Download Muscle tissue

Muscle tissue
192 SFST
Muscle
Characteristic feature of muscle tissue:
cells are capable of contraction –
movement – presence of actin and myosin
 Smooth muscle
 Skeletal muscle – striated
 Cardiac muscle - striated

Sarcomere
A band
I band
M line
H band
Z line
Actin fibre is composed from Gactin and regulatory proteins
(tropomyosin and troponin I,C,T)
Contraction

Mechanism of contraction is the same in
skeletal and cardiac muscle. Skeletal
muscle possesses higher pool of Ca,
therefore is less dependent on its
concentration in plasma .

Ca++ releases from sarcoplasmic reticulum (SER)
into the cytoplasm, binds on troponin C – it
changes configuration of troponin and
tropomyosin – bond of actin and myosin activates
myosin phosphatase – phosphate is cleaved off
from myosin – energy is used for changes of
myosin configuration - contraction
Contraction
Changes in myosin
space configuration
– movement of
myosin head =
actin slides along
myosin + length of
sarcomere is
reduced
Contraction
Contraction within smooth
muscle
Ca++ ions are bound on calmodulin in the smooth
muscle. Calmodulin activates kinase, which
catalyses the tranfer of phosphate on light chains
of myosin.
That reaction is needed for bond between actin and
myosin. Myosin is coiled without phosphate bond
Therefore, movement of smooth muscle is slower
Other proteins necessary for muscle
α-aktinin – within Z line
Desmin, plectin – they are necessary for
attachment between myofibrile and
superficial membrane
Nebulin – template for f-actin
Titin – keep myosin in sarkomera –
necessary for muscle elasticity
Attachment to cytoskeleton
Smooth muscle

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Smooth muscle is composed
from spindle -like (fussiform)
cells
Nucleus
Actin and myosin, but also
intermediate filaments (desmin
and vimentin)
Dense bodies
Hemidesmosomes, gap
junctiones and pinocytic
invaginations
Smooth muscle
Occurence: walls of organs, vessels, skin,
prostate, eye
 15 – 20 µm in vessels
 150 - 200µm in wall of organs
 Single or
in layers

Smooth muscle

Contraction is caused by:
 Release
of mediator into the cell vicinity
(neuromediator, hormone)
 Transfer through gap junctions
 Automatically
 Stretching
Cardiac muscle
Basic unit is cylindric cell – cardiomyocyte (85
-100 um)
 Nucleus is in the middle of cell , mitochondria
(almost 40% volume), glycogen, lipids
 Sarcoplasmic reticulum without cisternes - diads.
 Cells are connected by intercellular junctiones –
intercalated discs
In cardiac muscle, there are plenty capillaries

Cardiomyocyte
Actin and myosin
Mitochondria
Sarcoplasmic reticulum
Intercalated
disks
Cardiomyocyte
Intercalated disks
Fascia adherens –
anchoring the actin
filaments
 Desmosomes – anchoring
the intermediate filaments
 Gap junctions –
information transfer
between cells –
coordination of contraction
Function : adhesion and
information transfer

Cardiomyocyte
Atrial natriuretic factor
– granules within
cardiomyocytes
(mainly within atrial
cardiomyocytes) –
water volume
control – antagonist
of aldosteron
Antrial natriuretic factor – red, αactinin - green
Conduction system of the heart
Sino-atrial node
 Atrio-ventricular node
 His bundle
 Tawar bundles
 Purkyně fibers

Purkyně fibers
Less myofibrils and
mitochondria; no
intercalated disks.
Only gap junctions
and local adhesive
junctions
High content of
glycogen
Skeletal muscle

Basic unit of skeletal muscle is fibre –
multinuclear syncytium – diameter form 60 to
100 µm
Development of skeletal muscle
Myoblast
 Myotube
 Muscle fiber


Satelite cells –
myoblasts – muscle
regeneration
Skeletal muscle
Fiber – comprises many nuclei under
sarcolemma, organels are in vicinity of
nuclei (RER,GC)
 Cytoplasm filled by myofibriles
 Sarcoplasmic reticulum – tubules and
cisternes. T- tubulus + cisternes = triads
 Mitochondria, lipids a glycogen, myoglobin

Sarcoplasmic reticulum
Terminal cisternae
Tubules of
sarcoplasmic
reticulum
T-tubulus
Reservoir of Ca++
ions
Skeletal muscle
Actin and myosin are arranged regularly –
forming myofibrils, they are striated
 Sarcomera – part of fibril surrounding by
Z line (telofragma - α actinin, desmin)
 Actin and myosin are attached to
cytoskeleton and cellular membrane,
through it to surrounding connective tissue

Skeletal muscle

Skeletal muscle varies in structure,
function and metabolism
White fibre
 Red fibre
 Intermediate
fibre

Skeletal muscle
White fibre – wider diameter, more actin
and myosin, glycogen, less mitochondria,
lipids, myoglobin – anaerobic metabolism,
fast fibre
 Red fibre – thiner, more mitochodria, lipids
and myoglobin, less actin and myosin,
glycogen – slow fibre (similar to cardiac
uscle) – aerobic metabolism

Connective tissue
Endomysium
 Perimysium
 Epimysium

Fascia
 Tendon

Muscular dystrophy

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Genetic disease of skeletal
muscle
Mutation in gene for
Dystrophin and DAP
(dystrophin-associated
protein)
Function – transfers
power of contraction from
cytoplasm to sarcolemma
and connective tissue
Duchenn muscular
dystrophy - dystrophin
Muscular dystrophia
Inervation – neuromuscular plate
Synaptic junction
between
motoneuron and
skeletal muscle fibre – acetylcholin
Primary and
secondary synaptic
clefts
Lamina basale
Sensitive inervation – muscle
spindle
Motor (γ-motoneuron)
and sensitive
inervation
Control of movement
and tension