Skeletal muscle Flashcards
What is myology
Study of muscle
Muscle cells (fibres) properties
Contractility
Tension
what are the three types of muscle
skeletal
smooth
cardiac
skeletal muscle
-Attaches to and moves skeleton
-striated (striped) pattern
-under VOLUNTARY control
Smooth muscle
Found in walls of hollow organs
Smooth appearance
Under INVOLUNTARY control
Cardiac muscle
Has characteristics of both smooth and skeletal muscle
what are the characteristics of cardiac muscle
Like skeletal muscle- striations
Like smooth muscle- involuntary control
What is syncytium
A large cell-like structure formed by the joining together of two or more cells
What are the three actions that work together
Prime mover
Antagonist
Fixators/stabilizers
What is the origin
less moveable end of the muscle, usually proximal
What is an insertion of a muscle
More moveable end of a muscle, usually distal
what is the belly of a muscle
Widest portion of a muscle between origin and insertion
Do all muscles insert on bone?
No, most of the muscles that control facial expression originate from bone and insert in the skin
what is epimysium?
The epimysium is a dense layer of connective tissue that surrounds the entire muscle. -protects the muscle from friction and helps maintain its shape by connecting it to tendons and bones.
What is perimysium
The perimysium is a layer of connective tissue that surrounds and groups muscle fibers into bundles called fascicles. It provides support and carries blood vessels and nerves to the muscle fibers within each fascicle.
What is endomysium
The endomysium is a thin layer of connective tissue that surrounds each individual muscle fiber.
Are tendons or muscles stronger?
Tendons
What is a muscle cell called
Muscle fiber
What is found within each muscle fibre
many myofibrils
What do myofibrils consist of?
Each myofibril consists of a large array of contractile proteins arranged repeatedly in series.
What is each repeated array of contractile proteins in a myofibril called?
sarcomere
The two major contractile
proteins of the sarcomere are:
actin (thin) filament
myosin (thick) filament
What happens during muscle contraction according to the sliding filament theory?
When a muscle is activated, myosin attaches to actin and, using ATP, pulls the actin to slide over myosin. This shortens the sarcomere and causes muscle contraction.
How does blood supply differ between a sedentary person and a person who trains
sedentary- 3-4 capillaries surrounding each muscle fibres
Trained- up to 7 capillaries
what is occlusion
Occlusion is the blockage or closing of a blood vessel or hollow organ. It can restrict blood flow or obstruct passage through a body part.
at what % does occlusion happen
occlusion happens at 15-20% of max , complete occlusion happens at 50% of max force
activation of a muscle fibre can produce:
Max force and max velocity
What is a motor unit
A motor unit is the functional unit of a muscle.
What does a motor unit consist of?
A motor unit consists of a motor neuron and all the muscle fibers it innervates.
Where is the cell body of a motor neuron located?
spinal chord
How far can a motor neuron’s axon extend?
The axon can extend from the spinal cord to a muscle that may be a few millimeters to a few feet away.
What are the two motor units based on contraction speed
fast twitch
slow twitch
what is slow twitch also called
Slow twitch oxidative (SO) or Type I
What is the fast twitch oxidative-glycolytic motor unit also called?
Fast twitch oxidative-glycolytic (FOG) or Type IIa.
What is the fast twitch glycolytic motor unit also called?
Fast twitch glycolytic (FG) or Type IIx.
what is passive tension
Passive tension is the force generated in a muscle when it is stretched without any active contraction.
positive velocity, shortening muscle
concentric contraction
velocity is negative, muscle lengthening
eccentric contraction
velocity is 0, no change in muscle length
Isometric contraction
scaropenia is caused by (5):
Neural apoptosis (cell death)
imbalance of muscle protein synth/degradation
Physical inactivity
hormonal imbalance
food intake- insufficient protein
sarcopenia enhances: (4)
-loss of physical function
-risk of disability
-more dependancy towards others
-medical care costs
prevention of sarcopenia
strength training, hormone therapy, diet, reduction in sedentary time
