Muscle tissue Flashcards
T/F Contractility is the key feature of muscle
TRUE
Sarcolemma
Muscle cell membrane
Sarcoplasm
Is the cytoplasm of muscle
Skeletal Muscle
-Elongated, large, multinucleated fibers. Strong quick and voluntary contractions
Cardiac muscle
-Irregular branched cells bound together longitudinally by intercalated discs. Strong involuntary contractions
Smooth muscle
Grouped, fusiform cells. Weak involuntary contractions
Longitudinal section in skeletal muscle are separated by
-Very thin endomysium that includes fibroblast nucleus
Muscle nuclei are found
against sarcolemma
Each fiber has three of four
Myofibrils whose striations are slightly out of alignment
Myofibrils
Cylindrical bundles of thick and thin myofilaments
Cardiac muscles are bound together by
Intercalated discs. They have centrally located nuclei.
A fiber consists of cells in a series joined at interdigitating regions called
Intercalated discs
Transverse regions of the intercalated discs have
Abundant desmosomes and adherent junctions
Longitudinal discs have
Gap junctions to allow exchange of ions
Electric synapses
promoting rapid impulse conduction through many cardiac cells and contraction of many adjacent cells
Impulses of heartbeat are initiated, regulated, and coordinated by
Nodes of myocardial fibers
Contraction of individual myocardial fibers
All-or-none
Nerve fibers that accelerate heartbeat
Sympathetic
Nerve fibers that decrease heartbeat
Parasympathetic
Ischemia
Damage to tissue due to lack of oxygen
Adult mammal heart muscle has little potential to regenerate because
It lacks satellite cells
Smooth muscle is specialized for
involuntary slow, steady contractions under the influence of autonomic nerves
Smooth muscle forms a major component of what tracts?
Digestive, respiratory, urinary, and reproductive, blood vessels and their organs.
What allows multicellular tissue to contract as a unit in smooth muscle?
Thin filaments attached to dense bodies located at the cell membare
Which muscle tissue does not have all or noting contractions?
Smooth muscle
Fibers of skeletal muscle tissue
Single multinucleate cells in parallel
Cell shape of skeletal muscle tissue
Cylindrical cells, many cm lomg
Does skeletal muscle tissue have striations present?
Yes
What is the connective tissue of skeletal muscle?
endomysium, perimysium, epimysium
Locations of skeletal muscle tissue
skeletal muscles, tongue, eye, diaphragm
Key function of skeletal connective tissue
Voluntary
what is the only tissue with motor innervation?
Skeletal. Smooth and cardiac are autonomic
Contractions of skeletal muscle tissue
all or none, starting at the motor end plate
skeletal muscle response to increase overload
hypertrophy
Regeneration ability of skeletal muscle
Limited
Cardiac fibers
cells aligned in branching pattern
Cell shape of cardiac cells
cylindrical 50-100 micrometers long
Are striations present in cardiac muscle
yes
Special structures of cardiac muscle tissue
Intercalated discs
The connective tissue of cardiac
endomysium
Location of cardiac tissue
heart
key function of cardiac tissue
Involuntary (pumping of heart)
Contraction of cardiac muscles
all or none but, intrinsic
Response of cardiac tissue to increase overload
hypertrophy
regeneration ability of cardiac tissue
very poor
Fibers of smooth muscle tissue
single, small, closely pack fusiform cells
cell shape of smooth muscle
fusiform cells
does smooth muscle have striations
no they’re absent
Special features of smooth muscle
dense bodies
Connective tissue of smooth muscle
endomysium
Locations of smooth muscle
digestive, urinary, respiratory tracts, blood vessels, uterus, bladder, and other organs.
Key function of smooth muscle
involuntary
contractions of smooth muscle
partial, slow, and wavelike
response of smooth muscle to increase load
hypertophy and hyperplasia
Regeneration ability of smooth muscle
Good
Endomysium
surrounds individual muscles, include fibroblast muscle
Paramysium
surrounds a group of muscle fibers called fascicle
Epismysium
surrounds entire muscle
where is muscle nuclei found
against sarcolemma
3 to 4 myofibrils in each muscle fiber are composed of
myofilaments that fill each muscle fiber
Cardiac muscle is connected together by
intercalated discs
where is nuclei in cardiac muscle
centrally located
transverse regions have
desosomes and adherent junctions
longitudinal regions have
gap junctions
Electrical synapses
efficient contraction mechanism that produce conduction between cells and contraction of adjacent cells
Fiber contractions are
intrinsic and spontaneous
what do nodes of myocardiac fibers do
initiate, coordinate, and control heartbeat
Individual myocardial fibers have what kind of contraction
all or none
Sympathetic
increases rate of heartbeat
parasympathetic
decreases rate of heartbeat
ischemia
damage to tissue due to lack of oxygen
Smooth muscle has attachment to
dense bodies so multiple tissue can work together more efficiently as a unit
Within fascicles individual muscle fibers are wrapped by
endomysium
myotendinouns junction
tendons develop together with skeletal muscle and they joint muscle at the periosteum of bones
development of skeletal muscle
myoblast fuse to make longer tubes
myotubes make proteins to make myofilaments
satellite cells
myoblast cells that don’t fuse or differentiate, instead they proliferate and act when there’s injury
myofibrils are separated into sarcomeres by
z discs
thick filaments are a bundle of myosin connected by
titin
thick filaments span the entire
A band and bind to proteins to the M line and the Z discs
myofilaments are composed of
thick and thin filaments consisting of contractile protein regions
thick filaments contain
multiple myosin bundles
thin filaments contain
actin, troponin, and tropomyosin
what happens at contraction?
-nerve impulses release acetytoalcholine across the membrane which reacts with muscle impulses (depolarization) resulting in the release of Ca++ from sarcoplasmic reticulum
-Ca++ binds to troponin changing tropomyosin and allowing myosin heads to bind to actin forming cross bridges between thick and thin filaments
-myosin head pivots as ATP releases energy which pulls thin filaments along thick filaments
Myasthenia gravis
autoimmune disease that creates antibodies against acytoalcholine receptors leading to muscle weakness
Duchenne muscular dystrophy
Mutation of the dystrophin gene can lead to deffective linkages between the cytoskeletal and the ECM.
Muscle contraction can break these linkages causin atrophy of muscle fibers
Dystrophin
actin-binding protein involved in function of mycrofibrils
Two types of receptors in muscle
muscle spindle and Golgi tendon organs
Muscle spindle contractions begins in response to
stress
i5 to 15 intrafulsal muscle fibers are associated with
sensory and motor nerve fibers
Golgi tendon organs
detect changes in contraction and they inhibit contraction if it becomes too much
Slow oxidative
stain the darkest and have highest ATP activity
Fast glyocolitc
stain the lightest and have the lowest ATP activity
Fast oxidative-glycolytic
Middle ground between slow oxidative and fast glycolitic