Basic Science Flashcards
Name the three types of muscle, how they differ, and define the motor unit.
Cardiac, skeletal, smooth
Cardiac and skeletal are striated. Skeletal is multinucleated and voluntary. Cardiac has 1/2 nuclei, smooth has one; both involuntary
Each nerve has alpha-motor neurons, which divide into brutons to supply an area; the area supplied by one alpha-neuron is a motor unit
Describe the organisation of muscle cells.
Muscle fibre is one cell. Sarcoplasmic reticulum spans fibres. These split into myofibrils, then sarcomeres.
Sarcomere consists of HAZIM: H zone middle (between troponin), A band (length of actin), Z disc (end of sarcomere), I band (between actin), M(iddle) line
Describe contraction of muscle fibres, and name the types of fibres.
Action potentials summate to form a contraction at a threshold potential.
Slow - I - oxidative phosphorylation
Fast - IIa - creatine
Fast-glycolytic - IIx - anaerobic glycolysis
Describe the structure of the joint.
Three types - fibrous (synarthroses), cartilaginous (amphiarthroses) and synovial (diarthroses).
Articular cartilage encloses joint capsule, lined by synovial membrane. Hyaline (70% water, 20% collagen II, 10% proteoglycan). Synovial fluid consists of hyoluronic and uric acids.
Describe how the neuromuscular junction works.
Na/K pump brings in choline, which binds with acetyl-CoA to form ACh. Binds into vesicles and calcium influx causes its release. Then taken up by nAChRs (5 M2 subunits), which opens voltage gated Na/K antiport channels
Describe the pathogenesis of diseases of the neuromuscular junction.
Na/K pump (presynapse) = neuromyotonia
Release of ACh = Botulism toxin
Ca2+ influx = Lambert-Eaton
nAChRs = Myasthenia Gravis
How does pain form and transmit?
A (delta) transmit fast, C slow, TRANSDUCING to the spinal cord
TRANSMISSION within the dorsal horn by glutamate, substance P, or neurokinin. Travels via spinothalamic or spinoretinal tracts (localization / emotional) to the thalamus
Then synapses and travels via CN V or to cortex
Describe the classification of pain.
Nociceptive (can be early warning sign), pathologic, or inflammatory.
Nociceptive -> referred, pathologic -> neuropathic (burning, shooting), dysfunctional (e.g. fibromyalgia)
Describe the classification of MSK tumours and give examples of each.
Inflammatory, proliferative, benign and associated malignant
Inflammatory (4) -> ganglion cyst, gouty tophi, rheumatoid nodule, and tenosynovitis (giant cell tumour of tendon sheath, pigmented vilion, odular synovitis)
Proliferative (3) -> nodular fasciitis, myositis ossifcans, fibromatosis (Dupuytren’s, desmoid)
Benign/malignant -> lipoma, leiomyoma, rhabdomyoma, chondroma, osteoma, osteoid ostoma, osteochondroma etc.
