Muscle Flashcards
what are the five general functions of muscle?
moving, posture maintenance, protection, heat production, regulate elimination of materials
what is muscle excitability?
ability of a cell to respond to a stimulus
what is muscle conductivity?
electrical signal that is propagated along the plasma membrane as voltage-gated channels open sequentially during an action potential.
what is muscle contractility?
when contractile proteins in skeletal muscle slide past one another
what is muscle extensibility?
the lengthening of a muscle cell
what is muscle elasticity?
the ability of a muscle cell to return to its original length after either shortening or lengthening of the muscle.
what are skeletal muscle cells also called?
skeletal muscle fibers due to their extreme length. Muscle fibers also works
what is the epimysium?
a layer of dense irregular connective tissue that surrounds the whole skeletal muscle
what is the perimysium?
later of dense irregular connective tissue that surrounds each fascicle
what is endomysium?
areolar connective tissue that surrounds each muscle fiber and gives it nutrient.
what is deep fascia?
an additional expansive sheet of dense irregular connective tissue that is external to the epimysium
is skeletal muscle vascularized?
yes its filled with blood vessels and nerves
what are satellite cells?
muscular stem cells in adults
what is the sarcolemma?
the plasma membrane of a muscle cell
what are T-tubules?
network of narrow, membraneous tubules to the sarcoplasmic reticulum
what are myofibrils?
they’re what makes up a skeletal muscle fiber.
what is the sarcoplasmic reticulum?
internal membrane complex that’s similar to the Smooth ER
what are myofilaments?
contractile proteins that are bundled within myofibrils
what are thick filaments?
200-500 myosin protein molecules
what are thin filaments?
approx half the diameter of thick filaments and
what is the first physiologic event of contraction?
the muscle fiber excitation by a somatic motor neuron
what is a nerve signal?
electrical signal that is propagated down axons. Also the first step that occurs at a neuromuscular junction
what is the second occurrence at a neuromuscular junction?
the binding of Ca2+ to synaptic vesicles which results in the release of ACH
what is the third occurrence at a neuromuscular junction?
Binding of ACH at a Motor End Plate. this causes the excitation of skeletal muscle fiber
what is the first step of Excitation Contraction coupling?
development of endplate potential at the motor end plate
what is an end plate potential?
the threshold at which the motor end gate can trigger an opening of voltage gated channels in the sarcolemma to initiate an action potential
what is the second step of Excitation Contraction coupling?
initiation and propagation of Action potential along the sarcomere and T-tubules
what is the third step of excitation contraction coupling?
the release of calcium from the sarcoplasmic reticulum.
what is cross bridge cycling?
four step process that is repeated
what is the first step of cross bridge cycling?
cross bridge formation, where myosin heads which are “cocked” attach to exposed myosin binding sites of actin
what is the second step of cross bridge cycling?
power stroke; the myosin head swivels in what is called a power stroke, which pulls the thin filament where a small distance past the thick filament towards the center of sarcomere
what is the third step of cross bridge cycling?
release of myosin head atp, where ATP binds to the ATP binding site of a myosin head, which causes the release of the myosin head from the binding site on actin
what is the fourth step of cross bridge cycling?
resetting of myosin head; myosin ATPase splits ATP into ADP and P providing the energy to reset the myosin head in the cocked position
what is the first step to skeletal muscle relaxation?
the termination of the rapid nerve signals propagated along the motor neuron
what is creatine phosphate?
a molecule with a high energy chemical bond between creatine and P and is present in tissues with both large and fluctuating energy needs.
Aerobic Cellular Respiration
occurs within the mitochondria and requires oxygen; three stages: intermediate step, citric acid cycle, and the electron transport system
Oxygen Debt
amount of additional oxygen that is consumed following exercise to restore pre exercise conditions
Muscle power
relates to the diameter of a muscle fiber, larger muscle fibers have a larger number of myofibrils in parallel allowing them to produce a more powerful contraction
Muscle Speed
based on whether the skeletal muscle fiber expresses the relatively slow or fast genetic variant of myosin ATPase, the enzyme that splits ATP
slow oxidative fibers
type 1 fibers which typically have half the diameter of other skeletal muscle fibers and contain slow myosin ATPase. slower and less powerful contractions but they go over long amounts of time without fatigue
fast oxidative fibers
intermediate fibers or type IIa, least numerous of the skeletal muscle fiber types, they contain fast myosin ATPase and a fast and powerful contraction
fast glycolic fibers
fast anaerobic fibers or type Iix, most prevalent fibers in skeletal muscle which provides both power and speed, but fatigue quickly
muscle tension
the force a muscle exerts because a muscle can only pull on a structure. essentially allows for body part movement
muscle twitch
myogram of a single brief stimulation of a skeletal muscle thatt results in a single contraction event.
muscle tone
resting tension in a skeletal muscle generated by involuntary somatic nervous stimulation of the muscle
isometric contraction
when force generated is less than the load, therefore there’s no movement of the muscle
muscle fatigue
reduced ability or inability of the skeletal muscle to produce muscle tension
causes of muscle fatigue
excitation at the neuromuscular junction, excitation contraction coupling, cross bridge cycling
cardiac muscles
individual muscle cells arranged in thick bundles within the heart wall. thinner and shorter than skeletal muscles
muscle action
the primary action or movement of the muscle include flexor, extensor, and pronator
specific body regions
muscles that are close to the body surface are often termed superficial or externus
muscle attachments
muscle names identify prominent attachment
orbicularis
muscles that are in a circular shape, around the eye and mouth specifically
