muscular system anaphy Flashcards
Functions of Muscular System
- Movement
- Maintain posture
- Respiration
- Production of body heat
- Communication
- Heart beat
- Contraction of organs
and vessels
Types of Muscles
- Skeletal
- Cardiac
- Smooth
are muscle cell
Fibers
Abilities of Skeletal Muscles
- Contractility:
ability to shorten - Excitability:
respond to stimulus - Extensibility:
can stretch - Elasticity:
recoil
is cytoplasm
Sarcoplasm
- Contraction and shortening of muscles are due to the movement of
microfilaments
- Skeletal and smooth muscle cells are elongated (muscle cell =
muscle fiber
Skeletal Muscle Characteristics
- Makes up 40% of body weight
- Named because attached to bones (skeleton)
- Many nuclei per cell (near periphery)
- Striated
- Longest of muscle types
plasma membrane
Sarcolemma
endoplasmic reticulum of muscle
Sarcoplasmic reticulum
= contracting structures within a myofibrils; a section of the myofibrils
= joined end to end like train carriages, forms myofibril
=contain microfilaments that slide past
Sarcomeres
long thread-like proteins inside the muscle cell that make up muscle fibers
= contains many microfilaments
Myofibril
sheet or membrane around the cell.
Lemma
refers to flesh or muscle
Sarco
major component of a thin filaments
Actin
is a malignant tumor
Sarcoma
is a molecule that make up a thick micro filaments
Myosin
is a bundle of muscle fiber( cells)
Fascicle
connective tissue that surrounds
entire skeletal muscle (outside)
covers the entire skeletal muscle (protects the muscles from friction against other muscles and bones
- Epimysium
connective tissue around each muscle fasciculus
- Perimysium:
- skeletal muscle cells
Muscle fiber
bundle of muscle fibers
- Muscle fasciculus
thread-like proteins that make up muscle fibers
* long organelles inside muscle cell (cylindrical organelles)
- Myofibril:
connective tissue that surrounds each muscle fiber
- Endomysium
cell membrane
- contains T-tubules
- specialized plasma membrane
Sarcolemma
it is a muscle fiber membrane that contains nuclei which are pushed aside by long ribbon like
organelles called
myofibrils
give the muscle its striated (banded) appearance
Light (I) bands and dark (A)
- proteins that make up myofibrils
- Myofilament
- Thick filaments =
- Thin filaments =
Thick filaments = myosin filaments
Thin filaments = actin filaments
- contractile unit
- contains actin and myosin
- Sarcomere:
contractile unit of a muscle fiber
- Sarcomere
– Myofilaments produce banding (striped) pattern
- Organization of the sarcomere
– Composed of the protein myosin
– Contain ATPase enzymes to split ATP to release energy for muscle contractions
- Thick filaments
– Thick filaments Possess projections known as
myosin heads
are known as cross bridges when they link thick and thin filaments during contraction
– Myosin heads
– Myosin heads are known as
cross bridges
– Composed of the contractile protein actin
– Actin is anchored to the Z disc
- Thin filaments
- At rest, within the A band there is a zone that lacks actin filaments called the
the H zone
- thin myofilament
- resemble 2 strands of pearls
- Actin:
- thick myofilament
- resemble golf clubs
Myosin
- wrap around sarcomeres at A band
- associated with sarcoplasmic reticulum
-transports
- T-tubules (transverse)
- type of SER
- surrounds myofibril, myosin
- stores and releases Ca2+
- Sarcoplasmic reticulum
protein fibers that form attachment site for actin
- Z disk
- center of sarcomere
- contains only myosin
- H zone:
contains only actin
- I band
where actin and myosin overlap
- A band:
where myosin are anchored
- M line:
- cell membrane
- contains T-tubules
Sarcolemma
cytoplasm of muscle fiber (cell)
- Sarcoplasm:
- filament on grooves of actin
- attachment site on actin for myosin
- Tropomyosin:
attachment site on actin for Ca2+
Troponin
These are the long, thread-like structures that run the length of the muscle fiber and are responsible for contraction.
Myofibrils:
The basic contractile unit of muscle fibers, made up of actin (thin filaments) and myosin (thick filaments) proteins
Sarcomere
- Why is the inside of cell negative if K+ is positive?
K+ is able to diffuse out of cell freely but other larger negative molecules cannot.
A specialized form of the endoplasmic reticulum that stores and releases calcium ions
Sarcoplasmic Reticulum (SR):
Extensions of the sarcolemma that penetrate into the cell’s interior.
T-tubules (Transverse Tubules
Muscle fibers are multinucleated, meaning they contain more than one nucleus, which helps with the synthesis of proteins required for muscle function and repair
Nuclei
Resting Membrane Potential
Outside cell
Na+
+ charge
Na+ channels closed
Inside cell
K+
-charge
Some K+ channels open
is where the motor neuron communicates with the muscle fiber.
- The neuromuscular junction
- When a nerve impulse reaches the _____
NMJ
Is the momentary reversal of membrane potential that is the basis for electrical signaling within the neurons
Action Potential
nerve cells that carry action potentials to muscle fibers
- Motor neuron:
where nerve cell and muscle fiber meet
- Neuromuscular junction (synapse):
- chemicals that stimulate or inhibit a muscle fiber
- Ex. Acetylcholine
- Neurotransmitter:
end of nerve cell (axon)
- Presynaptic terminal:
muscle fiber membrane
- Postsynaptic membrane
space between presynpatic terminal and postsynaptic membrane
- Synpatic cleft:
- in presynaptic terminal
- store and release neurotransmitters
- Synaptic vesicle:
is the neurotransmitter that stimulates skeletal muscle
– Acetylcholine
group of muscle fibers that motor neuron stimulates
- Motor unit:
- Acetylcholine binds to receptor sites on Na+ channels, Na+ channels open, and Na+ rushes into postsynaptic terminal, this process is called?_______
(depolarization).
Steps in a Muscle Contraction (Sliding Filament Theory)
memorize and familiarize this bitch
- An action potential travels down motor neuron to presynaptic terminal causing Ca2+ channels to open.
- Ca2+ causes synaptic vesicles to release acetylcholine into synaptic cleft.
- Acetylcholine binds to receptor sites on Na+ channels, Na+ channels open, and Na+ rushes into postsynaptic terminal (depolarization).
- Na+ causes sarcolemma and t-tubules to increase the permeability of sarcoplasmic reticulum which releases stored calcium.
- Ca2+ binds to troponin which is attached to actin.
- Ca2+ binding to troponin causes tropomyosin to move exposing attachment sites for myosin.
- Myosin heads bind to actin.
- ATP is released from myosin heads and heads bend toward center of sarcomere.
- Bending forces actin to slide over myosin.
- Acetylcholinesterase (enzyme breaks down acetylcholine) is released, Na+ channels close, and muscle contraction stops.
– Gap between nerve and muscle filled with interstitial fluid
- Synaptic cleft
– Association site of axon terminal of the motor neuron and sarcolemma of a muscle
- Neuromuscular junction
The Nerve Stimulus and Action Potential
memorize and familiarize the steps of this bitch
Step 1: Calcium channels open, and calcium ions enter the axon terminal
Step 2: Calcium ion entry causes some synaptic vesicles to release acetylcholine (ACh)
Step 3: ACh diffuses across th synaptic cleft and attaches to receptors on the sarcolemma of the muscle cell
Step 4: If enough ACh is
released, the sarcolemma becomes temporarily more permeable to sodium ions (Na+
Step 5: Depolarization opens more sodium channels that allow sodium ions to enter the cell
Step 6: Acetylcholinesterase (AChE) breaks down acetylcholine into acetic acid and choline
- Na+ channels close
- change back to resting potential
Repolarization
explain the duration of Creatine Phosphate
This system provides energy for about 10-15 seconds of maximum effort.Location: Occurs in the cytoplasm of muscle cells
- What causes filaments to slide?
– Calcium ions (Ca2+) bind regulatory proteins on thin filaments and expose myosin-binding sites, allowing the myosin heads on the thick filaments to attach
– Each cross bridge pivots, causing the thin filaments to
slide toward the center of the sarcomere
– Contraction occurs, and the cell shortens
– During a contraction, a cross bridge attaches and detaches several times
is the primary energy source for muscle contraction, and it must be continuously replenished during physical activity.
ATP (adenosine triphosphate
This is the fastest way to regenerate ATP, especially during short bursts of intense activity (like sprinting or weightlifting).
Creatine Phosphate (Phosphocreatine) System
This pathway provides ATP when oxygen is not readily available, such as during short, high-intensity exercise.
Anaerobic Glycolysis (Lactic Acid System)
Creatine phosphate for quick, short bursts of energy.Anaerobic glycolysis for short to medium bursts when oxygen is low.
Replenishment
explain the reaction of Creatine Phosphate
Creatine phosphate (CrP) donates a phosphate group to ADP, quickly reforming ATP.
for sustained energy during long-term, low-intensity activities.
Aerobic respiration
for quick, short bursts of energy.
Creatine phosphate
for short to medium bursts when oxygen is low.
Anaerobic glycolysis
– Only energy source that can be used to directly power muscle contraction
- ATP
Muscle fiber contraction is ______ meaning it will contract to its fullest when stimulated adequately
“all-or-none,”
different degrees of skeletal muscle shortening
– Graded responses
- Graded responses can be produced in two ways
– By changing the frequency of muscle stimulation
– By changing the number of muscle cells being stimulated at one time
- Single, brief, jerky contraction
- Not a normal muscle function
– Muscle twitch
is achieved when the muscle is stimulated so rapidly that no evidence of relaxation is seen
– Fused (complete) tetanus
– When stimulations become more frequent, muscle contractions get
get stronger and smoother
- During a muscle contraction, H zone and I band shorten but A band _______
stays the same
weakest stimulus needed to produce a response
- Threshold:
muscle contracts or doesn’t (no in between)
- All or None Law
rapid contraction and relaxation of a muscle
- Twitch
muscle remains contracted
- Tetanus:
exercise (biking, jogging) results in stronger, more flexible muscles with greater resistance to fatigue
* Makes body metabolism more efficient
* Improves digestion, coordination
– Aerobic (endurance)
exercise (weight lifting) increases muscle size and strength
* Individual muscle fibers enlarge
– Resistance (isometric)
constant tension over a long period of time
- Tone
amount of tension increases (weight)
- Isometric
amount of repetitions increases
- Isotonic:
- Contract slowly
- Fatigue slowly
- Long distance runners
- Use aerobic respiration
- Energy from fat
- Dark meat
- Red or dark because of myoglobin
Slow Twitch Fibers
– Muscle remains firm, healthy, and constantly ready for action
- Muscle tone
Slow Twitch Fibers
- Contract slowly
- Fatigue slowly
- Long distance runners
- Use aerobic respiration
- Energy from fat
- Dark meat
- Red or dark because of myoglobin
helps O2 bind in muscle
- Myoglobin
- Contract quickly
- Fatigue quickly
- Sprinters
- Use anaerobic respiration
- Energy from glycogen
- White meat
Fast Twitch Fibers
- When the muscle contracts, the insertion moves ____the origin
toward the origin
Fast Twitch Fibers
- Contract quickly
- Fatigue quickly
- Sprinters
- Use anaerobic respiration
- Energy from glycogen
- White meat
– Decreases the angle of the joint
– Brings two bones closer together
- Flexion
attachment to a movable bone
- Insertion
attachment to an immovable or less movable bone
- Origin
– Opposite of flexion
– Increases angle between two bones
– Typical of straightening the elbow or knee
– Extension beyond 180º is hyperextension
- Extension
– Movement of a bone around its longitudinal axis
– Common in ball-and- socket joints
- Rotation
– Movement of a limb away from the midline
- Abduction
– Opposite of abduction
– Movement of a limb toward
the midline
- Adduction
– Combination of flexion, extension, abduction, and adduction
- Circumduction
– Lifting the foot so that the superior surface approaches the shin (toward the dorsum)
- Dorsiflexion
– Turning sole of foot
laterally
- Eversion
– Forearm rotates laterally so palm faces anteriorly
– Radius and ulna are parallel
- Supination
– Turning sole of foot
medially
- Inversion
– Pointing the toes away from the head
- Plantar flexion
Moving the thumb to touch the tips of other fingers on the same hand
- Opposition
- In general, groups of muscles that produce ____ lie on ____ of a joint
opposite actions
opposite sides
– Forearm rotates medially so palm faces posteriorly
– Radius and ulna cross each other like an X
- Pronation
muscle with the major responsibility for a certain movement
- Prime mover
muscle that opposes or reverses a prime mover
- Antagonist
specialized synergists that hold a bone still or stabilize the origin of a prime mover
- Fixator
muscle that aids a prime mover in a movement or reduces undesirable movements
Synergist
nonmovable end
- Origin
movable end
- Insertion
middle
- Belly
muscles that work together
- Synergists
muscles that oppose each other
- Antagonist:
