Term
| 2 main parts of nervous system and their functions |
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Definition
-CNS (brain and spinal cord), controls internal environment, voluntary movement, spinal cord reflexes, memory and learning
-PNS (neurons outside CNS), 2 sections: sensory (afferent) and motor (efferent) |
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Term
| motor portion of PNS is divided much further. |
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Definition
| Somatic motor (skeletal muscle) and autonomic motor (involuntary effector organ sm M) |
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Term
| 2 sections of autonomic motor |
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Definition
-sympathetic (activates organ and uses norepinephrine, located in throacic and lumbar regions)
-Parasympathetic (inhibits organs, releases acetylcholine (ACh)) |
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Term
| 3 regions of neuron and their purpose |
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Definition
-cell body (soma): center of operation...
-dendrites: cytoplasmic attachments that extend from cell body, conduct electrical impulses toward the cell body...
-Axon (nerve fiber): carry electrical message away from cell body toward other neurons or organ, only 1 axon per neuron but can be divided, synaspses are the contact poitns b/t axon and dendrite, schwann cells are the insulating layer of cells covering axons |
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Term
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Definition
They are the insulatin layer of cells covering axons.
They contain myelin and gaps b/t segments are called nodes of Ranvier |
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Term
| Resting Membrane Potential |
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Definition
electral charge difference = membrane potential (range is -40 mv to -75 mv)
negative charge on inside of cell resulted from unequal distribution of charged ions across cell membrane and - charged particles cannot penetrate cell membrane. Positive ions outside and negative ions inside. |
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Term
| Magnitude of RMP is determine by 2 factors: |
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Definition
1) permeability of plasma membrane to diff ion species...
2) the diff in ion concetrations b/t intracellular and extracellular fluids |
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Term
| What ions play biggest role in generating RMP? |
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Definition
Na, K, Cl...
-Na outsid and K inside
-@ rest Na channels closed and only a few K channels are open.
-cell's Na/K pump exchanges 3 Na for ever 2 K. |
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Term
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Definition
occurs when Na ions diffuse into neuron making it more +...
-when depolarization reaches "threshold" the Na gates open wide and an action potential is reached. |
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Term
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Definition
aka nerve impulse...
-forme when depolarization reaches threshold
-causes a sequence of ionic exchanges to occur along axon that propagates nerve impulse...(nodes of ravier)....
-"all or none law" = once nerve impulse is initiated the impulse travels the entire length of the axon w/out a decrease in voltage |
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Definition
-happens immediately after depolorization...
depolarization cuases brief increase in membrane permeability to K making K leave cell rapidly making inside
-Na gates close reducing + ions in cell |
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Term
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Definition
aka inhibitory postsynaptic potential (IPSP)....
-happens when inhibitory neurotransmitters cause neuron to become more negative |
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Term
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Definition
junctions b/t neurons where they communicate...
-communication occurs via synaptic transmission:
--happens when sufficient amouns of a specific neurotransmiter are released from asynaptic vesicles contained in presynaptic neuron
--impulse results in synaptic vesicles releasing stored NT (ie: actycholine) into the synaptic cleft
--NT bind to receptor on target membrane which produce graded depolarizations in dendrite and cell body
---graded depolarizations = excitatory posysynaptic potentials (EPSPs) |
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Term
| 2 ways EPSPs bring post synaptic neurons to threshold: |
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Definition
-Temporal summation: summing of serveral EPSPs over 1 PS neuron ove short time....
-Spatial Summation: sum EPsps from several diff PS neurons |
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Term
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Definition
site where motor neuron and muscle cell meet...
-junction forms pocket called motor end plate
-neuron and muscle seperated by neuromuscular cleft
-acetylcholine defuses across cleft to bind w/ sites on motor end plate which increases permeablity of sarcolemma to Na...
-results in depolarization called end-plate potential (EPP)...
--EPP is alwayrs large enough to exceed threshold and beng contractile process |
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Term
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Definition
-Function as a lenght detector...
-muscles that require real fine control (hands) have the most spindles
-composed of several thin M cells (intrafusal fibers) surrounded by a connective tissue w/in the muscle
-responsible for stretch reflex |
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Term
| 2 types of sensory nerve endings: |
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Definition
-Primary endings: respond to dynamic changes in M length...
-Secondary endings: doestn't respond to rapid changes in M length and provides CNS w/ continuous info about static M length |
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Term
| Spindles are innervated by what? |
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Definition
| gamma motor neurons, which stimulate the intrafusal fibers to contrac simulananeously along w/ extrafusal fibers (skeletal M) |
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Term
| What is a motor unit and how are they recruited? |
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Definition
-motor units consist of each motor neuron and all the fibers that it innervates.
-innervation ratio is the # of muscle fibers per motor neuron
--fine motor control M have a low ratio (eye M's = 23/1 ratio)
--Large M groups that don't need fine movments have high ratios (leg M = 1000/1)
-the somatic motor portion of PNS is responsible for carrying |
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Term
| 3 layers of connective tissue in Skeletal Muscle (extrafusal fibers) |
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Definition
1) epimysium: outermost layer, surrounds entire muscle...
2) perimysium: surroudns individual bundles of M fibers. bundles = fasicles
3) endomysium: surrounds individual M fiber |
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Term
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Definition
-individual segments
- Z-line: thin sheet of structural protieins that divides sarcomeres...
-A Band: dark portion of sarcomere where myosin is found...
-I bands - light regions where actin is found...
-H zone: center of sarcomere where myosin has no overlap of actin |
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Term
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Definition
-M shortening occurs due to movement of actin over myosin...
-Formation of cross-bridges b/t actin, myosin filaments "power stroke"
-1 power stroke shortens muscle 1%
-distance reduction b/t z-lines and sarcomere |
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Term
| excitation-contraction coupling- |
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Definition
| sequence of events in which a nerver impulse reaches the M membrane and leads to M shorening by cross brdige activity |
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Term
| 2 regulator proteins located on actin molecule: |
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Definition
1) troponin: attached directly to tropmyosin
2) tropomyosin: thin molecule, lies in groove b/t double rows of actin, blocks active sites on actin molecule where cross bridges attach (relaxed state) |
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Term
| Steps leading to Muscular contraction: |
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Definition
-the nerve impulse travels down transverse tubules and reaches sarcoplasmic reticulum, and Ca++ is released...
-Ca++ binds to protein troponin...
-Ca++ binding to troponin causes a positioin change in tropomyosin away from the "active sites" on the actin molecule and permits a stron binding state b/t actin and myosin
-muscular contraction occurs by multiple cycles of cross bridge activity, shortening will continue as long as energy is available and Ca++ is free to bind to troponin |
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Term
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Definition
1) type 1:(slow oxidative or slow twitch fibers, high # of oxidative enzymes, lots of mitochondria, most capilaries,lots of myoglobin, high resistane to fatigue, slow Vmax and specific tension compared to fast.).......
--2) Type IIx (fast glycolytic fibers, small # of mitochondria, limited capacity for aerobic metabolism, not resistant to fatigue, rich in gylcolytic enzymes, highes myosin ATPase activity, lease efficient, largest fiber).........
-3) Type IIa (intermediate or fast-oxidative glycolytic fiber, extremely adaptable) |
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Term
| why do fast fibers twitch faster? |
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Definition
| b/c the sarcoplasmic reticulum in fast fibers releases Ca++ at faster rate and fast fiber possess a higher ATPase activity compared to slow |
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Term
| peak force generated by M _________ as speed of movement ____________. |
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Definition
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Term
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Definition
| Static exerciese, muscle tension increases but M does not shorten, common in postural muscles of body |
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Term
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Definition
aka isotonic and involves movement of body parts.
-2 types: 1)Concentric (M action taht results in M shortening w/ movement of a body part) 2) Eccentric action (occurs when M produces force but length increases |
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Term
| Factors that regulate force production |
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Definition
1)types and # of motor units recruited...
2) the initial M length....
3) the nature of the motor units neural stimulation (summation and tetanus) |
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Term
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Definition
Summation - addition of successive twitches so that M does not have time to relax b/t stimuli and force appears to be additive
Tetanus - a single, sustain contraction that occurs when high frequency of stimuli cause contraction to be blended together |
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Term
| Role of Golgi tendon organs |
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Definition
-provide CNS w/ feedback concerning tension developed by muscle
-prevents damage during excess force generation....
-provides finer control over skeletal moevements....
-plays important role in peformance of strenght activities |
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Term
| What is ideal diff b/t core and shell temperatures? |
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Definition
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Term
| Role of Hypothalamus, specifically the anterior and posterior hypothalamus. |
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Definition
acts like thermostat by initiating changes in body heat loss and production...
-Ant Hypothalamus: deals w/ increasing body heat (stims sweat glands and vasomotor control center allows more blood to skin).................
-Post Hypothalamus: deals w/ decreased body heat. (blood vessels constrict, involuntary shivering, goosebumps, increases thyroxin which increases heat production, releases norepinephrien, increases rate of cell metabolism) |
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Term
| Body acclimatizing to hot/humid environment: |
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Definition
| -incrased plasma volume, earlier onset of sweating, higher sweat rate, reduced NaCl loss in sweat, Reduced skin blood flow) |
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Term
| Body acclimatizing to cold/ moderat environment: |
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Definition
| improved ability to sleep in cold environments, increased nonshiver thermogenesis, higher intermitten blood flow to the hands and feet |
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