Flashcards in Muscle Deck (49)
Functions of muscle tissue
maintenance of posture.
Protection and support.
Storage and movement of materials.
Characteristics of Muscle tissue
Excitability:cells can respond to stimulation (neurotransmitter-gated channels)
Conductivity: cells can conduct electrical charge.
Contractility: muscle fibers can shorten to generate tension.
Elasticity: ability to recoil (connection)
Extensibility: muscle can lengthen
Dense regular CT
Dense Irregular CT. Separates individual muscles, bind muscles with similar functions
Dense irregular CT surround entire individual muscle.
Dense irregular CT. Surround fascicle
Areolar CT. isolate and electrially insulate muscle fiber
sheet-like dense reg CT.
levels of gross muscle
cell=muscle fiber< fasicle< skeletal muscle
Development of muscle
myoblast fuse together to form fiber. Multinucleated and amitotic.
Resting membrane potential
Relative difference in charge across a plasma membrane. always negative.
determined by number of K+/Na+ pumps and leak channels
Na+ vs K+
More K in cell. More Na outside cell
Inside of cell becomes more positive due to opening of VGNaC allowing NA+ to rush in.
K+ exits cell to get back to RMP
wave of depolarization followed by repolarization
Muscle fibers (micro anatomy)
made of myofibrils, which are made of myofilaments
plasma membrane of muscle cell. Contains voltage gated channels that allow for excitability and conductivity. It spans length of muscle fiber
extensions of sarcoma that extend into myofibrils. It contains Na+ and K+ pumps and leak channels
flank t-tubules. enlarged regions of sarcoplasmic reticulum that contain Ca2+. Open in response to depolarization to release Ca2+
specialized ER that holds Ca2+.
contractile proteins. Thick and thin
made of proteins called myosin that contains actin binding and ATP binding site.
Made of actin and tropomyosin which wrap and block myosin binding site. When Ca2+ binds to troponin, it moves the tropomyosin so filaments can interact.
Unit of contraction
arrangement of proteins running perpendicular to longitudinal axis to muscle. The thin filament are attached towards M-line
Center line, thick filaments are anchored with myosin ears towards z-disc
Light. spans 2 sarcomeres. contains only actin
Dark. Both myosin and actin
single motor neuron and all the fibers it innervates
where motor neuron meets muscle fiber
1. synaptic knob: contains vesicles of neurotransmitters
2. synaptic cleft: space between knob and fiber
3. motor end plate: contains ACh gated Na+ channels
1. action potential travels down neuron to synaptic knob. AP stimulates opening of VGCaC
2. Ca enters synaptic knob and binds with vesicles allowing them to fuse with plasma membrane
3. ACh is released by exocytosis into synaptic cleft
4. ACh bind to ACh receptors on the motor end plate. Movement of Na ions create positive charge in cell and begin the End plate potential
1. EPP stimulates opening of VGNaC which open to depolarize sarcolemma. NA rushes in.
2. Depolarization moves down T-tubules and sarcolemma. Na rushes in
3. depolarazion is followed by depolarization as VGKC open and K flows out.
4. AP spreads to T-tubules, depolarizeation opens VGCaC in terminal cisternae and SR.
Cross bridge cycling
1. Ca from SR interact with thin filaments, Ca binds to troponin, shifting the tropomyosin off of actin which expose myosin head binding site.
2. Cross bridge is formed as myosin binds too myosin head binding site on actin
3. Myosin performs power stroke, pulling towards M-line
4. Myosin releases (ATP)
5. myosin resets to repeat.
occurs when voltage used to stimulate muscle reaches threshold. Delay is the latent period between stimulus and contraction. (enough time for excitation-contraction coupling to occur and Ca release from SR.)
Contaction occurs with power strokes from thick an thin filaments. , shortening the sarcomeres. Then period of relaxation
What happens when stimulus intensity increases?
more motor units are involved with increase of stimulus until all the motor units are being used creating maximum contractions
What happens with increased stimulation?
Muscle tension increase because there isn't enough time to relax, between stimulations, creating treppe
maximum contraction until you run out of ATP or Ca2+
muscle tension is less than resistance
Tension is greater than resistance
Cardiac muscle tissue
intercalated discs with gap junctions and desmosomes for coordinated contractions.
hollow organs, not striated, involuntary, same proteins contracting but in a different orientation
muscles Can be named by
action, body region, muscle attachment, muscle shape, size, number of heads or tendons
Axial muscle functions
Support and move head.
Chewing, non-verbal communication
Aid in breathing.
Support and protect abdominal muscles
Appendicular muscles functions
control movement of upper and lower limbs
control movement of pectoral and pelvic girdles
oppose action of prime mover
2 or more muscles working together for movement