9-1. Muscle Tissue Flashcards
What are the functions of muscle?
- producing movement (all body mvts are caused by muscles contracting)
- maintaining posture (must contract skeletal muscles to hold body in standing or sitting position)
- generating heat (contract produces heat that helps maintain constant body temp)
What is a characteristic that is unique to muscle?
contractility
What are the characteristics of muscle?
- excitability (receive and respond to stimuli)
- contractility (shorten forcibly when stimulated)
- extensibility (ability to be stretched)
- elasticity (return to original length)
What are the types of muscle?
skeletal, cardiac, smooth
Which muscle types are striated?
skeletal and cardiac
Which muscle types are voluntary?
skeletal
Which muscle types are involuntary?
cardiac and smooth
What do you call a muscle cell?
muscle fiber
What are the differences in muscle fibers in the types of muscle tissues?
skeletal - elongated, cylindrical and multinucleate, running parallel to each other in bundles
cardiac - branched, interconnecting to each other at intercalated discs
smooth - spindle shaped cells with one centrally located nuclus
Skeletal muscle can contract ___, but ____ than other types.
powerfully and quickly; fatigues faster
Which muscle type is striated and involuntary?
cardiac
Which muscle type is striated and voluntary?
skeletal
Which muscle type is not striated?
smooth
endomysium
covering of connective tissue around each muscle fiber
fascicle
bundles of skeletal muscle fibers
perimysium
connective tissue covering around a fascicle
epimysium
thick layer of connective tissue wrapped around entire muscle
deep fascia
sheet of fibrous connective tissue that binds muscles together into functional groups, allowing free movement
blood supply
muscles are highly vascular because contraction requires lots of energy, nutrients and oxygen. Capillaries are within the endomysium, so each muscle fiber is in close contact with blood
nerve supply
to contract, skeletal muscle must be stimulated by a nerve impulse. Each fiber makes contact with part of a motor neuron
tendon
thick sheet of connective tissue that attaches muscle to bone
What are the connective tissue layers, from fiber level up?
endomysium (around each fiber) >
perimysium (around each fascile) >
epimysium (around entire muscle) >
deep fascia (binds together into functional groups) >
tendon (connects to bone)
sarcolemma
plasma membrane surrounding each muscle fiber
sarcoplasm
fluid filling each fiber
multinucleate
many nuclei, lying near the edge of the sarcolemma
In addition to the usual organelles, muscles have many ___.
mitochondria
sarcoplasmic reticulum
network of fluid filled channels running lengthwise thorugh the cell
Transverse tubules
running from surface of sarcolemma to interior of fiber, perpendicular to the sarcoplasmic reticulum
myofibril
rodlike, running lengthwise through entire cell; contractile elements of muscle
What filaments make up myofibril?
thick filaments - myosin
thin filament - double stranded helix of actin, with trotomyosin lying in the groove between the strands and troponin covering myosin attachment sites
What structures are unique to muscle fibers?
T-tubules and myofibril
What causes striation?
thin and thick filaments partially overlap (light shines through the areas where there are only thin filaments)
I bands
light bands containing only thin filaments
A bands
dark bands where thin and thick filaments overlap
Z lines
dense protein that serves as an attachment line for the thin filaments
sarcomere
part of myofibril between two Z lines
What is the fundamental contractile unit of muscle?
sarcomere
