Muscles Flashcards
The 4 unique characteristics of muscle tissue
Excitability: respond to input from stimuli
Contractility: muscle fibres can contract and shorten
Elasticity: when tension is removed muscle cells return to their original length
Extensibility: muscle fibres can be stretched beyond their resting length
Why are muscles considered organs
they contain all 4 tissue types
Characteristics of Skeletal Muscle Tissue
striated
usually attached to bone (bar most facial muscles)
multi-nulcei
voluntary control
functions of skeletal muscle tissue
for body movement
maitain posture
regulate temperature
storage and movement of materials
support
composition of muscles
muscle fibres (muscle cells)
blood vessels
nerves
organisation of muscles
muscle
fascicle
muscle fibre (muscle cells)
myofibrils
myofilaments (actin and myosin)
how many layers of CT do muscles have
3 layers composed of collagen and elastic fibres
what is the purpose of the CT in muscles
provides protection
site for blood vessels and nerve distribution
means for attachment to the skeleton
What are the 3 CT layers
Endomysium
Perimysium
Epimysium
The location and tissue type of each CT layer
Endomysium - surrounds and electrically insulates each muscle fibre, Areolar CT
Perimysium - surrounds the fascicles, dense irregular CT
Epimysium - surrounds the entire muscle, dense irregular CT
what are the names for muscle-specific plasma membrane, cytoplasm and smooth ER
sarcolemma
sarcoplasm
sarcoplasmic reticulum (regulates Ca2+)
name the thick and thin filaments
thick - Myosin
thin - Actin
what is sliding filament theory
the mechanism for contraction where the myosin heads ‘walk’ along the binding sites of the Actin
cardiac muscle fibre features
striated
y-shaped
one/two nuclei
joined by intercalated discs (gap junctions for communication)
autorhythmic
under involuntary control
Smooth muscle fibre features
short fusiform cells (tear drop)
single central nucleus
no striations
thin filaments attached to Dense Bodies
under involuntary control
name of the convergence of CT of muscles
Tendons
What do Tendons join
Muscle to bone
What do Ligaments join
Bone to bone
name of the less moveable point of attachment of a muscle
origin (proximal end)
name the more moveable point of attachment of a muscle
insertion (distal end)
what is muscle tone
the constant tension in resting muscles, when motor units are randomly stimulated to avoid fatigue
what is isometric contraction
when the length stays constant while tension is changing
what is isotonic contraction
when the tension is constant, while length is changing
what are the two stages of isotonic contaction
concentric contraction
eccentric contraction
what is concentric contraction
when a muscle under tension shortens
what is eccentric contraction
when a muscle under tension lenghtens
what is the term for circular muscle fibre pattern
Orbicularis (ie. orbicular oris or orbicular oculi)
what is the term for parallel muscle fibre pattern
Rectus (ie. Rectus abdominis)
what is a convergent muscle pattern
when a muscle is widespread over a large area, and the fascicles come to a single common point.
ie. pectoralis major
what is a pennate muscle pattern
when muscle fibres attach obliquely (on an angle) to the tendon (for a greater force production)
what is a unipennate muscle pattern
a type of pennate muscle where all the fibres attach to a single side of the tendon
ie. extensor digitorum
what is a bipennate muscle pattern
a type of pennate muscle where the fibres attach to two side of the tendon
ie. Rectus femoris
what is a multipennate muscle pattern
a type of pennate muscle where multiple rows of muscle fibres attach to a tendon whose central tendon has branched into multiple tendons.
ie. Deltoid
what is the Agonist
it is the focus. It produces a specific movment
the Prime Mover
ie. triceps brachii is the agonist of antibrachium extension
what is the antagoinst
a muscle whose action apposes the agonist
ie. the biceps brachii is an antagonist to the triceps brachii
what is the synergist
a muscle whose action supports the agonist to perform its action
