Muscular System Flashcards
Give at least 4 functions of the muscular system.
Movement of the body
Maintenance of posture
Respiration
Production of body heat
Communication
Constriction of organs and vessels
Contraction of the heart
The function of this muscle is body movements.
Skeletal Muscle
The function of this muscle is moving food through the digestive tract, emptying the urinary bladder, regulating the blood vessel diameter, contracting ,any gland ducts.
Smooth Muscle
The function of this muscle is pumping blood; contractions provide the major force for propelling blood through blood vessels.
Cardiac Muscle
What are the autorhythmic of the three muscle types?
Skeletal Muscle - No
Smooth Muscle - Some of them
Cardiac Muscle - Yes
What are the control of the three muscle types?
Skeletal Muscle - Voluntary and involuntary (reflexes)
Smooth Muscle - Involuntary
Cardiac Muscle - Involuntary
What are the general properities of muscle tissue?
Contractility
Excitability
Extensibility
Elasticity
Forms a connective tissue sheath that surrounds each skeletal muscle.
Epimysium
Subdivides each whole muscle into numerous, visible bundles of muscle fibers.
Perimysium
a delicate layer of connective tissue that separates the individual
muscle fibers within each fascicle
Endomysium
Two main aspects to muscle contraction:
Electrical component
Mechanical component
What are the electrical component structures?
Sarcolemma
Transverse tubules
Sarcoplasmic reticulum
bundles of protein filaments
Myofibrils
thin filaments
Actin
thick filaments
Myosin
__________ are the structural and functional units of skeletal muscles
Sarcomeres
3 Proteins of Actin Myofilament
Actin
Tropomyosin
Troponin
composed of many elongated myosin molecules shaped like
golf clubs.
Myosin Myofilament
The heads bind to active sites on the actin molecules to form ____________ to contract the muscle. (Properties Myosin)
cross-bridges
The heads are attached to the rod portion by a _________
that bends and straightens during contraction (Properties Myosin)
hinge region
The heads break down _______________________,
releasing energy (Properties Myosin)
adenosine triphosphate (ATP)
The primary function of skeletal muscle cells is to generate force by? (Sliding Filament Model)
contracting, or shortening
The parallel arrangement of myofilaments in a sarcomere
allows them to ________, which causes muscle contraction. (Sliding Filament Model)
interact
When sarcomeres _________, myofibrils, muscle fibers, muscle fascicles, and muscles all shorten to produce muscle
contraction. (Sliding Filament Model)
shorten
During muscle relaxation, sarcomeres? (Sliding Filament Model)
lengthen
(Skeletal Muscle Fiber Physiology)
Action potentials travel from the? (Skeletal Muscle Fiber Physiology)
brain or spinal cord
Electrically excitable cells are?(Skeletal Muscle Fiber Physiology)
polarized
The phospholipid bilayer interior is a hydrophobic environment, which inhibits the movement of? (Ion Channels)
charged particles
The basis of the electrical properties of skeletal muscle cells is the movement of _____ across the cell membrane (Ion Channels)
ions
Ions can move across the cell membrane through? ion channels (Ion Channels)
ion channels
Give two types of Ion Channels.
Leak ion channels
Gated ion channels
Cell membrane is more _______ to K+ than to Na+(The Resting Membrane Potential)
permeable
Concentration of K+ inside the cell membrane is _______ than that outside the cell membrane (The Resting Membrane Potential)
higher
Concentration of _____ outside the cell membrane is higher than that inside the cell membrane (The Resting Membrane Potential)
Na+
Occurs when the excitable cell is stimulated. A reversal of the resting membrane potential such that the
inside of the cell membrane becomes positively charged
compared with the outside
Action Potential
Before a neuron or a muscle fiber is stimulated, the gated Na+ and K+ ion channels are? (Action Potential)
closed
When the cell is stimulated, ligand-gated Na+ channels open and Na+ _______ into the cell. (Action Potential)
diffuses
The __________ charged Na+ makes the inside of the cell membrane depolarized (more positive) (Action Potential)
positively
If the depolarization causes the membrane potential to reach _________, an action potential is triggered. (Action Potential)
threshold
Threshold is the membrane potential at which gated _____________ open. (Action Potential)
Na+ channels
The depolarization phase of the action potential is a brief period during which further depolarization occurs and the inside of the cell becomes even more? (Action Potential)
positively charged
As the inside of the cell becomes positive, this voltage change causes additional permeability changes in the cell membrane, which stop depolarization and start? (Action Potential)
repolarization
The repolarization phase is the return of the membrane
potential to its resting value. It occurs when? (Action Potential)
ligand-gated Na+ channels close and gated K+ channels open
When K+ moves out of the cell, the inside of the cell
membrane becomes more negative and the outside
becomes more positive. The action potential ends, and the
_____________________ is reestablished. (Action Potential)
resting membrane potential
Action potentials produced in the sarcolemma of a skeletal
muscle fiber can lead to contraction of the muscle fiber.
Muscle Contraction
Release of ______ from the sarcoplasmic reticulum is a “switch” or muscle contraction (Muscle Contraction)
Ca2+
The contraction of the fiber is due to the? (Muscle Contraction)
mechanical component
Ca2+ is stored in the? (Muscle Contraction)
sarcoplasmic reticulum
The sarcoplasmic reticulum actively transports Ca2+ into its? (Muscle Contraction)
lumen
Muscle contraction begins with the __________ at its resting membrane potential. (Muscle Contraction)
muscle fiber
Release of ____________ at the neuromuscular junction will produce an action potential in the sarcolemma. (Muscle Contraction)
acetylcholine
Occurs when acetylcholine is no longer released at the
neuromuscular junction.
Muscle Relaxation
The lack of _______________ along the sarcolemma stops
Ca2+ release from the sarcoplasmic reticulum (Muscle Relaxation)
action potentials
keeps acetylcholine from accumulating within the synaptic cleft where it would act as a constant stimulus at the motor end-plate, producing continuous contraction in the muscle fiber.
Acetylcholinesterase
The mechanical component of muscle contraction. Cause the sarcomeres to shorten and the muscle will contract
Cross-Bridge Movement
Response of a muscle fiber to a single action potential along its motor neuron.
Muscle Twitch
This phase of twitch is when the gap between the time of stimulus application to the motor neuron and the beginning of contraction.
Lag phase/latent phase
This phase of twitch commences once the Ca2+ released from the sarcoplasmic reticulum initiates cross-bridge formation and cross-bridge cycling.
Contraction phase
This phase of twitch is much longer than the contraction phase, because the concentration of Ca2+ in the sarcoplasm decreases slowly due to active transport into the sarcoplasmic reticulum.
Relaxation phase
Contraction where muscle does not shorten.
Isometric contractions
Example of Isometric contractions
lifting something that is far too heavy for you
Contraction where muscle shortens. Also increases the tension in the muscle and decreases the length of
the muscle.
Isotonic contractions
Example of Isotonic contractions
moving limbs in order to lift an object
are isotonic contractions in which tension in the muscle is great enough to overcome the opposing resistance, and the muscle shortens
Concentric
Example of Concentric Contraction
lifting a loaded backpack from the floor to a tabletop
are isotonic contractions in which tension is maintained in a muscle but the opposing resistance is great enough to cause the muscle to increase in length
Eccentric
Example of Eccentric Contraction
lowering a heavy weight
contract more slowly, have a better-developed blood supply, have more mitochondria, and are more fatigue-resistant than fast-twitch muscle fibers
Slow-Twitch Muscle Fibers
- have a less-well-developed blood supply
- have very little myoglobin, fewer and smaller mitochondria
- contract rapidly for a shorter time and fatigue relatively quickly
Fast-Twitch Muscle Fibers (type II)
Characteristics of Slow-Twitch Oxidative (SO) (Type I)
Myoglobin Content - High
Mitochondria - Many
Capillaries - Many
Metabolism - High aerobic
Characteristics of Fast-Twitch Oxidative Glycolytic (FOG) (Type IIa)
Myoglobin Content - High
Mitochondria - Many
Capillaries - Many
Metabolism - Intermediate
Characteristics of Fast-Twitch Glycolytic (FG) (Type IIb)
Myoglobin Content - Low
Mitochondria - Few
Capillaries - Few
Metabolism - Low
Temporary state of reduced work capacity.
Muscle Fatigue
________ and ATP depletion due to either an increased ATP consumption or a decreased ATP production (Muscle Fatigue)
Acidosis
_______ inflammatory reactions (Muscle Fatigue)
Local
A characterized by the buildup of excess reactive oxygen species (ROS; free radicals) (Muscle Fatigue)
Oxidative stress
Highly repetitive eccentric muscle contractions produce pain more readily than concentric contractions.
Muscle Soreness
The pain is related to the effects of ___________________ on the muscle fibers. (Muscle Soreness)
inflammatory chemicals
In people with exercise-induced muscle soreness, enzymes that are normally found inside muscle fibers can be detected in the? (Muscle Soreness)
extracellular fluid
These enzymes are able to leave the muscle fibers because injury has increased the permeability of plasma membranes, or has even? (Muscle Soreness)
ruptured them
They contain less actin and myosin than do skeletal muscle cells.
Smooth Muscle
Smooth muscle cells contract more ________ than skeletal muscle cells.
slowly
Cardiac muscle shares some characteristics with?
both smooth and skeletal muscle
The actin and myosin myofilaments are organized into sarcomeres but the distribution of myofilaments is not as ___________ as in skeletal muscle (striated).
uniform
The majority of our muscles extend from one bone to another and cross at least?
one joint
Muscle is connected to the bone by a?
tendon
Specific body movement a muscle contraction causes
Action
Muscles are typically studied in groups called?
agonists
antagonists
Example of the action of a single muscle or group of muscles is opposed
by that of another muscle or group of muscles.
the biceps brachii flexes (bends) the elbow and the triceps brachii extends the elbow
Members of a group of muscles working together to produce a movement.
Synergists
Example of Synergists
deltoid, biceps brachii, and pectoralis major working together to flex the shoulder
plays the major role in accomplishing the desired movement
Primer mover
Example of prime mover
brachialis is the prime mover in flexing the elbow
are muscles that hold one bone in place relative to the body while a usually more distal bone is moved
Fixators
Example of Fixators
muscles of the scapula act as fixators to hold the scapula in
place while other muscles contract to move the humerus
Muscle names are based by?
Location (pectoralis)
Size (gluteus maximus)
Shape (deltoid- triangular)
Orientation of fascicles (rectus- straight, parallel)
Origin and insertion (sternocleidomastoid)
Number of heads (biceps)
Function
Fascicles arranged in a circle around an opening; act as sphincters to close the opening.
Circular
Example for Circular Fascicle
Orbicularis oris
Orbicularis oculi
Broadly distributed fascicle converge at a single tendon.
Convergent
Examples of Convergent Fascicle
Pectoralis major
Pectoralis minor
Fascicles lie parallel to
one another and to
the long axis of the muscle
Parallel
Examples of Parallel Fascicles
Trapezius
Rhomboideus
Rectus abdominis
Effects of Aging (Give at least 2)
Reduction in muscle mass
lower response time for muscle contraction
Reduction in stamina
Increased recovery time
Loss of muscle fibers begins as early as 25 years of age, and by age 80 the muscle mass has been reduced by approximately 50%
Painful, spastic contractions of a muscle; usually due to a buildup of lactic acid.
Cramps
Non-life-threatening, chronic, widespread pain in muscles with no known cure; also known as chronic muscle pain syndrome.
Fibromyalgia
Enlargement of a muscle due to an increased number of myofibrils, as occurs with increased muscle use.
Hypertrophy
Decrease in muscle size due to a decreased number of myofilaments; can occur due to disuse of a muscle, as in paralysis.
Atrophy
Group of genetic disorder in which all types of muscle degenerate and atrophy.
Muscular dystrophy
Inflammation of a tendon or its attachment point, due to overuse of the muscle.
Tendinitis
Muscles are weak and fail to relax following forceful contractions; affects the hands most severely; dominant trait in 1/20,000 births.
Myotonic muscular dystrophy
Results from an abnormal gene on the X chromosome and is therefore a sex-linked (X-linked) condition
Duchenne muscular dystrophy
The gene is carried by females, but DMD affects males almost exclusively, at a frequency of? (Duchenne muscular dystrophy)
1 in 3000
The DMD gene is responsible for producing a protein called
_________, which plays a role in attaching myofibrils to other proteins in the cell membrane and regulating their activity (Duchenne muscular dystrophy)
dystrophin
