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nervous system
| Question | Answer |
|---|---|
| What is the basic function of the nervous system | to sense, interpret, and respond to stimuli |
| what are the 2 types of nervous system cells | neurons and neurological cells |
| what do neurons do | conduct impulses to transmit information |
| what do neurological cells do | non conducting cells that support, insulate, and nourish neurons |
| what are cell bodys | contains a nucleus and most of the usual organelles |
| what are dendrites | many short and branching afferent processes |
| what are axons | one long and skinny efferent process |
| what are nuerofibrils | protein fibers running the length of the neuron |
| what is the axon hillock | a funnel shaped region of the cell body leading toward the axon |
| what is the myelin sheath | some neurological cell membranes are filled with a lipoprotein called myelin, these cells wrap themselves around axons to insulate them |
| what are nodes of ranvier | Gaps between myelinating cells.` |
| what are axon terminals | The distal ends of axons that swell to become synaptic bulbs and contain chemicals called neurotransmitters. These terminals nearly touch the dendrites of the next neuron. |
| what is the synapse | The connection between two neurons. There is a gap between these neurons called the synaptic cleft. A signal is carried across this gap by neurotransmitters |
| what are the 3 neurons | sensory neurons, interneuron, and motor neuron |
| what do sensory neurons do | Send messages from a sensory receptor toward the central nervous system. |
| what do interneurons do | Neurons of the central nervous system that integrate and coordinate information |
| what do motor neurons do | Transmit messages of a response from the central nervous system to effectors |
| what are multipolar structures | most interneurons and motor neurons |
| what are bipolar structurs | only special ear, nose, and eye neurons |
| what are unipolar structures | most sensory neurons |
| What are the 2 divisions of the nervous system | central and peripheral nervous system |
| what does the cns consist of | brain and spinal cord |
| what does the CNS do | Interprets information and integrates it (puts it together) with existing information |
| what do myelinated neurons equal | white matter |
| what do unmyelinated neurons equal | grey matter |
| what are nuclei | clusters of neuron cell bodies CNS |
| what are tract | bundles of axons CNS |
| what are CNS neurons called | interneurons |
| what does the PNS consist of | nerves outside the CNS |
| what does the PNS do | sends messages to and from the CNS |
| what do schwann cells do | myelinate neurons PNS |
| what do oligodendrocytes do | myelinate CNS neurons |
| what are ganglia | clusters of cell bodies in the PNS |
| what are nerve | bundles of axons PNS |
| what are the 2 types of neurons in the PNS | sensory and motor |
| what does the sensory division do | Receives information about environmental changes (stimuli) and transmits it to the CNS |
| what does the motor division do | Transmits a signal about a course of action from the CNS to “effectors” (muscles or glands). |
| what are the 2 divisions of the motor | somatic and autonomic nervous system |
| what does the somatic nervous system do | Controls voluntary effectors like skeletal muscles |
| what does the autonomic nervous system do | Controls involuntary effectors like smooth muscle, cardiac muscle, and glands. |
| what are the 2 divisions under the autonomic nervous system | sympathetic and parasympathetic |
| what does the sympathetic nervous system do | Gets the body ready for stressful (fight or flight) situations ie. Dilates pupils. Increases heart rate, breathing, and blood to skeletal muscles. |
| what does the parasympathetic nervous system do | Returns the body to a “normal” state. ie. Constricts pupils. Decreases heart rate, breathing, and blood to skeletal muscles. |
| what are the 3 membrane potentials | resting, threshold, and action potentials |
| what is resting potential | When not conducting, neurons have a “resting potential” of –70 mV meaning they are “electrically charged” or “polarized. there is lots of potassium inside the cell and lost of sodium outside the cell |
| what is threshold potential | The membrane has 2 kind of “voltage-gated” channels for Na+ and K+ These channels open when a certain voltage is reached across the membrane. The Na+ channel opens at approximately -55mV. |
| what is action potential | A rapid “all-or-none” increase and decrease in membrane charge |
| what is step 1 of action potential | DEPOLARIZATION The inside of the neuron is raised to threshold Na+ channels open Na+ floods in until about +40mV is reached within the cell |
| what is step 2 of action potential | REPOLARIZATION At +40 mV, the Na+ channels close and the K+ channels open K+ rushes out of the cell causing the membrane to become negative again |
| what is step 3 of action potential | HYPERPOLARIZATION The K+ channels close at approximately -80 mV |
| what is step 4 of action potential | restoring the resting potential Sodium-potassium pumps move K+ in and Na+ out to restore the resting potential |
| what is nerve impulse conduction | As Na+ floods in, it spreads out and depolarizes a neighboring area. Na+ channels open in the neighboring area of the axon, repeating the process |
| what is synaptic transmission | Starting an impulse in the next neuron |
| what are the 2 impulse processes | convergence and divergence |
| what is convergence | Multiple neurons are used to stimulate a single neuron. |
| what is divergence | The axon of a single neuron branches to stimulate multiple neurons. |
| what is an excitatory neuron | If a presynaptic neuron INCREASES (depolarizes) the membrane potential of the postsynaptic cell… The presynaptic cell is called excitatory The postsynaptic cell is MORE likely to generate an action potential. |
| what is an inhibitory neuron | If a presynaptic neuron LOWERS (hyperpolarizes) the membrane potential of the postsynaptic cell… The presynaptic cell is called inhibitory The postsynaptic cell is LESS likely to generate an action potential. |
| how can a postsynaptic cell be stimulated | nearly simultaneous messages from separate excitatory presynaptic neurons or… repeated excitatory messages in quick succession from a single presynaptic neuron. |
| what are the major cranial nerves | olfactory, optic, oculomotor, and vestibulocochlear |
| what are the meninges | Three membranes that surround the brain and spinal cord. |
| what is the dura mater | Thick, outermost layer adhering to the vertebrae/skull |
| what is the arachnoid | Middle layer under which is found the fluid-filled subarachnoid space. |
| what is the pia mater | Deepest layer. Closely adheres to the surface of the spinal cord/brain. Follows every bulge (gyrus) and groove (sulcus) of the brain. |
| what are the ventricles in the brain and spinal cord | interconnected cavitites, They are continuous with the central canal of the spinal cord. Filled with cerebrospinal fluid. |
| what is the cerebrospinal fluid | Clear fluid found within the subarachnoid space, central canal of the spinal cord, and ventricles of the brain. Floats the brain so that the weight of the brain doesn’t impair its function. Moves wastes to the blood. |
| what are the functions of the spinal cord | Conduct sensory nerve impulses to the brain via ascending tracts Conduct motor nerve impulses from the brain to effectors via descending tracts Act as the center for spinal reflexes |
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24eproch21
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