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Muscle Tissue
For exam #2
50
Physiology
Undergraduate 2
02/17/2013

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Term
Accessory proteins link actin filaments to...
Definition
Endomysium
Term
Titin elastic filaments:
Definition
-Run through thick filament and attach to Z disk
-Resist overstretching
Term
Motor units:
Small for...
Definition
fine control (3-6 muscle fibers per nerve fiber) ex. Eye movement
Term
Muscular Dystrophy
Definition
-Muscle scars and weakens
-Women can get this but they are typically carriers
Term
Transfer contraction forces to...
Definition
connective tissue
Term
Most common form of: Muscular Dystrophy?
Definition
Duchenne MD
Term
Duchenne MD
Definition
Defect in gene that makes dystrophin
Term
Muscular Dystrophy: Sarcolemma and sacromeres move...
Definition
independently, tears membrane, degradation of contractile proteins.
(cant prepare muscle cell, it degrades)
Term
Motor units:
Large for...
Definition
Strength (1000 muscle fibers per fiber) ex. Gastrocnemius
Term
Synaptic knob
Definition
Contains synaptic vesicles with acetylcholine (ACh)
Term
Neuromuscular Junction
Definition
-Synaptic knob
-Synaptic cleft
-Synaptic vesicles
-Basal Lamina
Term
Neuromuscular Junction:
Schwann Cell
Definition
Envelops and isolates junction from surrounding tissue fluid
Term
Neuromuscular Junction:
Synaptic Vesicles...
Definition
undergo exocytosis releasing ACh into synaptic cleft
Term
Neuromuscular Junction:
ACh receptors in...
Definition
Sarcolemma
Term
Neuromuscular Junction:
Basal Lamina
Definition
Contains acetycholinestrase (AChE) that breaks down ACh
Term
Electrical Excitable Cells:
Recall
Definition
Applies to nerve and muscle cells
Term
Electrical Excitable Cells:
Unstimulated (resting) cell
Definition
-Plasma membrane is electrically charged
-Excess Na+ outside
-Excess K+ inside
Term
Resting membrane potential (RMP)
Definition
-Approx. -90mV
-Maintained by Na+/K+ pumps constantly operating (3 Na+ out, and 2 K+ in)
-Compensates for ion channel 'leakage,' gates opening
Term
Muscle contraction and relaxation:
Phases:
Definition
-Excitation
-Excitation-contraction coupling
-Contraction
-Relaxation
Term
Muscle contraction and relaxation:
Recall 2 types of channels (gates)
Definition
1. Ligand regulated
2. Voltage regulated
Term
Excitation (Steps 1 and 2)
Definition
Nerve signal opens voltage-gated calcium channels in synaptic knob
-ACh releases into synaptic cleft
Term
Excitation (steps 3 and 4)
Definition
-Two ACh molecules bind to each receptor protein, opening Na+ and K+ channels.
Term
Excitation (step 5)
Definition
Opening of voltage-regulated ion gates; creation of action potentials
Term
Excitation-contraction coupling (Steps 6 and 7)
Definition
-Action potential spreads down into T tubules
-Opens voltage-gated ion channels in T tubules and Ca +2 channels in SR
-Ca+2 enters the cytosol
Term
Excitation-contraction coupling (steps 8 and 9)
Definition
Calcium binds to troponin of thin filaments
Term
Contraction (Steps 10 and 11)
Definition
-Myonsin ATPase in myosin head hydrolyzes ATP
Term
Contraction (Steps 12 and 13)
Definition
-Myosin head releases ADP and Pi, pulls thin filament past thick (power stroke)
-Myosin binds more ATP, releases actin, process repeats
Term
Relaxation (steps 14 and 15)
Definition
-Nerve stimulation and ACh release stops
-AChE breaks down ACh
Term
Relaxation (step 16)
Definition
-Ca+2 pumped back into SR for storage
-ATP required for muscle relaxation also
Term
Rigor Mortis (definition)
Definition
Tightening of muscles when you die
Term
Rigor Mortis:
It is the hardening of muscles...hours post death.
Definition
3
Term
Rigor Mortis:
Muscle contraction but cannot...
Definition
relax
Term
Muscle relaxation requires ATP, however it is not produced after...
Definition
death
Term
Rigor mortis peaks at about...hours after death
Definition
12 hours
Term
Rigor mortis peaks about 12 hours after death, then diminishes over the next __ to ___ hours.
Definition
48-60 hours
Term
What decays during rigor mortis (after death)?
Definition
Myofilaments
Term
Curare
Definition
Blocks ACh receptors
Term
Botulinum Toxin
Definition
Inhibits ACh release
Term
Myasthenia gravis
Definition
Ig's to ACh receptros of motor end plates
Term
Smooth Muscle
Definition
Location, cell shape, striations, nuclei, connective tissues, T tubule, nervous stimuation
Term
Smooth muscle:
Multiunit
Definition
Typical synapse
Term
Smooth muscle:
single unit
Definition
Typically two or more muscle layers
Term
Smooth muscle:
Examples of single unit
Definition
ex. intestines, most blood vessels, visceral muscle layers (respiratory, digestive, reproductive, and urinary)
Term
Stimulation examples:
Involuntary
Definition
Responds to chemical stimulus such as hormones, high CO2, low pH, low O2, or stretch (GI tract)
Term
Stimulation examples:
Autonomic nervous system
Definition
ACh or norepinephrine (relax or contract)
Term
Stimulation examples:
Single unit
Definition
Neurotransmitter released at varicosities, multiple cells affected
Term
Contraction
Definition
Stimuli opens Ca+2 gates, Ca+2 enters cell
Term
Contraction:
Myosin binds to..
Definition
actin
Term
Contraction:
Fatigue resistance requires...ATP
Definition
Less
Term
Contraction:
Ca+2 binds to... (not troponin)
Definition
Calmodulin
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