Muscular system Flashcards
Cardiac muscle
Striated and involuntary, Makes up the wall of the heart.
Smooth muscle
Smooth and involuntary, Found in other organs such as those of the digestive system
Skeletal muscle
Striated, voluntary and fatigue easily. Attaches to bone, responsible for all movement. Most common muscle tissue in the human body)
Sarcomere
The contractile unit of muscle tissue
Z line
The lateral boundary of the sarcomere where the myofilament actin attaches.
Glycogen
The stored form of glucose found in the liver and muscles
Myofibrils
Parallel filaments that form muscle
Myofilaments
The filaments of myofibrils composed of actin and myosin
Actin
The thin filaments of muscle myofilaments where myosin binds to generate muscle contraction
Myosin
The thick filaments of myofilaments with a fibrous head, neck, and tail that binds to actin.
Endomysium
the connective tissue covering each muscle fiber.
Epimysium
Fibrous elastic tissue that surrounds a muscle
Fasciculi
Bundles of muscle fibers; the singular is ‘‘fascicle’’
Perimysium
The connective tissue that covers a bundle of muscle fibers
Tendon
A strong fibrous connective tissue that attaches muscle to bone
Periosteum
a dense layer of vascular connective tissue enveloping the bones except at the surfaces of the joints
Requirement for muscle contraction
Must receive a signal from the CNS
Neuromuscular junction
the space between a motor neuron and muscle fiber
Neurotransmitter
a chemical messenger that transmits messages between neurons or from neurons to muscles
Acetylcholine
the neurotransmitter (unique to the motor neuron) released by an action potential at the neuromuscular junction
Sliding-filament theory
the interaction of actin and myosin that describes the process of muscle contraction
From what are muscles made of
Muscles are made up of sarcomeres—a contractile unit of a myofibril (muscle fiber)
Size principle of fiber recruitment (also called Henneman’s size principle)
principle stating that motor units are recruited in order according to their recruitment thresholds and firing rates. In other words, motor units will be recruited in order from smallest and slowest firing rate to largest and fastest firing rate.
muscle fiber Type I
slow-twitch fibers and aerobic (good for endurance)
muscle fiber Type II
fast-twitch and anaerobic (good for power
muscle fiber Type IIa
fast-twitch, moderately fatigable muscle fibers with moderate mitochondrial density
muscle fiber Type IIx
fast-twitch, fast-fatigable muscle fibers with low mitochondrial density (white in color)
Mitochondria (singular “mitochondrion”)
an organelle with a double membrane and many folds inside responsible for generating the chemical energy needed for biochemical reactions; the “powerhouse of the cell”
How does muscle create movement
Muscles create movement by pulling on bones within the body.
Origin
the proximal (closer to the midline of the body) attachment
Insertion
the distal (farther from the midline) attachment
Action
the specific movements that each muscle is responsible for
Innervation
the specific distribution of nerves to a particular part of the body
Fusiform muscle
spindle-shaped muscle
Example: Biceps brachii
Convergent muscle (triangular muscle)
muscle fibers converging from a broad origin (fixed point where the muscle attaches closest to the torso) to a single tendon of insertion (fixed point where the muscle attaches farthest from the torso)
Example: Pectoralis
Circular muscle
muscle fibers surrounding an opening in the body
Parallel muscle
muscle fibers running parallel to the axis of the muscle
Example: Stylohyoid
Pennate muscle
muscles with fasciculi that attach obliquely (diagonally)
Unipennate muscle
muscle fibers extending from one side of a central tendon
Example: Flexor pollicis longus
Bipennate muscle
muscle fibers extending from both sides of a central tendon
Example: Soleus
Multipennate muscle
muscle fibers extending from both sides of multiple central tendons
Example: Deltoid
Concentric
muscles that shorten to produce movement. For example, during the pressing motion of a bench press, the pectoralis is concentrically contracting.
Eccentric
muscles that lengthen to allow movement. For example, during the downward motion of a biceps curl, the biceps brachii is eccentrically contracting. When applying tempo training, this is the part of the movement that should be the focus and, therefore, the slowest portion of the repetition.
Isometric
muscles where the joint angle and muscle length do not change during movement. For example, the entire body works to maintain a stable position when performing a plank.
Agonist
Main muscle responsible for movement; prime mover
Example: Biceps brachii during a biceps curl
Synergist
Muscle that plays a secondary role in movement
Example: Brachioradialis during a biceps curl
Antagonist
Muscle with an action directly opposite of the agonist
Example: Triceps during a biceps curl
All-or-none principle
The amplitude—or strength—of a nerve’s action potential is independent of the strength—or magnitude—of the stimulus
Stretch-shortening cycle (SSC)
the cycling between the eccentric (stretch) action of a muscle and the concentric (shortening) action of the same muscle
Three (3) phases:
Eccentric, Amortization, Concentric
