Chapter 9 Flashcards
What are the three types of muscles?
Skeletal
Smooth
Cardiac
Is skeletal muscle tissue striated?
Yes
Skeletal muscle tissue contractions
Are rapid, and in return it tires easily
Explain blood supply to skeletal muscle tissue
Arteries deliver oxygen and nutrients, veins take waste away
Is smooth muscle tissue striated?
No
Is cardiac muscle tissue striated?
Yes
Sarcolemma is the
Plasma membrane
Sarcoplasm is the
Cytoplasm of the muscle cell
Excitability/Irritability is
The ability to receive and respond to stimuli
Contractibility is
The ability to shorten
Extensibility is
The ability to be extended or stretched
Muscles maintain
Posture
Stabilize joints
Generate heat
Organization of a skeletal muscle
Muscle Fascicle Muscle fiber Myofibril Sarcomere Myofilament
Fascicles are a portion of
The muscle
Muscle fibers are also known as
Muscle cells
Myofibrils are complex
Organelle
Myofibrils have a ________ structure
Rod-like
Myofibrils occupy most of the
Muscle cell volume
What are myofibrils composed of?
Sarcomeres arranged end to end
Are myofibrils striated?
Yes
What make up the striations of myofibrils?
A bands and I bands
Sarcomere is a segment of
A myofibril
What is the smallest contractile unit?
The sarcomere
Sarcomere are composed of
Myofilaments
Where are sarcomeres found?
Between two Z-discs
What are the two contractile myofilaments?
Myosin and Actin
Myosin is what kind of filament?
Thick filament
Actin is what kind of filament?
Thin filament
What kind of structure does myosin have?
A head and a tail
Myosin tails are
Two interwoven polypeptide heavy chains
Myosin heads are
Two light/smaller polypeptide chains
Within actin, what two proteins play a part?
Tropomyosin and Troponin
Tropomyosin and Troponin are
Regulatory subunits that are bound to actin and play a role in contractions
How are myosin and actin involved contractions?
They slide past one another which causes shortening and contraction
What are the three connective tissue sheaths?
Epimysium
Perimysium
Endomysium
Sarcoplasmic reticulum functions in
The regulation of intracellular calcium levels
T tubules conduct
Impulses to the deepest region of muscle
The impulse from the t tubules signals
The release of calcium
Myosin extend the entire length of
The A band
Actin extend across
The I band
Z discs do what?
Anchor thin filaments
Where do thin filaments not overlap thick filaments?
In the H zone
The M line connects
Thick filaments
Sliding filament model of contraction (7)
(1) In a relaxed state,myosin and actin only overlap a little bit
(2) Upon stimulation, one myosin head will bind to actin and sliding begins
(3) Calcium binds to troponin
(4) Troponin changes shape
(5) When troponin changes shape, tropomyosin moves and uncovers head sites
(6) Myosin heads bind to actin
(7) ATP binds to the head and the head releases
The neuromuscular junction is made up of
Axonal endings
Axonal endings contain
Acetyl Choline (ACh)
Acetyl Choline is a
Neurotransmitter
What holds in ACh?
Axonal vesicles
The synaptic cleft is the
Space between the neuron and muscle tissue
Muscle Contraction (7)
(1) Nerve impulse travels to axon terminal
(2) Causes voltage gated calcium channels to open
(3) Influx of calcium
(4) Calcium causes sacs with ACh to fuse to the membrane
(5) Causes the release of ACh into the synaptic cleft
(6) ACh binds to ACh receptors on the sarcolemma
(7) ACh binding initiates an action potential
Breaking down steps 6 and 7 of the muscle contraction (7)
(1) Sarcolemma becomes permeable to Na and K
(2) Causes change in polarity; Inside of the cell becomes more negative (depolarization)
(3) Depolarization causes the action potential to travel down t tubules
(4) Causes release of calcium
(5) One calcium is released, it binds to troponin, which causes tropomyosin to move
(6) Allows myosin heads to bind to actin
(7) Allows contraction
What destroys ACh?
Enzyme acetyl cholinesterase (ACh enzyme)
Where is ACh destroyed?
Within the synaptic cleft
The deconstruction of ACh does what?
Prevents continued contractions
What would happen in a lack of ACh enzymes?
Contractions would be able to be stopped
would would happen with a lack of ACh receptors?
It would be hard to contract or possibly no contraction at all
Myasthenia Gravis is caused by
A lack of ACh receptors
What are symptoms of Myasthenia Gravis?
Weak muscles, weak vision, drooping eyelids, hard to speak or swallow
