Biology Muscular and Skeletal Systems Flashcards
The rib cage protects the thoracic organs (heart and lungs), whereas the skull and vertebral column protect the brain and ___ cord
spinal
The two major parts of the skeleton are ___ and bone
cartilage
___ are cells responsible for synthesizing cartilage
chrondrocytes
Bone is a specialized type of mineralized connective ___ that has the ability to withstand physical stress
tissue
There are two types of bone: ___ bone and spongy bone
compact
Compact bone is ___ bone that does not appear to have any cavities when observed with the naked eye and makes up 80% of the skeleton
dense
The bony ___ is deposited in structural units called osteons (Haversian systems)
matrix
Each osteon consists of a central microscopic channel called a Haversian canal, surrounded by a number of concentric circles of ___ matrix (calcium phosphate) called lamellae
bony
Spongy bone, which can be found at the ends of long bones, in the pelvic bones, skull, and vertebra, is much less dense and consists of an interconnecting ___ of bony spicules (trabeculae); the cavities between the spicules are filled with yellow or red bone marrow
lattice
Yellow marrow is ___ and infiltrated by adipose tissue; red marrow is involved in blood cell formation
inactive
Osteoblasts synthesize and secrete the organic ___ of the bone matrix; once they have become surrounded by their matrix, they mature into osteocytes
constituents
Osteoclasts are large, multinucleated cells involved in bone ___, wherein bone is broken down and minerals (namely Ca2+) are released into the blood
reabsorption
Bone formation occurs by either endochondral ossification or by ___ ossification
intramembranous
In ___ ossification, existing cartilage is replaced by bone
endochondral
Long bones arise primarily through endochondral ___
ossification
In intramembranous ossification, ___ (embryonic or undifferentiated) connective tissue is transformed into and replaced by bone
mesenchymal
The ___ skeleton is the basic framework of the body, consisting of the skull, vertebral column, and rib cage
axial
The axial skeleton is the point of attachment of the appendicular skeleton, which includes the bones of the ___ (limbs) and the pectoral and pelvic girdles
appendages
___ serve as bone to bone connectors
ligaments
The point of attachment of a muscle to a stationary bone (proximal end in limb muscles) is called the ___
origin
The point of attachment of a muscle to the ___ that moves (distal end in limb muscles) is called the insertion
bone
___ indicates a straightening of a joint, whereas flexion refers to a bending of a joint
extension
Extension and flexion require the contraction of ___ muscles
antagonist
Because there are no intervening ___, the pyramidal system is able to provide rapid commands to the skeletal muscles and various other organs
synapses
The red nucleus, located in the mesencephalon, is the component of the ___ system primarily in control of skeletal muscle tone
extrapyramidal
Skeletal muscle is responsible for voluntary movements and is innervated by the ___ nervous system
somatic
Embedded in the fibers of the skeletal muscle system are filaments called ___, which are further divided into contractile units called sarcomeres
myofibrils
The myofibrils are enveloped by a modified endoplasmic reticulum that stores calcium ions and is called the ___ reticulum
sarcoplasmic
The cytoplasm of a muscle fiber is called ___, and the cell membrane is called the sarcolemma
sarcoplasm
The ___ is capable of propagating an action potential and is connected to a system of transverse tubules (T system) oriented perpendicularly to the myofibrils
sarcolemma
The T system provides ___ for ion flow throughout the muscle fibers and can also propagate an action potential
channels
Because of the high-energy requirements of contraction, ___ are very abundant in muscle cells and are distributed along the myofibrils
mitochondria
___ muscle has striations of light and dark bands and is therefore also referred to as striated muscle
skeletal
The sarcomere is composed of ___ and thick filaments
thin
The thin filaments are chains of ___ molecules
actin
The thick filaments are composed of organized bundles of ___ molecules
myosin
acthin: actin ___ are thin while myosin filaments are thick
filaments
Electron microscopy reveals that the sarcomere is organized as follows: ___ define the boundaries of a single sarcomere and anchor the thin filaments
Z lines
In Skeletal muscle, the M line runs down the ___ of the sarcomere
center
The ___ is the region containing thin filaments only
I band
The ___ is the region containing thick filaments only
H zone
The ___ spans the entire length of the thick filaments and any overlapping portions o the thin filaments
A band
When the muscles contract, the ___ move toward each other
Z lines
During contraction, the A band is not reduced in size, whereas the H zone and ___ are
I band
Z is the end of the alphabet and therefore the end of your ___
sarcomeres
M is the middle and is attached to the mighty myosin ___
filaments
I is the thinnest letter so the ___ has only thin filaments
I band
___ is a thick letter and has only thick filaments
H (zone)
The ___ is an in between sized letter and the A band includes the overlap of thick and thin
A band
Muscle ___ is stimulated by a message from the somatic nervous system sent via a motor neuron
contraction
The link between the nerve terminal (synaptic bouton) and the sarcolemma of the muscle fiber is called the ___ junction
neuromuscular
The space between the nerve terminal and the neuromuscular junction is known as the synapse, or ___ cleft
synaptic
In skeletal muscle, the ___ diffuses across the synaptic cleft and binds to special receptor sites on the sarcolemma
neurotransmitter
In skeletal muscle, if enough receptors are stimulated, the permeability of the ___ is altered and an action potential is generated
sarcolemma
In skeletal muscle, once an action potential is generated, it is conducted along the sarcolemma and the ___ and into the interior of the muscle fiber
T system
In ___ muscle, once an action potential is generated, the sarcoplasmic reticulum releases calcium ions into the sarcoplasm
skeletal
In skeletal muscle, once the sarcoplasmic ___ releases calcium ions, calcium ions initiate the contraction of the sarcomere by binding to troponin C on the actin filaments
reticulum
In skeletal muscle, once calcium ions initiate the contraction of the sarcomere, allosteric changes occur in the proteins that allow ___ heads to bind to these sites on the actin
myosin
In skeletal muscle, after allosteric changes, use of energy allows a power stroke to occur, pulling the ___ closer together
Z bands
In skeletal muscle, once a power stroke occurs, actin and ___ slide past each other, and the sarcomere contracts
myosin
A simple ___ is the response of a single muscle fiber to a brief stimulus at or above the threshold stimulus and consists of a latent period, a contraction period, and a relaxation period
twitch
The ___ period is the time between stimulation and the onset of contraction
latent
During the latent period, the action potential spreads along the ___, and Ca2+ ions are released
sarcolemma
After the ___ period, there is a brief relaxation period during which the muscle is unresponsive to stimulus; this period is known as the absolute refractory period
contraction
When the contractions begin to combine, becoming stronger and more prolonged, this is known as ___ summation
temporal
When the ___ become continuous when the stimuli are so frequent that the muscle cannot relax this type of contraction is known as tetanus and is stronger than a simple twitch of a single fiber
contractions
If ___ is maintained, the muscle will fatigue, and the contraction will weaken
tetanus
___ is a state of partial contraction
tonus
___ are never completely relaxed and maintain a partially contracted state at all times
muscles
During periods of strenuous activity, skeletal muscles convert glucose to pyruvic acid through the process of ___
glycolysis
Glycolysis enables ___ muscles to continue contracting even in the absence of oxygen
skeletal
Lactic acid is generated in the absence of ___ in muscle contraction when pyruvic acid reacts with the enzyme lactate dehydrogenase
oxygen
when ___ acid is generated, this process allows the pyruvate to enter the citric acid (or Krebs) cycle
lactic
Smooth muscle is responsible for involuntary actions and is innervated by the ___ nervous system
autonomic
___ muscle is found in the digestive tract, bladder, uterus, and blood vessel walls, among other places
smooth
Smooth muscle cells possess one centrally located nucleus and lack the ___ of skeletal muscle
striations
Smooth muscle
nonstriated, one nucleus per cell, involuntary/autonomic nervous system, smooth, continuous contractions
Cardiac Muscle
striated, one to two nuclei per cell, involuntary/autonomic nervous system, strong, forceful contractions
Skeletal Muscle
___, multinucleated cells, voluntary/somatic nervous system, strong, forceful contractions
striated
In vertebrates, energy can be temporarily stored in a high-energy compound called ___ phosphate
creatine
___ has a high oxygen affinity (found in muscle tissue) and maintains the oxygen supply in muscles by tightly binding to oxygen
myoglobin
