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sensory structures
sensory processes, neurons, neural organization & sensory organs
| Question | Answer |
|---|---|
| name the 4 physiological processes of the nervous system | maintenance of resting membrane potential, action potential generation, action potential propagation, chemical synapse |
| define resting membrane potential | the polarity difference between the inside of the cell relative to the outside = inside of the plasma membrane is more negative relative to the outside; electrochemical state of cell when resting |
| name 3 factors that contribute to the resting membrane potential | 1. action of the sodium-potassium pump, 2. intracellular protein anions, 3. selective permeability of the membrane to ions |
| for the factor: action of the sodium-potassium pump, give the: definition, what ions are involved, in which direction do they move, affect on concentration of ions, affect on polarity of membrane | protein in the plasma membrane that moves Na+ out of cell and K+ into the cell by primary active transport, creates larger Na+ outside of the cell than inside and vice versa for K+, net loss of cations every time the pump acts = more neg. inside |
| for the factor: intracellular protein anions, give the: definition, what ions are involved, in which direction do they move, affect on concentration of ions, affect on polarity of membrane | trapped in the cell membrane are large protein anions (PO43-), contribute to resting potential by increasing concentration of negative charges inside the cell, accumulative & stationary (cannot leave) |
| for the factor: selective permeability of the membrane to ions, give the: definition, what ions are involved, in which direction do they move, affect on concentration of ions, affect on polarity of membrane | there are more K+ channels than Na+ channels in the plasma membrane, cells lose more cations (K+ ions) passively over time than gaining them -> increases concentration of positive charges on outside of cell = makes inside more negative, K+ in, Na+ out |
| neuron | an excitable cell that can change its resting membrane potential (membrane polarity) in response to stimulus, neurons are the most specialized type of cell we can produce & have the capability to communicate between cells |
| basic structure of a neuron | cell body (where nucleus & organelles are contained), dendrites (receive info from other neurons), axon (send signals to other neurons), axon hillock (base of axon), synapse (space between where two neurons meet) |
| 3 types of nerve cells | sensory neurons - retrieve info from the environment, long axons; interneurons - transfer info between neurons (most in brain), extensive branching; motor neurons - receive info from other neurons & stimulate an effector (ex. muscle, gland), long dendrite |
| glial cells | cells that support the neurons, have many functions, ex. maintaining quality of spinal fluid, modulating blood circulation, facilitate info transfer, myelinating axons, protecting against pathogens |
| action potential | reversable, temporary change in the resting potential of the plasma membrane (only in the vicinity of stimulus), travels in 1 direction along a neuron or muscle cell membrane, every time it is triggered it happens & it can't go backwards |
| voltage-gated channels | ion channels in the plasma membrane that are sensitive to a specific change in voltage (+ or -) that causes it to open or close |
| name the 5 stages of a full action potential cycle & draw it on a graph | 1. membrane resting, 2. depolarization, 3. rising phase, 4. falling phase, 5. undershoot. (includes threshold) |
| for depolarization, give: definition, what activates it, ions (which & where they move), what proteins, effect on membrane potential | when a section of the cell membrane becomes less negative, activated by external + change or nearby depolarization, voltage-gated Na+ channels open and Na+ rushes into cell, makes cell membrane more positive, upon reaching +30mV, channels close quickly |
| for repolarization, give: definition, what activates it, ions (which & where they move), what proteins, effect on membrane potential | bringing the membrane back to negative values and closer to the resting membrane potential, activated by + volage change, voltage-gated K+ channels open in response, K+ rushes out of cell, membrane become more (-), reaching -70mV channels start to close |
| for hyperpolarization, give: definition, what activates it, ions (which & where they move), what proteins, effect on membrane potential | voltage reaching resting membrane potential (-70mV), voltage-gated K+ channels closing slowly, allowing K+ ions to continue leaving the cell, causing a dip (-90mV) below the resting membrane potential until they fully close |
| describe the action potential threshold | The action potential only triggers if depolarization reaches the threshold (-55mV). Any depolarization below this point does not trigger an action potential |
| Describe action potential propagation | Depolarizaiton hops from one voltage-gated Na+ channel to the next (between nodes of Ranvier on myelinated neurons), triggered by the change in voltage in the previous part of cell membrane. Action potential moves in one direction&in many areas at once |
| Difference between myelinated & unmyelinated neurons | Myelinated: faster, no space btwn voltage-gated channels, sheathed by Schwann cells, used for conscious action, unmyelinated: slower processes (ex.digestion), no myelin sheath, space between voltage-gated channels causes depolarization to propagate slowly |
| Describe chemical synapse | Depolarization triggers voltage-gated Ca2+ channels in presynaptic cell to open; Ca concentration up -> exocytosis of vesicles carry neurotransmitters to synaptic cleft, NT bind to & open ligand-gated channels on postsynaptic cell,depolarization continues |
| How does chemical synapse stop? | Once action potentials stop, voltage-gated Ca2+ channels close and enzymes released into the synaptic cleft break down leftover neurotransmitters |
| Describe types of invertebrate nervous systems | Simple -> complex: nerve net (hydra), radial nerve w nerve ring (sea star), parallel ventral nerve cords (planaria), longitudinal nerve cords (chiton), central ventral nerve cord (leech, insect) |
| Compare adult radially symmetric animal nervous systems with bilaterally symmetric animals | Radial - nerve net (cnidarian) or central nerve ring & cords running to arms (echinoderm), bilateral inverts - ventral nerve cord(s), bilateral verts - dorsal nerve cord |
| CNS vs PNS | Central nervous system - brain & spinal cord, peripheral nervous system - all other nerves |
| What is a reflex | An immediate reaction (often to a threat) conducted by the spinal cord that doesn’t involve the brain or conscious thinking |
| Compare afferent & efferent neurons | Afferent - sensory receptors, efferent - motor neurons, divided into the autonomic & motor systems |
| What is autonomic nervous system & the 3 divisions of the autonomic nervous system | Control of smooth muscles, cardiac muscles & glands; sympathetic (fight, flight, freeze), parasympathetic (rest & digest), enteric division (digestion) |
| 3 parts of vertebrate brain & their functions | Forebrain: processing smell, regulation of sleep, learning & complex processing; midbrain: coordinates routing of sensory info; hindbrain: involuntary activities, blood circulation, movements |
| 3 types of sensory receptors | Mechanoreceptors, chemoreceptors & electromagnetic receptors |
| Mechanoreceptors | Pressure, temperature, vibration & balance, ex. Cilliated receptors in a human ear |
| Chemoreceptors | Receptors selective to 1 type of chemical or macromolecule, ex. Sugar-sensing taste buds on human tongue |
| Electromagnetic receptors | Light, electricity & magnetism, ex. Photoreceptors in the eye spot of a planaria :3 |
| Thermoreceptors | Sense temperature, ex. Heat-sensing organ on a snake’s head |
| Proprioreceptors | Mechanoreceptors that sense limb & body positioning without sight - sense of how body parts are arranged in space, tracks limb movement. Ex. In the cerebellum |
Created by:
AntBanana
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