Download Muscle Tissue

Muscle Tissue
Muscle - Prefixes
Myo (Greek) = muscle
eg. Myology = the study of muscle
Myositis = inflammation of muscle
Sarco (Greek) = “flesh”
eg. Sarcoplasm = the cytoplasm of muscle
Sarcomere = basic contractile unit of
muscle
Contractile mechanisms
This is fundamental to many cell types -not
just “muscle”
eg. Macrophages
Muscle
Packaging of contractile proteins is related to the
functions required
Thus there are different such arrangements
These are classified into different “types” of
MUSCLE
Contractile mechanisms
Macrophages = phagocytes which move freely to
engulf (phagocytose) cell debris & microorganisms
Specialised contractile proteins
Muscle is a concentration of such proteins
Myosin
Actin
Troponin
Tropomysin
& many structural
proteins
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Packaging of muscle proteins
Depends on the force required
eg. Slow steady contraction of tubes in the body to maintain “tonus” or steady contractions
Use individual cells with orientated packages of
contractile proteins
Slow contracting packages of
muscle proteins
Common in tubes of the body
Arteries & veins
Intestine
Lungs
Urinary system
Reproductive tubes
Slow contracting packages of
muscle proteins
Slow contracting packages of
muscle proteins
PROPERTIES
Cells contract slowly
Often rhythmically – eg. peristalsis in gut tube
Have tonic and slowly changing tensions
Under nervous control of the
Autonomic Nervous System (involuntary)
Called then INVOLUNTARY muscle
Contractile proteins arranged in a dispersed
pattern - not in regular parallel arrays as
in muscle which moves the skeleton
ie. Skeletal muscle is “striped” in
appearance
INVOLUNTARY muscle is not striped
& is thus then called
Smooth muscle
Skeletal muscle
Skeletal muscle - mass
Muscles which move the skeleton need
Much more power = mass – many Kg
1. Much more power
2. Tougher connective tissue support
3. Much faster contraction
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Skeletal muscle – anatomical forms
Skeletal muscle – Connective tissue
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Skeletal muscle – Connective tissue
Aponeurosis
A fibrous or
Membranous
sheet-like tendon
Fascia
Fibrous sheet
binding skin to
underlying muscle s
or supporting/
separating muscle s
Tendon
Band of connective
tissue that attaches
muscle to bone
Skeletal muscle - contraction
Cross
striations
Skeletal muscle
Design characteristics
Large cells = syncytium of
fused myoblasts to form
long multinuclear muscle
fibres
Highly organised contractile
protein myofilaments
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Skeletal muscle
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Design characteristics
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Large cells = syncytium of
fused myoblasts to form
long multinuclear muscle
fibres
&
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Skeletal muscle – cell = fibre
Packaging
Myofilaments
(contractile
proteins)
into
small bundles
myofibrils
Highly organised contractile
protein myofilaments
Sarcomere
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Sliding myofilaments
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Skeletal muscle - LS
Skeletal muscle - tubules
Transport problem because of huge cells
1. To transport wave of depolarisation into
contractile filaments –
T Tubes, which are extensions of the
sarcolemma
2. Internal tubules to hold calcium Sarcoplasmic reticulum
Skeletal muscle - TS
Large fibres
&
peripheral
nuclei
Skeletal muscle – tubules
Complex system of tubes within fibres (cells) for internal
transport
Transport
Problem
1. External
2. Internal
Skeletal muscle – large cells
Comparison of Smooth & Skeletal muscle
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Skeletal muscle – Nerve supply
Skeletal muscle – Nerve supply
Skeletal muscle – Nerve supply
Skeletal muscle – Capillaries
Muscle
Spindle
Skeletal muscle – Blood supply
Skeletal muscle – Blood supply
Large muscle fibres & metabolically active
& need a large amount of blood = oxygen
But some muscles can work without oxygen
for short times
These are
Fast twitch muscles as in sprinters
Most muscles use oxygen & can work for a
long time – with an adequate blood supply
These are Slow Twitch muscles
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Skeletal muscle - Types
Cardiac Muscle
Heart
Left
Ventricle
muscle
Cardiac muscle
A variant of skeletal muscle Striated or striped
Very fast contraction – but critical relaxation
Internal tubular system
Differences:
Individual cells joined very tightly at
Intercalated discs
Branched individual fibres
Central nuclei – like smooth muscle
Cardiac Muscle - size
Smooth – Cardiac
Skeletal
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Cardiac Muscle - TS
Cardiac Muscle - LS
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Cardiac muscle
A variant of skeletal muscle Striated or striped
Very fast contraction – but critical relaxation
Internal tubular system
Cardiac Muscle - LS
Intercalated
disc
Differences:
Individual cells joined very tightly at
Intercalated discs
Branched individual fibres
Central nuclei – like smooth muscle
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