NEURONS (TYPES OF NEURONS)
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The document explains impulse conduction in neurons, detailing the structure and function of various neuron components such as dendrites, cell body, axon, and axon terminals. It outlines the types of neurons (sensory, interneurons, and motor), the process of impulse transmission including depolarization and repolarization, and the concept of synapses in neurotransmission. Additionally, it mentions the refractory period and the significance of neurotransmitters in the generation and inhibition of action potentials.
![Impulse TransmissionImpulse Transmission
Start with a RESTING neuron – one NOTStart with a RESTING neuron – one NOT
transmitting an impulsetransmitting an impulse
Plasma membrane controls [ ] of ionsPlasma membrane controls [ ] of ions
inside the cellinside the cell
NaNa++
and Kand K++
on both sides of membraneon both sides of membrane
NaNa++
Higher Conc OutsideHigher Conc Outside
KK++
Higher Conc InsideHigher Conc Inside
Remember NaRemember Na++
/K/K++
ATPase PumpATPase Pump](https://image.slidesharecdn.com/grv-4-181219051427/85/NEURONS-TYPES-OF-NEURONS-8-320.jpg)
NEURONS (TYPES OF NEURONS)
- 1. Impulse Conduction InImpulse Conduction In NeuronsNeurons By : Gaurav PandeyBy : Gaurav Pandey
- 3. NeuronNeuron ”Nerve Cell””Nerve Cell” Functional Unit of Nervous SystemFunctional Unit of Nervous System 1.1. Cell BodyCell Body – center part of the cell containing the– center part of the cell containing the nucleusnucleus 2.2. DendritesDendrites Carries messagesCarries messages towardtoward the cell body.the cell body. Fingerlike projectionsFingerlike projections 1.1. AxonAxon Carries messagesCarries messages awayaway from the cell body.from the cell body. Elongated extension of the cell bodyElongated extension of the cell body End of the axon is divided into fingerlike projections calledEnd of the axon is divided into fingerlike projections called axon terminalsaxon terminals..
- 4. Neuron ModelNeuron Model To check for understanding you will needTo check for understanding you will need to construct a neuron model that containsto construct a neuron model that contains dendrites, a cell body (soma), axon, anddendrites, a cell body (soma), axon, and axon terminals.axon terminals.
- 6. Types of NeuronsTypes of Neurons Sensory NeuronsSensory Neurons – picks up the stimuli– picks up the stimuli (nerve impulse) and carries it to the spinal(nerve impulse) and carries it to the spinal cord and brain.cord and brain. Interneurons-Interneurons- Found within the brain andFound within the brain and spinal cord. Relays the message betweenspinal cord. Relays the message between the sensory neurons and the motorthe sensory neurons and the motor neurons.neurons. Motor NeuronsMotor Neurons – transfers impulses– transfers impulses away from the brain to the spinal cordaway from the brain to the spinal cord
- 7. How Neurons WorkHow Neurons Work 1.1. ReceptionReception Receptors in the skin sense stimuliReceptors in the skin sense stimuli 1.1. TransmissionTransmission Sensory neurons transmit the touch messageSensory neurons transmit the touch message 1.1. Data InterpretationData Interpretation Information is sorted and interpretedInformation is sorted and interpreted 1.1. TransmissionTransmission Motor Neurons transmit a response message to aMotor Neurons transmit a response message to a musclemuscle 1.1. ResponseResponse Muscles are activated causing a responseMuscles are activated causing a response
- 8. Impulse TransmissionImpulse Transmission Start with a RESTING neuron – one NOTStart with a RESTING neuron – one NOT transmitting an impulsetransmitting an impulse Plasma membrane controls [ ] of ionsPlasma membrane controls [ ] of ions inside the cellinside the cell NaNa++ and Kand K++ on both sides of membraneon both sides of membrane NaNa++ Higher Conc OutsideHigher Conc Outside KK++ Higher Conc InsideHigher Conc Inside Remember NaRemember Na++ /K/K++ ATPase PumpATPase Pump
- 9. Sodium Potassium PumpSodium Potassium Pump
- 10. How an Impulse TravelsHow an Impulse Travels Stimulus excites a neuronStimulus excites a neuron Na+ channels open, Na+Na+ channels open, Na+ build up insidebuild up inside Inside more + that outsideInside more + that outside Change in chargeChange in charge (depolarization)(depolarization) Membrane immediatelyMembrane immediately behind depolarization returnsbehind depolarization returns to RESTING STATEto RESTING STATE RESTING STATE – insideRESTING STATE – inside negative, outside positivenegative, outside positive
- 11. 1. Resting State1. Resting State A neuron is not conducting an impulseA neuron is not conducting an impulse The K+ concentration is much higherThe K+ concentration is much higher inside the cell than outinside the cell than out The Na+ concentration is much higherThe Na+ concentration is much higher outside the cell than inoutside the cell than in
- 12. 2. Depolarization2. Depolarization A nerve cell is stimulatedA nerve cell is stimulated Membrane becomes permeable to Na+ forMembrane becomes permeable to Na+ for an instant and they quickly move into thean instant and they quickly move into the cellcell The inner surface of the cell membrane isThe inner surface of the cell membrane is now more positively charged then thenow more positively charged then the outside.outside.
- 13. 3. Repolarization3. Repolarization When the cell membrane becomesWhen the cell membrane becomes depolarized, K+ automatically leaves thedepolarized, K+ automatically leaves the cell until the cell is back to its resting state.cell until the cell is back to its resting state.
- 14. 4. The Impulse Travels4. The Impulse Travels ““Wave” of depolarization – transmission of anWave” of depolarization – transmission of an impulse along length of axonimpulse along length of axon All or None PrincipleAll or None Principle – must reach a threshold– must reach a threshold level or the impulse dieslevel or the impulse dies Covered by a white covering called aCovered by a white covering called a myelinmyelin sheath (Schwann Cells)sheath (Schwann Cells), an insulator, an insulator Myelin sheath causes the ion exchange to occurMyelin sheath causes the ion exchange to occur only at theonly at the nodesnodes which speeds up the processwhich speeds up the process For a short time after depolarization; the neuronFor a short time after depolarization; the neuron cannot be stimulatedcannot be stimulated
- 15. 5. Transmission Across a Synapse5. Transmission Across a Synapse Neurons do not actually touch. This gapNeurons do not actually touch. This gap between the two cells is call abetween the two cells is call a SYNAPSESYNAPSE Impulses are carried across a synapse byImpulses are carried across a synapse by chemical messengers calledchemical messengers called neurotransmitters.neurotransmitters. Approximately 30 different neurotransmitters;Approximately 30 different neurotransmitters; do one of two things:do one of two things: 1.1. Stimulate the action potential in a second cellStimulate the action potential in a second cell 2.2. Inhibit the action potential in the next cellInhibit the action potential in the next cell
- 16. 6. Refractory Period6. Refractory Period The period of time it takes a neuron toThe period of time it takes a neuron to return to its resting potential after beingreturn to its resting potential after being stimulatedstimulated A neuron cannot be stimulated during thisA neuron cannot be stimulated during this periodperiod This period of time is about 0.0004 of aThis period of time is about 0.0004 of a secondsecond
- 18. ElaborationElaboration Neurotransmission:Neurotransmission: Nifty Neurons and Muscle MessagesNifty Neurons and Muscle Messages
- 19. EvaluationEvaluation Parts of Nervous SystemParts of Nervous System List the Four Major Parts of theList the Four Major Parts of the Nervous SystemNervous System NeuronsNeurons NervesNerves BrainBrain Spinal CordSpinal Cord