physiology:: Skeletal Muscle Structure & Contraction Flashcards
skeletal muscle
- classification
- typical location
- function
- striated voluntary muscle
- attached to bone of skeleton
- movement of body in relation to external environment
cardiac muscle
-classification
typical location
function
- striated involuntary muscle
- wall of heart
- pumping blood out of heart
smooth muscle
-classification
typical location
function
- unstriated involuntary muscle
- walls of hallow organs and tubes …eg blood vessels and stomach
- movement of contents within hallow organs
description of skeletal muscle
- grouped
- length
- thickness
- shape
- striated
- type of cells
- bundles
- long
- thick
- cylindrical
- striated
- contractile multinucleate
description of smooth muscle
- grouped
- length
- thickness
- shape
- striated
- type of cells
- interlinked network
- short
- slender
- cylindrical
- striated
- contractile cell connected by interculated disk
description of cardiac muscle
- grouped
- length
- thickness
- shape
- striated
- type of cells
- loose network
- short
- slender
- spindle -shaped
- unstriated
- contractile cells arranged in sheets
Skeletal Muscle: Structure
what are muscles made up of
-group of Fascicles (these contain bundles of muscle fibres)
muscle fibers are surrounded by
connective tissue
Layers (of / encompassing) Muscle Tissue
sarcolemma endomysium perimysium edimysium fascia
sarcolemma
cell membrane that encloses each muscles cell (muscle fibers)
endomysium
connective tissue that wraps each muscle fiber
perimysium
connective tissue that wraps bundles of muscle fibres (bundles aka fasciles)
epimysium
connective tissue that wraps the whole muscle
fascia or aka deep fascia
layer of thickened connective tissue that covers all of muscle
right above epimysium
Skeletal Muscle: Contraction Basics
what do skeletal muscles need in order to contract
how does this work
-stimulation by nervous system
-communication at nueromuscular junction…..
impulse travels down nerve and reaches NMJ which causes chemical transmitter to be released causing to trigger muscle contraction
Skeletal muscle is supplied by the
efferent arm of somatic nervous system (SNS)
Motor neuron activity is
cholinergic, nicotinic and only excitatory
Muscle Fibre Organisation
- sarcolemma: plasma membrane
- transverse T tubules :folds of sarcolemma
- sarcoplasm: cytoplasma (contains many myofibrals)
- sarcoplasmic recticulum: smooth ER
muscle fibre structure
regular striated patterns of filaments and organelles hint at functionality
Muscle Fibre Organisation
muscle fibre composed of myofibrils
myofibrils are repeating units of sarcomeres
sacromeres are regular arrays thick filaments (myosin polymer) and thin filament (actin polymer)
Myofibrils give skeletal (and cardiac) muscle
striated appearance
striations
due thin and thick filaments that run parrell to long axis
what forms sarcomeres
what are sarcomeres
filaments
functional unit…… z line to z line
sarcomere dimensions
H zone - thick filament (myosin only)
A band- thick filament. and overlapping thin filament(actin)
I band -thin. filament only
