5. Muscular System Flashcards
Flexion
decreases the angle of a joint
Extension
increases the angle of a joint
Rotation
movement of bone around it’s longitudinal axis
Abduction
away from the midline
Adduction
towards midline
Dorsiflexion of foot
toes towards head
Plantar flexion of foot
pointing toes away from head
Supination
radius and ulna are parallel, palms face anteriorly
Pronation
radius rotates over ulna, palms face posteriorly
The 3 types of muscle tissue:
skeletal muscle
smooth muscle
cardiac muscle
Muscle tissues differ in:
structure
function
location
activation
4 qualities of muscle tissue:
excitability/irritability
contractility
extensibility
elasticity
Excitability/irritability:
ability to receive and respond to stimuli
Contractility:
ability to shorten forcibly
Extensibility:
ability to be stretched or extended
Elasticity:
ability to recoil and resume resting length
Cardiac muscle tissue:
branching chains of cells, uninucleate, striations, intercalated discs
involuntary - controlled by pacemaker, NS, hormones
Intercalated discs
stick cardiac muscle cells close to each other to allow ions to travel quickly from cell to cell
Smooth muscle tissue
single, fusiform, uninucleate, no striations
involuntary - controlled by NS, hormones, chemicals, stretch
Skeletal muscle tissue
single, very long, cylindrical, multinucleate, very obvious striations
under voluntary control
A muscle is an organ composed of:
muscle tissue
blood vessels
nerve fibres
connective tissue
Epimysium
outer wrapping of connective tissue around a muscle
Fascicles
bundles of muscle fibres wrapped in connective tissue
perimysium
Perimysium
connective tissue wrapped around fascicles
Muscle fibre
single muscle cell
long and thin
Endomysium
connective tissue wrapped around each muscle fibre
Sarcolemma
cell wall of muscle cell
Myofibrils:
complex organelle made of bundles of myofilaments
contractile elements within muscle fibre/cell
densely packed, rod-like
Sarcomere:
smallest contractile unit of a skeletal muscle
region of a myofibril between 2 successive Z discs
Two types of myofilaments with myofibril:
actin and myosin
Actin:
thin myofilament - contractile proteins
Myosin:
thick myofilament - contractile proteins
Describe the arrangement of myofibrils within a muscle cell:
perfectly aligned repeating series of dark A bands and light I bands
A single segment of thick and thin filaments and the Z disc is called a ________
sarcomere
A single motor neuron and all it’s connections to muscle cells is called a ________
motor unit
Describe a small motor unit:
a motor neuron connected to a few muscle fibres
needed for fine control
Describe a large motor unit:
a motor neuron connected to many muscle fibres
generates higher force
What is acetylcholine (ACh)?
the neurotransmitter for skeletal muscle
Tension:
an active muscle
cross-bridges attempt to contract the length of sarcomere
Concentric contraction:
a shortening muscle
active muscle with sarcomeres shortening
Eccentric contraction:
a lengthening muscle
active muscle with sarcomeres lengthening
Isometric contraction:
no change in muscle length
active muscle with no shortening or lengthening
Where would you find vesicles containing acetylcholine?
in axon terminals
Circumduction
circular movement of a bone at a joint
Eversion
turning the sole of foot outward, with the weight of the inside of foot
Inversion
turning the sole inwards, weight on outside of foot
Sarcoplasmic reticulum:
organelle within muscle cell, stores calcium ions
