Shared Flashcard Set

Details

6a
6a
23
Anatomy
Undergraduate 1
07/27/2011

Additional Anatomy Flashcards

 


 

Cards

Term
myofibrils
Definition
densely packed rodlick elements
make up 80 percent of cell volume
exhibit striations: perfectly aligned repeating series of dark a bands and light i bands
Term
sarcomere
Definition
smallest contractile unit of a muscle fiber
the region of a myofibril between two successive z disks
composed of thick and thin myofilaments composed of contractile proteins
Term
features of a sarcomere: thick filaments
Definition
run the entire length of an A band
Term
functions of a sarcomere: thin filaments
Definition
run the length of the i band and partway into the a band
Term
features of a sarcomere: z disk
Definition
proteins that anchor thin filaments
Term
H zone
Definition
lighter midregion where filaments do not overlap
Term
M line
Definition
protein that hold adjacent thick filaments together
Term
ultrastructure of thick filaments
Definition
composed of the protein myosin
- myosin tails
- myosin heads
are atpase enzymes
Term
ultrastructure of thin filaments
Definition
twisted strand of the protein actin
bears active sites for myosin head attachment during contraction
Term
sarcoplasmic reticulum
Definition
stores ca2
network of SER surrounding each myofibril
Term
T tubules
Definition
continuous with the sarcolemma
penetrates cell's interior at each A band-I band junction
- t tubules conduct impulses deep into muscle fiber
Term
Events at the Neuromuscular Junction -Axons of motor neurons:
Definition
travel from the central nervous system via nerves to skeletal muscles
Term
Events at the Neuromuscular Junction - Each axon:
Definition
forms several branches as it enters a muscle
Term
Events at the Neuromuscular Junction - Each axon ending forms:
Definition
a neuromuscular junction with a single muscle fiber
Term
Events at the Neuromuscular Junction - Axon terminal and muscle fiber are:
Definition
separated by the synaptic cleft
Term
Events at the Neuromuscular Junction Synaptic vesicles of axon terminal contain:
Definition
the neurotransmitter acetylcholine
Term
Events at the Neuromuscular Junction - Junctional folds of the sarcolemma contain:
Definition
Ach receptors (motor end plate)
Term
Events at the Neuromuscular Junction - A nerve impulse:
Definition
arrives at axon terminal
Term
Events at the Neuromuscular Junction - Ach is:
Definition
released an it binds with the receptors on the sarcolemma
Term
Nerve stimulus and action potential:
Definition
study on own
Term
Role of calcium in contraction - low intracellular calcium concentration:
Definition
Active sites on actin are blocked
Myosin heads cannot attach to actin
muscle fiber relaxes
Term
Role of calcium in contraction - high intracellular calcium concentration
Definition
Calcium causes binding sites on actin to be exposed
Events of the cross bridge cycle occur
When nervous stimulation ceases calcium is pumped back into the sarcoplasmic reticulum and contraction ends
Term
Cross bridge cycle
Definition
Continues as long as the calcium signal and adequate atp are present
Cross bridge formation: myosin head attaches to thin filament
Working (POWER) stroke myosin head pivots and pulls thin filaments toward the M line
Cross bridge detachment - atp attaches to myosin head and the cross bridge detaches
"cocking of the myosin head": energy from hydrolysis of atp cocks the myosin head into the high energy state
Supporting users have an ad free experience!