Muscular System Flashcards
What are the classifications of muscles?
Cardiac, skeletal, smooth
Skeletal
Voluntary, stratified
Located in overlying skeleton
Multinucleated
Smooth
Involuntary, nonstratifed
Located in the organs or visecra
One nucleus
Cardial
Involuntary, stratified
Located in the heart, myocardium
One nucleus
Name of the muscle cell
Myocyte, muscular fiber
Every muscle is covered by a layer of?
Connective tissue/ fascia
Fascia has three layers
Epimysium (most external), perimysium (middle), endomysium (most internal)
Parts of muscular fiber
Sarcoplasmic reticulum (has calcium inside), Sarcolemma (plasmatic membrane), T-tubule
What is a fascicile?
bundle of muscle fibers, also called myocytes, bound together via the endomysium tissue that provides pathways for the passage of blood vessels and nerves.
What is inside the myofibril?
Myosin and actin (make contraction)
What is the main function of skeletal muscle?
Contraction
Thin filaments
Actin
Thick filament
Myosin
When thick and thin filaments come together it is
contracted
What does the actin and myosin need?
Calcium
What is the sliding mchanism of the filament?
1) Myosin heads make contact with actin
2)Myosin heads rotate
3)Actin is pulled to the center of the
sarcomere
What is the sliding mchanism of the filament?
1) Myosin heads make contact with actin
2) Myosin heads rotate
3) Actin is pulled to the center of the
sarcomere
4) Sarcomere shortensmuscle
contraction
When a patient has a lumbar injury
the neuron can’t stimulate the muscle
Where is the calcium stored?
Sarcoplasmic reticulum
Calcium allows
the interaction of actin, myosin, ATP
Muscles relax when
Calcium returns to SR
Skeletal muscle contraction only takes
place
when it is first stimulated by a
nerve
Where does somatic motor nerve emerge from?
Spinal chord –> skeletal muscle
Single muscle vs whole muscle
single muscle has an “all or nothing” response, but
a whole muscle can vary its force of contraction
-motor unit, recruitment
Innervation
Nerves that supplies a muscle for contraction
What is neurmuscular junction?
The joining between neurocyte and myocyte
Three different types of neurons?
Sensory, motor, interneuron
Twitch
Single muscle response in which
muscle contracts and then fully relaxes
Tetanus
Sustained muscle contraction
caused by repeated stimulation
Tonus
Normal, continuous state of
partial muscle contraction
Fights against gravity force, lets you be erect
What are the energy sources for muscle contraction?
Metabolism of creatinine, glycolisis (anaerobic metabolsim), aerobic metabolism
Muscle terms
Origin, insertion, prime mover, synergist, antagonist
Product of anaerobic metabolism
2 ATP, lactic acid
Origin
Stationary attachment
Insertion
Mobile attachment
Synergy
coordinated movements that occur when multiple muscle groups are activated simultaneously
-Ex: the biceps brachii and brachialis muscles both act to flex the forearm.
Antagonist
The muscle that opposes the action of another
Ex: When the triceps oppose the contraction of the flexing biceps by relaxing
Prime mover
Principal muscle that performs action
Hypertrophy
Growth in response to overuse
Atrophy
Disuse atrophy (cast) , denervation atrophy (no stimulation of nervous system/paralysis), senile atrophy (older)
Innvervention and irrigation
Nerves in muscle, blood in muscle
How skeletal muscles are named?
Size, shape, direction, location, number of origins, origin and insertion, muscle action
What is the somatic motor neuron?
Supplies skeletal muscle and emerges from the spinal cord and to skeletal muscles, contractions only take place when stimulated by a nerve
Contracture
abnormal fibrous formation in muscle that freezes in flexed position
What is meant by motor unit recruitment?
the process by which different motor units are activated to produce a given level and type of muscle contraction.
Each fibre within a motor unit contracts according to _____
The all or none law
When a motor unit receives a stimulus of sufficient intensity to bring forth a response, all the muscle fibres within the unit will contract at the same time, and to the maximum possible extent.
What is the neuromuscular junction?
-Space between motor neuron and muscle
-Where nerves and muscle fibers meet—is an essential synapse for muscle contraction and movement
Steps of Information Transfer from Neuron to NMJ
-Neuron stimulation causes an electrical
impulse to move toward the neuron’s
end
-Vesicles move toward and fuse with the
membrane
-ACh diffuses and binds to muscle
membrane receptor sites
-ACh stimulates receptors, causing an
electrical impulse
Things that can cause impairement of NMJ
Myasthenia gravis- neuromuscular disease that causes weakness in the skeletal muscles
Curare- muscle relaxent
Neurotoxins- bacteria that causes tetanus, botox, and botulism
Tonic contraction
Sustained contraction of different groups of muscles, maintains continual muscular contraction
Where is myoglobin found?
Striated muscles such as skeletal or heart muscles
Main function of myoglobin
Supply oxygen to the cells in your muscles (myocytes).
-Remember by hemoglobin that provides oxygen for organs and tissues
Isometric contraction
Muscle contraction without motion
Isotonic contraction
Muscular contraction in which length of muscle changes
What is a sphincter?
A ring of muscle surrounding and serving guard to an opening or closing tube
Provide examples of a sphincter
Anus, opening of stomach, urinary bladder
What happens when urinary sphincters contract?
When these muscles contract, the urethra narrows, and urination stops or slows
Muscle cells or myocytes are also called
muscular fibers
What are the z lines?
Part of the sarcomere and where thin filaments attach
What happens when the sarcomere shortens?
Muscle contraction, the thick and thin filaments slide up against eachother
Myofibrils form
muscle fibers
