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92 Cards in this Set
- Front
- Back
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Exoskeleton |
Hard outer skeleton on arthropods that is composed of chitin and needs to be molted
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Endoskeleton |
Basic framework for all vertebrates that provides physical support, facilitates locomotion, and provides protection for delicate internal organs (rib cage protects the thoracic organs while skull and vertebral column protect the brain and spinal cord) -The two major components are cartilage and bone |
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Cartilage |
Connective tissue synthesized by chondrocytes that is softer and more flexible than bone so it is retained in adults where firmness and flexibility is needed (e.g. the external ear, nose, walls of the larynx and trachea, and skeletal joints) -Avascular so it receives nutrients through diffusion -Composed mostly of collagen (a triple helix with hydroxyproline and hydroxylysine, ground substance, and elastin fibers) -Three types: 1) hyaline 2) fibrocartilage; 3) elastic |
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Hyaline cartilage |
Smooth-looking cartilage with fewer fibers than other types of cartilage -Most common type of cartilage -Lines the nasal septum, forms the rings of the trachea, connects the ribs to the sternum to allow them limited movement, and lines the ends of growing bone |
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Elastic cartilage |
Similar in structure to hyaline cartilage, but contains a large amount of elastin fibers which stretch and enable elastic cartilage to be very flexible -Found in the ear and the epiglottis |
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Fibrocartilage |
Transitional tissue between dense regular connective tissue and bone that contains many thick, interlaced collagenous fibers, which are stiffer and less flexible than elastin fibers -Found between vertebral discs, in menisci (the crescent-shaped structures that cushion certain joints including the knee), and in the pubic symphysis, and is often present where ligaments and tendons are attached to bones |
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Chondrocytes |
Cells that originate from mesenchyme tissue and synthesize the collagen that forms cartilage |
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Bone |
Specialized type of mineralized connective tissue that is hard and strong while also elastic and lightweight, giving it the ability to withstand physical stress and provide body support Functions: 1) support of soft tissue, 2) protection of internal organs, 3) assistance in body movement, 4) mineral storage (most Ca2+ in the body is stored as hydroxyapatite in bone tissue), 5) red blood cell production, and 6) energy storage (through the adipose cells in bone marrow) -Two basic types are compact bone and spongy bone (bones can be made of compact bone, spongy bone, or a combination of the two) |
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Compact bone |
Highly-organized, dense bone that does not appear to have any cavities when observed with the naked eye -Matrix is composed of structural units called osteons and filled with yellow bone marrow that contains adipose cells for fat storage |
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Osteon |
System of Haversian canals and lamellae that comprises the basic structural unit of the compact bony matrix |
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Haversian Canal |
Central microscopic channel within an osteon that contains lymph vessels, nerves, and blood vessels -Created by osteoclasts burrowing through the bony matrix |
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Lamellae |
Concentric circles of bony matrix (calcium phosphate) that surround the Haversian Canals in an osteon and are formed by osteoblasts laying down new matrix onto canal walls |
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Canaliculi |
Vessels by which trapped osteocytes in compact bone exchange nutrients |
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Lacunae |
Osteocytes that have been trapped within the lamellae they secrete in compact bone |
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Volkmann's Canals |
Tunnels that connect Haversian Canals in compact bone |
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Spongy bone (a/k/a cancellous bone) |
Type of bone that is less dense than compact bone and consists of an interconnecting lattice of bony spicules (trabeculae) surrounded by yellow or red bone marrow |
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Yellow marrow |
Bone marrow that is inactive and infiltrated by adipose tissue |
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Red marrow |
Bone marrow that is involved in red blood cell formation |
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Osteoprogenitor/osteogenic cells |
Bone cells that differentiate into osteoblasts |
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Osteocytes |
Bone cells that are incapable of mitosis and exchange nutrients and waste materials with blood |
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Osteoblasts |
Bone cells that synthesize and secrete collagen and the other organic constituents of the bone matrix and mature into osteocytes once they become surrounded by the matrix they have secreted |
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Osteoclasts |
Large, multinucleated bone cells that develop from monocytes and are involved in bone resorption |
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Bone resorption |
Process whereby bone is broken down and its minerals are released into the blood |
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Endochondral ossification |
Bone formation in which existing cartilage is replaced by bone -How long bones like those in limbs, fingers, and toes develop |
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Intramembranous ossification |
Bone formation in which mesenchymal connective tissue is transformed into and replaced by bone -How flat bones like those in the skull, sternum, mandible, and clavicles develop |
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Mesenchymal tissue |
Embryonic or undifferentiated tissue |
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Bone growth in length |
Occurs at cartilagineous epiphyseal plates that are replaced by bone in adulthood |
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Bone growth in diameter |
Occurs along the diaphysis and continues into adulthood |
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Axial skeleton |
Basic framework of the body consisting of the skull, vertebral column, and rib cage |
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Appendicular skeleton |
Consists of the bones of the appendages and the pectoral and pelvic girdles |
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Sutures |
Immovable joints that hold the bones of the skull together |
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Movable joints |
Joints that hold together bones that move relative to one another and are supported by ligaments |
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Ligaments |
Bone-to-bone connectors |
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Tendons |
Attach skeletal muscle to bones and bend the skeleton at movable joints |
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Origin |
Point of attachment of a muscle to a stationary bone (proximal end in limb muscles) |
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Insertion |
Point of attachment of a muscle to a bone that moves (distal end in limb muscles) |
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Extension |
Straightening of a joint |
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Flexion |
Bending of a joint |
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Joint types |
1. Fibrous 2. Cartilaginous 3. Synovial |
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Fibrous joint |
Connects bones without allowing movement -Found in the skull, pelvis, spinous process, and vertebrae |
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Cartilaginous joint |
Connects bones to cartilage and allows little movement -Found in the spine and ribs |
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Synovial joint |
Most common joint type and allows much more movement than other types due to the synovial fluid that fills the joint and acts as a lubricant -Found in carpals, wrists, elbows, humerus and ulna, shoulder and hip joints, and knee joint |
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Muscular system |
Composed of muscle tissue and generates force, facilitates locomotion, allows for stabilization of position, facilitates movement of materials throughout the body, and generates body heat |
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Muscle tissue |
Consists of bundles of specialized contractile fibers held together by connective tissue
3 types: 1) skeletal, 2) smooth, and 3) cardiac |
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Pyramidal system |
Center of motor control that rapidly transmits motor commands from the brain to the skeletal muscles and various other organs -Consists of the axons of the pyramidal cells of the motor cortex, which descend from the brain to lower motor neurons in the brain stem and spinal cord |
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Extrapyramidal system |
Composed of centers outside of the pyramidal system and their associated tracts that can issue somatic motor commands as a result of processing at the unconscious, involuntary level |
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Red nucleus |
Component of the extrapyramidal system that is primarily in control of skeletal muscle tone -Located in the mesencephalon |
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Skeletal muscle |
Type of muscle responsible for voluntary movements and innervated by the somatic nervous system -Composed of numerous muscle cells called muscle fibers -Striated due to the alternation of thick bands of myosin that appear dark in color and thin bands of actin that appear light in color -Increases in size (hypertrophy), but does not usually undergo mitosis to create new muscle cells (hyperplasia) -Abundant mitochondria for strong, forceful contractions |
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Muscle fiber |
Multinucleated cell created by the fusion of several mononucleated embryonic cells -Composed of sarcoplasm, a sarcolemma, a T system, abundant mitochondria, nuclei which lie along the periphery of the cell and form swellings visible through the sarcolemma, and myofibrils which are divided into sarcomeres and enveloped by a sarcoplasmic reticulum |
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Myofibrils |
Numerous long filaments embedded in muscle fibers along which mitochondria are abundant due to the high energy requirements of muscle contraction -Divided into sarcomeres and enveloped by a sarcoplasmic reticulum |
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Sarcomeres |
Individual contractile units into which myofibrils are divided -Composed of thin and thick filaments and organized into several distinct regions |
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Sarcoplasmic reticulum |
Modified endoplasmic reticulum of a muscle cell that surrounds myofibrils and stores calcium ions |
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Sarcoplasm |
Cytoplasm of a muscle cell |
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Sarcolemma |
Cell membrane of a muscle cell that can propagate an action potential and is connected to a system of transverse tubules (T system) |
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T system |
System of transverse tubules oriented perpendicularly to the myofibrils of a muscle cell that provides channels for ion flow through the muscle fibers and can propagate an action potential |
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Thin filament |
Two chains of actin molecules |
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Actin |
Globular protein arranged in a double helix with troponin and tropomyosin molecules covering special binding sites along the length of the helix |
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Thick filaments |
Organized bundles of myosin molecules |
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Myosin |
Filamentous protein with 'heads' that protrude from numerous positions at both ends of the molecule, providing binding sites for ATP and actin |
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Z lines |
Lines that define the boundary of a single sarcomere and attach to thin filaments only -Move toward each other during a contraction |
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M line |
Line that runs down the center of a sarcomere |
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I Band |
Region of a sarcomere containing only thin filaments -Reduces in size during a contraction |
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H zone |
Region of a sarcomere containing only thick filaments -Reduces in size during a contraction |
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A band |
Region that spans the entire length of the thick filaments and any overlapping portions of the thin filaments -Not reduced in size during contraction |
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Neuromuscular junction |
Synapse between the motor nerve terminal and the sarcolemma of the muscle fiber |
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Stimulation of muscle contractions |
Initiated by a message from the somatic nervous system sent via a motor neuron 1. Motor neuron is depolarized and releases a neurotransmitter (e.g. acetylcholine) from the nerve terminal 2. The neurotransmitter diffuses across the synaptic cleft and binds to special receptor sites on the sarcolemma. If enough receptors are stimulated, the permeability of the sarcolemma is altered, an action potential is generated, and depolarization of the muscle fiber occurs. 3. The action potential spreads along the sarcolemma through the T system, triggering the sarcoplasmic reticulum to release Ca2+ ions into the sarcoplasm. |
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Sliding Filament model |
Model that describes the process of muscle contractions 1. If ATP is available, it binds to myosin heads and is converted to ADP and inorganic phosphate but remains attached to the myosin heads. 2. Ca2+ released by the sarcoplasmic reticulum binds to troponin on the actin molecule, prompting an allosteric change that results in tropomyosin exposing binding positions on the actin filament. 3. Myosin heads bind to the exposed attachment sites on the actin filament, forming cross bridges. 4. The formation of cross bridges causes myosin to release its bound ADP and inorganic phosphate, which changes its shape. The change in conformation generates a sliding movement of the actin toward the center of the sarcomere (a "power stroke"), pulling the Z lines together and contracting the muscle fiber. 5. When a new ATP molecule binds to the myosin head, the cross bridge between myosin and actin breaks and the myosin returns to its unattached conformation. |
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Rigor mortis |
Condition occurring in the several hours after death in which muscles contract and remain rigid even in the absence of action potentials because the ATP that is necessary to release cross bridges and terminate a contraction is not being generated -Typically persists for 12-24 hours after death until the muscle proteins degrade |
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Types of muscle contractions |
1. Dynamic 2. Concentric 3. Eccentric 4. Isotonic 5. Isometric |
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Dynamic contraction |
Muscle contraction that results in a change in muscle length and a corresponding change in tension on the muscle -Combines both concentric and eccentric types of contraction |
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Concentric contraction |
Type of muscle contraction in which the muscle fibers shorten and the tension on the muscle increases |
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Eccentric contraction |
Type of muscle contraction in which the muscle fiber lengthens and the tension on the muscle increases |
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Isotonic contraction |
Muscle contraction in which a muscle fiber shortens against a fixed load while the tension on the muscle remains constant |
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Isometric contraction |
Muscle contraction in which both ends of the muscle are fixed and no change in length occurs but the tension on the muscle increases |
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Motor unit |
Group of muscle fibers innervated by a single neuron -All muscle fibers in a muscle usually don't contract simultaneously ---> smaller motor units are activated first then larger ones to cause an increase in the strength of the contraction (the strength of contraction of an individual muscle fiber cannot be increased regardless of the strength of the stimulus, i.e. 'all-or-nothing response') -E.g. fine movements are caused by the activation of smaller motor units |
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Simple twitch |
Response of a single muscle fiber to a brief stimulus at or above the threshold stimulus -Consists of a latent period, a contraction period, and a relaxation period |
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Latent period |
Lag time between stimulation and the onset of contraction during which the action potential spreads along the sarcolemma and Ca2+ ions are released |
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Absolute refractory period |
Brief relaxation period after contraction during which the muscle is unresponsive to stimuli |
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Temporal summation |
Condition in which the fibers of a muscle are exposed to very frequent stimuli and cannot fully relax, so the repeated action potentials summate and the contractions begin to combine, becoming stronger and more prolonged |
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Tetanus |
Muscle contraction that is continuous and sustained as a result of exposure to stimuli that are so frequent that the muscle cannot relax and its twitches blur into one smooth constant -If maintained, the muscle will fatigue and the contraction will weaken |
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Tonus |
State of partial contraction in which the muscles are never completely relaxed and maintain a partially contracted state at all times |
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Cori cycle |
Metabolic pathway in which lactic acid in the liver is converted to glucose and discharged into the bloodstream for use by the muscles as an immediate source of energy during strenuous exercise or to rebuild their glycogen reserves after exercise |
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Smooth muscle |
Type of muscle that is mainly responsible for involuntary action and is innervated by the autonomic nervous system -Found in the digestive tract, bladder, uterus, blood vessel walls, etc. -Possesses one centrally located nucleus -Lacks the striations of skeletal muscle because it lacks sarcomeres. Instead, intermediate filaments are attached to dense bodies spread throughout the cell. When thick and thin filaments attached to the intermediate filaments contract, the filaments pull the dense bodies together and smooth muscle shrinks. -Two types: 1. single-unit (visceral) and 2. multi-unit -Myogenic - also responds to hormones, changes in pH, changes in levels of O2 and CO2, changes in temperature, and changes in ion concentration -Smooth, continuous contractions |
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Myogenic |
Capable of contraction without neuronal stimulation |
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Single-unit (visceral) smooth muscle |
Smooth muscle that is attached by gap junctions and contracts as a single unit -Found in the stomach, uterus, and urinary bladder |
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Multi-unit smooth muscle |
Smooth muscle in which each muscle fiber is directly attached to a neuron and can contract independently -Found in the iris, bronchioles, etc. |
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Cardiac muscle |
Comprises the muscle tissue of the heart and possesses characteristics of both skeletal and smooth muscle -Striated appearance like skeletal muscle due to the arrangement of myosin and actin filaments into sarcomeres -Only possesses one or two centrally located nuclei like smooth muscle -Separated by intercalated discs with gap junctions to allow action potentials to chain flow via electrical synapse -Controls involuntary movements and innervated by the autonomic nervous system -Possesses abundant mitochondria for strong, forceful contractions -Myogenic |
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Creatine phosphate |
High-energy compound in which vertebrates can temporarily store energy |
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Myoglobin |
Hemoglobin-like protein in muscle tissue that has a high oxygen affinity and maintains the oxygen supply in muscles by binding tightly to oxygen |
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Slow oxidative/Slow twitch/Type 1 skeletal muscle |
-Red in color due to an abundance of myoglobin and many capillaries -Aerobic endurance and slow fatigue rate due to an abundance of mitochondria -Has small fibers |
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Fast oxidative/Fast twitch/Type IIA skeletal muscle |
-Pink in color due to an intermediate level of myoglobin and capillaries -Aerobic and intermediate fatigue rate due to the presence of mitochondria -Has intermediate-sized fibers |
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Fast glycolytic/Fast twitch/Type IIB skeletal muscle |
-White in color due to low myoglobin and few capillaries -Lots of glycogen due to glycolysis -Generates power and has a fast fatigue rate -Has large-diameter fibers |
