Muscles and locomotion Flashcards
musculoskeletal system
forms the basic internal framework of the vertebrate body. Muscles and bones work in close coordination to produce voluntary movement in addition to other functions. the skeletal system are the physical support and locomotion, the muscles generate force.
unicellular locomotion
protazoans and primitive algae may move by beating cilia or flagella.
cilia and flagella
each contain a cylindrical stalk of 11 microtubules- 9 paired arranged in a circle with 2 single microtubules in the center.
power stroke
how flagella achieve movement, a thrusting motions generated by the sliding action of microtubles
recovery stroke
the return of the cillium or flagellum to its original position
amoeba movement
they use pseudopodia for locomotion, the advancing cell membrane extends forward allowing the cell to move.
flatworms worms hydrostatic skeletons
the muscles within the body wall of advanced flatworms, such as planaria are arranged in two antagonistic layers. longitudinal and circular. The muscles contract against the resistance of incompressible fluid within the animals tissues. circular layers lengthen the animal and the longitudinal layer shortens the animal.
segmented worms hydrostatic skeleton
has the same skeleton seen in flatworms, each segment can expand or contract independently. the bristles in the lower part of each segment, called setae, anchors it into the ground while muscles push it ahead.
Exoskeleton
a hard skeleton that covers all muscles and organs of some invertebrates. found principally in arthropods.
Insect skeleton
composed of chitin. all exoskeletons are composed of noncellular material secreted by the epidermis. offers protections yet shunts growth.
molting
periodic formation and deposition of a new exoskeleton are necessary to permit body and growth.
endoskeleton
serves as the framework within all vertebrae organisms. also provides protection by surrounding delicate vital organs in bone.
two components of skeleton
cartilage and bone
cartilage
type of connective tissue that is softer and more flexible then bone. retained in adults in places where firmness and flexibility are needed.
bone
specialized type of mineralized connective tissue that has the ability to withstand physical stress. designed for body support, bone tisssue is hard and strong while elastic and lightweight. two types
-compact bone and spongy bone
compact bone
dense bone that does not appear to have any cavities when observed by the naked eye. the boney matrix is deposited in structural units called osteons.
Osteons
(haversian systems) each osteon consists of a central microscopic channel, called Haversian canal, surrounded by a number of concentric circles of bony matrix called lamellae.
spongy bone
much less dense and consists of an interconnecting lattice of bony spicules (trabeculae): the cavities between the spicules are filled with yellow and or red bone marrow.
yellow marrow
is inactive and infiltrated by adipose tissue
red marrow
is involved in blood cell formation.
osteocytes
two other types of cells found in the bone tissue are osteoblasts and osteoclasts.
Osteoblasts
synthesize and secrete the organic constitutents of the bone matrix; once they have become surrounded by their matrix they mature into osteocytes
Osteoclasts
are large multinucleated cells involved in bone resorption or breakdown.
bone formation
occurs by either endochondral ossification or by intramembranous ossification.
endochondrial ossification
existing cartilage is replaced by bone. long bones araise primarily this way.
intramembranous ossification
mesenchymal (embryonic, undifferentiated) connective tissue is transformed into an replaced by bone.
axial skeleton
is the basic framework of the body consisting of the skull, vertebral column, and the rib cages. it is the point of attachment of the appendicular skeleton
appendicular skeleton
includes the bones of the appendages and the pectoral and pelvic girdles.
sutures
immovable joints hold the bones of the skull together
movable joints
holds bones that do move relative to one another together and are additionally supported and strengthen by ligaments.
ligaments
serve as bone to bone connectors
tendons
attach skeletal muscle to bones and bend the skeleton at the movable joints
muscular system
muscle tissue consists of bundles of specialized contractile fibers held together by connective tissue. there are three distinct types of muscle in mammals: skeletal, smooth and cardiac
skeletal muscle
responsible for voluntary movements and is innervated by the somatic nervous system. each fiber is multinucleated cell created by the fusion of several mononucleated embryonic cells.
myofibrils
filament embedded in the fibers of skeletal muscle, which are further divided by sarcomeres.
-enveloped by a modified ER that stores calcium ions
sarcoplasmic reticulum
a modified endoplasmic reticulum that stores calcium ions
sarcoplasm
the cytoplasm of muscle fibers
sarcolemma
cell membrane of muscle fiber that is capable of propagating an action potential and is connected to a system of transverse tubules that are perpendicular to the myofibrils.
T system
provides channels for ion flow throughout the muscle fibers and can also propagate an action potential.
mitochondria presence in skeletal muscle
very abundant due to all of the energy requirements of contraction, distributed along the myofibrils
striated muscle
the repeating unit of the sacromere in the skeletal muscle gives it the light and dark bands of striation. hence the name
sacromere composition
composed of thick and thin filaments. the thin are chains of actin molecules, thick are organized bundles of myosin molecules.
sacromere organization
- Z lines defines the boundaries of a single sacromere and anchor the thin filaments
- M line runs down the center of the sacromere
- H zone the region containing thick filaments only.
- I band region containing thin filaments only
- A band spans the entire length of the thick filaments and any overlapping thin.
contraction
stimulated by a message from the SNS sent via a motor neuron.
neuromuscular junction
the link between the nerve terminal and the sarcolemma of the muscle fiber
contraction process
once an action potential is generated it is conducted along the sarcolemma and the T system and into the interior of the muscle fiber. Causing the sarcoplasmic reticulum to release calcium ions into the sarcoplasm. the ions initiate the contraction of the sarcomere by binding to tropomysin, allowing actin and myosin to slide past each other. contracting
stimulus and muscle response
individual muscle fibers generally exhibit an all or none response. The strength of the contraction of a single muscle fiber cannot be increased, but the strength of the contraction of the entire muscle can be by recruiting more muscle fibers
simple twitch
the response of a single muscle fiber to a brief stimulus at or above threshold stimulus. it consist of a latent, contraction and relaxation period.
latent period and contraction period
the time between stimulation and the onset of contraction. during this time the action potential spreads along the sarcolemma and Ca+ ions are released into the sarcoplasm.
relaxation period
the muscle is unresponsive to a stimulus this is also the absolute refractory period.
Summation
when fibers of a muscle are exposed to very frequent stimuli, the muscle cannot fully relax, the contractions begin to combine becoming stronger and more prolonged
tetanus
contractions are continuous when the stimuli is so frequent that the muscle cannot relax at all. much stronger then a simple twitch of single fiber.
tonus
state of partial contraction at all times. muscles are never completely relaxed
smooth muscles
responsible for involuntary actions and is innervated by the ANS. found in the digestive tract, bladder, uterus, and blood vessel walls and other places. lacks striations, cells posses once centrally located nucleus
cardiac muscle
muscle tissue of the heart is compose of cardiac muscle fibers These fibers possess characteristics of both skeletal and smooth muscles. as in skeletal actin and myosin filaments are arranged in sarcomeres, giving cardiac muscle a striated appearance. controlled by the ANS
energy reserves
ATP is the primary source of energy for muscle contraction. very little ATP is actually stored in the muscles and other forms must be stored and rapidly converted to ATP for contractions
creatine phosphate and arginine phosphate
in vertebrates and some inverts (echinoderms) energy can be temporarily stored in a high energy compound called creatine p. inverts called arginine p.
Mygoglobin
a hemoglobin like protein found in muscle tissue. has high oxygen affinity and maintains the oxygen supply in muscles by binding oxygen tightly. can use this O2 to generate ATP via cellular respiration.
