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Anatomy chap 10
Anatomy dogs! Mostly muscles!
108
Anatomy
Undergraduate 1
11/06/2011

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Term
Movement
Definition
sometimes locomotion, sometimes movement within given area
Term
Posture
Definition
maintains body in stable positions
Term
Thermogenesis
Definition
heat production - as much as 85% of body heat is from muscle contractions
Term
Regulating organ volume
Definition
contraction of sphincters may prevent outflow of contents of hollow organ
Term
Excitability (irritability)
Definition
ability to receive and respond to stimuli
Term
Contractility
Definition
ability to shorten and thicken
Term
Extensibility
Definition
ability to stretch
Term
Elasticity
Definition
ability to return to original shape after stretching
Term
Skeletal
Definition
striated, voluntary muscle
Term
Smooth
Definition
visceral, involuntary muscle
Term
Cardiac
Definition
striated, involuntary
Term
Epimysium
Definition
- fibrous connective tissue sheath that envelops each muscle (around the muscle)
Term
Perimysium
Definition
partitions each muscle into fascicles or bundles of fibers
Term
Endomysium
Definition
extension between individual muscle fibers
Term
Tendon
Definition
strong, tough cord, continuous at one end with fibrous wrappings of muscle and other end with periosteum
Term
Aponeurosis
Definition
- broad flat sheet of fibrous connective tissue continuous at one border with fibrous wrappings of muscle and at other border with fibrous coverings of adjacent structure, usually another muscle (ex. The tissue that holds the scalpulas together.)
Term
Tendon sheaths
Definition
tubes of fibrous connective tissue that enclose certain tendons (wrist and ankle); synovial membrane lines tendon sheaths
Term
Superficial fascia (subcutaneous layer)
Definition
Stores water and fat
Forms layer of insulation
Provides mechanical protection against blows
Provides pathway for nerves and blood vessels to enter and exit muscles
Term
Deep fascia
Definition
layer of dense fibrous connective tissue underlying superficial fascia; extensions of deep fascia form epimysium, etc.; and also enclose viscera, glands, blood vessels, and nerves
Term
Sarcolemma
Definition
cell membrane of muscle fiber
Term
Sarcoplasm
Definition
cytoplasm of muscle fiber
Term
Sarcoplasmic reticulum
Definition
smooth endoplasmic reticulum
Term
Myofibrils
Definition
fine fibers packed close together in sarcoplasm; consist of 3 kinds of myofilaments
Term
Sarcomere
Definition
section of myofibril between Z lines (Unit of muscle contraction)
Term
Thick filaments
Definition
made of myosin molecules; heads of myosin are cross bridges of thick filaments
Term
Thin filaments
Definition
- actin, tropomyosin, and troponin molecules arranged in complex fashion; contains myosin-binding site
Term
Elastic filaments
Definition
- titin (connectin); anchors thick filaments to Z discs; stabilizes thick filaments
Term
A bands (anisotropic)
Definition
Dark Stripes, composed of both thick and thin filaments
Term
H zone runs across midsection of each dark A band
Definition
composed only of thick filaments
Term
M line
Definition
- divides H zone; formed by protein molecules that connect adjacent thick filaments
Term
I bands (isotropic)
Definition
Light Stripes, - composed only of thin filaments
Term
Dark Z discs extends across center of each light I band
Definition
- regions of dense material; separates sarcomeres
Term
Sarcoplasmic reticulum (SR)
Definition
encircles each myofibril; stores calcium; contains calcium release channels (pores)
Term
Transverse tubules
Definition
tunnel-like infoldings of sarcolemma in region of Z discs; on either side are dilated end sacs of SR called terminal cisterns
Term
Triad
Definition
triple-layered structure consisting of T tubule sandwiched between sacs of sarcoplasmic reticulum
Term
One motor neuron together with skeletal muscle fibers it supplies
Definition
constitutes a motor unit
Term
Number of muscle fibers per motor unit varies
Definition
Learn it dawg!
Term
More precise movements produced by muscle in which motor units include fewer muscle fibers
Definition
(voice 2-3 muscle fibers/unit; gross movements - gastrocnemius as many as 2000/unit)
Term
Synapse found between
Definition
motor neuron and skeletal muscle
Term
Axon of motor neuron branches into
Definition
axon terminals which contain synaptic vescicles
Term
Vescicles contain
Definition
neurotransmitter substance, acetylcholine (ACh), which diffuses across synaptic cleft
Term
Muscle fiber contains motor end plate which contains
Definition
acetylcholine receptors
Term
recognize and bind to ACh which opens channels for Na+ to diffuse into
Definition
muscle fiber generating action potential which leads to muscle contraction
Term
Sliding filament theory
Definition
Cross bridges of thick filaments (myosin) attach to thin filaments (actin) and pull them toward the middle of the sarcomere
Term
In uncontracted state - calcium is
Definition
stored in SR, ATP is attached to cross bridges, and tropomyosin-troponin complex is attached to calcium
Term
Upon stimulation by nerve impulse, acetylcholine is
Definition
by motor axon synaptic end bulbs
Term
ACh diffuses across myoneural junction and
Definition
initiates an action potential (movement of sodium into fiber and potassium out)
Term
Impulse is conveyed from
Definition
T tubules to sarcoplasmic reticulum which releases its calcium by opening calcium release channels
Term
Calcium ions combine with
Definition
troponin causing troponin-tropomyosin complex to move which exposes the myosin-binding site on the actin molecule.
Term
Energy released from ATP is used for
Definition
attachment of myosin cross bridges to myosin-binding sites on actin; energy is then used to pull actin filaments inward (power stroke) resulting in sliding of thin filaments past thick filaments
Term
Sliding draws Z discs
Definition
toward each other, sarcomere shortens, muscle fibers contract, muscle contracts
Term
After action potential, ACh is
Definition
inactivated by acetylcholinesterase (AChE)
Term
calcium is transported back into
Definition
sarcoplasmic reticulum
Term
tropomyosin-troponin complex reattaches
Definition
to actin
Term
myosin cross bridges separate from
Definition
actin; ATP is resynthesized; muscle relaxes
Term
Phosphogen system
Definition
– Muscle fibers contain creatine phosphate (phosphocreatine) which breaks down to creatine + phosphate + energy
– 3-5 times more plentiful than ATP
– Used for maximal short bursts of energy (15 secs)
Term
Phosphate and energy can be used to remake
Definition
ATP
Term
Glycogen-lactic acid system
Definition
When creatine phosphate gone, glucose catabolized and glycogen broken down

– If oxygen is not available, anaerobic respiration takes place in the form of glycolysis with formation of lactic acid and some energy (30-40 sec)
Term
Lactic acid diffuses into blood
Definition
liver can convert lactic acid back to glucose
Term
Aerobic system
Definition
– Activity longer than 30 sec. depends on aerobic process
Term
– With oxygen available cellular respiration occurs to produce
Definition
ATP and carbon dioxide and water
Term
oxygen comes from blood and is released from
Definition
from myoglobin inside muscle fibers
Term
– Provide ATP for prolonged activity as long as
Definition
oxygen available and glucose available
Term
Maximum rate of oxygen consumption is called
Definition
maximal oxygen uptake; affected by gender, age, size, training
Term
After heavy muscle activity
Definition
heavy breathing continues to repay oxygen used in activity (oxygen debt or recovery oxygen consumption)

All or none law
Term
Muscle cells either
Definition
contract with all force possible under existing conditions or do not contract at all
Term
Tonic contraction (tone, tonus)
Definition
– Continual, partial contractions produced by simultaneous activation of small group of motor units, followed by relaxation of their fibers and activation of another group of motor units
– Specialized receptors called muscle spindles and neurotendinous end-organs detect degree of muscle stretch
Term
Isotonic contraction
Definition
muscle shortens but its tension remains constant; isotonic contractions produce movements
Term
Concentric contractions
Definition
muscle shortens and pulls on another structure to produce movement and reduce angle of joint
Term
Eccentric contractions
Definition
- overall length of muscle increases (repeated contractions produce more muscle damage than concentric)
Term
Isometric contractions
Definition
muscle length remains unchanged but tension within muscle increases; isometric contractions “tighten” muscles but do not produce movements; energy expended
Term
Twitch contraction
Definition
quick, jerky contraction in response to single stimulus; consists of 3 phases - latent period(before the muscle contracts), contraction phase, and relaxation phase; rare in normal body
Term
Tetanic contraction (tetanus)
Definition
sustained smooth contraction produced by series of stimuli bombarding muscle in rapid succession
Term
Treppe (staircase phenomenon)
Definition
series of increasingly stronger contractions in response to constant-strength stimuli applied at rate of 1 or 2 per second (ex) Getting your muscles to warm up before an athletic event!)
Term
Contracture
Definition
incomplete relaxation after repeated stimulation (ex. Like Kale’s mom-with her curled up arm and hand-you can’t relax it)[Hannah-you wouldn't understand. lol]
Term
Fatigue
Definition
failure of muscle to contract in response to strongest stimuli after repeated stimulation; true muscle fatigue seldom occurs in body (It seldom occur-we can usually get some response from our muscles)
Term
skeletal muscle fibers
Definition
vary in colors
Term
– Red muscle fibers
Definition
high myoglobin(Stores oxygen) content; more mitochondria and blood capillaries. (Muscles are used the most, ex. Chicken-white and dark meat. Dark meat are in the legs-and contract a lot more-meaning they need more oxygen and glucose. The breast wouldn’t be as much)
Term
– White muscle fibers
Definition
low myoglobin content (ex. Chicken breast) [This is a generality.
Term
Slow oxidative (type I) fibers (slow twitch or fatigue-resistant fibers)
Definition
• Look red and have high capacity to generate ATP by aerobic system
• Split ATP at slow rate so have slow contraction velocity
• Resistant to fatigue; capable of prolonged, sustained contractions
• Found in head and neck muscles(posture, marathon runners have these types of fibers)
Term
Fast oxidative (type II) fibers (fast-twitch A or fatigue-resistant fibers)
Definition
• Look red and have high capacity to generate ATP
• Split ATP rapidly and have fast contraction velocity
• Resistant to fatigue
• Found in sprinter's leg muscles (walking, running)
Term
Fast glycolytic (type II) fibers (fast-twitch B or fatigable fibers)
Definition
• Look white; contain lots of glycogen
• Generate ATP by anaerobic processes so fatigue easily
• Largest diameter fibers
• Split ATP fast so strong, rapid contraction
• Muscles of arm (weight lifting, throwing)
Term
Fibers are
Definition
quadrangular shaped and single nucleus [Fibers are striated, intercalated discs]
Term
Fibers branch interconnect
Definition
with each other; intercalated discs are irregular transverse thickenings of sarcolemma that connects neighboring fibers
Term
Two networks of fibers
Definition
one in atria and one in ventricles; allows entire network to contract together
Term
Cardiac muscles Contracts and relaxes an average
Definition
75 times/minute thus requiring constant oxygen supply [Needs to create ATP]
Term
Cardiac Muscles
Definition
Contains more mitochondria than skeletal muscle so depends on aerobic system to generate ATP
Term
Cardiac muscle can contract without
Definition
extrinsic stimulus; has specialized conducting network within heart (autorhythmicity)
Term
Remains contracted 10-15 times longer than skeletal muscle but also
Definition
has long refractor period
Term
Smooth muscles are
Definition
Smaller fibers than skeletal; thickest in middle and tapered at ends with single nucleus in middle
Term
Smooth muscles contains
Definition
Contains thick and thin filaments but not arranged in sarcomeres as in [skeletal and cardiac] striated muscle
Term
Smooth muscles contain what kind of filaments
Definition
Contain intermediate filaments which attach to structures called dense bodies (similar to Z discs); some dense bodies are scattered in sarcoplasm and some attach to -sarcolemma [shortens the cell=lengthwise shortening of muscle fibers]
Term
Bundles of intermediate fibers stretch from
Definition
one dense body to another; contraction causes intermediate filaments to pull on dense bodies causing a lengthwise shortening of muscle fiber
Term
Two types of smooth muscles
Definition
visceral and Multiunit
Term
Visceral (single unit) smooth muscle
Definition
most common; forms part of walls of small arteries and veins and hollow viscera such as stomach, intestines, uterus, and bladder; contain gap junctions which allows stimulation of many fibers at once
Term
Multiunit smooth muscle
Definition
individual fibers each with own motor neuron terminals and with few gap junctions between neighboring fibers; stimulation causes contraction of only one fiber; found in walls of large arteries, in large airways of lungs, in arrector pili muscles, and in radial and circular muscles of iris [When the stimulus comes-it only stimulates one or two fibers-this is from more precise movements. These are found in the arteries, the bronchi of the lungs]
Term
Contraction starts
Definition
more slowly and lasts longer than striated muscle; can shorten and stretch more than striated
Term
No T tubules and calcium enters through
Definition
sarcolemma as well as released from SR
Term
Contains calmodulin (it’s like troponin) and myosin light chain kinase which are needed for myosin binding to actin
Definition
for myosin binding to actin
Term
Muscle tissue comes from
Definition
mesoderm pg. 357 (good comparison chart for muscles) 358 (Developmental anatomy)
Term
Calcium moves slowly out of cell, which delays
Definition
relaxation resulting in prolonged muscle tone
Term
Smooth muscle contraction is controlled
Definition
by the autonomic nervous system
Term
Muscles arise from mesoderm except
Definition
for muscles of iris and arrector pili muscles
Term
Mesoderm forms somites (segmented blocks)
Definition
1st pair appears at 20 days and by 30 days have all 44 pairs of somites
Term
Sclerotome
Definition
forms vertebrae
Term
Dermatome
Definition
forms connective tissue and dermis
Term
– Myotome
Definition
forms skeletal muscles
Term
Cardiac and smooth muscle develop from
Definition
other mesodermal cells (primarily splanchnic mesoderm)
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