Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
26 Cards in this Set
- Front
- Back
In skeletal muscle, what are the A, I, and H bands, and what are the Z discs? |
A band- anisotrophic dark band, thick and thin alternating filament region I band- isotropic light band, thin filament region H band- central area with only thick filament Z disc- anchors elastic and thin filaments, one z disc to next is a sarcomere |
|
Where do the cell bodies of somatic motor neurons reside?
|
Brainstem and spinal cord |
|
What is a motor unit?
|
Motor unit: each motor neuron and all the muscle fibers it innervates |
|
What is the purpose of having some muscles with very large motor units and others with many very small motor units?
|
Purpose: provides ability to sustain long-term contraction as motor units take turns resting (postual control) |
|
What structure of the body has very small/large motor units that control its movement?
|
Large motor unit: for strength and power, 1000 muscle fibers per nerve fiber. (ex. gastrocnemius Small motor unit: fine control, has 20 muscle fibers per nerve fiber (ex. eye muscle) |
|
What is the neurotransmitter of neuromuscular junctions (NMJ)?
|
Neuromuscular Junction: functional connection between nerve fiber and muscle fiber Neurotransmitter: released from nerve fibers to stimulate muscle cells and initiate contraction. |
|
What ion flows into the nerve terminal of the NMJ prior to the release of neurotransmitter to the synaptic cleft?
|
Ca2+ flows into the synaptic knob prior to the release of neurotransmitter |
|
What organelle is found in abundance in the nerve terminal near the neurotransmitter filled vesicles?
|
mitochondria are abundantly found in the nerve terminal near the neurotransmitter filled vesicles |
|
What is the difference between a ligand gated channel and a voltage gated channel of the postsynaptic membrane (what specifically triggers opening of the gate)? |
Ligand gated: Acetylcholine triggers the opening of the gate Voltage gated: EPP triggers the opening of this gate (check the last two) |
|
Where precisely are acetylcholine receptors of the NMJ located?
Are these muscarinic or nicotinic receptors? |
Definition 21 The acetylcholine receptors are located in the junctional folds of the muscle cell They are nicotine receptors |
|
What type of muscle impairment will be caused by pesticide poisoning that inhibits cholinesterase?
|
Neuromuscular impairment: Pesticides will bind to acetylcholinesterase and prevent degradation of acetylcholine, so it will cause spastic paralysis and possible suffocation |
|
By what mechanism does Tetanus toxin affect muscle?
|
Tetanus- caused by toxin Clostridium bacteria, blocks glycine (inhibitory neurotransmitter in spinal cord) release in spinal cord and causes overstimulation of the muscles and spastic paralysis |
|
How about curare?
|
Curare- causes flaccid paralysis and respiratory arrest because it completes with acetylcholine at nicotine Ach receptors |
|
How about botulinum toxin?
|
Botulism- food poisoning caused by bacterium clostridium botulinum, blocks release of Ach and causes flaccid muscle paralysis |
|
Describe the resting membrane potential (RMP).
What is the voltage of the RMP in muscle? |
RMP: an excess of Na+ and other cations outside the cell and excess negative ions inside the cell creating a difference in charge across the membrane Voltage of the RMP in muscle: -90mV |
|
Describe an action potential?
|
Quick up and down voltage shift.... depolarization and then repolarization |
|
What is depolarization and what is repolarization?
What ionic events are taking place during these components of an action potential? |
Depolarization- when the inside of the plasma membrane briefly becomes positive because of the rush of Na+ into the cell Repolarization- when the inside of the cell becomes negative again because after depolarization, the inside is too positive so Na+ gates close, K+ gates open to allow K+ to come out of the cell |
|
What is an end plate potential (EPP)?
|
End Plate Potential (EPP): the rapid fluctuation in membrane voltage at the motor end plate Na+ enters, shifting RMP goes from -90mV to +75mV, then K+ exits and RMP returns to -90mV - quick voltage shift is called an end-plate potential (EPP). |
|
What is excitation-contraction coupling?
|
Excitation-contraction coupling- when an action potential on the sarcolemma activates myofilaments for contraction |
|
What is the power stroke of muscle contraction?
|
Power stroke- myosin head releases ADP and Pi as it flexes pulling the thin filament past the thick |
|
What is the cause of rigor mortis?
|
Deteriorating sarcoplasmic reticulum releases calcium activates myosin and actin cross bridgesàmuscles stay contracted and cannot relax because you need ATP to relax them (after death you cannot produce ATP) |
|
Where is calsequestrin found and what is its function?
|
Found in the Sarcoplasmic Reticulum Function: binds calcium to hold it in the sarcoplasmic reticulum during muscle relaxation |
|
Discuss the disease process of Myasthenia Gravis
|
Progressive weakness that remits with rest and is worsened by exercise Autoimmune disease |
|
What binds to ACh receptors?
|
Antibodies bind to Ach receptors |
|
What are some of the signs of this disorder?
|
Signs- drooping eyelids, double vision, difficulty swallowing, respiratory failure, weak limbs |
|
What are the treatment options available? |
|