by trauma, extreme
exertion, crash injuries, seizures, or drug toxicity)
causes the release of intracellular contents, including the protein pigment myoglobin,
into the extracellular space and bloodstream
•Can result in hyperkalemia, cardiac arrhythmia, acute renal failure due to myoglobin
precipitation in the renal tubules
Rhabdomyolysis Triad of manifestations - •Muscle pain
•Weakness
•Dark urine
What is the main risk of rhabdomyolysis? - Acute Kidney Injury
-from accumulation of myoglobin in renal tubules
Potassium levels (increase/decrease) with rhabdomyolysis - Increase, because
potassium is released as cells breakdown
Treatment of rhabdomyolysis - Rapid intravenous hydration: To maintain adequate
kidney flow/urine output
Hyperkalemia: May require temporary hemodialysis
Compartment Syndrome can be caused by any condition that disrupts what? - the
vascular supply to an extremity
Muscle ischemia causes edema, rising compartment pressure, and tamponade that
lead to muscle infarction and neural injury
6 Ps of compartment syndrome - •Pain- uncontrolled by opioids
•Pressure/swelling
•Pallor
•Paresthesia
•Paresis- nerves now affected from the pressure
, •Pulselessness- artery is collapsed
Volkmann ischemic contracture - damage to the artery with contracture of muscles
Compartment Syndrome Diagnosis - confirmed by measurement of intracompartmental
pressure
Compartment Syndrome Treatment - •Relieve pressure with fasciotomy when pressure
reaches 30 mm Hg
•Skin graft
metabolic bone diseases - abnormal bone structure caused by altered or inadequate
biochemical reactions due to genetics, diet, or hormones (bone mineralization depends
on a narrow range of of calcium and phosphorus)
i.e. osteoporosis
Osteoporosis pathophysiology - decreased density and strength of bone because of
alterations in bone microarchitecture
old bone reabsorbed faster than new bone being made, causing progressive loss of
bone mass
most common sites of osteoporosis (3) - 1. spine
2. femoral neck
3. wrist
sites that bear a lot of weight
Osteoporosis causes (6) - 1. Endocrine dysfunction
•Parathyroid hormone, cortisol, thyroid hormone, and growth hormone
•Decline of estrogens during menopause
2.Medications
•Glucocorticoids, PPI (prevent absorption of Ca), some antidiabetics, SSRIs
5. Low physical activity- if you don't use bones/weightbear, they won't mineralize
normally
6. Abnormal BMI
Postmenopausal osteoporosis - Estrogen deficiency, increase in PTH, less physical
activity
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