Chapter 9 - Muscles and Locomotion Flashcards
basic internal framework of the vertebrate body
musculoskeletal system
muscles and bones work in close coordination to produce
voluntary movement
in addition to working together, bone and muscle perform many
independent functions
physical support and locomotion are hte functions of the animal
skeletal system
force is generated by
muscular system
protozoans and primitive algae may move by
(unicellular locomotion)
beating cilia or flagella
cilia and flagella of all eukaryotic cells possess same basic structure
each contains
a cylindrical stalk of eleven microtubules - nine paired microtubules arrounged in a circle with two single microtubules in the center
flagella achieve movement by means of a
power stroke
power stroke
means of movement for flagella
thrusting movement generated by sliding action of microtubules
recovery stroke
return of cilium or flagellum to original position
pseudopodia
locomotion of amoeba
advancing cell membrane extends forward, allowing cell to move
invertebrate locomotion
hydrostatic skeletons
flatworms
e.g. planaria
muscles within body wall of advanced flatworms arranged in two antagonistic layers
longitudinal and circular
the muscles of the flatworm contract against the restistance of the
incompressible fluid within the animal’s tissues
hydrostatic skeleton of flatworm
hydrostatic fluid against which muscles contract
contraction of the circular layer of muscles causes
(flatworm locomotion)
incompressible interstitial fluid to flow longitudinally, lengthening the animal
contraction of the longitudinal layer of muscles
flatworm locomotion
shortens the flatworm
hydrostatic skeleton in which each segment of animal can expand or contract independently operates the same in
flatworms and annelids
annelids
earthworms advance by axn of muscles on a
(invertebrate locomotion)
hydrostatic skeleton
setae
bristles in the lower part of each segment of the earthworm
anchor the earthworm temporarily in the earth
as bristles in the lower part of each segment of the earthworm anchor the worm to the earth, _____ push ahead
muscles
exoskeleton
(invertebrate locomotion)
hard skeleton that covers all muscles and organs of some invertebrates
exoskeletons found primarily in
arthropods
e.g. insects
insect exoskeleton
composition
chitin
composed of noncellular material secreted by epidermis
advantage vs. disadvantage of exoskeleton
offer protection
but
growth limitations
molting
to overcome limitations on growth imposed by exoskeleton
periodic molting and deposition of new skeleton are necessary tp permit body growth
endoskeleton
framework within all vertebrate organisms
muscles attached to bones, permitting movement
in addition to permitting movement, endoskeleton also
provide protection by surrounding delicate vital organs in bone
example of protective function of endoskeleton
rib cage protects thoracic organs (heart and lungs)
skule protects brain
vertebrate colum protects spinal cord
two major components of skeleton
cartilage
bone
cartilage
connective tissue
softer, more flexible than bone
cartilage retained in adults in places where
firmness and flexibility are needed
human adult cartilage components
external ear
nose
walls of larynx, trachea
skeletal joints
bone
mineralized connective
has ability to withstand physical stress
bone tissue is ideally designed for body support
hard and strong
elastic and lightweight
two types of bone
compact bone
spongy bone
compact bone
dense bone
naked eye cannot see cavities
osteons
fxn
(Haversian systems)
(compact bone)
bony matrix deposited in structural units - osteons
osteon
structure
central microscopic channel - Haversian canal
surrounded by concentric circles of bony matrix (calcium phosphate) - lamellae
Haversian canal
central microscopic channel of osteon
lamellae
concentric circles of bony matrix (calcium phosphate) surrounding Haversian canal
bony matrix is composed of
calcium phosphate
spongy bone
less dense than compact bone
spongy bone
structure
interconnecting lattice of bony spicules (trabeculae)
cavities in between spicules filled with yellow and/or red bone marrow
yellow bone marrow
found in cavities between spicules of spongy bone
inactive
infiltrated by adipose tissue
red bone marrow
fills cavities between spicules of spongy bone
involved in blood cell formation
osteocytes
two types
cells found in bone tissue
osteoclasts
osteoblasts
osteoblasts
synthesize and secrete organic constituents of bone matrix
once surrounded by matrix, mature into osteocytes
osteoclasts
large multinucleated cells
bone resorption
osteoBLASTS vs osteoCLASTS
build bone
vs
destroy bone
two mechanisms for bone formation
- endochondrial ossification
- intramembraneous ossification
endochondral ossification
existing cartilage replaced by bone
long bones arise primarily via endochondral ossification
intramembraneous ossification
messenchymal (embryonic, undifferentiated) connective tissue is transformed into, and replaced by, bone
axial skeleton
basic famework of the body
skull, vertebral column, rib cage
appendicular skeleton
attaches to axial skeleton
bones of appendages, pectoral, pelvic girdles
sutures, immovable joints
hold bones of skull together
movable joints
hold together bones that move relative to one another
ligaments
support and strengthen movable joints
bone-to-bone connectors
tendons
attach skeletal muscle to bones
bend skeleton at movable joints
origin
point of attachment of a muscle to a stationary bone
(proximal end in limb muscles)
insertion
point of attachment of muscle to bone that moves
(distal end in limb muscles)
extension
straightening of a joint
flexion
bending of a joint
muscle tissue
bundles of specialized contractile fibers held together by connective tissue
three morphologically and functionally distinct types of muscle in mammals
skeletal muscle
smooth muscle
cardiac muscle
skeletal muscle
voluntary movements
innervated by somatic nervous system
the skeletal muscle is composed of muscle fibers, which are made up of
multinucleated cells
multinucleated cell is created by the fusion of
several mononucleated embryonic cells
myofibrils
filaments embedded in the muscle fibers
sarcomeres
contractile units which make up the myofibrils
sarcoplasmic reticulum
evelopes myofibrils
modified endoplasmic reticulum
stores calcium ions
sarcoplasm
cytoplasm of a muscle fiber
sarcolemma
muscle cell membrane
the sarcolemma is capable of
propagating an action potential
the sarcolemma is connected to
system of transverse tubules (T system) oriented perpindicularly to the myofibrils
T system (transverse tubules)
channels for ion flow throughout muscle fibers
can propagate action potential
because of the high energy requirements of contraction, ______ are abundant in muscle cells
mitochondria
mitochondria in muscle cells
very abundant
distributed along myofibrils
striations
light and dark bands of skeletal muscle
skeletal muscle is aka
striated muscle
two components of muscle cell that can propagate an action potential
sarcolemma
t system (transverse tubules)
sarcomere
structure
thin and thick filaments
the thin filaments of sarcomere are
chains of actin molecules
the thick filaments of the sarcomere are
organized bundles of myosin molecules
sarcomere
organization
Z line
M line
I band
H zone
A band
Z lines
define boundaries of a single sarcomere
anchors thin filaments
M line
runs down center of sarcomere
I band
region containing thin filaments only
A band
spans entire length of thick filaments
and any overlapping portions of thin filaments
during contraction of the sarcomere
A band NOT reduced in size
H zone, I abnd are reduced in size
H zone
region containing thick filaments only
(pg 117)
muscle contraction is stimulated by
a message from the somatic nervous system
sent via a motor neuron
neuromuscular junction
link between nerve terminal (synaptic bouton) and sarcolemma of muscle fiber
synapse (synaptic cleft)
space between sarcolemma and nerve terminal
depolarization of motor neuron results in
release of neurotransmitters (acetylcholine) from nerve terminal
neurotransmitter diffuses across synaptic cleft and
binds to special receptor sites on sarcolemma
action potential is generated when
enough of receptors on sarcolemma are stimulated and permeability of sarcolemma is altered
once action potential is generated, it is conducted along the
sarcolemma and T system
after the action potential is conducted along the sarcolemma and T system, it is conducted into the
interior of the muscle fiber
conduction of action potential into interior of muscle fiber causes the
sarcoplasmic reticulum to release calcium ions
the sarcoplasmic reticulum releases calcium ions into the
sarcoplasm
once calcium ions are released into the sarcoplasm from the sarcoplasmic reticulum, they intiate the
contraction of the sarcomere
all-or-none response
and the threshold value
individual muscle fibers generally exhibit an all-or-none response
only a stimuls above a minimal value called the threshold value can elicit contraction
threshold value
minimal value above which a stimulus can elicit contraction
strenght of a contraction of a single muscle fiber cannot be
increased, regardless of strength of stimulus
although strength of contraction of single muscle fiber cannot be increased, regardless of the strength of the stimulus, the strength of contraction of the entire muscle can be increased by
recruiting more muscle fibers
simple twitch
definition
response of a single muscle fiber to a brief stimulus at or above threshold stimulus
simple twitch consists of
latent period
contraction period
relaxation period
latent period
(simple twitch)
time between stimulation and onset of contraction
action potential spreads along sarcolemma and Ca2+ ions are released
contraction period caused by
(simple twitch)
action potential spreads along sarcolemma and Ca2+ ions released
relaxation period
(absolute refractory period)
(simple twitch)
muscle is unresponsive to stimululs
temporal summation
fibers of a muscle are exposed to very frequent stimuli
muscle cannot fully relax
contractions begin to combine, becoming stronger and more prolonged
tetanus
contractions become continuous when stimuli are so frequent that muscle cannot relax
stronger than simple twitch of a single fiber
if tetanus is maintained
muscle will fatigue and contraction will weaken
tonus
state of partial contraction
muscles are never completely relaxed and maintain partially contracted state at all times
smooth muscle is responsible for
involuntary actions
smooth muscle is innervated by
autonomic nervous system
smooth muscle is found in the
digestive tract, bladder, uterus, blood vessel walls, etc
smooth muscles possess ____ nuceus
one centrally located
smooth muscles ________ skeletal muscles
lack the striations of
cardiac muscle fibers
compose muscle tissue of the heart
cardiac muscle possess characteristics of
both skeletal and smooth muscle
as in skeletal muscle, cardiac muscle has
actin and myosin filaments arranged in sarcomeres
this is what gives muscle a striated appearance
actin and myosin filaments arranged in sarcomere
like smooth muscle, cardiac muscle has
only one or two centrally located nuclei
primary source of energy for muscle contraction
ATP
where does ATP for muscle cells come from?
very little ATP stored in muscles
other forms of energy must be converted to ATP
creatine phosphate
(vertebrates and some invertebrates - echinoderms)
high-energy compound
temporarily stores energy for muscles
arginine phosphate
(invertebrates)
high-energy compound
temp. stores energy for muscles
similar to creatine phosphate used in vertebrates and some invertebrates (echinoderms)
myoglobin
hemoglobin-like protein
found in muscle tissue
high oxygen affinity
maintains oxygen supply in muscles by binding oxygen tightly
