Muscles Flashcards
Myo
Muscle
Myology
The study of muscles
The human body has ______ skeletal muscles
600+
How many skeletal muscles are in the face and neck
162
4 functions of the muscular system
Movement
Posture
Joint stability
Heat production
Type of muscle tissue that is attached to bone and skin
Skeletal
Type of muscle tissue that appears striated
Skeletal muscle
Type of muscle tissue that is very powerful
Skeletal muscle
Type of muscle tissue that is voluntary
Skeletal muscle
Type of muscle tissue that is multinucleated
Skeletal muscle
Type of muscle tissue that is found in the heart
Cardiac muscle
Type of muscle tissue that appears striated and branched
Cardiac muscle tissue
Type of muscle tissues that are involuntary
Cardiac and smooth
Type of muscle tissues that have a single nuclei
Cardiac and smooth
Type of muscle tissue that is found in the wall of hollow organs
Smooth muscle
Type of muscle tissue that appears stratified squamous, NO striations
Smooth
5 rules of skeletal muscles
- All muscles cross at least one point
- Most of the muscle lies proximal to the joint crossed
- All muscles have two attachments: origin and insertion
- Muscles only pull NEVER push
- During contraction the insertion moves towards origin
Less movable attachment site or muscle attachment to stationary bone
Origin
More movable attachment site or muscle attachment to moveable bone
Insertion
Primary mover responsible for causing a movement (joint action)
Agonist
Muscle that opposes movement of the agonist; provides precision and control
Antagonist
Muscles that assist the agonist by producing the same movement at the same time. Makes a more effective movement
Synergist
Example of an agonist
Biceps brachii is the main flexor of the elbow joint
Example of an antagonist is
Triceps brachii performs the opposite function of the biceps brachii in the elbow joint
Example of a synergist
Brachialis assists the biceps brachii in flexion of the elbow
Thick filaments of a muscle fiber
Myosin
Type of muscle that connects to bones, voluntary
Skeletal
Stores neurotransmitters
Vesilles
Neurotransmitter used to cause muscle contraction
Acetylcholine
Connects muscle to bone
Tendon
Organelle that provides the energy needed for muscle contractions
Mitochondria
Connects bones to other bones
Ligament
Surrounds fascicles
Perimysium
Thin filaments of a muscle fiber
Actin
Minimal level of stimulus to cause a contraction
Threshold
Section of myofibril from one Z line to the next Z line
Sarcomere
Bundle of muscle fibers
Fascille
Theory that explains how muscle contraction works; sliding _____ theory
Filament
Outermost layer, surrounds entire muscle
Epimysium
Describes muscles that are striped in appearance
Striated
Muscle fiber membrane
Sarcolemma
Space between a neuron and the muscle, synaptic ____
Cleft
Overlapping patterns of actin and myosin; I and A _______
Bands
Membranous channels that surround the myofibrils; sarcoplasmic _________
Reticulum
When muscles become tired
Fatigue
Type of muscle found in the digestive tract, involuntary
Smooth
Type of muscle that makes up the heart
Cardiac
The space where the nerve and muscle meet
Neuromuscular junction
Carries messages towards myofibril
Axon
Stores acetylcholine
Synaptic vesticles
Gap between axon and muscle fiber
Synaptic cleft
Specialized area of sarcolemma that receives messages
Motor end plate
Chemical that causes a contraction
Acetylcholine
What is the name of the stimulus that travels down the axon to the muscle fiber?
An action potential
Does the terminal end of the axon enter the muscle fiber
No there is a gap between the two
Does acetylcholine enter the muscle fiber
No
What chemical enters the muscle fiber, resulting in an action potential through the muscle fiber
Sodium
____ is bound to myosin side arm
ATP
ATP _______ into ADP + P (high energy)
Cleaves
What are the steps for muscle movement?
Action potential Myosin-actin binding Power stroke ATP Binding actin-myosin released ATP Cleavage
What happens in step one (action potential)
A nerve action potential releases acetylcholine into the synaptic cleft opening the Na+ channels
Action potential spreads across sarcolemma releasing Ca into sarcoplasma
What happens in step two (myosin actin binding)
- Ca binds to troponin
- A shape change in troponin moves tropomyocin out of the way of actin binding site
- Actin and myosin bind using energy from cleaved ATP
What happens in step 3 (power stroke)
- Side arm pivots so myosin and actin slide by each other shortening the sarcomere
- ADP and P released low energy
What happens in step 4 (actin-myosin release)
- A different ATP molecule binds to active site
2. Actin released
Step 5 (ATP cleavage)
- Return to high energy state
2. Cycle will repeat if Ca still available
If a muscle is contracted what happens if a new molecule of ATP is not available
Muscle stays contracted -cramps
Why does rigor mortis occur
ATP is not available to control Ca release so contractions are continuous 6-8 hours after death. Body relaxes 16-24 hours as enzymes break down contractive structures
What happens to the length of the sarcomere during a contraction
The sarcomere shortens
What chemical exposes the binding site for actin and myosin
Calcium
What is the source of energy for a contraction?
ATP
What is the name of the step in which the actin filament is actively contracted
Powerstroke
During muscle contraction the muscle becomes ________
Tense
During muscle contraction the muscle ______ in length
Shortens
During muscle contraction the diameter of the muscle _______
Expands
A muscle that provides the major force for producing a specific movement is called
An agonist
A muscle group that works with and assists the action of a prime mover is a
Synergist
In flexing the forearm at the elbow, the triceps brachii acts as
An antagonist
In skeletal muscle contraction, calcium apparently acts to
Remove the blocking action of tropomyosin
Calcium ions bind to the ________ molecule in skeletal muscles
Troponin
An elaborate network of membranes and skeletal muscle cells that functions in calcium storage is the
Sarcoplasmic reticulum
A sarcomere is
The area between two Z discs
The major function of the sarcoplasmic reticulum in muscle contraction is to
Regular intracellular calcium concentration
The sliding filament model of contraction involves
Actin and myosin sliding past each other and partially overlap
During vigorous exercise there maybe insufficient oxygen available to completely break down pyruvic acid for energy. As a result, the pyruvic acid is converted to
Lactic acid
The role of calcium ions in muscle contraction is to
Bind to regulatory sites on troponin, changing the configuration
One functional unit of a skeletal muscle is
A sarcomere
The contractile units of skeletal muscles are
Myofibrils
Rigor mortis occurs because
No ATP is available to release attached actin and myosin molecules
During muscle contraction, myosin cross bridges attach to which active sites?
Actin filaments
Which of the following are composed of myosin?
Thick filaments
The striations of skeletal muscle cells are produced, for the most part, by
The arrangement of myofilaments
Muscle that opposes and reverses the action of another muscle
Antagonist
Muscle that aids another by promoting the same movement
Synergist
Muscle that is primarily responsible for bringing about a particular movement
Agonist
Which type of muscle generally remains in a state of partial contraction when you’re keeping your legs straight
Skeletal muscle
Where is cardiac muscle tissue located in the body?
Heart
Moves your eyeball
Skeletal muscle
A ___________ is a single skeletal muscle cell
Muscle fiber
Muscle fibers are made up of fiber bundles of that contain hundreds of ________
Myofibrils
Composed of a T-tubule, the terminal cisternae, and gaps
Longitudinal tubules
Cylindrical structures that carry out contraction
Myofibril
Extensions of the sarcolemma that separate the sarcomeres
Transverse tubules
Specialized plasma membrane of the skeletal muscle cell; forms membrane connections between each of the sarcomeres
Sarcolemma
The specialized endoplasmic reticulum of the muscle cell
Sarcoplasmic reticulum
Units of the myofibrils
Mitochondria
The bands that mark the sarcomere’s borders
Z line
The bands that mark the middle of the sarcomere
M line/ M disc
Under a micrograph they are the lightest and least dense structures; composed of actin, troponin, tropomyosin
Thin filaments
Much more dense than think filaments; composed of myosin
Thick filaments
The distance between the ends of the thin filaments known as
H zone
The distance between the thick filaments of one sarcomere and the thick filaments of an adjacent sarcomere was known as the
I Band
The length of the thick filaments was known as the
A band
The _______ and ______ shortens, but the ______ does not shorten during muscle contraction
I band
H zone
A band
Chemically, muscle contraction is driven by ___________ and triggered by the release of ______ from the sarcoplasmic reticulum
ATP hydrolysis
Ca2+
Ca2+ binds to __________ in the thin filaments, exposing the myosin binding sites on actin
Troponin
The movement where the myosin head pulls the thin filaments inward is called the
Power structure
What is the order of chemicals in a muscle contraction
- Electrochemical signal causes release of Ca2+ from sarcoplasmic reticulum
- Ca2+ binds troponin causing a conformational change of the thin filament
- Myosin heads bind to actin
- Power stroke (ADP and P dissociate from myosin)
- ATP binds myosin head
- Thin filament returns to relaxed state