Physiology Flashcards
what types of muscles are striated
skeletal and cardiac
what is skeletal muscle contraction initiated by
motor neuron stimulation
what are the physiological functions of skeletal muscles
maintenance of posture
purposeful movement in relation to external environment
respiratory movements
heat production
contribution to whole body metabolism
what innervates skeletal muscles
the somatic nervous system
what innervates cardiac and smooth muscles
the autonomic nervous system
what muscles are involuntarily controlled
cardiac and smooth
what causes the striation of cardiac and skeletal muscles
alternating dark bands (thick myocin filaments)
and light bands (thin actin filaments)
what initiates and propagates contraction of cardiac muscle cells
myogenic (originating within muscle tissue- pacemaker potential)
do cardiac muscles have motor units
no
which type of striated muscle has a neurovascular junction
skeletal
which type of striated muscle has gap junctions
cardiac muscle
where is skeletal muscle Ca++ from
entirely from sarcoplasmic reticulum
where is cardiac muscle Ca++ from
from extra cellular fluid and sarcoplasmic reticulum (Ca++ induced Ca++ release)
what determines the gradation on skeletal muscle contraction
motor unit recruitment
summation of contractions
what determines the gradiation of cardiac muscle contraction
depends on the the extent of the heart filling with blood (pre-load, frank sterling mechanism)
is there continuity of cytoplasm between nerve and skeletal muscle cells
NO need neurotransmitters
what is the neurotransmitter at neurovascular junctions
acetylcholine
what is a motor unit
a single alpha motor neuron and all the skeletal muscle fibres it innervates
where do motor neurons come from
spinal chord
what does the number of muscle fibres per motor unit depend on- explain
the function served by the muscles- fine movement (eye, facial, hand muscles) have fewer fibre per unit (aprox ten). powerful muscles have more units eg thigh muscles (100-1000s)
what makes up muscle fibres (aka muscle cells)
myofibril (contractile intracellular structure) which make up sarcomere (functional unit)
what are the protein molecules contained within myofibril and sacromeres
myocin and actin
how are skeletal muscles usually attached to the bone
by tendons
how are the protein filaments arranged in skeletal myofibrils
alternating actin (light) and myocin (dark) make sarcomeres (functional units)