Muscle Cell Histology Flashcards
what are the 3 places where skeletal muscle is not attached to bone? (visceral striated muscle)
tongue, esophagus and diaphragm
what are nearly all muscle pathologies associated with?
ECM fibrosis
what is contained in the epimysium
surrounds a muscle Dense connective tissue containing fibroblasts, collagen and elastic fibers Merges with dense collagen of tendons, aponeuroses, and superficial fascia Contains blood vessels, nerves, and lymphatic vessels
what is contained in the perimysium
surrounds a fascicle dense, connective tissue Functions to bundles myofibers into fascicles Conduits for nerves, arteries, arterioles, veins, and houses muscle spindles
what is contained in the endomysium
surrounds a single muscle fiber ( a fiber is a muscle cell) Delicate connective tissue composed of collagen, elastic fibers, reticulin fibers, as well as extracellular matrix proteins, e.g., laminin-2, Contains capillaries which are permeable and often closed at rest: 1.7 capillaries adjacent to each individual fiber 0.7 capillaries per fiber when looking at a cross-sectional area Contains terminal axons that synapse on myofibers at neuromuscular junctions
define a costamere
help bridge the contractile apparatus to the extracellular matrix. TRANSMIT FORCE TO ENDOMYSIUM “rib-like” complexes of proteins connecting z-lines to sarcolemma
Dystroglycan/Sarcoglycan complex
help bridge the contractile apparatus to the extracellular matrix. TRANSMIT FORCE TO ENDOMYSIUM Sarcolemmal complex transmitting internal forces to ECM Dystrophin is t connects complex to subcortical actin cytoskeletal
What are Myotendinous Junctions
Function: Highly folded membrane increases surface area and converts tensile stress to sheer stress Last sarcomere lacks a z-line Actin filaments extend from the A-band and attach to the sarcolemma Collagen fibrils extend between the projections of the membrane (arrows)
Identify the type of muscle shown here
The whole thing is the epimysium, the
perimyseum are the bundles
The endomysium are inside of the fasicles
ID this structure
How do you differentiate the nervous tissue from the tendon and the skeletal muscle
The nerve has the flat perineurym, the tendon is in the skeletal muscle and also has microfilaments
what is the function of the pacinian corpusle
detect vibration
How does proprioception occur
provide afferent signals to the CNS that tells us where our body is postioned based on how tensed the intrafusal muscle fibers are
the intrafusal fibers have afferent and efferent information
intrafusal fibers send sensory information via large myelinated fibers from the central zone to dorsal root to spinal cord; anterior horn cells neurons (gamma fibers) innervate the distal zones and regulate contraction of the distal regions
what are infusal fibers and how dothey relay
A muscle spindle is encapsulated by modified perimysium, with concentric layers of flattened cells, containing interstitial fluid and a few thin muscle fibers filled with nuclei and called intrafusal fibers. Several sensory nerve axons penetrate each muscle spindle and wrap around individual intrafusal fibers. Changes in length (distension) of the surrounding (extrafusal) muscle fibers caused by body movements are detected by the muscle spindles and the sensory nerves relay this information to the spinal cord.
Different types of sensory and intrafusal fibers mediate reflexes of varying complexity to help maintain posture and to regulate the activity of opposing muscle groups involved in motor activities such as walking.
What is the signifince of the T tubule
allows to spead the wave of depolarization down into the layers of cytoplasm within the muscle cell
define the triad
the T tubule with the 2 cisterns of SR on each side
where does the triad reside
A-I junction
ID these structure
function of the M
function of Z-disk
function of A band
function of I band
a actin
M: bisects the sarcomere and organize myosin filaments
Z-disk: Organizes actin filaments and Defines the boundaries of sarcomeres
A band: where mysosin filaments reside, defines the legnth the only one that wont change
I band: Regions lacking myosin, Stretches across two sarcomeres
name these components
muscle spindle shows the capsule (C), lightly myelinated axons (MA) of a sensory nerve, and the intrafusal muscle fibers (MF). These thin fibers differ from the ordinary skeletal muscle fibers in having very few myofibrils. Their many nuclei can either be closely aligned (nuclear chain fibers) or piled in a central dilation (nuclear bag fibers). Muscle satellite cells (SC) are also present within the external lamina of the intrafusal fibers.
What is this characteristic of
fiber grouping is a pathological condition that occurs which chronic denervation.
The devervation leads to angular shaped atrophied cells, which the other axon resprouts to innervate these muscle cells. This results in diminished mixing of muscle types
what is this characteristic of
fiber disarray in the central region of cells seen with NADH-tetrozoliumreductase (TR) staining
Central region lacks mitochondria/sarcoplasmic reticulum (SR)
Intermediate region has a high proportion of mitochondria and SR
Peripheral region is normal in mitochondria content and myofibril architecture
what is the timeline of muscle and nerve injury after ischemia
decreased ox phosphorylation
loss of ATP and pump maintence
decrease in aerobic functions, decrease in NA pump detachment of ribosomes
the loss of the pumps lead to increased Ca influx and K efflux –> necrosis and cell swelling
Loss of aerobic functions leads to an increase in lactic acid and decreased pH and decreased glycogen –> clumbing of nuclear chomatin
the loss of chromosomes –> decrease in protein synthesis
