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| composed of brain and spinal cord and serves as the control center of the entire nervous system. All sensory info must be relayed to CNS b4 it can be interpreted and acted on. Most impulses that stim glands to act and muscles to contract originate in the CNS |
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| peripheral nervous system - cordlike nerve processes that connect the CNS w/ the various glands, muscles, and receptors in the body – subdivided into a somatic nervous system and autonomic nervous system |
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afferent nerves conduct impulses from the periphery TOWARD the CNS (ad means toward, ferre means to carry). Aka sensory nerves as they condict sensations from the sensory receptors in the skin and elsewhere to the CNS.
• Efferent division |
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| efferent nerves conduct nerve impulses AWAY from the CNS toward muscles and other organs (ex means away). Aka motor nerves because efferent impulses are the one that, among other things, cause skeletal muscle contraction and movement. |
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| somatic nervous system – conscious or voluntary nervous system controlling skeletal muscles.; somatic motor fxn is the efferent branch and the somatic sensory fxn is the afferent branch |
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| autonomic nervous system– the part of the nervous system that controls involuntary activities - smooth muscle, cardiac muscle, and endocrine glands automatically w/o conscious control; has motor and sensory branches. . Has 2 subdivisions – parasympathetic ( cholinergic) and sympathetic (adrenergic) |
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| the chemical released by the presynaptic neuron that diffuses across the synaptic cleft, binds w/ the receptor on the postsynaptic membrane, and stimulates (excitatory neurotransmitter) or inhibits (inhibitory neurotransmitter) |
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| the junction between 2 neurons or between a neuron and another target cell |
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| the reflex arc is composed of the sensory receptor, sensory neuron , interneuron(s), motor neuron, and target tissue or organ involved with a stimulus and involved with a stimulus |
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| Compare and contrast afferent and efferent nerves. Which are sensory nerves and which are motor nerves? What types of actions will stimulation of these nerves create? |
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afferent nerves conduct impulses from the periphery TOWARD the CNS (ad means toward, ferre means to carry). Aka sensory nerves as they conduct sensations from the sensory receptors in the skin and elsewhere to the CNS
• efferent nerves conduct nerve impulses AWAY from the CNS toward muscles and other organs (ex means away). Aka motor nerves because efferent impulses are the ones that, among other things, cause skeletal muscle contraction and movement. |
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| - a reduction in the voltage across a neuron or muscle cell membrane from its normal poorest state (resting membrane potential). This results in an action potential (nerves impulse) in the case of an neuron or the initiation of contraction in the case of muscle cell. It is the opening of the sodium channels and the sudden influx of many sodium ions into the cell. It is called DE polarization because the sodium influx results in the loss of 2 distinct poles of sodium and potassium on either side of the membrane. |
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| the process following depolarization wherein potassium ions diffuse rapidly out of the neuron .the sodium channels snap shut and potassium channels snap open. Potassium passively diffuses out of the cell, propelled by the both the potassium’s concentration gradient (high concentration inside/lower conc outside) and the strong + charge brought into the cell by the influx of sodium ions. Like charges repel, + K ions are repelled by the relatively + charge outside the neuron caused by the Na influx. Because K+ ions are +, the exodus of K+ ions causes the charge inside the cell to swing back into the negative direction |
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| What is the Sodium-Potassium Pump? How does it work? What is the its purpose? |
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| Active transport molecule that moves sodium molecules out of the neuron and potassium molecules into the neuron to maintain the resting state. The sodium potassium pump creates the resting membrane potential. This is the electrical difference in charges across the membrane by keeping the sodium on one side of the membrane and potassium on the other (inside) inside the cellular membrane separating the two is said to be polarized as it has two distinct poles of ions on either side of the membrane |
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| What is a synapse? Briefly describe what occurs during a chemical synapse? |
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- A synapse is the junction between two neurons or a neuron and a target cell. It consists of a physical gap between the 2 cells called the synaptic cleft.
- the neuron bringing the depolarization wave to the synapse and releasing the chemical to stimulate the next cell is called the presynaptic neuron. The chemical released by the presynaptic neuron is the neurotransmitter, and the neuron that contains the receptors that receive the neurotransmitter is the postsynaptic neuron.
- Neurotransmitters are released into the synaptic space, where they combine w/ receptors on the postsynaptic membrane (another neuron or effector cell) |
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| What is the role of a neurotransmitter? Briefly describe the relationship between a neurotransmitter and receptor. |
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| Neurotransmitters are released into the synaptic space, where they combine w/ receptors on the postsynaptic membrane (another neuron or effector cell). If the neurotransmitter and receptor are not matched, they will not bind to each other and no change will be triggered in the postsynaptic cell. Thus, synaptic transmission is only effective if receptors to the neurotransmitter exist on the postsynaptic cell’s membrane |
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| a neurotransmitter that allows the nerve impulse to cross the synaptic junction (gap) between two nerve fibers or between a nerve fiber and an organ (eg, muscle, gland) |
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| enzyme that brings about the breakdown of acetylcholine in the synaptic gap |
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| a term used to describe an action or a receptor that is activated by epinephrine or norepinephrine. (sympathetic) |
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| a state of involuntary muscle rigidity that is accompanied by immobility, amnesia, and variable amts of analgesia. Some reflexes may be preserved. |
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| the class of neurotransmitters that includes dopamine, epinephrine, and norepinephrine. When given therapeutically, catecholamines mimic the effect of stimulating the sympathetic nervous system |
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| a term used to describe an action or receptor that is activated by acetylcholine (Parasympathetic ) |
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| the site of the synapse between neuron one and neuron two of the ANS |
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| receptors activated by acetylcholine and muscarine that are found in glands, the heart, and smooth muscle. An acronym for remembering muscarinic effects is “SLUD”: S = Salivation, L = Lacrimation, U = Urination, D = defecation |
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| receptors activated by acetylcholine and nicotine found at the neuromuscular junction of the skeletal muscle and at the ganglionic synapses. |
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| • Parasympathetic nervous system |
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| system (adrenergic) – that portion of the autonomic nervous system that arises from the craniosacral portion of the spinal cord, is mediated by the neurotransmitter acetylcholine, and is concerned primarily with conserving and restoring a steady state in the body. One of the two subdivisions of the ANS |
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| a drug that mimics the effects of stimulating the parasympathetic nervous system |
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| • Sympathetic Nervous System |
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| • that portion of the autonomic nervous system that arises from the thoracolumbar spinal cord, is mediated by catecholamines, and is concerned w/ the fight or flight response |
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| – a drug that mimics the effects of stimulating the sympathetic nervous system |
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| What is the difference between an excitatory and an inhibitory neurotransmitter? |
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| An excitatory neurotransmitters majes a postsynaptic neuron more likely to generate an action potential. An inhibitory neurotransmitter makes a postsynaptic neuron less likely to generate an action potential |
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| How is acetylcholine different from acetylcholinesterase? |
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Acetylcholine - a neurotransmitter that allows the nerve impulse to cross the synaptic junction (gap) between two nerve fibers or between a nerve fiber and an organ (eg, muscle, gland)
Acetylcholinesterase - enzyme that brings about the breakdown of acetylcholine in the synaptic gap |
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| Main concern of the parasympathetic nervous system (cholinergic) |
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| conserving and restoring a steady state in the body |
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| Main concern of the sympathetic nervous system (adrenergic) |
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| What does stimulation of the sympathetic nervous system cause? |
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- increase in heart rate and RR
- decrease in GI activity
- pupil dilation
- constriction of blood vessels in skeletal muscle
- dilation of bronchioles
- increase in BG levels
- these actions prepare animal to fight or flee |
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| What does stimulation of the parasympathetic nervous system cause? |
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- decrease in HR/RR
- increase in GI activity
- pupil constriction
- constriction of bronchioles |
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| 9) List the primary neurotransmitters associated with the CNS and PNS. What is their purpose or role? |
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Acetylcholine – allows the nerve impulse to cross the synaptic junction (gap) between two nerve fibers or between a nerve fiber and an organ
Norepinepherine
Epinephrine – equally stimulates alpha and beta receptors and is therefore a potent stimulator of the heart and an equally powerful dilator of bronchioles
Dopamine
Serotonin
Gamma-aminobutyric acid (GABA |
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