13.9 Voluntary & Involuntary Muscles Flashcards
What are the 3 types of muscle?
- SKELETAL
- make up bulk of body muscle tissue
- for movement
- CARDIAC
- found only in heart
- myogenic - contract without need for nervous stimulus
- SMOOTH
- walls of hollow organs, blood vessels, digestive tract etc
- constrict/dilate pathways
Describe the properties of the different types of muscle:
- SKELETAL
- striated
- voluntary
- cells/fibres regularly arranged >> unidirectional muscle contraction
- tubular & multinucleated
- rapid contraction speed & short duration of contraction
- CARDIAC
- striated (fainter)
- involuntary
- cells branch >> simultaneous contraction
- branched & uninucleated
- intermediate contraction speed & duration
- SMOOTH
- non-striated
- involuntary
-
no regular arrangement >> different cells can contract in different directions
- spindle-shaped & uninucleated
- slow contraction speed but long contraction duration
Describe the properties of skeletal muscle:
- striated
- voluntary
- cells regularly arranged >> unidirectional muscle contraction
- rapid contraction speed, short duration
- fibres are tubular & multinucleated
Describe the properties of cardiac muscle:
- striated (fainter than skeletal)
- involuntary
- branched >> simultaneous contraction
- intermediate contraction speed & duration
- fibres are branched & uninucleated
Describe the properties of smooth muscle:
- non-striated
- involuntary
- irregular
- slow contraction speed but long duration
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Describe the properties of smooth muscle:
- non-striated
- involuntary
- no regular arrangement >> different cells can contract in different directions
- slow contraction speed but long duration
- fibres are spindle shaped & uninucleated
Compare the structure of fibres of skeletal, cardiac & smooth muscle tissue:
- skeletal: tubular & multinucleated
- cardiac: branched & uninucleated
- smooth: spindle-shaped & uninucleated
Compare the arrangement of cells within skeletal, cardiac & muscle tissue & link it to their function:
- SKELETAL
- regular
- unidirectional contraction, for movement of limb in 1 direction
- CARDIAC
- branched
- simultaneous contraction, for contracting heart chambers
- SMOOTH
- irregular arrangement, spindle shaped
How are muscle fibres formed?
fusion
of individual embryonic muscle cells
What is sarcoplasm?
shared cytoplasm
within a muscle fibre
(cytoplasm is shared by cells due to fusion of muscle cells)
What is a sarcolemma?
plasma membrane
which envelops muscle fibres
of skeletal muscle
What are T tubules?
sections of sarcolemma which fold inwards
helps spread electrical impulses throughout sarcoplasm
so that whole fibre contracts simultaneously
What is the sarcoplasmic reticulum & its function?
modified endoplasmic reticulum found in skeletal muscle cells
contains calcium ions for muscle contraction
Skeletal muscles are made from bundles of ____ ____ enclosed in the ____.
muscle fibres
sarcolemma
What are myofibrils?
long, cynlindrical organelles
found in muscle
made of protein
& specialised for contraction
Describe the structure of myofibrils:
Made from 2 types of protein filaments:
- ACTIN
- thinner filament
- consists of 2 strands twisted around each other
- MYOSIN
- thicker filament
- long rod-shaped fibres with bulbous heads
Which protein filaments form myofibrils?
ACTIN & MYOSIN
What causes the presence of light bands on skeletal muscle fibres?
absence of myosin
/ areas where only actin is present
(not myosin, the thicker filament)
What causes the presence of dark bands in skeletal muscle fibres?
presence of myosin
(the thicker protein filament)
label the diagram:
What is a sarcomere?
functional unit of the myofibril
Voluntary & Involuntary Muscles
What is the A-band?
section of sarcomere
which contains myosin
Voluntary & Involuntary Muscles
What is the H-zone?
section of sarcomere
which contiains myosin without actin
Voluntary & Involuntary Muscles
What is the I-band?
section of sarcomere
which contains no myosin
Describe the structure of a sarcomere:
- z-line to z-line = sarcomere
- H-zone = myosin without actin
- I-band = no myosin
- A-band = myosin
- z-line = middle of light band
Describe & explain which sarcomere section each image is taken from:
small dots are actin, since thinner
large dots are myosin, since thicker
- LIGHT BAND - only actin present
- H-zone - only myosin present
- DARK BAND - actin & myosin present
