Muscle Tissue 🏋️♀️ Flashcards
Muscle Tissue
Consists of contractile cells and responsible for movement. Derived from the mesoderm.
Myofibrils
Bundles of myofilaments and the structural and functional subunit of the muscle cell.
Actin/thin filaments
Composed mainly of F-actin, with associated proteins like tropomyosin, troponin complex, and nebulin for regulation and stabilization.
I-band
Region of the sarcomere where only thin (F-actin) filaments are present.
Sliding Filament Hypothesis of Huxley
Theory explaining muscle contraction where myofilaments slide past each other without changing length.
Sarcoplasmic reticulum
Membranous network around myofibrils that stores calcium ions and communicates with T-tubules in muscle cells.
Muscle Spindle
Encapsulated sensory receptor in muscle belly that senses changes in muscle length or stretch, containing modified muscle fibers.
Smooth Muscle Cells
Cells that secrete connective tissue matrix, synthesize various types of collagens and elastin, and possess well-developed rER and golgi.
Sarcomere
The specific organization of contractile proteins of the myofibril observed in all striated muscle types.
Sarcomere
Basic contractile unit of striated muscles containing thick (myosin II) and thin (F-actin) filaments.
H-band
Central region of the sarcomere made up of thick filaments (myosin II) only.
Golgi Tendon Organ
Encapsulated proprioceptor located at myotendinous junction that senses tension in muscles and is part of the Golgi tendon reflex.
Peripheral protein
Proteins found on the periphery of membranes or structures, serving various functions such as structural support or cell signaling.
T tubules
Extensions of the cell membrane that help transmit action potentials deep into muscle fibers, facilitating muscle contraction.
Gap junctions
Specialized protein channels that allow direct communication and passage of ions and small molecules between adjacent cells.
Contractile cells
Cells responsible for muscle movement, such as myofibers. Derived from the mesoderm.
Myosin II/thick filament
Motor protein binding to actin subunits in striated muscles for movement, consisting of head and tail regions connected by a lever arm in the S2 region.
A-band
Region of the sarcomere where thick filaments (myosin II) are predominantly located.
Myofilaments
Contractile proteins (F-actin, myosin II) responsible for muscle contraction.
Intercalated Discs
Attachment sites between adjacent cardiac myocytes, containing macula adherens and fascia adherens for structural integrity.
Juxtanuclear region
The area near the nucleus of a cell, often involved in functions related to transport, signaling, or organelle positioning.
Myofilaments
Contractile proteins/elements occupying the bulk of the sarcoplasm, classified into thin filaments mainly composed of F-actin and thick filaments mainly composed of myosin II.
Actomyosin Cross-Bridge Cycle
Series of stages in muscle contraction involving attachment, release, bending, force generation, and reattachment.
Duchenne Muscular Dystrophy
Genetic disorder characterized by progressive muscle weakness, typically fatal in early adulthood due to breakdown of muscle fibers.
Purkinje Fibers
Modified cardiac muscle cells specialized for conducting impulses of the A-V bundle and synchronizing ventricular contraction.
Myosin light chain kinase
Enzyme responsible for phosphorylating myosin, leading to muscle contraction by interacting with actin filaments.
Hypertrophy and hyperplasia response
Cellular growth due to increased demand or stimulation, involving either enlargement of existing cells (hypertrophy) or increase in cell number (hyperplasia).
