Skeletal muscle Flashcards
Types of muscle
akeletal, cardiac and smooth
Muscle contractions occur through the interaction of two proteins:
actin and myosin
Muscle is derived from what germ layer?
mesoderm
Muscle cells are called
myofibre
myoblasts fuse to form ___
myotubes
What are satellite cells
stem cells that can undergo proliferation in response to muscle damage
How many nuclei in skeletal muscle cells?
multi-nucleated
location of skeletal muscle cell nuclei
perpheral
Shape of skeletal muscle cells
long, cylindrical and of uniform diameter
Why are skeletal muscle cells striated?
due to ordered arrangement of actin and myosin filaments
contraction of which muscle is under voluntary control?
skeletal
3 layers of connective tissue in skeletal muscle
- endomysium
- perimysium
- epimysium
endomysium
fine layer of CT surrounding each myofibre
perimysium
bundles fibres into a collection called a fascicle
epimysium
bundles fascicles into a whole muscle (continuous with tendon)
functions of skeletal muscle CT
transfers forces from myofibres to tendon. Carries within it the blood vessels and nerves that supply the muscle
Duchenne’s muscular dystrophy
- x-linked degenerative disease
- caused by defect in dystrophin gene
- muscle degeneration, immobility, resp failure
- more liely to develop OCD, autism, hyperactivity
Each myofibre consists of numerous ____
myofibrils
___ is the functional unit of individual myofibrils
sarcomere
a single sarcomere extends from where to where?
from one Z disc to the next
Each sarcomere consists of overlapping ___ filaments and ___ filaments
Each sarcomere consists of overlapping ACTIN (THIN) filaments and MYOSIN (THICK) filaments
Sliding filament theory
- filaments do not change length during contraction
- contractions occur when filaments slide past eachother
Sarcomere shortens in length in response to
ncrease in Ca++ released from SR in response to depolarization of membrane
Myasthenia gravis
autoimmune disorder caused by reduction in percent of functional ACh receptors
- binding of antibodies against ACh receptors
- weakening of actie muscels in face, eyes, tongue
Define muscle atrophy
decrease in size in individual muscle cells that occurs as a result of disuse or damage to nerve that innervates the muscle
Muscle hypertrophy
increase in size of individual muscle cells that can occur as a result of exercise
muscle that forms the walls of the heart
cardiac muscle
cardiac muscle cells connected end to end by ___
intercalated disks
disks are sites of attachment of cells to eachother (_____) and communication between cells (____)
disks are sites of attachment of cells to eachother (DESMOSOMES) and communication between cells (GAP JUNCTIONS)
up to 40% of volume of cardiac muscle is made up of
mitochondria
Nuclei of cardiac muscles
1 or 2 per cell, centrally located
What are the names of the modified muscle fibres in CT that conduct impulses within the heart?
Purkinge fibres
Shape of smooth muscle
spindle
nuclei in smooth muscle
single elongated nucleus
smooth muscle is found where?
in walls of hollow structures (GI tract, respiratory tract, and circulatory system)
Slow, sustained and involuntary contractions of smooth muscle are regulated by ____
autonomic nervous system
