Exam # 3 Chapter 10 Flashcards
-muscular tissue contributes to _____ by producing body movements, moving substances through the body, and producing heat to maintain normal body temp
homeostasis
-the scientific study of muscles
myology
-from the most superficial layer to deepest layer, _____ of skeletal muscle:
- superficial fascia
- deep fascia
- epimysium
- perimysium
- endomysium
connective tissue
- functions of _____:
- producing body movement
- stabilizing body position
- storing and moving substances
- sphincters, cardiac muscles, vessels, intestines
- generating heat (thermogenesis)
muscle tissue
- properties of _____
- electrical excitability
- contractility
- extensibility
- elasticity
muscle tissue
-muscle actions potentials, similar to neurons
electrical excitability
-ability of muscular tissue to contract forcefully when stimulated by AP
contractility
-stretch without being damaged, key feature when considering antagonist muscle tissue
extensibility
-return to its original shape after contraction or extension
elasticity
- each of your skeletal muscles is a separate organ composed of hundreds to thousands of cells called _____
- the fiber is the cellular unit
- the cellular level
- always have the same number of fiber cells
muscle fibers
- these are _____ components:
- subQ
- fascia
- epimysium
- perimysium
- endomysium
connective tissue
-separates the muscle from the skin
subQ
-dense sheet of dense irregular connective tissue surrounding and supporting muscle groups
fascia
-3 layers of the fascia are : ______, _____, and _____
epimysium, perimysium, and endomysium
-“upon” the outer layer of fascia
epimysium
-“around” bundles groups of fibers into fascicles
perimysium
-“within” separates individual fibers
endomysium
-the epimysium and perimysium are made of _____ tissue
dense irregular
-the endomysium is made of mostly _____
reticular fibers
-narrow bands connective tissue that connect muscles to bone
tendons
-bands of connective tissue that join bone to bone
ligaments
-bands of connective tissue that attach flat muscle to another muscle or to several bones
aponeuroses
- muscle fibers result from the fusion of hundreds of mesodermal cells called _____, so each fiber has 100’s of nuclei
- once fused fibers can no longer _____
- _____ function as stem cells to repair damaged muscls
myoblast
divide
satellite cells
-invaginations of the sarcolemma, perfect Ap delivery structure
transverse tubules (T tubules)
- sarcoplasmic protein that binds oxygen and releases it is needed by the mitochondria
- red colored
myoglobin
-sacs of sarcoplasmic reticulum storing Ca2+
terminal cisterns
-plasma membrane of muscle cell
sarcolemma
-cytoplasm of muscle fiber
sarcoplasm
-a fluid filled system of membranous sacs, encircles each myofibril
sarcoplasmic reticulum
-fascicles bundled by epimysium
muscle
-fibers bundled by perimysium
fascicle
-the contractile organelle of skeletal muscle
myofibril
- smaller protein structures
- actin and myosin
myofilaments
- thick proteins, _____
- thin proteins, _____
myosin
actin
-the filaments inside a myofibril do not extend the entire length of a muscle fiber, they are arranged in compartments called _____
sarcomeres
-dense proteins, defines border of sarcomeres, separates them from one to the next
Z disc
_____ are the length of the filament
bands
- dark middle part of sarcomere that extends entire length of myosin
- includes those parts of thin filaments that overlap thick filaments
A band
- lighter, less dense area of sacomere that contains remainder of thin filaments, actin only
- a Z disc passes through each
I band
-narrow region in center of each A band that contains only myosin
H zone
- region in center of H zone that contains proteins that hold thick filaments together at center of sarcomere
- midline, rubber band of proteins
M line
-2 contractile proteins:
myosin
actin
- makes up thick filament
- molecule consist of a tail and two heads, which bind to sites on actin molecules of thin filament during muscle contraction
myosin
- main component of thin filament
- each molecule has a myosin binding site where myosin head of thick filament binds during muscle contraction
actin
-2 regulatory proteins:
tropomyosin
troponin
- component of thin filament
- when skeletal muscle fiber is relaxed, it covers myosin binding sites on actin molecules, preventing myosin from binding actin
tropmyosin
- component of thin filament
- calcium ions bind to it, it changes shape, which moves tropomysin away from myosin binding sites on actin molecules
- muscle cntraction subsequently begins as myosin binds to actin
troponin
-skeletal muscle shortens during contraction because the thick and thin filaments slide past one another
sliding filament mechanism
-sarcomeres exert force and shorten through repeated cycles during which the myosin heads attach to actin (forming cross bridges), rotate and detach
contraction cycle
4 steps in the _____:
- ATP hydrolysis
- attachment of myosin to actin
- power stroke
- detachment of myosin from actin
contraction cycle
-cross bridge rotate and move the thin filaments pst the thick filaments towards the center of the sarcomere
power stroke
- myosin head hydrolyzes ATP and becomes energized and oriented
- ATP into ADP
- hydrolyzing ATP cocks the myosin head
1st step in contraction cycle
- myosin head binds to actin, forming a cross bridge
- calcium binds to troponin
2nd stage in contraction cycle
- myosin head pivots, pulling the thin filament past the thick filament toward the center of the sarcomere (power-stroke)
- no energy required here
- rotating 45 degrees
- shortening step
3rd step in contraction cycle
- as myosin head binds ATP, the cross bridge detaches from actin
- needs ATP to detach
- rictor mortis happens here if there is no ATP
4th step contraction cycle
- RECAP: impulse from pre-synaptic neuron causes voltage gated channels to open, allowing Ca2+ to rush in to the axon terminus
- the difference is it binds to a _____
motor end plate
-neurons that stimulate skeletal muscle fibers to contract
somatic motor neurons
-muscle AP arise at the _____, the synapse between a somatic motor neuron and a skeletal fiber
neuromuscular junction (NMJ)
the ______:
- release of ACh
- activation of ACh receptors
- production of muscle action potential
- termination of ACh activity
neuromuscular junction
-the effect of ACh binding lasts only briefly b/c ACh is rapidly broken down by an enzyme called _____
acetylcholinesterase (AChE)
_____ released at the NMJ triggers a muscle AP which leads to muscle contraction
ACh
- nerve AP in somatic motor neuron triggers release of ACh
- ACh binds to receptor in motor end plate, triggering muscle AP
- AChE destroys ACh so another muscle AP does not arise unless more ACh is released from somatic motor neuron
- a muscle AP traveling along a transverse tubule triggers a change in the voltage gated Ca+ channels that causes the Ca+ release channels to open, allowing the release of Ca+ ions into sarcoplasm
- Ca2+ binds to troponin on the thin filament, exposing the myosin bindng sites on actin
- contraction: myosin heads bind to actin, undergo power strokes, and release, thin filaments are pulled toward center of sarcomere
- Ca2+ release channels close and Ca2+ -ATPase pumps use ATP to restore low level of Ca2+ in the sarcoplasm
- tropomysin slides back into position where it blocks the myosin binding sites on actin
- muscle relaxes
muscle contraction and relaxation
- most of the excess ATP is used to synthesize _____, an energy rich molecule that is found in muscle fibers
- created by resting muscles when ATP production in fibers exceeds demand
- as ATP demand increases, its converted back to ADP
creatine phosphate
-an example of _____, a single motor neuron branching out and connecting to multiple muscle fibers
signal divergence
-a _____ is a single neuron plus every fiber it stimulates
motor unit
-recruitment of motor units allows us to produce _____ instead of a series of jerks
smooth movements
-is the brief contraction of all muscle fibers in a motor unit in response to a single AP in its motor neuron
twitch contraction
- the delay, which lasts about 2msec
- muscle AP sweeps over the sarcolemma and calcium ions are released from sarcoplasmic reticulum
latent period
- lasts 10-100 msec
- Ca2+ binds to troponin, myosin binding sites on actin are exposed and cross bridges form
contraction period
- lasting 10-100 msec
- actively transported back into sarcoplasmic reticulum, myosin binding sites are covered by tropomyosin, myosin heads detach from actin, and tension in the muscle fiber decreases
relaxation period
-when a muscle fiber receives enough stimulation to contract, it temporarily loses its excitability and cannot respond for a time
refractory period
-stimuli arriving at different times cause larger larger contractions
wave summation
- skeletal muscle fiber is stimulated at a rate of 20 30 times per second, it can only partially relax between stimuli
- the result is a sustained but wavering contraction (bumpy)
unfused tetanus
- skeletal muscle fiber is stimulated at a higher rate 80 to 100 times per second
- does not relax at all (smooth)
fused tetanus
- glucose converted to 2 pyruvic acid and 2 ATP
- pyruvic acid is broken down into lactic acid, which can build up in the blood and cause soreness
anaerobic glycolysis
-in the presence of oxygen, pyruvic acid can instead be used by the mitochondria to make 30 ATP (+2 from glycolysis=32), CO2 water and heat
aerobic respiration
- associated with Ca2, creatine phosphate, O2 low
- feeling like ceasing activity
muscle fatigue
- oxygen dept, remove lactic acid, make creatine phosphate and ATP, reload myoglobin
recovery oxygen uptake
-muscle contracts, shortens, and creates enough force to move the load
isotonic contraction
-muscle contracts but does not shorten, force cannot move the load
isometric contractions
- myoglobin content in large amount
- many mitochondria and capillaries
- red in color
- capacity for generating ATP is high by aerobic respiration
- rate of ATP hydrolysis by myosin ATPase is slow, which makes contractions slow
- fatigue resistance is high
- creatine kinase is lowest amount
- glycogen stores low
- first in recruitment
- postural muscles of the neck, maintaining posture and aerobic endurance activities
slow oxidative fibers (SO)
-myoglobin content large amounts
-many mitochondria and capillaries
-red-pink color
-capacity for generating ATP is intermediate, by both aerobic respiration and anaerobic glycolysis
-rate of ATP hydrolysis by myosin ATPase is fast
-fatigue resistance, creatine kinase, glycogen stores
intermediate
-second in recruitment
-lower limb muscles, walking and sprinting
fast oxidative-glycolytic fibers (FOG)
- myoglobin content small amount
- mitochondria and capillaries are few
- white pale color
- capacity for generating ATP is low by anaerobic glycolysis
- rate of ATP hydrolysis by myosin ATPase is fast
- contraction velocity is fast
- fatigue resistance is low
- highest amount of creatine kinase
- glycogen stores high
- third is recruitment
- extra ocular muscles
- rapid intense movements of short duration
fast glycolytic fibers (FG)
-baseline tautness of a muscle due to involuntary contractions of some motor units
muscle tone
-no tone, possibly resulting from neurons being cut or damaged
flaccid muscle
- growth of the existing muscle fibers
- remember they have lost the ability to divide
hypertrophy
-decrease in fiber size due to non-use
atrophy
-the two bands that don’t change in muscle contractions are the _____ and _____ bands
A and M bands
-glucose —
cytosol
mitochondria
organization of ______ from big to small :
- skeletal muscle
- fascicle
- muscle fiber
- myofibril
- filaments
muscle
