Chapter 10 - Muscle Tissue Flashcards
what are the 3 layers of connective tissue in skeletal muscle?
(outer to inner)
- epimysium (“upon the muscle”)
- perimysium (“around the muscle”)
- endomysium (“within the muscle”)
*these connective tissues come together at the ends of muscle to create tendons or aponeurosis
what are the layers of muscle structure?
(outer to inner)
- muscle (the rope)
- fascicle (the braids)
- muscle fiber: muscle cells. (the strings)
- have mitochondria
- multiple nuclei
- sarcolemma (cellular membrane)
- myofibril (the threads)
- sarcomeres
label the part of the muscle fiber
sarcomere
what are the thick and thin myofilaments of a muscle fiber called?
- actin (thin)
- myosin (thick) (myosin medusa heads)
*throughout the muscle fiber, think 3d.
what are the ends of the sarcomere?
z lines (zig zag lines).
*z lines come closer together during contraction
what are the membrane and fluid of muscle cells called?
- sarcolemma (membrane)
- sarcoplasm (fluid)
name the part of the muscle cell.
sarcoplasmic reticulum
- like the endoplasmic reticulum in other cells: the SER and the RER.
- for storage of energy
- walls are loaded with calcium pumps
what is the neurotransmitter that motor neurons release?
acetylcholine
name the parts of the model
- motor neuron, or muscle fiber, or muscle cell.
- axon
- neuromuscular junction = synapse + cleft
- synaptic cleft (the space where neurotransmitters are released and absorbed)
- sarcoplasm (the cytoplasm of the muscle cell)
- myofibrils (the threads of the muscle fibers, made of actin and myosin)
- sarcomere (the segment of z-line to z-line in each myofibril)
- nucleus
- sarcolemma (the cell membrane of the muscle cell)
- endomysium (the fibrous connective tissue around each fiber)
explain action potential at the neuromuscular junction.
- a motor neuron creates an action potential (electrical current) through to the neuromuscular junction.
- acetylcholine is released into the synaptic cleft from the action potential impulse.
- ACh binds to the membrane receptors on the sarcolemma and opens the sodium channels
- Sodium rushes though and creates an action potential in the sarcolemma
*acetylcholine is broken down by acetylcholine rase (AChE - enzyme), or diffuses.
what are the common properties of muscle tissue? (hint, there are 4)
- Excitability - responsiveness
- Contractility - ability to shorten
- Extensibility - ability to lengthen
- Elasticity - ability to recoil
what are the functions of muscle tissue?
- producing movement
- maintaining posture and body position
- supporting soft tissue
- guarding body entrances and exits
- maintaining body temperature
- storing nutrients
explain how a muscle fiber is created. what is the cell on the outside of the fiber called?
muscle fibers are made by the fusion of embryonic cells called myoblast cells.
*myosatelite cell is on the outside of the fiber
what are transverse tubules? (t-tubules). what do they do?
tubes that extend from the surface of muscle fiber into the sarcoplasm. they transmit action potentials from sarcolemma into the cell interior. action potentials trigger contraction
what is the storage net surrounding each myofibril?
the sarcoplasmic reticulum
what is the triad?
two terminal cisternae + t-tubule
what is the functional unit of a muscle fiber?
myofibril
what is the functional unit of a myofibril?
sarcomere
what is titin?
elastic, spring like protein that connects end of myosin to the z line. helps stabilize the myosin filament and length
where is the M line in a sarcomere?
the middle line
what is nebulin?
stabilizes actin structure (to M line?)
what are the parts of actin?
- troponin - a globular protein, made of multiple parts
-tropomyosin - the bodyguard between troponin and myosin. does not allow troponin and myosin to freely interact.
what is a motor unit?
a group of muscle fibers that all get their signals from the same, single motor neuron. = they act together as a unit
what are action potentials?
electrical impulses
what is the section where the neuron and the muscle meet? what is the synapse space between these sites? what is the neurotransmitter released in this space? what does this neurotransmitter bind to?
- the neuromuscular junction
- the synaptic cleft
- acetylcholine (ACh)
what is resting membrane potential? what are the ions involved?
the extracellular fluid contains a high concentration of Na+ (sodium)
explain the action potential from the sarcolemma to the sliding filaments.
- Action potential from the sarcolemma travels down to t-tubules, which release Ca+ (calcium) from the cisternae of the sarcoplasmic reticulum.
- Ca+ binds with troponin sites, which remove the myotroponin barrier.
- the myosin head uses ATP and ADP to power stroke with the actin and shorten the sarcomere
what is rigor mortis?
a stiffening of the muscles after death, which results when ATP runs out (produced by mitochondria), and calcium ions build up in the cytosol
where is calcium stored in the muscle fiber?
in the sarcoplasmic reticulum
isotonic vs isometric
- isotonic - change in length
- concentric - shortening
- eccentric - lengthening - isometric - no change in length
fast fiber vs slow fibers
- fast fibers - few mitochondria, run out of ATP quickly
- slow fibers - many mitochondria and ATP, contain myoglobin - binds to oxygen
- intermediate - mix of both
