Cranial NERVE Flashcards

Question

Neuromuscular Juno ( NMJ)

Answer 1

*A type of synapse *Site where an axon of motor neuron and skeletal muscle fiber interact. *Skeletal muscle fibers only contract when stimulated by a motor neuron

Answer 2

Motor Neuron : Neuron that controls skeletal muscle fiber. Motor end plate: Specialized folded portion of skeletal muscle fiber ,where fiber binds to neurotransmitter Synaptic Cleft: Space between neuron and muscle fiber, across which neurotransmitter travels. Synaptic Vesicles : Membrane bound sacs containing neurotransmitter Neurotransmitters: Chemicals released by motor neuron to deliver message to muscle fiber.

Answer 3

Acetylcholine ( ACh) is the neurotransmitter. Nerve impulse ( action potentials) causes release of ACh from synaptic vesicles in the motor neuron. ACh binds to ACh receptors on motor end plate. ACh causes changes in membrane permeability to sodium and potassium ions, which generates a muscle impulse(action potential) * Impulse cause release of calcium ion from sarcoplasmic reticulum, which leads to muscle contractions

Answer 4

An autoimmune disorder Antibodies attack acetylcholine receptors on skeletal muscle fibers ( motor end plates) in neuromuscular junctions. Persons may have only one third normal number of ACh receptors Leads to widespread muscle weakness and muscle fatigue Treatments: Drugs that inhibit acetylcholinesterase (an enzyme that breaks down acetylcholine and removes it from acetylcholine receptors) Immunosuppressants drugs Administering antibiotics that inactivate harmful antibodies Plasma exchange

Answer 5

Deficiency or abnormality/mutation in scarce muscle protein called dystrophin Binds to internal side of muscle cell membranes, and holds them together during concentration In absence of normal dystrophin , cell lose normal structure and die

Answer 6

Anaerobic bacteria that produce a toxin that prevents the release of ACh from the pre-synaptic neuron at the neuromuscular junction. Grows in food that is not properly preserved If ACh is not released from the neuron at the NMJ, what symptoms will occur? Digestive, muscular, respiratory symptoms Treated with an antitoxin Used in small doses as Botox to smooth wrinkles, treat migraines

Answer 7

Connection between muscle fiber stimulation and muscle contraction.

Answer 8

Ca+2 ions are stored in SR Troponin tropomyosin complex’s cover binding sites on actin filaments

Answer 9

Action potentials cause SR to release Ca +2 ions into cytosol Ca+2 ion bonds to troponin to change its shape Each tropomyosin is held in place by a troponin molecule; change in shape of troponin alters the position of tropomyosin, exposing the binding sites on actin Myosin heads bind to actin, forming cross bridges

Answer 10

When sarcomeres shorten , thick and thin filaments slide past each other H zones and I bands narrow Z lines move closer together Thin and thick filaments do not change length Overlap between filaments increases

Answer 11

1) Myosin head attaches to actin binding site , forming cross bridge 2)Myosin cross bridge pulls thin filament toward center of sarcomere 3). ADP and phosphate are released from myosin 4)New ATP binds to Myosin 5). Linkage between actin and myosin cross bridge break 6) ATP splits 7). Myosin cross bridge goes back to original postion , ready to bind to another binding site actin

Answer 12

When neural stimulation of muscle fiber stops: Acetylcholinesterase enzyme rapidly decomposes ACH remaining in the synapse Muscle impulse stops when ACh is decomposed Stimulus to sarcolemma and muscle fiber membrane ceases Calcium pump ( requires ATP) moves Ca+2back into sarcoplasmic reticulum (SR) Troponin tropomyosin complex again covers binding sites on actin Myosin and actin binding are now prevented Muscle fiber relaxes

Answer 13

First source of energy for muscle contraction Muscle cells store only a small amount

Answer 14

Initial source of energy to regenerate ATP from ADP and P Stores energy in phosphate bond like ATP ATP + creatine phosphate can only fuel 10 seconds of intense muscle contraction

Answer 15

Must be used to fuel longer periods of muscle contraction Breaks down glucose to produce ATP Glucose stored as glycogen in muscle cells