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48 Cards in this Set
- Front
- Back
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what is the negative charge inside cells at rest? |
-70mv |
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how is the resting membrane potential determined? |
-permeability of plasma membrane to ions K and Na -differences in ion concentrations across membrane -Ca and Cl cancel out |
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how is the -70mv maintained? |
by the Na K pump |
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how is the resting membrane potential maintained? |
maintained by the sodium-potassium pump |
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how is the membrane potential membrane maintained by the sodium-potassium pump? |
-k tends to diffuse out of the cell -Na/K pump moves 2 K in and 3 Na out Net effect in 1 ion outside of the cell This prevents the inside from becoming too negative |
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what is constantly leaking out of the membrane? |
K |
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what happens when K leaks out of the membrane? |
this makes the inside of the cell more negative (-70) because you are losing ions |
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what does the sodium-potassium pump help prevent? |
this helps prevent the inside from becoming too negative |
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when does an action potential occur? |
this occurs when a stimulus of sufficient strength depolarizes the cell--becomes more positive -opens Na channels, and Na diffuses into cell (lots of Na floods into the cell) -this effects the inside of the cell to become more positive |
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what is repolarization? |
this is when the inside of the cell becomes more negative. |
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what about repolarization in regards to the action potential? |
-this return to resting membrane potential -K leaves the cell rapidly (membrane is more permeable)- inside is more negative -Na channels close thus stopping influx of positive ions. |
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what is the All-or-None law? |
once a nerve impulse is initiated, it will travel the length of the neuron. |
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in respect to a graph, what direction indicates depolarization and repolarization? |
Upward and downward, respectively |
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what is a synapse (gap junction)? |
small gap between presynaptic neuron and postsynaptic neuron |
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what is a neurotransmitter? |
-chemical messenger released from presynaptic membrane -binds to specific receptor on post synaptic membrane -causes depolarization (acetyl CoA) of post synaptic membrane |
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how does a neurotransmitter cause depolarization? |
makes the inside more positive -increases permeability of membrane to Na -Na gates open -Na floods in -inside positive |
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what about Excitatory Postsynaptic potentials (EPSP)? |
these cause depolarization - Na gates open - inside becomes more positive |
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what is temporal summation? |
summing several EPSPs from one presynaptic neuron over time |
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what is spatial summation? |
summing from several different presynaptic neurons |
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what are Inhibitory postsynaptic potentials (IPSP)? |
these cause hyper polarization or repolarization -closes Na gates for this -occurs at one time point |
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what are proprioceptors? |
receptors that provide CNS with info about body position -located in joints and muscles |
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what is kinesthesia? |
conscious recognition of the position of body parts -limb movement rates |
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what are some joint proprioceptors? |
-free nerve endings -golgi-type receptors -pacinian corpuscles |
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what are free nerve endings? |
sensitive to touch and pressure -located everywhere |
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what are golgi-type receptors? |
found in ligaments and around joints -similar to free nerve endings |
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what are pacinian corpuscles? |
-stops pitchers from throwing hard -in tissue and around joints -detects rate of joint rotation |
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what are muscle proprioceptors? what are the two popular ones? |
provide sensory feedback to nervous system -tension development by muscle (force development -account of muscle length (how much does it stretch?) muscle spindle (length) golgi tendon organ (force) |
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what does the muscle spindle do? consist of? |
responds to changes in muscle length consists of: - intramural fibers(nerve part) run parallel to normal muscle fibers (extrafusal) - gamma motor neurons (decision makes whether counteract the stretch) these stimulate intramural fibers to contract with extrafusal fibers (by alpha motor neurons) |
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what is the stretch reflex? |
stretch on muscle causes reflex contraction -knee jerk reflex happens by the muscle spindle |
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what does the Golgi Tendon Organ do? |
monitors tension developed in muscle -prevents muscle damage during excess force generation stimulation results in reflex relaxation of muscle -inhibitory neurons send IPSPs to muscle fibers ability to voluntarily oppose GTO inhibition may be related to gains in strength |
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what are muscle chemoreceptors? |
sensitive to changes in the chemical environment surrounding a muscle -H ions, CO2 and K Provides CNS with information about metabolic rates of muscular activity -important in regulation of cardiovascular and pulmonary responses |
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regarding the withdrawal reflex, what about the reflex contraction of skeletal muscle? |
occurs in response to some sensory input -not dependent on higher brain centers primitive reflex |
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regarding the withdrawal reflex, what about pathways of neural reflex? |
-sensory nerve sends impulse to spinal column--NOT brain -interneurons activate activate motor neurons -motor neurons control movement of muscles *pulling hand away from hot stove |
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what about reciprocal inhibition? |
EPSPs- to muscles to withdraw away from stimulus IPSPs to antagonistic muscles |
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what about crossed extensor reflex? |
opposite limb supports body during withdrawal or injured limb *walking and step on a tack, other leg then supports body weight |
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what are the somatic motor neurons of PNS? |
responsible for carrying neural messages from spinal cord to skeletal muscles |
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what is a motor unit? |
motor neuron and all of the fibers it innervates |
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what is the innervation ratio? |
number of muscle fibers per one motor neuron low ratio in muscles that require fine motor control -23/1 in extraocular muscles higher ratio in other muscles/gross movement 1000/1 or greater in large muscles |
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what about motor unit recruitment? |
recruitment of more muscle fibers through motor unit activation |
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what about the size principle? |
smallest motor units are recruited first (slow switch oxidative) -produce larger EPSP and result in action potential sooner--because nerve impulse travels a short distance-b/c it's smaller |
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what are the types of muscles fibers? |
type S slow/ or type 1 fibers/smallest/very oxidative//marathon runners type FR/ (fast fatigue resistant) intermediate type IIa//can never be trained to complete type 1 or 2x type FF (fast, fatiguable) or type 2x fibers (largest)--sprinters, very glycolytic |
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what is the recruitment pattern during incremental exercise? |
type 1, type 2a, type 2x |
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what is central fatigue? |
high brain centers and/or motor neurons -depleteion of excitatory neurotransmitters in the motor cortex//you do not have an infinite number of these transmitters -reduced motor output to the muscle -less movement, rate, force |
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what is the central governor theory? |
central control center regulates exercise performance reduces motor output in exercising muscle protects against catastrophic disruptions of homeostasis -current research suggests that fatigue is related to both central and peripheral factors |
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what two parts make up the autonomic nervous system? |
sympathetic and parasympathetic |
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what is the autonomic nervous system responsible for? |
maintaining internal environment -effector organs not under voluntary control -smooth muscle, cardiac muscle, and glands |
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what about the sympathetic division? |
releases NE -excites an effector organ- B1 receptors- increases HR after stimulation, NE is removed from synapse or inactivated |
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what about the parasympathetic division? |
releases Ach -inhibits effector organ after stimulation, Ach is degraded by Acetylecolinesterase |
