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CHAPTER 9
| Question | Answer |
|---|---|
| define muscle tone | continous state of partial contraction in resting muscles |
| define isotonic | muscle contracts and changes length; equal force |
| define concentric | shortening contraction |
| define eccentric | lengthening contraction |
| define isometric | muscle contracts but does not change length; change in force |
| define origin | less moveable end |
| define insertion | move moveable end |
| define agonist | muscle that causes an action |
| define prime mover | agonist primarily responsible for movement |
| define synergist | muscles that assist agonist/prime mover |
| define antagonist | muscles whose contraction causes movement in the opposite direction of the prime mover |
| what are the major function of the muscular system | produce movement posture and body position support soft tissues guard entrances and exits body temperature |
| what are the common characteristics of the muscles | contraction excitability/irritability extensibility elasticity |
| describe contraction | reduces space |
| describe excitability/irritability | respond to stimuli |
| describe extensibility | ability to stretch |
| describe elasticity | ability to return to original length when relaxed |
| what are the three major muscle types | skeletal, cardiac, smooth |
| skeletal muscle (location, function, characteristic, example) | location: attaches to bones of skeleton function: moves skeleton characteristics: contract quickly, fatigue easily, contract for short periods of time. Example: Shoulder |
| skeletal muscle - striated or non straited, voluntary or involuntary | striated and voluntary |
| cardiac muscle (location, function, characteristic, example) | location: branched together in wall of heart function: pumping action of the heart characteristics: contract quickly, do not fatigue easily, receive electrical stimuli and contract together example: heart |
| smooth muscle (location, function, characteristic, example) | location: walls of internal organs such as the digestive tract function: controls involuntary organs characteristics: contract slowly, do not fatigue easily, stay contracted for long periods of time example: stomach, uterus, intestines |
| cardiac muscle striated or non straited, voluntary or involuntary | straited and involuntary |
| smooth muscle striated or non straited, voluntary or involuntary | non striated and involuntary |
| what does the term striated mean? | stripped in appearance |
| what are the types of connective tissue coverings of skeletal muscles ? | fascia, tendons, aponeuroses |
| describe fascia | thin sheath of fibrous tissue surrounding each muscle holding it in place |
| describe tendons | flexible cord attaching muscle to bone |
| describe aponeuroses | sheet like fibrous tissue that attach to bone or coverings of adjacent muscles |
| what are the different types of muscle coverings? | epimysium, perimysium, endomysium |
| describe epimysium | surrounds whole muscle |
| describe perimysium | surrounds fascicles within a muscle |
| describe endomysium | surrounds muscle fibers (cells) inside a fascicle |
| function of sarcomere | functional unit of the muscle |
| function of sarcolemma | surrounds fibers of skeletal muscles |
| function of sarcoplasm | cytoplasm of striated muscles |
| function of myofibrils | contractile thread found in striated cells |
| function of actin | protein that serve as contractile filament |
| function of myosin | protein that serve as contractile filament |
| function of troponin and tropomyosin | protein involved in muscle contraction binds with myosin |
| what is the neuromuscular junction | site where motor neurons axon and the muscle fiber interact (synapse/myoneural junction) skeletal muscles will only contract when they are stimulated by a motor neuron |
| what are the different parts of the neuromuscular junction | motor neuron, motor end plate, synaptic cleft, neurotransmitters |
| motor neuron | controls muscles |
| motor end plate | nuclei and mitochondria are abundant, and a sarcolemma is folded |
| synaptic cleft | gap that separates the membrane of the neuron and muscle fiber |
| synaptic vesicles | connects axon of neuron to muscle cell |
| neurotransmitters | chemicals sent by neurons that control the cell |
| what is acetylcholine (ACh) | the neurotransmitter that controls muscle contraction, produced in the cytoplasm and stored in the synaptic vessels |
| step 1 of stimulus contraction | 1. Nerve impulse is sent from nervous system to the synaptic vessel |
| step 2 of stimulus contraction | 2. ACh is released |
| step 3 of stimulus contraction | 3. ACh binds to receptors |
| step 4 of stimulus contraction | 4. ACh opens Na+ and K+ ion channels, excitation generates nervous impulse (action potential) |
| step 5 of stimulus contraction | 5. Ca+2 is released from the sarcoplasmic reticulum due the impulse |
| step 6 of stimulus contraction | Ca+2 ions bind to troponin and change shape |
| step 7 of stimulus contraction | Tropomyosin moves |
| step 8 of stimulus contraction | Binding sits on actin are now exposed |
| step 9 of stimulus contraction | Actin and myosin bind 9 forms a cross-bridge |
| step 10 of stimulus contraction | Muscle contracts |
| what is excitation contraction coupling | a connection between muscle fiber (actin and myosin) stimulation and muscle contraction (movement). This step is controlled by the release of Ca+2 into cytosol |
| what are the primary energy sources used during muscle contraction | ATP: reserves small amount Creatine phosphate: stores energy that quickly converts ADP to ATP Cellular respiration |
| what is the oxygen debt ? | occurs when oxygen is not available. glycolysis continues pyruvic acid is used to make ATP produces lactic acid |
| what is Anaerobic (lactic acid) threshold | threshold shifts in metabolism from anerobic to aerobic occurs during strenuous muscle activity when the body cannot supply necessary oxygen lactic acid is produced (causes muscle fatigue and cramping ) |
| what is muscle fatigue? | inability to contract muscle |
| common causes of muscle fatigue | decreased blood flow, ion imbalances, loss of desire to exercise and accumulation of lactic acid |
| what is muscle cramps | sustained, painful and involuntary muscle contraction |
| common causes of muscle cramps | changes in electrolyte concentration in extracellular fluids accumulation of lactic acid |
| what comprises a motor unit? | consists of motor neurons and muscle fibers that control it |
| what are the ranges in fibers? | as few as 4 or as many as 1000 fibers |
| how does the number of fibers activate impact the types of movements | coarse movements are produced with large numbers of fibers in a motor unit precise movements are produced with fewer muscle fibers in a motor unit |
| what is motor unit recruitment? | increase in the number of motor units activated to produce more force |
| why is motor unit recruitment important? | because it controls the intensity of a contraction by recruiting additional motor units when needed |
| characteristics of slow twitch fibers | always oxidative resistant to fatigue red fibers, have myoglobin good blood supply many mitochondria slow ATPase activity, slow to contract |
| characteristics of fast twitch fatigue resistant fibers | intermediate twitch fibers intermediate oxidative capacity intermediate amount of myoglobin white fibers resistant to fatigue |
| characteristics of fast twitch glycolytic fibers | anaerobic respiration white fibers poorer blood supply fewer mitochondria than fast twitch more SR than fast twitch susceptible to fatigue fast ATPase activity; contract rapidly |
| what are the two types of smooth muscle | multi unit smooth muscle and visceral smooth muscle |
| describe multi unit smooth muscle | location: iris of eye, walls of blood vessels stimulated by neurons and hormones cells are less organized function as separate units fibers function independently |
| describe visceral smooth muscle | location: walls of most hollow organs most common type of smooth muscle cells respond as unit held together by gap junction conduct peristalsis exhibit rhythmicity |
| what determines the type of movement a skeletal muscle produces? | the type of joint it is associated with and they way the muscle is attached on either side of the joint |
| what are the circular muscles that control the passages of substances into and out of a structure? | bladder and sphincter muscle |
| where is the location of bladder and sphincter muscles | openings in the stomach, between esophagus and small intestine walls of anus, urethra, mouth |
| do muscles pull or push on bones? | muscles pull on bones |
| what is meant by muscles have an antagonistic relationship | it means they work against each other, they move in opposite directions |
| injection administered in the muscle is called? | intramuscular injections |
| what is the most common site for IM injection | gluteus Medius vastus latealis (thigh/leg deltoid (shoulder/arm |
| what are the different ways skeletal muscles are named? | location size direction number of origins insertion action |
| what are the two major groups of muscles | axial and appendicular |
| axial muscles | moves muscles of the axial skeleton located in the midline of the body |
| appendicular | stabilizes and moves bones of the appendicular skeleton |
| how does age impact the muscular system | muscle strength decreases, reflex become slow by age 80 almost half of muscle mass has atrophied myoglobin, ATP and creatine phosphate decline starting in 40's connective tissue and adipose cells replace some muscle tissue |
Created by:
ShyKiera