Muscle Flashcards
Every cell in the human body is ________ to some extent.
Contractile
In muscle tissue, contractility is highly ________.
Developed
Muscles convert _______ energy into ________ energy.
- Chemical
- Mechanical
Three categories of muscle
- Smooth
- Skeletal
- Cardiac
Smooth muscle cells are fu_____, un______, responsive to _____, in_______, and found in _______.
- Fusiform
- Uninucleate
- ANS
- Involuntary
- Viscera
Skeletal muscle is associated with ________, vo______, and innervated by _____.
- Skeleton
- Voluntary
- CNS
In skeletal muscle, the cells are lo____, cy_____, mu_______, nuclei ______, contain large # of packed filaments called _______, and cells are called _______.
-long
-cylindrical
-multinucleate
-nuclei peripheral
myofibrils
-muscle fibers
In cardiac muscle, cells are similar to skeletal muscle cells but _____ and nuclei _____. It is found only in ______, in______, and au______.
- uninucleated
- central
- heart
- involuntary
- autorhythmic
Muscle cell
Muscle fiber
Cell membrane (plasmalemma)
Sarcolemma
Cytoplasm
Sarcoplasm
Endoplasmic reticulum
Sarcoplasmic reticulum
Longitudinal endoplasmic reticulum tubules
Sarcotubule
Bundle of myofibrils
Sarcomere
Histological unit of skeletal muscle is a ______.
Fiber
A fiber is a long, cylindrical __________ cell.
Multinucleate
Large numbers of muscle fibers are grouped into ________.
Fascicles
Fascicles are arranged in several forms to form different ______, such as _______, _______, etc.
- Muscles
- Bipennate
- Unipennate
CT surrounding the entire muscle is called _______.
Epimysium
CT surrounding the fascicles is called ________.
Perimysium
CT surrounding individual muscle fibers is called _________.
Endomysium
CT allows ______ and individual ______ of movement.
- Firmness
- Freedom
Skeletal muscle is richly supplied with ______.
Blood
Normal thickness of muscle fiber is _______ micrometers.
10-70
Uninucleate mesenchymal cells differentiate into ______ which fuse to form multinucleate ______, which lengthen and incorporate more ______.
- Myoblasts
- Myotubes
- Myoblasts
Some myoblasts fail to fuse and form _____ or _______ cells.
- Satellite
- Myosatellite
Myotubules then synthesize _________ (actin and myosin).
Myofilaments
In adults, further growth of muscles is either ________ of use or ______ of disuse.
- Hypertrophy
- Atrophy
Repair is by ________ which are a residual population of myoblasts.
-Satellite cells
All muscle fibers in a muscle are ______.
Not identical
Muscle fibers vary in _______ and _______ and physiological properties.
- Diameter
- Cytochemical
Most muscles contain a ______ of three kinds of fibers. The ____ of each depends on type of muscle activity.
- Mixture
- Percent
Muscles of low intensity contractions such as muscles of back and legs that support body weight have ________.
Red muscles
Contraction time for:
- Type I or Red Fibers
- Type IIA or Intermediate Fibers
- Type IIB or White Fibers
- Slow
- Fast
- Very Fast
Size of motor neurons for:
- Type I or Red Fibers
- Type IIA or Intermediate Fibers
- Type IIB or White Fibers
- Small
- Large
- Very Large
Resistance to fatigue for:
- Type I or Red Fibers
- Type IIA or Intermediate Fibers
- Type IIB or White Fibers
- High
- Intermediate
- Low
Activity used for:
- Type I or Red Fibers
- Type IIA or Intermediate Fibers
- Type IIB or White Fibers
- Aerobic
- Long term anaerobic
- Short term anaerobic
Force production for:
- Type I or Red Fibers
- Type IIA or Intermediate Fibers
- Type IIB or White Fibers
- Low
- High
- Very high
Mitochondrial density of:
- Type I or Red Fibers
- Type IIA or Intermediate Fibers
- Type IIB or White Fibers
- High
- High
- Low
Capillary density of:
- Type I or Red Fibers
- Type IIA or Intermediate Fibers
- Type IIB or White Fibers
- High
- Intermediate
- Low
Oxidative capacity of:
- Type I or Red Fibers
- Type IIA or Intermediate Fibers
- Type IIB or White Fibers
- High
- High
- Low
Glycolytic capacity of:
- Type I or Red Fibers
- Type IIA or Intermediate Fibers
- Type IIB or White Fibers
- Low
- High
- High
Major storage fuel of:
- Type I or Red Fibers
- Type IIA or Intermediate Fibers
- Type IIB or White Fibers
- Triglycerides
- Glycogen
- Glycogen
The structural components of a typical skeletal muscle fiber are:
- sa_______, sa_____, sa_______
- myo_______, ________ bands or _______
- ________ and _______ cells
- ________ nuclei
- ______ nucleoli per nucleus
- Sarcolemma, sarcoplasm, sarcoplasmic reticulum
- Myofibrils, transverse bands or striations
- Multinucleate and elongated cells
- Peripheral nuclei
- 1-2 nucleoli per nucleus
Sarcolemma inside is coated with ________ for mechanical reinforcement.
Dystrophin
Genetic disorder due to dystrophin deficiency
Duchenne muscular dystrophy
Duchenne muscular dystrophy affects ________ who are unable to walk and die before age 20. It’s manifestation is also reported in ________ muscle.
- Only boys and young men
- Cardiac
_____ droplets, ______ particles, and oxygen binding ______ are present in sarcoplasm.
- Lipid
- Glycogen
- Myoglobin
Myoglobin is of little significance in humans, but is important in ______ and ________.
- Birds
- Diving animals
In transverse sections, muscle fibers appear in polygonal shape termed __________.
Fields of Conheim
Anisotrophic or A bands
Dark bands
Isotrophic or I bands
Light bands
Length of A bands is _________ in all phases of contraction.
Constant
Length of I bands ______ during contraction.
Changes
Muscle fibers also contains __ and __ lines, __ zone, and ______.
- Z and M lines
- H zone
- Sarcomeres
SKM fiber contains all common ________, and the mitochondria are _______.
- Organelles
- Peripheral
SR is a system of membrane limited _______.
Sarcotubules
Sarcotubules from a close ________ canalicular network occupying narrow spaces between ________.
- Meshed
- Myofibrils
Sarcotubules are _________ in A band region but ________ in H region.
- Longitudinal
- Anastamose
In the ultrastructure of SKM fibers, ______ tubules, _______ cisternae, and _______ are present.
- Transverse tubules
- Terminal Cisternae
- Triads
______ are specialized complexes consisting of a narrow central T tubule flanked (bordered) on each side by the terminal cisternae.
Triads
Triads are located at the _____ junction in skeletal muscles and help provide ______ contractions.
- A-I
- Uniform
Transverse tubules do not belong to _________.
Sarcoplasmic Reticulum
Transverse tubules are invaginations of ________ and are continuous with extracellular space.
Sarcolemma
Longitudinal sarcotubules and terminal cisternae regulate _____ concentration in the microenvironment of myofibrils.
Ca++
Myofibrils are the _______ units of contractile material in a muscle fiber.
Smallest
Each myofibril consists of _____ or myosin filaments (A bands) and ____ or actin filaments (I bands).
- Thick
- Thin
Myosin filaments are ____ micrometers long, have a _____ central segment, but ends are projected by ________.
- 1.5
- Smooth
- Cross fibers
Myosin molecules are _____ shaped with ______ projections.
- Rod
- Globular
The two components of myosin filaments are __________ and ________.
- Heavy meromyosin
- Light meromyosin
Heavy meromyosin contains ______ (120KD), _______ (60KD), and heads with ______ activity.
- HMM1
- HMM2
- ATPase
A large protein _____ holds myosin filament in position and attaches to Z line
Titin
Actin filaments are ___ micrometers long and located on either sides of ______.
- 1
- Z line
The ____ varies in different muscles.
Z line
The Z line contains a protein ______ which plays an important role in actin binding.
-alpha actinin
At the level of Z band, actin filaments are surrounded by a honeycomb like structure called _______.
Z filaments
Filamentous actin is composed of ______ actin subunits.
Globular
Actin filaments are oriented in ______.
Double helix
Associated with double helix are ______ filament and a complex of three _____: ___, ___, and ___.
- Tropomyosin
- Troponin
- TnT, TnC, TnI
Tropomyosin filaments are located in grooves of _____.
Helix
The complex of three troponin molecules are located at _______.
Regular intervals
TnT attaches ___ to ____.
Troponin to Tropomyosin filament
TnC has a binding site for ____.
Ca++
TnI inhibits interaction between _____ and ____ filaments.
Actin and myosin
Decreased ___ levels in sarcoplasm: Actin filament binding sites to myosin filaments are ______.
Unexposed
Increased ___ levels in sarcoplasm: Actin filament binding sites to myosin filaments are ______.
Exposed
Function of titin
Anchors thick filament to Z line
Function of alpha-actinin
Anchors thin filaments to Z line
Function of nebulin
Helps alpha-actinin anchor thin filaments to Z line
Function of tropomodulin
Maintains length of actin filament
Function of desmin
Stabilizes crosslinks between neighboring sarcomere myofibrils
Function of myomesin and C proteins
Holds thick filaments at M-line
Function of dystrophin
Mechanical reinforcement of sarcolemma
Excitation-Contraction Coupling:
_____ Impulse –> ________ –> ______ Tubules –> ________ Reticulum –> ____ release –> Muscle ______
- Nerve Impulse
- Sarcolemma
- Transverse Tubules
- Sarcoplasmic Reticulum
- Ca++ release
- Muscle Contraction
In relaxed muscle, Ca++ is stored in _________ and there is very low Ca++ in ________.
- Sarcoplasmic reticulum
- Sarcoplasm
In relaxed muscle, ____ is attached to ______ heads on cross bridges, and myosin heads cannot bind to actin filaments because of _________ and ______ complex.
- ATP
- Myosin
- Tropomyosin and troponin
During the nerve impulse at the neuromuscular junction, ______ along nerve membrane reach synaptic knobs.
Action potentials
In response to the action potential, Ca++ enters the nerve membrane at synaptic knobs and causes release of _______ into the synapse.
Acetylcholine
Acetylcholine diffuses across the synapse and binds to ______ located on the ______ of the muscle cell.
- ACh receptors
- Sarcolemma
Interaction of ACh with sarcolemma generates ______ in the sarcolemma, which travels to ______ and then to ______ of sarcoplasmic reticulum.
- Action potential
- Transverse tubules
- Terminal cisternae
In response to the action potential, the terminal cisternae release Ca++ which in turn:
- Binds to ____ and exposes active sites on _____
- Activates ____ to function as _____
- Allows binding of _____ with _____
- TnC; Actin filaments
- Myosin heads; ATPase
- Myosin heads; actin filaments
Energy from _____ drives the power stroke to pull actin filaments over myosin filaments; _____ are brought closer together. This causes ______ of sarcomere, muscle fiber, and then the muscles as a whole.
- ATP hydrolysis
- Z lines
- Contraction
After contraction, ACh rapidly diffuses or is hydrolyzed by _________ and impulse stops; Ca++ is actively transported back to sarcoplasmic reticulum by a transport protein _______ and ATP.
- Acetylcholinesterase
- Calsequesterin
After contraction, low Ca++ in sarcoplasm results in detachment of ____ and ____ which slip back; Z lines move apart and muscle _____.
- Actin filaments
- Myosin filaments
- Relaxes
ATP is resynthesized after contraction by ______.
ATPase
Skeletal muscles are innervated by nerves containing axons from ________ in the spinal cord.
Motor neurons
At the muscle, the nerve divides into ______ that penetrate muscle through ___________.
- Branches
- Perimysial septa
Individual axons then branch into the endomysium to form ________ - a few to several hundred.
Endings
A single motor neuron, its axon and the muscle fiber it innervates, constitutes a ________.
Motor unit
Activity of motor unit is ________.
All or none
At the site of contact with muscle fiber, axon loses _________ and forms several short axons terminals.
Myelin sheath
Axon terminals occupy a shallow depression of the muscle fiber membrane called ___________.
Primary synaptic cleft
Sarcolemma then forms several ____________ to increase surface area.
Secondary synaptic clefts
Axoplasm has mitochondria and synaptic vesicles which are the sites of ______ (10,000 molecules/vesicle)
Acetylcholine
Acetylcholine is released by _______.
Exocytosis
Nerve impulse –> ________ –> Sarcolemma –> _________ –> Sarcoplasmic Reticulum –> ___________ –> Muscle Contraction
- Action Potential
- Transverse Tubules
- Ca++ Release
Action potentials increase _________ of sarcolemma to Na+
Permeability
Sarcolemma has ________ for degradation of ACh
Acetylcholinesterase
An autoimmune disease - antibodies against sarcolemma - causes weakness, fatigue, paralysis
Myasthenia gravis
Myasthenia gravis involves reduction of _________ at the neuromuscular junction.
ACh receptors
Normally 30-40 million receptors/NMJ; in Myasthenia gravis _______% reduction; anti AChE chemicals help
70-90
Neuromuscular spindles are complex _______ organs, _______ shaped, and encapsulated with striated muscle fibers with their endings enclosed in a sheath.
- Sensory
- Fusiform
Capsules of Neuromuscular Spindles are continuous with _____ and _________.
Peri- and Endomysium
Muscle fibers of Neuromuscular Spindles are called __________.
Intrafusal fibers
Central portion of intrafusal fibers have no ________ and cannot stretch.
Myofibrils
Intrafusal fibers are categorized as either __________ or __________.
- Nuclear bag fibers
- Nuclear chain fibers
Two categories of Special Nerve Endings of Neuromuscular Spindles
- Sensory or afferent
- Motor or efferent
Sensory or afferent nerve endings are primary to _________ and secondary to _______ on two sides of primary.
- Nuclear bag or chain
- Nuclear chain
Motor of efferent nerve endings are gamma to _______ and alpha to ________.
- Intrafusal fibers
- Extrafusal fibers
Sensory Nerve Endings in Tendons are called _________, and encapsulated and sense _______ stress by _______, and consist of collagen fibers.
- Tendon organs
- Tensional
- Muscle pull
Cardiac muscle fibers are separate cellular units joined ________ by specializations called _________ with traverse across the fiber.
- End to end
- Intercalated discs
Cardiac muscle fibers ______ or ______ to form a network.
Bifurcate or converge
Cardiac muscle fibers contain ______ nuclei, elongate and situated deep centrally, abundant cytoplasm, numerous mitochondria, and sarcoplasm rich in glycogen.
Single
Cardiac muscle fibers beat spontaneously and exhibit _______ control.
Involuntary
Myofibrils of cardiac muscle fibers are NOT in discrete ______ in cross sections as in skeletal muscles.
Bundles
In cardiac muscle fibers, mitochondria appear ________ in myofibrils.
Enclosed
Cardiac muscle transverse tubules are ______ than those in skeletal muscle and are at the level of z lines, not at _________ junctions as in skeletal muscle.
- Thicker
- A-I junctions
Intercalated discs are deeply _______, appear wavy, and important in cell to cell adhesions.
Sculptured
Intercalated discs have fascia ______, gap _______, and de_______.
- Adherens
- Junctions
- Desmosomes
Intercalated discs are rich in _______ and ______.
- Alpha-actinin
- Vinculin
Myocardial Endocrine Cells are located in _____.
Atria
Myocardial Endocrine Cells have membrane bound ________ granules with a family of biologically active polypeptides called ca________ or ________________ (ANP) or ________________.
- Atrial-specific granules
- Cardiodilatins
- Atrial natriuretic peptides
- Atrial natriuretic hormone
ANP is a ________ and a strong ______ or natriuretic.
- Vasodilator
- Diuretic
The effects of ANP are mediated by inhibition of _________ (ADH) from posterior pituitary and _________ from adrenal gland.
- Vasopressin
- Aldosterone
The Sinoatrial Node is located beneath __________ at the junction of superior _________ and right _______.
- Epicardium
- Vena Cava
- Atrium
The Atrioventricular Node is located beneath ________ in the lower part of the _______ septum.
- Endocardium
- Interatrial
The Atrioventricular Bundle originates anteriorly from ________ and divides into right and left _____.
- Atrioventricular Node
- Branches
The Purkinje Fibers are fine branches of ______________.
Atrioventricular Bundle
Nodal cells are smaller than cardiac muscle fibers and seldom have ____________.
Intercalated discs
There is ___ direct connection between Sinoatrial Node and Atrioventricular Node.
No
The conducting system of the hear is richly innervated with _____________. Sympathetic ANS _____ heart rate and parasympathetic ANS _____ heart rate.
- Autonomic Nervous System
- Increases
- Decreases
Initiation of heart beat is ____ dependent on nervous system. It is __________.
- Not
- Autorhythmic
Smooth muscle fibers form _______ portions of walls of ____ tract, ____ of glands, ____ and ____ ducts, _____ passages, and _____ vessels.
- Contractile
- Digestive
- Ducts
- Urinary and genital
- Respiratory
- Lymphatic
Smooth muscle fibers are also found in ____ (Arrectores pilorum), _____ glands, ____ and ____ of eye, _____ and _____.
- Hair
- Mammary
- Iris
- Ciliary body
- Testes and uterus
Smooth muscle fibers are ____, ____ shaped or _____, closely associated in bundles. Length and diameter are highly ______.
- Long
- Spindle
- Fusiform
- Variable
Smooth muscle fibers have _____, elongate nuclei with _____ nucleoli.
- Single
- 1 or 2
Smooth muscle fibers are thick portions of fibers ________ to thin portions of adjacent fibers.
Juxtaposed
The sarcoplasm of smooth muscle fibers is _________, containing mitochondria, Golgi complex, centrioles, glycogen and longitudinal fibrils called myofibrils.
Homogenous
Smooth muscle fibers can be organized in _____ patterns.
- ________ in loose connective tissue
- In slender ______ as in hair, iris of eye
- Oriented ________ - arterioles, arteries
- _____ or _____ layers - intestinal walls
- ______ defined layers - hollow organs (bladder, uterus)
- Various
- Singly
- Fascicles
- Circumferentially
- Circular or longitudinal
- Poorly
Variations in form of smooth muscle fibers:
- Smooth _____ or _____: bladder uterus
- ___________ cells of mammary glands - several radiating processes
- ______ - in certain capillaries - rounded cells with several tapering processes
- Fusiform or branched
- Myoepithelial
- Pericytes
The smooth muscle fibers have sarcoplasm with _______ (actin, myosin, intermediate) ________ to axis.
- Myofibrils
- Parallel
Scattered in the cytoplasm of smooth muscle fibers are cytoplasmic _______ (analogous to z lines of skeletal muscle) - these bodies contain a protein called __________.
- Dense bodies
- Alpha actinin
Along sarcolemma of smooth muscle fibers are subplasmalemmal _______ made of _____ and ____.
- Dense plaques
- Vinculin
- Talin
Sarcolemma of smooth muscle fibers between plaques has _______ called ______ which are believed to store ____ for release during muscle contraction.
- Inpocketings
- Caveolae
- Ca++
Contraction of smooth muscle is ____ than skeletal muscle and sustains forceful contraction for _____ periods.
- Slower
- Longer
Contraction of smooth muscle may be initiated by ______ impulse, _______, or local ______ (stretching).
- Nerve
- Hormones
- Changes
In the smooth muscle, the tropomyosin complex of skeletal muscle is ______.
Absent
In smooth muscle, extracellular Ca++ diffuses from _____ or ___________.
- Caveolae
- Subplasmalemmal reticulum
In smooth muscle, Ca++ binds to ______ which activates ______ in myosin heads.
- Calmodulin
- ATPase
ATP ______ and induces a conformational change which causes ________.
- Hydrolyzes
- Muscle contraction
Two kinds of smooth muscle
- Visceral or unitary
- Vascular or multiunit
Visceral or unitary smooth muscle has _________ and impulses travel through gap junctions - responsible for peristalsis in GI, ureter, bile duct etc.
Autorhythmicity
Vascular or multiunit smooth muscle in found in large _______, ciliary body, iris of eye, walls of male reproductive tract.
Blood vessels
Vascular or multiunit smooth muscle impulses are _____ through gap junctions. Each fiber is innervated _________.
- Not
- Separately
Vascular or multiunit smooth muscle fibers in blood vessels maintain a muscle _____; blood vessels have receptors for:
- ___________: Norepinephrine, Vasopressin, Oxytocin
- ___________: Bradykinin, Prostaglandins
- Tone
- Vasoconstriction
- Vasodilation
