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Name the three types of muscle tissue?
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What is the definition of skeletal muscle tissue?
Pulls on bones
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Define smooth muscle tissue?
- Pushes fluids, & solids
- Rythmic
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Define cardic muscle tissue?
Pushes blood
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Name the four characteristics of all muscle tissue?
- Contractibility
- Excitability
- Extensibility
- Elasticity
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What is contractibilty?
Primary function
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What is purpose of excitability?
Respond to a stimulus
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What is the purpose of extensibility?
- Extend beyond its original
- Lenght & still contract
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What is the purpose of elasticity?
Rebound to its original length
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How many skeletal muscles are there?
Over 700
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Each muscle is what type of tissue?
An organ
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What type of muscles are skeletal?
Voluntary
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Name the functions of skeletal muscles?
- Produce skeletal movement by pulling on muscles
- Maintain body posture, tension continual in some muscles
- Support soft tissue, abdominal wall
- Guard orifices, voluntary control over swallowing, defection, urination
- Heat production, homeostasis (body temp.)
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Define muscle fiber?
A long cylindrical "cell"
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How long are huge fused "cells"?
16 inches
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Name the three connective tissue wrappings of the skeletal muscles?
- Endomysium
- Perimysium
- Epimysium
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What are muscle fibers arranged into?
Fascicles
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Where is endomysium?
Around single muscle fiber
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Where is perimysium?
Around a fascicle (bundle) of fibers
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Where is epimysium found?
Covers the entire skeletal muscle.
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What function does the epimysium serve? What is it made of?
- Overcoat
- Dense irregular tissue
- Blood vessels & nerves
- Epimysium continous with tendon
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What is the funciton of perimysium? What is it made of?
- Divides muscle into compartments called fascicles
- Blood vessels & nerves; collagen &
- Elastic fibers
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What is the function of the endomysium? What is it made of?
- Surrounds each muscle fiber (fused cells)
- Delicate network with capillaries;
- Recticular fibers
- Myosatellite cells
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What is aponeuroses?
Flat broad tendons
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What are characteristics of connective tissue sheaths?
- Endomysium and perimysium are interwoven
- All sheaths continous with muscle tendon &
- Aponeuroses. Take force of contraction
- To bone, muscle or skin
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What is muscle fiber? Name some characteristics.
- Muscle fiber is formed during development
- From the fusion of several undifferentiated
- Immature cells known as myoblasts into long,
- Cylindrical, multi-nucleanated cells.
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What are myofibrils?
- Cylindrical organelles found within
- Muscle cells
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What is the sarcolemma?
- Plasma membrane of a muscle cell
- Invaginates into the cytoplasm of the muscle cell,
- Forming membranous tubules called
- Transverse tubules (T-tubules).
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What is the scaroplasma? What does it contain?
- The cytoplasm of the muscle cell
- Myofibrils with myofilaments (protein fibers)
- Multinucleated (pushed to cell membrane)
- Mitochondria (more than any other cells of the body)
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What is the sarcoplasmic reticulum? Where is it located? What else about it is important?
- Corresponds to smooth endoplasmic reticulum
- Sits as a sleeve around myofibrils
- Has terminal cisternae which holds
- And releases Ca++ ions
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What fills the myofibril?
Myofilaments
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Beginning with skeletal muscle what is the are next layers contained?
- Skeletal muscle contains muscle fascicle
- Muscle fascicle contains muscle fibers
- Muscle fiber contains myofibrils
- Myofibrils surrounded by sarcoplasmic
- Reticulum consits of sacromeres
- Contains thin and thick filaments
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What is actin?
Thin strands of protein
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What is myosin?
Thick filaments of protein
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Define sacromere.
- Bundle of thin and thick filaments
- Repeating units formed of actin
- And myosin
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Which area of the muscle cell does the actual contracting?
- Sarcomere
- Contracts to 1/3 of
- Length
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How many sacromeres/myofibrils are there?
10,000 linearly arranged
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On a microscopic slide of muscle what is indicated by the light and dark bands?
- Zones of actin
- & Myosin overlap
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What is the length of a relaxed sacromere?
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What is muscle contraction?
- Muscle fiber shorten in length (exerts a pull)
- Result of interatcions between action &
- Myosin filaments
- (Sliding filament theory)
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What has been observed about the sliding filament theory (of muscle contraction)?
- The H band & I band
- Get smaller the Z lines
- Get closer together
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When we use the word bands to describe the lines of myosin and actin filaments what is meant? Why?
- They are actually discs
- As the structure is cylindrical
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Describe the sliding filament theory.
- Myosin heads attache to actin & pull
- It toward the M line myosin head is
- The crossbridge myosin head binds,
- Pulls, detaches, re-sets, repeats
- Sarcomere shortens
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When muscles contract what is the ration of myosin to actin?
3 myosin to 1 actin filament
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What is tropomyosin molecules?
- An actin binding protein that forms
- A long chain that covers the active sites
- Preventing actin-myosin interaction
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What is function of troponin?
Holds the tropomyosin in place
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What does sarkos mean?
Flesh
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What does lemma mean?
Husk
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What happens in the zone of over lap?
- The thin filaments pass between
- The thick filaments
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What is the triad area?
- Combination of the terminal cisternae
- & trasverse tubules
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What does the A band contain?
Area containing thick filaments
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What is region from the Z line to the A band?
- I band
- Which contains thin filaments
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What does the amount of tension depend on?
- Number of cross bridge
- Interactions that occur
- In the sarcomeres
- Individual structure
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When does contraction stop?
- When Ca++ are returned &
- Stored in sacroplasmic reticulum
- Uses ATP
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What does myosin need to detach from actin during contraction? What position does it return to?
- Require ATP and returns
- To "cocked" position
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Define Rigor Mortis
- Circulation ceases with death
- Skeletal muscles can not produce ATP without oxygen
- Fiber can not recapture Ca++ to SR, contraction continues
- No ATP to release myosin head from actin filament
- Muscle locks in contracted position
- "stiff as a board" lasts 15-20 hrs.
- Tell time of death
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What is each muscle controlled by?
A motor neuron
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What is each muslce fiber controlled by?
A motor neuron
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Where can a motor neuron's cell body by found?
In the spinal cord
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What do a motor neuron and muscle fiber make up?
Neuromuscular junction
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What is the axon? Where is it located?
- Long process of the motor neuron
- Extends to the fiber
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What is the motor end plate and synaptic terminal separated by?
Synaptic cleft
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What is the synaptic terminal?
- The expanded tip of the axon
- At the neuromuscular synapse
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Where is the ACh (acetylcholine) released?
- At the synaptic terminal
- Of the nerve
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What is the action potential?
- An electrical impulse (excitibilty) that sweeps over
- The suface of the sarcolemma
- & into each T tubule
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What generates the action potential?
- ACh is released into the synaptic cleft
- The ACh released then binds to receptor sites
- On the motor end plate, initiating a change in the
- Local transmembrane potential.
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What is the result of the action potential?
Contraction
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What enzyme breaks down the ACh molecules?
- AChE
- Acetylcholinesterase
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Define the motor unit?
- All of the muslce fibers
- Controlled by a single motor neuron
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Where are small motor units found? What is there function?
- Found in fingers
- For fine control
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What is fine control defined as?
- Fewer fibers controlled by one
- Neuron
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What does all or nothing mean?
- Each fiber contracts completely
- Or not at all
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What does the amount of tension depend on?
- Frequency of stimulation
- Number of motor units involved
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What gives the precise control of muscle tension?
Nervous system
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Define muscle twitch?
A single momentary contraction
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How is the amount of force determined?
- Depends of how many motor units
- Are activated (recruitment)
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Within a muscle are bundles of muscle fibers called what?
Fascicles
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How do muscle fibers arrange themselves within the fascicle?
They lie paralle to one another
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What are the four basic types of fascicle arrangements? What do they affect?
- Parallel
- Pennate
- Convergent
- Circular
- Power, range, & speed
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What is defined as a parallel muscle?
- Fibers run the length of the muscle
- (maximum shortening 1/3 of length)
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What type of muscle are most muscles in the body?
Parallel
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What is the shape of parallel muscles?
Strap-like or spindle shaped
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Define convergent muscles?
- Muscles having a broad origin;
- Fibers converge on a single insertion from
- Multiple directions
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What is the shape of convergent muscles?
Triangle or fan-shaped
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Define versatile? What muscle type is versatile?
- Direction of pull can be changed
- Convergent
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Define pennate muscles.
- Short fibers attach at oblique angles to a central
- Tendon
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What muscle types are the most powerful & have more tension?
Pennate
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What is unipennate?
All fibers on the same side of the tendon
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What is bipennate?
Muscle fibers on both sides of the tendon
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What is multipennate?
Tendon branches within the muscle
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Define circular muscles?
- Concentric rings around external body openings
- Usually sphincters or valves
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What do circular muscles guard?
Entrances/exits by contracting
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What is the minimum of points that every skeletal muscle is attached to bone or connective tissue?
- Two points
- If it's from bone-bone
- Always crosses articulation
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Where is the muscles origin attached to?
To the immovable bone
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Where does a muscle begin?
At an origin
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Where does a muscle end?
At the insertion
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Where is the insertion attached to?
The movable bone
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How does action occur?
As the insertion moves towards its origin
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Name the three primary actions?
- Prime movers (Agonists)
- Synergists
- Antagonists
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Define Agonists? Give examples.
- Cheifly responsible for producing a
- Particular movement
- Flexion at the elbow
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Define Synergists?
- Contracts, it assists the prime mover in
- Performing that action
- Provide additonal pull near the insertion
- Or stabilize the point of origin
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Give an example of a synergist.
- Latissimus dorsi assisted by
- Teres major pull the arm inferiorly
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Define antagonist? Give example.
- Oppose the action of the agonist (prime mover)
- If the agonist produces flexion, the antagonist
- Will produce extension
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What are fixators?
- Synergists that assist an agonist by preventing
- Movement at a joint and thereby stablizing
- The origin of the agonist.
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What is idea behind the principal of levers?
- Skeletal muscles do not work in isolation
- Muscles working with bone
- Simple machines make it easier to do work (with bone)
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Name the simple machines?
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Define lever? Name the parts of the body that correspond to lever system.
- A rigid bar (bones) that moves on a fulcrum (joint)
- (Fixed point) when a force (effort) (muscle contraction)
- Is applied to it to move a resistance (load)
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What is the first class lever? Give example.
- See saw
- They are rare in the body
- Occipital condyle & C1
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What is the second class lever? Give example
- Wheel barrow
- Force is magnified
- Resistance covers a shorter distance & is slower
- Uncommon
- Plantar flexion
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How common are the third class levers in the body? Name the characteristic of this type. Give examples
- Most skeletal muscle of the body
- Speed and distance increased at the expense of force
- Biceps brachii
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