The Muscle System Flashcards
Musculoskeletal system
Comprised of muscles and skeltons
Muscles and skeletons are ____ that produce movment
effectors
3 types of vertebret muscle
skeletal, cardiac, smooth
Skeletal muscle involves
voluntary movement, breathing
Cardiac involves
beating of the heart
Smooth muscle
involuntary, movement of internal organs
What does it mean when skeletal muscles are “striated”
they have “strips” of muscle cells
skeletal muscle cells are called
muscle fibers
Muscle fibers are extremely ____, _____ cells
large - multinucleated
Skeletal muscles form by _____ of _____
fusion of embryonic myoblasts
One muscle consists of many _____ bundled together by connective tissue
muscle fibers
Each muscle fiber has several ______
myofibrils
Myofibrils consist of
bundles of actin and myosin filaments
The contractile proteins
Actin and myosin
Actin are ____ filaments
thin
Myosin are ____ filaments
thick
Sarcomere
overlapping actin and myosin filaments
Each myofibril consists of repeating units called
Sarcomeres
Titin and what does it do?
the largest protein in the body that holds bundles of myosin filaments in place
Describe the “sliding filament mechanism”
myosin heads bind to specific sites on actin molecules to form cross bridges, then change conformation to cause the actin filments to slide 5-10 nm
During the sliding filament mechanism mysoin heads _____ to specific sites on ____ to form ______
bind; actin; crossbridges
Muscle contration is initiated by ______ from a ____ neuron at the ______
action potentials, motor neruon, neuromuscular junction
A motor unit
all the muscle fibers that are activated by one motor neuron
Muscle cells are inhibited or excited?
excited
the plasma membrane of the muscle cells can ____ action potentials
conduct
____ is released by the motor neuron at the ______ and opens _____ in the _______
ACH; neuromuscular junction; ion channels; motor end plate
The chemical synapse between a motor neuron and a muscle cell is
the neuromuscular junction
Action potentials move through fibers via
T-tubules (transverse tubules)
T-tubules descend into the
sarcoplasm (muscle fiber cytoplasm)
The sarcoplasm is
the muscle fiber cytoplasm
T-tubules run close to the
sarcoplasmic reticulum
The sarcoplasmic reticulum (SR) is
a closed compartment that surrounds every myofibril, the ER of muscle cells
the SR has ____ pumps
Ca2+
At rest here is a ____ concentration of Ca in the _____ of the SR
high concentration; lumen
An action potential will ____ Ca channels and Ca flows ______ of the SR and triggers the interaction of
open; out; action and myosin
Actin filaments also include
tropomyosin and troponin
3 subunits of troponin bind to ___,__,___
actin, tropomyosin, and Ca2+
At rest, _____ blocks binding sites on actin
tropomyosin
Troponin changes conformation when
Ca2+ is released and binds to it