Seminario 3: Sistema Muscular 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 contracción-relajación. 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 Troponina Tropomiosina Miosina

Fuentes de ATP Glucolisis CP TCA-OP Duracion Uso Requerimientos

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 Contracciones isométricas e isotónicas, ejemplos. Curvas tensión-longitud.

Longitud (% largo relativo) 60 80 100 120 140 160 0.5 1.0 1.25m 1.65m 2.0m 2.25m 3.65m Longitud (% largo relativo) Tensión relativa

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 Smooth Cardiac 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 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.