muscular Flashcards
responsible for movement of the arms, legs, heart, and other parts of the body; maintenance of posture; respiration; production of body heat; communication; constriction of organs and vessels; and heartbeat.
mucles
responsible for most body movements
skeletal muscle
found in the walls of hollow organs and tubes and moves substances through them
smooth muscle
in the heart and pumps blood.
cardiac muscle
shortens forcefully
contractility
responds to stimuli
excitability
can be stretched and still contract
extensibility
recoils to resting length
elasticity
shortens forcefully but lengthens passively
muscle tissue
associated with connective tissue, blood vessels, and nerves.
skeletal muscle fibers
bundles of muscle fibers, are covered by the connective tissue layer called the perimysium.
muscle fascicles
The entire muscle is surrounded by a connective tissue layer
epimysium
extend together with arteries and veins through the connective tissue of skeletal muscles.
motor neurons
axons of motor neurons branch, and each branch projects to a muscle fiber to form a neuromuscular junction.
perimysium
axons of motor neurons branch, and each branch projects to a muscle fiber to form a neuromuscular junction.
perimysium
single cell consisting of a plasma membrane (sarcolemma), cytoplasm (sarcoplasm), several nuclei, and myofibrils.
muscle fiber
what components of a muscle fiber include the sarcolemma, the T tubules, and the sarcoplasmic reticulum.
electrical components
what components of a muscle fiber include the myofibrils and the myofilaments.
mechanical component
composed of two major protein fibers: actin and myosin.
myofibrils
consist of actin (composed of G actin monomers), tropomyosin, and troponin.
actin myofilaments
consisting of heads and a rodlike portion, constitute myosin myofilaments.
myosin molecules
forms when the myosin binds to the actin.
cross bridge
organized to form sarcomeres.
actin and myosin
bound by Z disks that hold actin myofilaments.
sarcomeres
the location where a motor neuron is in close proximity to the muscle fiber.
neuromuscular junction
contains synaptic vesicles that house the neurotransmitter, acetylcholine.
motor neuron axon terminal
-are polarized, which means that a charge difference, called the resting membrane potential
-becomes polarized because the tendency for K+ to diffuse out of the cell is resisted by the negative charges of ions and molecules inside the cell.
plasma membrane
-responsible for membrane permeability and the resting membrane potential.
-responsible for producing action potentials.
ion channels
The charge difference across the plasma membrane of cells
resting membrane potential
-results from an increase in the permeability of the plasma membrane to Na+.
-the action potential results when many Na+ channels open in an all-or-none fashion.
depolarization
the action potential occurs when the Nat channels close and the K+ channels open briefly.
repolarization
separates the presynaptic terminal of the axon from the motor end-plate of the muscle fiber.
synaptic cleft
released from the presynaptic terminal binds to receptors of the motor end-plate, thereby changing membrane permeability and producing an action potential.
acetylcholine
splits acetylcholine into acetic acid and choline.
acetylcholinesterase
reabsorbed into the presynaptic terminal to re-form acetylcholine.
choline
a T tubule and two terminal cisternae (an enlarged area of sarcoplasmic reticulum).
triad
move into the T tubule system, causing Ca* channels to open and release Ca2+ from the sarcoplasmic reticulum.
action potentials
diffuse from the sarcoplasmic reticulum to the myofilaments and bind to troponin, causing tropomyosin to move and expose active sites on actin to myosin.
calcium ions
occurs when myosin heads bind to active sites on actin, myosin changes shape, and actin is pulled past the myosin.
contraction
occurs when calcium is taken up by the sarcoplasmic reticulum, ATP binds to myosin, and tropomyosin moves back so that active sites on actin are no longer exposed to myosin.
relaxation
-required for the cycle of cross-bridge formation, movement, and release.
-required to transport Ca+ into the sarcoplasmic reticulum and to maintain normal concentration gradients across the plasma membrane.
ATP
-transported into the sarcoplasmic reticulum.
-diffuse away from troponin, preventing further cross bridge formation
calcium ions
-the contraction of a single muscle fiber or a whole muscle in response to a stimulus.
-has lag, contraction, and relaxation phases.
muscle twitch
results in graded contractions of increased force through either summation or recruitment.
stimulus of increasing magnitude
partial relaxation between contractions; complete tetanus is no relaxation between contractions.
incomplete tetanus
increases the force of contraction (wave summation).
stimulus of increasing frequency
cause muscles to shorten and tension to increase.
concentric contraction
cause muscle to lengthen and tension to decrease gradually.
eccentric contractions
the maintenance of steady tension for long periods.
muscle tone
break down ATP slowly and have a well-developed blood supply, many mitochondria, and myoglobin.
slow twitch muscle fibers
break down ATP rapidly.
fast twitch muscle fibers
have a well-developed blood supply, more mitochondria, and more myoglobin.
type IIa muscle fibers
have large amounts of glycogen, a poor blood supply, fewer mitochondria, and little myoglobin.
type IIb muscle fibers
hypertrophy
muscle increase
atrophy
muscle decrease
develops type Ilb muscle fibers.
anaerobic exercise
develops type I muscle fibers and changes type IIb muscle fibers into type Ila fast-twitch muscle fibers.
aerobic exercise
-The ATP synthesized by anaerobic respiration provides energy for a short time during intense exercise.
-produces ATP less efficiently but more rapidly than aerobic respiration. Lactate levels increase because of anaerobic respiration.
anaerobic respiration
-The ATP synthesized by aerobic respiration produces energy for muscle contractions under resting conditions or during exercises such as long-distance running. Although ATP is produced more efficiently, it is produced more slowly.
-produces more ATTP than anaerobic respiration, but at a slower rate.
aerobic respiration
the decreased ability to do work, can be caused by the central nervous system, depletion of ATP in muscles, or depletion of acetylcholine in the neuromuscular junction.
fatigue
the inability of muscles to contract or relax
physiological contracture
stiff muscles after death result from inadequate amounts of ATP.
rigor mortis
caused by inflammation in the muscle.
soreness
spindle-shaped with a single nucleus. They have actin myofilaments and myosin myofilaments but are not striated.
smooth muscle cells
poorly developed, and caveolae may function as a T tubule system.
sarcoplasmic reticulum
are striated, have a single nucleus, are connected by intercalated disks (and thus function as a single unit), and are capable of autorhythmicity.
cardiac muscle fibers
causes a certain movement
agonist
acts in opposition to the agonist.
antagonist
muscles that function together to produce movement.
synergists
mainly responsible for a movement.
prime movers
stabilize the action of prime movers.
fixators
The origins of facial muscles
skull bones or fascia
into the skin, causing movement of the facial skin, lips, and eyelids.
insertions
Three pairs of muscles close the jaw; gravity opens the jaw. Forced opening is caused by the lateral pterygoids and the hyoid muscles.
mastication
muscles change the shape of the tongue; extrinsic tongue muscles move the tongue.
intrinsic tongue
can depress the jaw and assist in swallowing.
hyoid muscles
open and close the openings to the nasal cavity, auditory tubes, and larynx.
muscles
the origins of these muscles are mainly on the cervical vertebrac (except for the sternocleidomastoid); the insertions are on the occipital bone
neck muscles
-These muscles extend, laterally flex, rotate, or flex the vertebral column.
-A more superficial group of muscles runs from the pelvis to the skull, extending from the vertebrae to the ribs.
-A deep group of muscles connects adjacent vertebrae.
vertebral column muscles
-Most respiratory movement is caused by the diaphragm.
-Muscles attached to the ribs aid in respiration.
thoracic muscles
hold and protect abdominal organs and cause flexion, rotation, and lateral flexion of the vertebral column.
abdominal wall muscles
These muscles support the abdominal organs inferiorly.
pelvic diaphragm and perineum muscles
how many are the muscles attach the scapula to the trunk and enable the scapula to function as an anchor point for the muscles and bones of the arm
six
how many muscles attach the humerus to the scapula.
seven
how many muscles attach the humerus to the trunk.
two additional muscles
These muscles cause flexion and extension of the shoulder and abduction, adduction, rotation, and circumduction of the arm.
arm movements
the elbow are accomplished by three muscles in the arm and two in the forearm.
flexion and extension
accomplished primarily by forearm muscles.
supination and pronation
muscles in the forearm.
extrinsic hand muscles
muscles are in the hand
instrinsic hand muscles
cause flexion of the hip.
anterior pelvic muscles
responsible for extension of the hip and abduction and rotation of the thigh.
muscles of the buttocks
extend the leg,
anterior thigh muscles
flex the leg.
posterior thigh muscles
muscles flex the hip and extend the knee.
anterior compartment
muscles adduct the thigh.
medial compartment
muscles extend the hip and flex the knee.
posterior compartment
cause dorsiflexion, inversion, or eversion of the foot and extension of the toes.
anterior compartment
plantar flex and evert the foot
lateral compartment
flex the leg, plantar flex and invert the foot, and flex the toes.
posterior compartment
flex or extend, and abduct or adduct, the toes.
intrinsic foot muscle
