Muscle Tissue 3 Flashcards

Terms Definitions


fused tetanus
Muscle plasma membrane
Attatches muscle to bone
H zone
Thick myofilaments only
Substance theat transmits nerve impulses across a synapse
attachs thin filaments to sacrolemma
Muscle is:
highly innervated and vascularized
creation of action potentials
nerurons connect to each fiber
nutrients and oxygen for atp synthesis
waste removal
every muscle fiber close to one or more capillaries
An increase in muscle mass
muscle shortens and does work
I (isotropic) band
Thin myofilaments only
Muscle contraction is ultimately controlled by nerve-initiated electrical impulses that travel along the ______
muscle tissue functions
movement, maintain posture, stabilizing joints, generating body heat
Contain 2 types of myofilaments(actin myofilaments and myosin myofilaments)
sacroplasmic reticulum
stores calcium released through calcium release channelscontains active calcium transport pumpactively pulls calcium into sr during relaxation
Anaerobic Respiration
No oxygen
Take place around protein filaments
Fast pathway (glycolysis)
Produces ATP 2 1/2 times faster than aerobic
Lasts only 30-40 seconds of intense exercise
Not efficient
waste produce is lactic acid
Leads to muscle fatigue
Leaves muscle tissue with 30 mins after exercise stops
2 ATP per glucose (5% as much ATP from glucose as the aerobic pathway)
Mainly used for short bursts of energy
100 meter swim
A sustained contraction with no relaction between stimuli
Skeletal muscles are responsible for:
...all locomotion
NAMEis a pigment that transports oxygen in the blood
NAMEis an inhibitory subunit that binds calicum ions
Motor neuron
Neurons that stimulate skeletal muscle fibers to contract
describe endomysium.
fine areolar connective tissue surrounding each muscle fiber
the sracoplasm contains unsusually large amounts of____ (granules of stored glycogen) , and ____, a red pigment that stores oxygen
glycosomes, myogobin
External oblique
flexes vertebral column and rotates the trunk (part of the body from below the neck down to the waist) and bends it from the side (laterally)
within each muscle there are bundles of muscle fibers that are grouped into fascicles or bundles that are wrapped by perimysium much like if you were to wrap tightly several hundred strands of uncooked spaghetti with saran wrap
Calcium ions
Stimulates movement of vesicles and ultimately muscles
combination of a pair of terminal cisternae (bulges) of sacroplasmic reticulum  (SR) on either side of a T-tubule
function to release calcium
motor end plate
portion of muscle sacrolemmacontains ach receptors on integral proteinsligand gated ion channels
A rigid structure that allows movement around a pivot joint
Red Muscle Fibers
Slow twitch oxidative, fatigue resistant fibers. Red due to myoglobin. Found in long distance runners.
Somatic motor neurons
neurons that activate muscle fibers
NAMEis a layer of fibrous connectve tissue that surrounds each fascicle
Which muscle are the involunatry muscles?
(1)smooth (2)cardiac
T or Fonce initiated, the action potential is stoppable
stack or unit of myofilamentsfrom z line to z line
what are the 3 connective tissue sheaths of skeletal muscle?


The innervating nerve fibers of smooth muscle tissue, which are part of the autonomic nervous system, have numerous bulbous swellings, called _____
Motor unit
consist of one alpha motor neuron (large lower motor neurons of the brainstem and spinal cord) together with all the muscle fibers it stimulates
Actin Myofilaments
Myofibrils that are active in muscular contractions, cellular movement, and maintenance of cell shape
Elastic Filaments
Made of titin. They anchor thick filaments to the z-disc.
Disuse Atrophy
Results form lack of use
Loss of neural stimulation
Begins as soon as muscles become immobilized
Lose muscle strength at a rate of about 5% per day
Lost muscle tissue may be replaced by fibrous connective tissue
Action Potential
An electrical signal consisting of the depolarization and subsequent repolarization of a nerve or muscle cell membrane.Travels along the membrane and functions as a signal to initiate an activity (i.e. a muscle contraction)
What is the contractile unit of a muscle cell?
Immediatly after the (1), the sacrolemma permeability changes
depolarization wave passes
NAMeis a light stripe on the midsection of each band
H zone
arrangements of muscle fibers
1. circular (mouth)2. parallel (abs-straight)3. convergent (pectoralis)4. pennate (feather-like)
The central ___ filaments extend the entire length of the A band while The more lateral ____ filaments extend across the I band and partway into the A band.
thick, thin
smooth muscle characteristics
found in visceral organ walls(stomach, intestine), uninucleate, no striations, involuntary, never fatigue
the ability of the muscle to shorten - contract
basic characteristics of muscles 1.
electrial excitability production of action potentials across the cellular membrane
Small motor units
Contain few muscles and are found where precise movements are needed. Like in the muscles of the eye.
What is TnT?
is an inhibitory subunit that binds to tropomyosin and helps to postion it on actin
first class lever
ex: head and neck-fulcrum is centered between resistance and effort force
Because _ ___ are continuations of the sarcolemma, they can and do conduct impulses to the deepest regions of the muscle cell and to every sarcomere
T tubules
Skeletal Muscle1. location2. in/voluntary3. cell appearance4. Speed of contraction5. Ability to regenerate
1. attaches to skeleton. (bone or cartilage) In the face, it goes through skin.2. Voluntary, to a certain extent3. Striated. Multiple nuclei. 4. Can be slow or rapid.5. low
2. basic characteristcs of muscles
contractility tension is created as muscle fibers shorten ( contract)
Thin filaments (actin)
Extend across the I band and partway into the A band
What are four important functions for the muscles? (4)
(1)movement (2)maintains posture (3)stabilizes joints (4)generates heat
stay the same
What happens to the length of thick and thin myofilaments during muscle contraction?
muscle development. how musculature of trunk and limbs is formed
myotomes from somites, embryo stuff
What is an indirect muscle attachment?
is when the muscle's connective tissue wrapping's extend beyound the muscle either as a ropelike tendon or aponeurosis
___ is the ability to receive and respond to a stimulus, that is, any change in the environment whether inside or outside the body.
Excitability, also termed responsiveness or irritability
What is the cross bridge?
is where the myosin heads link the thick and thin filaments
differentiate between the two types of myofilaments
Thick: myosin with heavy and light subunits (15 nm diameter)
Thin: made of troponin and tropomyosin (5nm diameter)
(1) results in the contraction of a muscle
the iniatiation of the action potential
what are the functions of the smooth muscles?
to force fluids and other substances through internal body channels
What is the role of Mg in sliding filament model?
Allows the hydrolysis of ATP to ADP+ PI
surrounds the entire muscle
What does T-Tubules stand for?
Transverse Tubules
What does ATP stand for?
Adenosine triphosphate
What improves muscle performance (speed and proportionality)?
Negative feedback
reticular fibers and basal lamina surrounding FIBERS (innermost)
What does aerobic endurance emphasize?
slow twitch fibers
skeletal muscle
striated muscle used to create movement applying force to bones and joints through contraction. Multiple nuclei.
In a picture of striated banding structure determine where the myofibril is, one sarcomere, I band, A band, H zone, M line, thick and thin filaments
What are T-Tubules?
Tubular extensions of cell membrane into a cell.
What are Sarcomeres?
The basic contractile unit of muscles.
What is Rigor Mortis?
A fixed muscular contraction after death.
What are Myofibrils?
Bundles of protein filaments that are responsible for muscle contraction.
epithelial tissue
sheets of cells that cover the body's surfaces. Multiple functions include protection, sensation, absorption, secretion, excretion, diffusion, cleaning, and reducing friction
Sliding Filament Theory
Amount of tension is proportionate to the overlap lenght of the thick and thin filaments
- Sarcomere length shortens as the muscle contracts and the filaments slide over each other
What is an Isometric Contraction?
muscle tension = resistance, causing muscle to stay the same length
How is aerobic endurance improved?
By building up cardiovascular fitness through repetitive training
Describe smooth muscle in the uterus
1. hypertrophy (increase size)
2. hyperplasia ( increase number)
What is the muscle spindle?
A proprioceptor sensing strain and velocity of contraction for delicate movement control with intrafusal and extrafusal fibers
What do the connective tissue elements of muscle contribute to the muscle? (2)
1. mechanical force2. nutrition
What is the Sarcoplasmic Reticulumn responsile for?
Releasing calcium in response to Action Potential in T-Tubules.
Describe:1. slow twitch fibers2. fast twitch fibers
1. oxidative fibers depending on oxidative phosphorylation (mitochondria and myoglobin) RED2. glycolytic fibers - WHITE (due to glycogen) - anaerobic glycolysisoxidative glycolytic fibers (between red and white)
Where can smooth muscle be found?
1. GI tract
2. uterus
3. blood vessels
4. ducts and tubes
What are the 3 types of Skeletal muscle fibers?
Fast, Slow, and Intermediate Fibers
Skeletal muscle:
1. varies with regard to fiber type (fast v. slow)
2. contracts more slowly than heart muscle
3. utilizes lipid preferentially for eneryg
4. contraction is inhibited by Ach
5. contracts more forecefully when sarcomere length exceeds
1. Fast and slow twitch fibers are characteristic
Resting skeletal muscle shave about ___mM ADP, ____mM ATP, and ____ mM PC
ADP = 0.01
ATP = 6
PC = 32
What happens when the Active Site becomes exposed?
Myosin heads on the adjacent Thick Filaments bind to them.
What are the different banding components of striated muscles?
What is a sarcomere?
1. I-band - thin filament with light staining
2. Z-line -middle of the I band
3. A -band - thick filament with thick/thin overlap region of dark staining
4. H-zone - central region of A band (ONLY thick filament)
5. M-line - midline of A band
Sarcomere - a unit of contraction (from Z to Z line), myofibril
What happens when the Zone of Overlap is too small?
Tension is lowered because not all myosin heads can attach to the thin filaments
What can be found in the intercalated discs?
1. fsaciae adherens 2. desmosomes 3. gap junctions
Describe the steps of the skeletal muscle contraction.
1. The motor neuron in the spinal cord causes an action potential (the motor endplates have specialized synapses)
2. Acetylcholine (Ach) is released from the terminal bouton into the synaptic cleft (which contains Ach-esterase)
3. Ach-receptors are found in the junctional folds and the Ach reaches the T system and DHPR receptor
4. Ach reaches the feet, terminal cisternae of SR, RyR1
5. Ca2+ is released from the RyR1 and binds to Tnc which binds to TnI which binds to TnT and binds to tropomyosin, uncovering the actin active site
6. Actin and myosin form a cross-bridge - contraction
7. Ca2+ is sequestered by calsequestrin in the SR - relaxation
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