Ch 6: Muscle Tissue Flashcards
What are the properties of Muscular tissue?
Electrical excitability
Contractility
Extensibility
Elasticity
What’s this:
Most fibers are attached by tendons to bones
Fibers are large, cigar-shaped, and multinucleate
Skeletal Muscle
What are the other names for Skeletal muscle?
Striated and Voluntary
Which muscle is the only voluntary one?
Skeletal
What is this:
No Striations
Walls of hallow organs
Spindle shaped fibers that are uninucleate
Contractions are slow and sustained
Smooth Muscle
What is this:
Striations
Involuntary
Found only in the walls of heart
Uninucleate
Cardiac Muscle
What are the functions of the skeletal muscle?
Producing body movements
Stabilizing body positions
Generating heat
In the sarcomere which is the name for the thin filaments?
Actin
In the sarcomere which is the name for the thick filaments?
Myosin
What does the Sarcoplasmic Reticulum (SR) do?
Stores and releases calcium
Surrounds the myofibril
What do the sarcomere do?
Responsible for the shortening of muscle
INFO FOR SLIDING FILAMENT MECHANISM
See picture on notes
What are motor units?
I motor nerve and all fibers it innervates
Innervated by somatic motorneurons
What are the 4 steps in the Skeletal muscle contraction?
- Events at neuromuscular junction
- Muscle fiber excitation
- Excitation - contraction coupling
- Cross bridge cycling
What are the nerve stimulus and action potential parts we need to know?
Neuromuscular junction
Neurotransmitter (ACh)
Presynaptic membrane
Postsynaptic membrane
Synaptic Cleft
Ion Channels
LOOK AT PICTURE TO KNOW WHICH PART EACH IS
The smaller the motor unit, the ________ there is
finer control
What is motor unit recruitment?
Process in which the number of active motor units increases
Motor units contract alternatively to sustain contractions for longer periods of time
In which muscle is it impossible to have fused tetanus?
Cardiac muscle
What is the difference between unfused and fused tetanus?
Fused is a sustained contraction; whereas unfused has moments of relaxation
How do muscles derive the ATP necessary to power the contraction cycle?
Creatine Phosphate - Anaerobic (10 sec of running)
Anaerobic glycolysis (30-40 secs - a sprint)
Cellular respiration - Aerobic (hours - a marathon)
Force of Muscle Contraction:
Depends on number of cross bridges attached, which is affected by what 4 factors?
- Number of muscle fibers stimulated: the more MUs recruited, the greater the force
- Relative size of fibers: bulkier the muscle, greater the contraction
- Frequency of Stimulation
- Degree of Muscle Stretch
Compared to the skeletal muscle, what’s different about the cardiac muscle?
More mitochondria (because it never gets to rest)
Contractions last 10-15 times longer
Don’s summate
What are the 2 layers of sheets with fibers oriented at right angles to each other in the smooth muscle?
Longitudinal layer
Circular layer
What is the longitudinal layer?
Fibers run parallel to long axis (outer) of organ
Contraction causes organ to shorten
What is the circular layer?
Fibers run around circumference of organ (inner)
Contraction causes lumen of organ to constrict
What is the difference between leaky ion channels and gated ion channels?
Leaky are always open
Gated (or ligand or voltage gated) open in response to stimulus
