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108 Cards in this Set
- Front
- Back
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Which american scientist discovered the size principle? |
Elwood Henneman |
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Why does membrane potential peak at +30mV and then rapidly decrease? |
The increased Na+ concentration increases Na/K pump activity |
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Most organs receive ______ _______ by both sympathetic and parasympathetic divisions of the ANS. |
Dual innervation |
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At the cessation of exercise which ANS division decreases in activity while the other increases? |
Sympathetic division decreases in activity, while parasympathetic division increases in activity. |
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At the beginning of a bout of exercise, which division of the ANS has an increase in activity, while the other decreases? |
Sympathetic division increases in activity, while parasympathetic division activity decreases. |
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What happens to acetylcholine after parasympathetic nerve stimulation? |
It is released and rapidly degraded by the enzyme acetyl-cholinesterase. |
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What neurotransmitter is associated with the parasympathetic nervous system? |
Acetylcholine |
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What neurotransmitter is associated with the sympathetic nervous system? |
Norepinephrine |
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In what two ways is norepinephrine removed from the target effector organ after sympathetic stimulation? |
Reuptaked into the post-ganglionic fiber, and/or broken down into non-active products. |
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What neurotransmitter is released at the effector organ and how does it exert its actions on the effector organ? |
Norepinephrine is released and binds to alpha or beta receptors on the membrane of the target organ. |
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What is the name of the neurotransmitter that is between the pre-ganglionic and post-ganglionic neurons? |
Acetylcholine |
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Where are the cell bodies of the parasympathetic division located? |
The brain stem and sacral portion of the spinal cord. |
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Where are the cell bodies of the sympathetic division located? |
Thoracic and lumbar regions of the spinal cord. |
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What is this autonomic nervous system responsible (ANS) responsible for? |
Maintaining internal environment by activating/inhibiting organs such as smooth muscle, cardiac muscle, and glands. |
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The activity of a particular organ can be determined by? |
The ratio of sympathetic/parasympathetic impulses to the tissue. |
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What are the functions of the sympathetic and parasympathetic divisions of the ANS? |
The sympathetic division tends to activate an organ whereas the parasympathetic division tends to inhibit the organ (opposes the action of the sympathetic division). |
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What are the two different divisions of the ANS? |
Sympathetic division and the parasympathetic division. |
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How does exercise enhance brain health? |
Promotes a cascade of brain growth factor signaling which enhances learning and memory, stimulates neurogenesis, improves brain vascular function and blood flow, and attenuates the mechanisms driving depression. |
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What are the major health risks associated with a concussion? |
Permanent brain damage or death associated with delayed brain swelling, second impact syndrome, same season repeat concussion, and late-life consequences. |
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What is a concussion defined as? |
A complex brain injury resulting from a traumatic force to the head, neck, or body. |
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What does current research suggest about fatigue? |
That it is related to both CNS and peripheral factors. |
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What is the central governor theory and what does it protect against? |
Proposes that exercise-induced fatigue is regulated by the action of the brain. This type of control system would limit muscle activation during exercise by reducing motor output from high brain centers. It protects the body against catastrophic disturbances in homeostasis by promoting fatigue and the cessation of exercise before damage occurs. |
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What is central fatigue, what causes it, and how does it impact exercise performance? |
Exercise induced fatigue that results from CNS dysfunction. It is caused by the depletion of excitatory neurotransmitters in the motor cortex and limits exercise performance by limiting the activation of motor neurons and the muscle fibers they innervate. |
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What are the three types of motor units? |
Type S (slow) or Type 1 Fibers (smallest), Type FR (fast, fatigue resistant or Type 2a fibers (intermediate), Type FF (fast, fatigueable) or Type 2x fibers (largest) |
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Why are the smaller motor neurons activated first? |
Smaller motor neurons have a smaller surface area and would produce a larger EPSP, which would reach threshold sooner, resulting in action potential. |
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What is the size principle? |
The process of motor unit recruitment in which the smallest motor neurons are recruited first followed by larger motor neurons. Type 1 ---> Type 2a ------> Type 2x |
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The term motor unit recruitment refers to? |
The progressive activation of more and more motor neurons. |
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What is considered a high/low innervation ratio? |
23/1 = low (extraocular muscles) 1000-2000/1 = high (leg muscles) |
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There is a low innervation ratio in muscles that require what kind of motor control? High ratios? |
Low innervation ratios = fine motor control High innervation ratios = gross motor control |
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What is the innervation ratio? |
The number of muscle fibers innervated by a single motor neuron. # of muscle fibers/1 motor neuron. |
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After the axon reaches the muscle, the axon splits into _________ __________ each of which is responsible for innervating a single muscle fiber. |
Collateral branches |
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The axon of the motor neuron leaves the spinal cord as a spinal nerve and extends to? |
The muscle that it is responsible for innervating |
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The cell body of motor neurons is located where? |
Within the spinal cord |
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Each motor neuron and all the muscle fibers that it innervates is known as? |
a motor unit |
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The somatic neuron that innervates skeletal muscle fibers is called? |
Motor neuron or alpha motor neuron |
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What is the function of the somatic motor portion of the PNS? |
Responsible for carrying neural messages from spinal cord to skeletal muscle fibers which signal the muscle to contract. |
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What does the term somatic refer to? |
The outer (non-visceral) regions of the body |
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During the withdrawal reflex, the opposite limb is extended to support the body during the removal of the injured limb. What is this called? |
The crossed-extensor reflex |
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The simultaneous excitatory and inhibitory activity is known as? |
reciprocal inhibition |
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Where are chemoreceptors found within the cardiovascular system? |
Carotid artery and carotid arch |
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What info do chemoreceptors provide to the CNS? Why is it important? |
Info about metabolic rate of muscular activity which is an important factor in the regulation of cardiovascular and pulmonary responses. |
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How do chemoreceptors send info to the CNS? What stimulates them? |
They send info via slow conducting fibers classified as group 3 (myelinated) and group IV (unmyelinated) fibers. They are stimulated by H+ ions, CO2, and K+, all of which are potent stimulators. |
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How does strength training impact the golgi tendon organ? |
Reduces the inhibitory influences of the GTO which allows for a greater amount of muscle force production. |
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What is the function of the golgi tendon organ and how does it perform this function? |
Prevents muscle damage during excessive force generation. It does this by sending info to the spinal cord via sensory neurons which inturn excite inhibitory neurons (sends IPSPs). This prevents motor neurons from firing, reducing muscle force production. |
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What does the golgi tendon organ detect? |
Tension/Force |
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What are stretch reflexes (myotatic reflex)? |
Stretch on a muscle that causes a reflex contraction. It is present in all muscle, but is most dramatic in the extensor muscles. |
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How are muscle spindles innervated? |
Gamma motor neurons |
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What are the two types of sensory nerve endings within muscle spindles? What are their functions? |
Primary endings which respond to dynamic changes in muscle length and secondary endings which provide the CNS with continious info concerning static muscle length and does not respond to rapid changes in muscle length. |
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What is the muscle spindle composed of? |
Several thin muscle cells called intrafusal fibers that are surrounded by a connective tissue sheath. They run parallel to with skeletal tissue (extrafusal fibers) and insert into connective tissue within the muscle. |
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Would muscles that require the finest degree of control, such as the hands, have a low or high amount of muscle spindles? |
High amount |
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What info does the muscle spindle relay to the CNS? |
info about muscle length |
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To properly control skeletal muscle contraction, the CNS must receive what kind of sensory feedback continously? |
info concerning muscle tension and muscle length |
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What are chemoreceptors? |
Specialized free nerve endings that send information to the CNS in response to changes in muscle pH, concentrations of extracellular K+, and changes in O2/CO2 tensions. |
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What are the three types of muscle proprioceptors? |
chemoreceptors, muscle spindles, and golgi tendon organs |
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Describe the function and location of pacinian corpuscles? |
They are found in tissues around joints and detect the rate of joint rotation. |
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Describe the function and location of golgi-type receptors. |
They are found in ligaments around joints and are sensitive to touch and pressure. |
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Describe the function and location of free nerve endings. |
They are located on the skin and are sensitive to touch and pressure. |
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What is the most abundant joint proprioceptor? |
free nerve endings |
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What are the three types of joint proprioceptors? |
Free nerve endings, golgi-type receptors, pacinian corpuscles. |
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Conscious recognition of the position of body parts with respect to one another as well as recognition of limb movement rates is referred to as? |
Kinesthesia |
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What are proprioceptors and where are they located? |
Receptors that provide the CNS with info about body position and are located in the joints and muscles. |
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How does acetlycholine serve as an inhibitory and excitatory neurotransmitter? |
Depolarization of skeletal muscle (excitatory) and hyperpolarization of the heart which moves the membrane potential further from the threshold value (inhibitory). |
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Whether a neuron reaches threshold or not is dependent on? |
The ratio of EPSPs to IPSPs |
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What are inhibitory postsynaptic potentials? |
Inhibitory neurotransmitters that cause a hyperpolarization (increased negativity) of the post synaptic membrane. It causes a more negative resting membrane potential which means it will resist depolarization. |
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To prevent chronic depolarization, what must happen to acetylcholine at the neuromuscular junction? |
It must be broken down into a less-active molecule via the enzyme acetyl-cholinesterase which is loceted within the synaptic cleft. |
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What is spatial summation? |
The sum of EPSPs from several different presynaptic inputs. |
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What is temporal summation? |
The summing of several EPSPs from a single presynaptic neuron over a short period of time. |
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What are the two ways EPSPs can bring the post synaptic neuron to threshold? |
Temporal summation and spatial summation |
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Graded depolarizations in the dendrites and cell body are called? |
Excitatory postsynaptic potentials (EPSPs) |
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Where are neurotransmitters released from? |
Synaptic vesicles |
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A chemical messenger that neurons use to communicate with each other is called? |
neurotransmitter |
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A small gap (20 - 30 nanometers) between the synaptic end foot of the presynaptic neuron and a dendrite of a post synaptic neuron. |
Synapse |
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What is an action potential? |
Nerve impulse |
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What does the all or none law mean? |
If a nerve impulse is initiated, the nerve impulse will travel the entire length of the axon without a decrease in voltage. |
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What causes the diffusion of potassium out of the cell at rest? |
High membrane permeability of the membrane for K+ than Na+ and the concentration gradient for K+ inside to outside of the cell |
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Negative membrane potential in a resting neuron is due primarily to? |
The diffusion of K+ outside of the cell. |
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Growing evidence indicates that regular exercise, including both endurance and resistance, can improve the functional capacity of patients suffering from multiple sclerosis. (True or False) |
True |
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A neurological disease that progressively destroys the myelin sheaths of axons in multiple areas of the CNS. |
Multiple sclerosis |
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What are the concentrations of ions outside of a typical cell membrane? |
Na+ = 145mM K+ = 5mM Cl- = 125mM Ca++ = 2.5mM |
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What are the concentrations of ions inside of a typical cell membrane? |
Na+ = 12mM K+ = 150mM Cl- = 9mM Ca++ = .0001mM |
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What regulates permeability of the neuron membrane? |
Proteins within the membrane that open or close to function as gates. |
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Which ions assist in the regulation of cell membrane potential? |
Na+ K+ Cl-,Ca++ (these two counteract each other) |
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The magnitude of resting membrane potential is primarily determined by what two factors? |
The permeability of the plasma membrane to different ion species and the difference in ion concentrations between the inside and outside of the cell |
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What is the charge inside of the membrane at rest? |
-70mV |
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Which objects inside the cell are negatively charged? |
cellular proteins, phosphate groups, and nucleotides |
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The transmission of the neural impulse along the axon is called? |
Conductivity |
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The ability of the dendrites and neuron cell body to respond to a stimulus and convert it to a neural impulse is called? |
Irritability |
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In general, the larger the diameter of the axon, the greater the? |
Speed of neural transmission. Axons with large myelinated sheaths conduct impulses more rapidly than small, not myelinated fibers. |
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The gaps or spaces between the myelin segments along the axon are called? |
nodes of ranvier |
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In large nerve fibers like those innervating skeletal muscle, the axons are covered with an insulating layer of cells called? |
schwann cells |
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Contact points between an axon of one neuron and the dendrite of another neuron are called? |
Synapses |
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Carries the electrical message away from the cell body toward another neuron or effector organ. |
Axon, or nerve fiber. |
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Narrow, cytoplasmic attachments that extend from the cell body and serve as a receptive area that can conduct electrical impulses toward the cell body. |
Dendrites |
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The center of operation for the neuron is called? |
Cell body, or soma |
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Neurons are composed of these three regions? |
Cell body, dendrites, and axon |
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What is the functional unit of the nervous system? |
neuron |
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Motor nerve fibers that conduct impulses away from the CNS are called? |
Efferent fibers |
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What is the autonomic motor division responsible for? |
innervating involuntary effector organs like smooth muscle, cardiac muscle, and glands. |
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What is the somatic motor division responsible for? |
innervating skeletal muscles |
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Sensory nerve fibers that conduct info towards the CNS are called? |
Afferent Fibers |
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What is the sensory division of the PNS responsible for? |
The transmission of neuron impulses from receptors to the CNS. |
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The PNS can be subdivided into what two portions? |
Sensory portion and motor portion |
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What does the term innervation refer to? |
The supply of nerves to a particular organ |
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What is the PNS composed of? |
neurons outside of the CNS |
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What is the CNS composed of? |
Brain and spinal cord |
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What are the two parts of the nervous system? |
CNS and PNS |
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What are the four major functions of the nervous system? |
1. Control of the internal environment 2. Voluntary control of movement 3. Programming spinal reflexes 4. Assimilation of experiences necessary for memory and learning |
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