Muscular Tissue Flashcards
What is an example of a disease where the muscules are erratic and there is loss of control over body movements?
Huntington’s Disease
In relation to movement, what are the specific kinds of movement which muscular tissue has control over?
1) skeltal movement
2) organ movement
3) prevention of unwanted movements
4) heat production
What process occurs when a muscle takes up a major part of one’s blood glucose after a meal? This plays a substantial role in regulating glucose levels.
Normoglycemia
Muscles store which kind of monosacchiride?
glycogen
Which kind of muscle tissue is striated and voluntary?
skeletal muscle
The expression of “musclar system” refers to only which kind of muscle tissue?
skeletal muscle
Which kind of muscle tissue is striated and involuntary?
cardiac muscle
Which kind of muscle tissue is only part of the circulatory system?
cardiac muscle
Which kind of muscle tissue is non-striated and involuntary?
smooth muscle
Which kind of muscle tissue is found in many organ systems such as: circulatory, respiratory, reproductive, digestive, etc.?
smooth muscle
A ____ is an individual cell of skeletal muscle. They are called this because they are long, slender, threadlike cells.
muscle fibers
Each muscle fiber is enclosed in a thin sleeve of reticular connective tissue, which allows nerve fibers and blood capillaries to reach it and which furnishes the extracellular chemical environment (electrolytes) for muscle excitation. This also provides end-to-end mechanical connectivity, because few muscle fibers extend for the whole length of a muscle. What is this called?
endomysium
A ____ is a bundles of muscle fibers enclosed in a thicker connective tissue sheath, the perimysium.
fascicle
What is a layer of fibrous connective tissue, that is thicker than the endomysium, surrounding each fascicle and seperating it from others? It is well endowed with blood vessels.
perimysium
What is a layer of dense irregular connective tissue that covers the muscle as a whole, seperating it from neighboring muscles?
epimysium
A ____ is a sheet of connective tissue between adjacent muscles or between muscles and skin.
fascia
Which two structures of skeltal muscle grade into each other with no distinctly identifiable boundary between the two?
epimysium and fascia
Each skeleltal muscle fiber forms by the fusion of multiple embryonic cells called ____.
myoblasts
Skeletal muscle can be identified in ____ sections as having parallel, straight-side cells.
longitudinal
Skeletal muscle can be identified in ____ sections as having polygonal, angular cells.
cross
Why does skeletal muscle look faintly stippled in cross sections?
internal myofibrils
What is structure #1 in the muscle fiber below?
sarcolemma
not done
What is structure #2 in the muscle fiber below?
nuclei
not done
What is structure #3 in the muscle fiber below?
sarcoplasm
not done
What is structure #4 in the muscle fiber below?
transverse (T) tubules
not done
What is structure #5 in the muscle fiber below?
myofibrils
not done
What is structure #6 in the muscle fiber below?
sarcoplasmic reticulum
not done
What is structure #7 in the muscle fiber below?
terminal cisternae
not done
What is structure #8 in the muscle fiber below?
mitochondria
What are the three main myofilaments?
1) myosin
2) thick filament
3) thin filament
What are thick filaments composed of?
myosin
What are thin filaments composed of?
actin
Which two myofilments overlap one another during muscle contraction?
thick and thin filaments
On thin filaments, what is the “head” called and what is the “fiber” called?
“head” - troponin
“fiber” - tropomyosin
The basic structural unit of a thin filament is a globular protein called what?
G actin
When G actins are strung together like a pearl necklace, it forms elongated ____ ____.
F actin
Which actin filaments wind together into a double helix to form thin filaments?
F actin
What is the purpose of the active site on G actin?
It binds one myosin head when the muscle is contracting
Which calcium-binding protein is involved in triggering contraction when the sarcoplasmic reticulum releases calcium?
troponin
List the sequence of events which occur during a muscle contraction.
1) myosin is now capable of binding to these exposed active sites
2) a nerve fiber stimulates (electrically excites) a muscle fiber
3) Ca2+ binds to troponin
4) The force on the actin is transferred through a protien called dystrophin to the sarcolemma and the surrounding endomysium, and then via the endonysium to perimysium and epimysium, and ultimately to the tendon that pulls on a bone.
5) Through a series of events activated by ATP, and consuming one ATP per cycle, the myosin heads bind the actin like your hand grabbing a rope, then flex like your bending elbow pulling in the rope. Repeated flecions in the myosin pulls the actin filaments along in the sliding filament mechanism of muscle contraction.
6) The electrical excitation spreads in a wave over the surface of the muscle fiber and into the T tubules.
7) Excitation traveling down the T tubules opens Ca2+ gates in the terminal cisternae of the sarcoplasmic reticulum, releasing a flood of CA2+ into the cytosol.
8) A calcium-bound troponin stimulates its associated tropmyosin molecule to move out of the way of the active sites of the G actin.
2, 6, 7, 3, 8, 1, 5, 4
What is significant about the bare area of thick filaments?
there are no myosin heads and regions on each side of this where the myosin heads angle off in opposite directions
What are the light bands in muscle striations called?
I bands
LIGHT bands
The I bands is occupied only by thin filaments but is bisected by a protien plaque called a(n) ____ ____.
Z disc or Z line
What are the dark bands in straitions called?
A bands
DARK bands
Thin and thick filaments overlap in the darkest parts of the A band, but the A band is bisected by a lighter ____ ____.
H band
What is one section of a contraction muscle called with a fit set of myofilaments?
sarcomere
What is a nerve cell (neuron) that innervates a skeletal muscle called?
somatic motor neuron
What is the axon of a somatic motor nerve called?
somatic motor nerve fiber
The branch of a somatic motor fiber ends in an ovoid area called what?
neuromuscular junction (NMJ)
NErve fibers dilate to form a knob-like ____ terminal. This is filled with secretory vesicles called ____ vesicles.
axon; synaptic
What is the myolin sheath?
It acts a barrier to prevent electrical impulses from “leaking” out.
What is located inside the synaptic terminal?
- packets of neutrotransmitters
- acetylcholine (ACh)
What is the gap betweent the axon terminal and the muscle tissue called?
synaptic cleft (synapse)
What attracts acetylcholine across the synaptic cleft?
acetylcholine (ACh) receptors
Where are ACh receptors located?
in junctional folds
Which enzyme halts the calcium chain reactions, inhibiting muscle contraction?
Acetylcholinesterase (AChE)
Which muscle contracts faster: cardiac or skeletal muscles?
skeletal muscles
Which muscle has a better developed sarcoplasmic reticulum: cardiac or skeletal muscles?
skeletal muscles
Which visible structure can we see under the microscope that sets cardiac muscles apart from other kinds of muscles?
intercalated discs
Cardiac muscles are said to be ____ because it sets the rhythm itself.
autorhythmic
The muscle cells in a given heart chamber must contract in unison to achieve a coordinated, effective expulsion of blood. This comes about partly because of ____ ____ in cardiac muscle
gap junctions
What are the cells of cardiac muscles called?
cardiocytes or cardiomyocytes
What is the nucleus of cardiocytes surrounded by?
a light halo of glycogen
Which kind of muscle tissue does not have sarcomeres or striations?
smooth muscle
In smooth muscle, where do thin filaments attach to?
dense bodies
Which category of the nervous system controls smooth muscles?
autonomic nervous system
What are some key characteristics of smooth muscles?
- low ATP requirement
- regenrate rather quickly
- fatigue-resistant
- slow twitches
What are some locations where you might find smooth muscles?
- GI tract
- respiritory tract
- renal (urinary bladder)
- sensory
- genital
- cardiovascular (heart beating)
What are the two types of smooth muscles called?
- multiunit smooth muscle
- single-unit smooth muscle
Cardiac muscles are ____ coupled.
electrically