Fundamentals of the Nervous system
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43 terms
Terms | Definitions |
|---|---|
 CNS | the portion of the vertebrate nervous system consisting of the brain and spinal cord |
| PNS | the sensory and motor neurons that connect the CNS to the rest of the body |
| sensory (afferent) | neurons that carry incoming information from the sense receptors to the central nervous system |
| motor (efferent) | neurons that carry outgoing information from the central nervous system to the muscles and glands |
| somatic | 1. skeletal muscle 2. skeleton 3. joints 4. skin |
| autonomic | this nervous system provides involuntary control over smooth muscle, cardiac muscle, and glands. |
| axon | The extension of a neuron, ending in branching terminal fibers, through which messages pass to other neurons or to muscles or glands |
| dendrites | branching extensions of neuron that receives messages from neighboring neurons |
| cell body (soma) | structure of a cell that contains the nucleus |
| trigger zone | nerve impulses arise most often at the junction of the axon hillock and initial segment |
| tract | a bundle of mylenated nerve fibers following a path through the brain |
| nerve | any bundle of nerve fibers running to various organs and tissues of the body |
| neuroglia | sustentacular tissue that surrounds and supports neurons in the central nervous system |
| astrocyte | A type of CNS supporting cell with a star shape that assists in exchanges between blood capillaries and neurons. Helps to form the blood-brain barrier. |
| microglia | smallest neuroglial cells; phagocytic cells that enculf cellular debris, waste products and pathogens. increase in number as a result of infection or injury |
| oligodentrocyte | a type of glia; produce myelin sheath around nerve fibers in cns. Macroglia |
| ependymal cell | a glial cell that lines membranes within the brain and spinal cord and helps form cerebrospinal fluid |
| schwann cell | One of the two peripheral nervous system supporting (glial) cells. Forms the myelin sheath on axons of peripheral neurons. |
| leak channel | An ion channel that is constitutively open, allowing the movement of teh ion across the plasma membrane according to its concentration gradient. |
| ligand gated channel | A protein pore in the plasma membrane that opens or closes in response to a chemical signal, allowing or blocking the flow of specific ions. |
| voltage gated channel | - An ion channel that is oepend or closed based on the electrical potential across the plasma membrane. - Once opened, the channel allows ions to cross the membrane according to their concentration gradients. - Ex. Na+ and K+ voltage-gated channels involved in the action potential of neurons. |
| mechanically gated channel | gated channel that depends on several proteins connected together and changing one will cause the channel to pop open |
| electrochemical gradient | The diffusion gradient of an ion, representing a type of potential energy that accounts for both the concentration difference of the ion across a membrane and its tendency to move relative to the membrane potential. |
| resting potential | the potential difference between the two sides of the membrane of a nerve cell when the cell is not conducting an impulse |
| sodium potassium pump | a carrier protein that uses ATP to actively transport sodium ions out of a cell and potassium ions into the cell |
| Blood brain barrier | Blood vessels (capillaries) that selectively let certain substances enter the brain tissue and keep other substances out |
| depolarization | sodium rushes into neuron through membrane, potassium ruses out; results in a change in charge |
| hyperpolarization | The movement of the membrane potential of a cell away from rest potential in a more negative direction. |
| graded potential | A local change in membrane potential that varies directly with the strength of the stimulus, declines with distance. |
| action potential | a neural impulse; a brief electrical charge that travels down an axon. the action potential is generated by the movement of positively charged atoms in and out of channels in the axon's membrane |
| absolute refractory period | the minimum length of time after an action potential during which another action potential cannot begin |
| absolute refractory period | A period of time following an action potential during which no additional action potential can be evoked regardless of the level of stimulation. (usually because Na+ channel closed whle K+ efflux) |
| saltatory conduction | A rapid from of action potential conduction along the axon of a neuron in which the action potential appears to jump from nodde of Ranvier to node of Ranvier. |
| mylein sheath | encases the axon, speeds up signal transmission (destruction causes MS) |
| nodes of Ranvier | Gaps in the myelin sheath of the axons of peripheral neruons. Action potentials can 'hump' from node to node, thus increasing the speed of conduction (saltatory conduction). |
| continuous conduction | signals that are conducted down unmyelinated axons :are slower |
| multiple sclerosis | a chronic progressive nervous disorder involving loss of myelin sheath around certain nerve fibers |
| synapse | the junction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron |
| neurotransmitter | a chemical messenger that travels across the synapse from one neuron to the next and influences whether a neuron will generate an action potential(impulse) |
| epsp | - Excitatory postsynaptic potential - a slight depolarization of a postsynaptic cell bringing the membrane potential of that cell closer to the threshold for an action potential. |
| ipsp | - Inhibitory postsynaptic potential - a slight hyperpolarization of the postysynaptic cell moving the membrane potential of that cell further from threshold. |
| temporal summation | Occurs when a single synapse generates EPSPs so quickly that each is generated before the previous decays. This allows the EPSPs to add up to reach a threshold voltage that triggers an action potential. |
| spacial summation | comes from 2 or more synapse to cause AP. Majority wins if inhibitory and excitatory neurotransmitters released |
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