Muscular and Skeletal Systems Flashcards
Skeletal System
- an endoskeleton serves as the framework within all vertebral organisms
- muscles are attached to the bones permitting movement
- provides protection by surrounding delicate internal organs w/ bone
Cartilage
- a type of connective tissue that is softer and more flexible than bone
- chrondocytes are cells responsible for synthesizing cartilage
Bone
a specialized type of mineralized connective tissue that has the ability to withstand physical stress
Compact Bone
dense bone that does not appear to have any cavities when observed with the naked eye
Osteons
this is where the bony matrix is deposited
Spongy Bone
much less dense and consists of an interconnecting lattice of bony spicules
Yellow Marrow
inactive and infiltrated by adipose tissue
Red Marrow
involved in blood cell formation
Osteocytes
cells found in bone tissue
Osteoblasts
synthesize and secrete the organic constituents of the bone matrix
Osteoclasts
large, multinucleated cells involved in bone reabsorption, wherein bone is broken down and materials are released into the blood
Bone Formation
occurs either by endochondrial ossification or by intramembranous ossification
Endochrondial Ossification
existing cartilage is replaced by bone - long bones arise from this process
Intramembranous Ossification
mesencymal connective tissue is transformed into and replaced by bone
Organization of the Skeleton
-the axial skeleton is the basic framework of the body, consisting of the skull, vertebral column, and rib cage
Origin
the point of attachment of a muscle to a stationary bone
Insertion
the point of attachment of muscle to the bone that moves
Extension
indicates a straightening of a joint
Flexion
refers to a bending of a joint
Muscular System
nervous control of the muscular system involves the axons of the pyramidal cells of the motor cortex
Pyramidal System
able to provide rapid commands to the skeletal muscles and various other organs
Skeletal Muscle
responsible for voluntary movements and is innervated by the somatic nervous system
Myofibrils
filaments embedded in fibers
Sarcomeres
- further divided myofibrils
- composed of thin and thick filaments
- thin filaments are chains of actin molecules
- thick filaments are composed of organized bundles of myosin molecules
Sarcoplasmic Reticulum
enveloped myofribrils by a modified endoplasmic reticulum
Sarcolemma
the cell membrane muscle fiber, capable of propagarting an action potential and perpendicular to the myofibrils
T system
provides channels for ion flow throughout the muscle fibers and can also propogate an action potential
Striated Muscle
skeletal muscle that has striations of light and dark bands
Z-lines
- define the boundaries of a single sarcomere and anchor the thin filaments
- when the muscles contract, z lines move toward each other
M-lines
runs down the center of the sarcomere
I-band
the region containing thin filaments
A-band
spans the entire length of thick filaments and any overlapping portions of the thin filaments
Contraction
- stimulated by a message from the somatic nervous system sent via motor neuron
- depolarization of the motor neuron results in the release of neurotransmittors from the nerve terminal
- once an action potential is generated, it is conducted along the sarcolemma and the T system and into the interior of the muscle fiber, which causes the sarcoplasmic reticulum to release calcium ions into the sarcoplasm
Neuromuscular Junction
the link between the nerve terminal and the sarcolemma of the muscle fiber
Rigor Mortis
all of the muscles in the body go into this state several hours after death. Muscles contract and go rigid because of the absence of ATP
Isotonic
occurs when a muscle shortens against a fixed load while tension on the muscle remains constant
Dynamic
includes both concentric and ecentric types of contractions. Results in a change in length of the muscle with corresponding change in tension on that muscle
Concentric
a type of dynamic contraction where muscle fibers shorten and the tension on the muscle increases
Eccentric
a type of dynamic contraction where the muscle fiber lengthens and the tension on the muscle increases
Isometric
occurs when both ends of the muscle are fixed and no change in length occurs during the contraction, but the tension increases
Stimulus and Muscle Reponse
- only a stimulus above a minimal value, called the threshold value, can elicit a contraction
- strength of contraction cannot be increased by recruiting more muscle fibers
Simple Tuition
the response of a single muscle fiber to a brief stimulus at or above the threshold stimulus and consists of a latent period, contraction period, and a relax action period
Absolute Refractory Period
occurs after contraction and is a brief period during which the muscle is unresponsive to the stimulus
Temporal Stimulation
when contractions combine becoming stronger and more prolonged
Tetanus
contractions become continuous when the stimuli are so frequent that the muscle cannot relax
