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36 Cards in this Set
- Front
- Back
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Question of the Day:
What areas of the brain are responsible for slow and fast movements? |
Fast- cerebellum
Slow, deliberate- basal ganglia |
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What is the CNS?
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Central Nervous System
Composed of brain and spinal cord Works with the PNS |
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What are the two major divisions of the PNS?
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Sensory (afferent) division
and Motor (efferent) Division |
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What are the divisions of the motor division of the PNS?
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Autonomic--> Sympathetic and Parasympathetic
Somatic |
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What are the three regions of a neuron?
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Cell body (soma)
Dendrites Axon |
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What is a nerve impulse?
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An electrical charge that acts as a signal which passes from one neuron to the next until it reaches the end organ and then returns to the CNS
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What is the resting membrane potential?
What causes/maintains this charge? |
-70 mV (the inside of the neuron is negative relative to the outside. when the charges across a membrane differ, the membrane is POLARIZED)
K+ is concentrated on the inside of the cell because K+ can move more freely across the membrane than Na+ Sodium-potassium pumps (which contain ATPase) move 3 Na+ out of the cell for each two K+ it brings in If the membrane potential fluctuates from -70, you will have a big impulse going through the cell! |
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What is depolarization?
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When the membrane potential becomes less polarized...it becomes close to zero...the result of an increase is Na+ permeability in the membrane
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What is hyperpolarization?
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When the membrane potential becomes even more negative
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What are graded potentials?
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Localized changes in membrane potential (either depolarization or hyperpolarization)
Stimuli such as AP from another neuron or senosry stimuli cause ion channels/gates in the membrane to open, causing a graded potential |
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What is an action potential?
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-Begins as a graded potential, requires depolarization greater than 15-20mV
-rapid, substantial depolarizations of the cell membrane (-70mV-->+30mV-->-70mV in 1 millisecond) -All or none principle! |
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What is an absolute refractory period?
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When a given segment of an axon is generating an action potential, its sodium gates are open adn it is unable to respond to another stimulus
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What is a relative refractory period?
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When the Na gates are closed, the K gates are open and repolarization is occuring, the segment of the axon can respond to a new stimulus, but the stimulus must be substancially greater to provoke an AP
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What are the five events that occur during an action potential
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1. resting state
2. depolarization 3. propagation of an action potential 4. repolarization 5. return to resting state (w. the help of a Na/K pump) |
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How do action potentials travel down the axon?
Is it faster down myelinated fibers or unmyelinated? How does neuron diamter affect the speed? |
Saltatory conduction- from one node of Ranvier to the next
Faster in myelinated Larger-diameter neurons conducts impulses faster (less resistance) |
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What is the Synapse?
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Site of impulse transmission
Neurotransmitters from presynaptic neuron's axon terminal cross the synapse to get to the dendrites of the postsynaptic neuron |
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What is the neuromuscular junction?
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Site where an alpha-motor neuron communicates with a muscle fiber
Neurotransmitter binding cause depolarization-->AP speads across the sarcolemma |
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What is the refractory period?
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Period of REPOLARIZATION
The muscle fiber can not respond to further stimulation Limits a motor unit's firing frequency |
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What are the two categories of neurotransmitters and name the two most common ones for regulating exercise
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-Small molecule, rapid-acting
-Neuropeptide, slow-acting Acetylcholine (skeletal muscle and papsympathetic nerves) Norepinephrine (sympathetic neurons) |
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How are neurotransmitters destroyed?
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By enzymes, removed by reuptake into the presynaptic terminal, or diffused away from the synapse
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What is the "postsynaptic response"?
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-Excitatory postsynaptic potentials (EPSPs) are depolarizations of the postsynaptic membrane
-Inhibitory postsynaptic potentials (IPSPs) are hyperpolarizations of the membrane -Summation of impulse causes an AP and is monitored at the axon hillock |
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What are the four major regions of the brain?
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Cerebrum
Diencephalon Cerebellum Brain Stem |
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What are the two parts of the Peripheral Nervous System (PNS)?
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Sensory division- carries sensory information from the body via afferent fibers-->CNS
Motor division- transmits info from CNS via efferent fibers--> target organs |
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What are the different kinds of receptors of the Sensory Division of the PNS?
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Mechanoreceptors- mechanical forces
Thermo- temp Noci- pain Photo- light/visual Chemo- chemical from food/odors/etc |
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Explain proprioception on a physiological level
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Kinesthetic receptors in joint capsules sense the position and movement of joints
Muscle spindles sense how far it is stretched Golgi tendon organs sense tension of muscle on tendom=strength of contraction |
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What are the two divisions of the motor division of the PNS?
AKA the two divisions of the autonomic nervous system |
Sympathetic and parasympathetic
The effects of these two are often antagonistics, but work together to regulate stuff |
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Describe the sympathetic nervous system
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Uses norepinephrine to excite effector organs
"fight or flight"- increase HR, BP, metabolic rate, glucose release from liver, mental activity |
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Describe the parasympathetic nervous system
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"housekeeping"- digestion, glandular secretion
Decreases HR |
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What nerves does the PNS contain?
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43 pairs:
12 cranial and 31 spinal |
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Describe the process of sensory motor integration
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This is the process by which the PNS works with the CNS
1. Sensory stimulus is recieved by sensory receptors 2. Sensory neurons transmit AP to the CNS 3. CNS interprets the signal and determines best response 4. Sends APs for a response through alpha motor neurons 5. The motor AP is transmitted to muscle, response occurs |
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What are the three places that motor responses can originate from
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Spinal cord
Lower regions of brain Motor areas of cerebral cotrex |
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What is a motor reflex?
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The simplest form of motor control- A preprogramed response that's integrated by the spinal cord without concious thought
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What is a muscle spindle?
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between regulay skeletal muscle fibers
middle of the spindle cannot contract, but can stretch reflexive muscle contraction is triggered here to prevent overstreching |
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What are Golgi Tendon Organs (GTOs)?
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Encapsulated sensing organs through which a small bundle of tendon muscle fibers pass
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What are the higher brain centers and what do they control?
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Primary motor cortex: locate din frontal lobe, fine and discrete CONCIOUS muscle movement
Basal ganglia: sustained and repeptitive movement (walking and running) posture and muscle tone Cerebellum: all rapid and complex muscular activity |
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What is different between the control of small vs. large motor responses?
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Muscles contorlling tiny movements have few muscle fibers per motor neuron.
Muscles for more general function have MANY fibers/motor neuron |
