midterm 2 Flashcards
three types of muscle
smooth, cardiac, skeletal
striated muscle
skeletal and cardiac
unstriated muscle
smooth muscle
voluntary muscle
skeletal innervated by somatic NS
involuntary muscle
cardiac and smooth, innervated by autonomic NS
name for a single skeletal muscle cell
muscle fibre
in embryonic development, skeletal muscle fibres are formed by the fusion of ____
myoblasts
specialized contractile elements that make up 80% of the muscle fibre volume
myofibrils
thick filaments
special assemblies of the protein myosin
thin filaments
primarily made of protein actin
level of organization in a skeletal muscle
whole muscle, muscle fibre, myofibril, thick and thin filaments, myosin and actin
purpose of connective tissue
provides structure to the muscle and allows transfer of force to the bone, providing tension for stabilization/ movement
the connective tissue which covers the whole muscle
epimysium
connective tissue that divides the muscle fibres into bundles or fascicles
perimysium
inner most connective tissue, covers each muscle fibre or cell
endomysium
dark bands
a bands
light hands
I bands
the lighter area within the middle of the A band where the thin filaments do not reach
H zone
extends vertically down the middle of the A band within the centre of the H zone, system of supporting proteins holding thick filaments together
M line
the area between two Z lines
sarcomere, the functional unit of skeletal muscle
a flat cytoskeletal disc that connects the thin filaments of two adjoining sacromeres
Z line
largest protein in the body, 30 000 amino acids
titin
functions of titin
helps stabilize the position thick filaments in relation to the thin filaments, and greatly augments muscle elasticity
(helps muscle recoil)
a motor protein molecule consisting of two identical subunits each shaped somewhat like a golf club
myosin
the two important sites on a cross bridge crucial to the contractile process
an actin binding site, and an ATPase (ATP splitting) site
three proteins that that make up thin filaments
actin, tropomyosin, troponin
are myosin an actin unique to muscle cells?
no, but they are abundant and highly organized in muscle cells
what is excitation-contraction coupling?
the series of events linking muscle excitation to muscle contraction
skeletal muscles are stimulated to contact by release of _____
acetylcholine (ACh)
what do the sarcoplasmic reticulum lateral sacs store?
Ca2+
what are ryanodine receptors
foot proteins / bridge the gap and serve as ca2+ release channels because they are locked in the open position but the plant chemical ryanodine
how long does a single action potential in a skeletal muscle fibre last
1 to 2msec
a single action potential that is too short and weak to be useful
twitch
tetanus
if a muscle fibre is stimulated so rapidly that it doesn’t have a chance to relax between stimuli, tetanus occurs and is 3-4x stronger than a single switch
most common type of lever system in the body
flexion of the elbow joint
