CATEDRA DE FISIOLOGIA ANIMAL
Facultad de Ciencias Naturales y Museo
Universidad Nacional de La Plata
Seminario 3: Sistema Muscular
Temario
SISTEMA MUSCULAR
Características y funciones de las proteínas contráctiles y
regulatorias.
Mecanismo de contracción el músculo estriado
esquelético. Placa motora.
Músculo estriado cardíaco: características funcionales.
Músculo liso : estructura y mecanismo de contracciónrelajación.
Papel del Calcio y del ATP en los distintos tipos
musculares.
Contracciones isométricas e isotónicas, ejemplos. Curvas
tensión-longitud.
Características funcionales de las fibras fásicas y tónicas.
Propiedades del musculo
•
•
•
•
Contractibilidad
Excitabilidad
Extensibilidad
Elasticidad
Características y funciones de las
proteínas contráctiles y regulatorias.
Mecanismo de contracción el músculo
estriado esquelético. Placa motora.
Músculo esquelético
•Ubicación
•Núcleos
•Control
Resumiendo
Miosina
Tropomiosina
Troponina
Fuentes de ATP
Glucolisis
CP
•Duracion
•Uso
•Requerimientos
TCA-OP
Velocidad de contraccion
Músculo estriado cardíaco:
características funcionales.
•Ubicación
•Núcleos
•Control
•Uniones
Actividad eléctrica en el corazón
Músculo liso : estructura y
mecanismo de contracción-relajación.
•Ubicación
•Núcleos
•Control
•Uniones
Características funcionales de las
fibras fásicas y tónicas.
•Contracción
•Diámetro
•Irrigación
•Color
•Mitocondrias
•Depositos de CH2O
En resumen, ¿Qué determina las
características de las fibras?
-Graduada o todo o nada?
-Velocidad de contracción
-Resistencia a la fatiga
Después del esfuerzo: Recuperación
Contracciones isométricas e
isotónicas, ejemplos. Curvas
tensión-longitud.
2.25m
2.0m
1.65m
Tensión relativa
1.0
0.5
3.65m
1.25m
0
60
80 100
120
140
160
Longitud (% largo relativo)
Tension vs. tiempo
Temas especiales
Organización neuromuscular en
vertebrados e invertebrados
Esqueletos rígidos e hidráulicos
Músculos del vuelo en insectos
Musculo estriado
•Ubicación
•Nucleos
•Control
SLIDING FILAMENT THEORY
•
Muscle
Tissue
Types
Skeletal
– Attached to bones
– Nuclei multiple and peripherally located
– Striated, Voluntary and involuntary (reflexes)
• Smooth
– Walls of hollow organs, blood vessels, eye, glands,
skin
– Single nucleus centrally located
– Not striated, involuntary, gap junctions in visceral
smooth
• Cardiac
– Heart
– Single nucleus centrally located
– Striations, involuntary, intercalated disks
The sarcomere. The upper panel shows a transmission electron micrograph of a human cardiac sarcomere.
The boundaries of the sarcomere are the 2 Z-discs (Zwischencheibe) which are dark and electron dense.
On each side of the Z-discs, there is an area of electron-lucent material with fine filaments that run
perpendicular to the Z-disc. These represent actin filaments which insert into the Z-disc. The area that
encompasses a Z-disc and adjacent electron-lucent area of actin filaments from two sarcomeres is
designated the I band (Isotropic band). In the middle of this electron-lucent actin rich area, there are some
subtle electron-dense streaks that run parallel to the Z-disc and are named the N-disc (Nebenscheibe) . In
this area, there are some proteins that interact with titin, actin and α-actinin. The mid portion of the
sarcomere is comprised of the A band (Anisotropic band). Within the A band, there are several areas with
specific patterns of electron density. There is a middle line or M band (Mittellinie) which bisects the A band.
Adjacent to the M band, there are two lighter electron-lucent areas designated the H band (Helle). The M
band corresponds to the insertion site of the tails of the thick filaments into a matrix of proteins that keep
them organized and in register. Within the M band, there are subtle electron-dense core of proteins which
correspond to myomesin and other proteins that serve to anchor the thick filaments. The larger dark areas
that flank the M and H bands are the actual rows of thick filaments. In the middle third of these areas, there
are some vertical striations which correspond to electron-dense myosin binding protein C. The lower portion
of the figure shows a simplified illustration of the sarcomere. The M band shows the tails of the thick
filaments interacting with a light brown lattice of myomesin molecules. The thick filaments extend away from
the M band with the heads (green) protruding away from the axis of the filament. Myosin binding protein C is
visible as small blue subunits that cover about one third of the length of the thick filament. The thin
filaments (red) are made of several proteins (see The Thick and Thin Filaments). The yellow coils shown at
the level of the Z-disc represent intermediate filaments of desmin which connect adjacent myofibrils to each
other and to the sarcolemma. An animation of the sarcomere contraction is shown here and here
http://www.youtube.com/watch?v=-pg09F5V63U.
Descargar

seminario muscular - Facultad de Ciencias Naturales y Museo